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Native Trees, Urban Forest Management Planning, and
Residents: Knowledge, Attitudes, and Actions
by
Andrew David Almas
A thesis submitted in conformity with the requirements
for the degree of Doctor of Philosophy
Department of Geography and Planning
University of Toronto
© Copyright by Andrew David Almas 2017
ii
Native Trees, Urban Forest Management Planning, and
Residents: Knowledge, Attitudes, and Actions
Andrew David Almas
Doctor of Philosophy
Department of Geography and Planning
University of Toronto
2017
Abstract
In the past decade, municipalities across North America have increased investment in their urban
forests in an effort to maintain and enhance the numerous benefits provided by them. Some
municipalities have drafted long-term urban forest management plans (UFMPs) that emphasize
the planting of native trees to improve ecological integrity, and participation of residents, since
the majority of urban trees are typically located on residential property. Yet it is unclear if
municipal foresters are mindful of UFMP goals or what residents’ level of knowledge, attitudes,
and actions are regarding native trees and urban forestry goals. Through a case study of southern
Ontario municipalities, I administered interviews with municipal foresters and a survey exploring
residents’ ability to identify the native status of common tree species, as well as their attitudes
and actions regarding urban forest issues. The results indicate that all municipalities with
management plans emphasize native species, and many justify their planting as a way to increase
ecological integrity. However, only a fraction of species native to the region are available
through nursery stock, meaning many are not planted by municipalities. The results of the
survey indicate that residents are better able to identify common native trees than non-native
trees, although knowledge-levels are low, and there are failures of resident outreach within the
iii
case study municipalities. Although residents generally have positive attitudes towards native
trees, few are interested in planting native species if they create a hazard or increase costs. These
positive attitudes do not translate into emphasizing native species when actually selecting tree
species to plant. This dissertation adds to existing research surrounding native species
management in urban ecosystems, and understandings about how urban forestry policy
influences residents and municipal actors. Future research is needed to determine species
suitability for urban plantings and meaningful ways of engaging with new residents.
iv
Acknowledgments
I am offering a heartfelt thank you to the myriad of people who have inspired my curiosity,
overseen my development, proven me wrong/right/somewhere in between, critically engaged
with this material, and shown patience for it’s completion. My PhD Supervisor, Tenley Conway
deserves recognition for the sound judgment, advice, and support that brought this dissertation to
fruition. My PhD Committee Members, Virginia Maclaren and Sandy Smith deserve recognition
for their compelling critiques and thought-provoking ideas about this study. My family, who
have been incredibly supportive of my studies, and Meredith and Matthew who have inspired
this whole thing. I would also like to acknowledge my colleagues in the House Lab that helped
with data collection and discussed formative ideas of this project, as well as the municipal
foresters and survey participants who took time out of their busy schedules to interact with me
about my dissertation. Finally, I would like to thank the University of Toronto and Department
of Geography and Planning, among others for funding my research, conference attendance, and
other academic endeavours. If it “takes a village to raise a child”, it takes a nation to develop a
PhD student!
Chapter Acknowledgments
This dissertation has been written as a compilation of the following co-authored manuscripts that
have been or will be submitted for publication in peer-reviewed journals. Chapter 2 and 3 have
already been published and are included in this dissertation with permission from Elsevier and
Springer Nature, respectively. All chapters were designed and written by the principal author and
Ph.D. candidate. The co-author (Dr. Tenley Conway) was involved in conceptual discussions,
v
assistance with statistical analysis and survey design, interview format design, and participation
in review and editing of the written materials.
1) Almas, A. and Conway, T.M., 2016. The role of native species in municipal urban forest
planning and practice: A case study of Carolinian Canada. Urban Forestry and Urban
Greening 17 (1), 54-62. (Chapter 2)
2) Almas, A. and Conway, T.M., In press. Residential knowledge of native tree species: A case
study of residents in four southern Ontario municipalities. Environmental Management doi:
10.1007/s00267-016-0772-5. (Chapter 3)
vi
Table of Contents
Acknowledgments.......................................................................................................................... iv
Table of Contents ........................................................................................................................... vi
List of Tables ................................................................................................................................. ix
List of Figures ................................................................................................................................ xi
List of Appendices ........................................................................................................................ xii
Chapter 1 Introduction .....................................................................................................................1
1.1 Background Information ......................................................................................................1
1.1.1 Dissertation Context.................................................................................................1
1.2 Research Objectives and Dissertation Overview .................................................................2
1.3 The Urban Forest .................................................................................................................3
1.3.1 Benefits of the Urban Forest ....................................................................................5
1.4 Urban Forest Theory and Concepts .....................................................................................7
1.4.1 Native Species in the Urban Forest ..........................................................................7
1.4.2 Ecosystem Services and Ecological Integrity ..........................................................9
1.4.3 Assisted Migration .................................................................................................11
1.5 Urban Forest Stakeholders .................................................................................................13
1.5.1 Municipalities and UFMPs ....................................................................................13
1.5.2 Residents and the Urban Forest .............................................................................16
1.6 Study Area – Carolinian Canada........................................................................................18
Chapter 2 The Role of Native Species in Municipal Urban Forest Planting and Practice: A
Case Study of Carolinian Canada .............................................................................................20
2.1 Introduction ........................................................................................................................20
2.2 Ecological Integrity, Assisted Migration, and Non-native Trees in the Urban Forest ......22
2.3 Methods..............................................................................................................................27
vii
2.3.1 Study Area .............................................................................................................27
2.3.2 Urban Forest Management Plan and Planting List Review ...................................29
2.3.3 Interviews ...............................................................................................................29
2.4 Results ................................................................................................................................32
2.4.1 Urban Forest Management Plans and Planting Lists .............................................32
2.4.2 Planting Practice ....................................................................................................34
2.4.3 Ecological Integrity and Assisted Migration in Practice .......................................41
2.5 Discussion and Conclusion ................................................................................................42
Chapter 3 Residential Knowledge of Native Tree Species: A Case Study of Residents in Four
Southern Ontario Municipalities ...............................................................................................47
3.1 Introduction ........................................................................................................................47
3.2 Residents and the Urban Forest .........................................................................................49
3.3 Methods..............................................................................................................................53
3.3.1 Study Area .............................................................................................................53
3.3.2 Resident Surveys ....................................................................................................55
3.4 Results ................................................................................................................................58
3.4.1 Knowledge .............................................................................................................61
3.4.2 Factors related to knowledge-level ........................................................................64
3.5 Discussion ..........................................................................................................................66
Chapter 4 Resident Attitudes and Actions Towards Native Tree Species: A Case Study of
Residents in Four Southern Ontario Municipalities ..................................................................72
4.1 Introduction ........................................................................................................................72
4.2 Native Species and Residential Actors in the Urban Forest ..............................................74
4.3 Methods..............................................................................................................................78
4.3.1 Study Area .............................................................................................................78
4.3.2 Resident Surveys ....................................................................................................79
4.3.3 Analysis..................................................................................................................79
viii
4.4 Results ................................................................................................................................81
4.4.1 Native Species Attitudes ........................................................................................83
4.4.2 Native Species Actions ..........................................................................................88
4.5 Discussion and Implications ..............................................................................................91
Chapter 5 Summary and Recommendations ..................................................................................96
5.1 Dissertation Summary ........................................................................................................96
5.1.1 UFMPs, Municipalities, and the Attitudes and Actions of Municipal Foresters
Regarding Native Tree Species ..............................................................................96
5.1.2 Residents’ Level of Knowledge of Native Tree Species and Urban Forest
Issues ......................................................................................................................98
5.1.3 Resident Attitudes and Actions Regarding Native Tree Species and Urban
Forest Issues ...........................................................................................................99
5.2 Recommendations for Management and Future Research ..............................................101
5.2.1 Management Recommendations ..........................................................................101
5.2.2 Future Research Recommendations .....................................................................104
References ....................................................................................................................................107
Appendices ...................................................................................................................................122
ix
List of Tables
Table 1 Carolinian Zone municipalities with an Urban Forest Management Plan……………..28
Table 2 Carolinian Zone municipalities included in the study that were contacted for an
interview but have not enacted an Urban Forest Management Plan as of March 2015………….28
Table 3 Terms that were defined for the interviewees for ideological consistency…………….31
Table 4 Most commonly planted tree species in Carolinian Canada…………………………...35
Table 5 Reasons given as to why the use of native species should be increased in municipal
plantings………………………………………………………………………………………….39
Table 6 Municipal demographics……………………………………………………………….55
Table 7 Terms that were defined for the survey respondents for ideological consistency……..56
Table 8 Summary of socio-demographic and tree planting variables, shown as percentage
of all respondents…………………………………………………………………………...……60
Table 9 Comparison between survey participant demographics and municipal
demographics…………………………………………………………………………………….61
Table 10 Number and percentage of all survey participants in each category of knowledge of the
native-status of common tree species……………………………………………………………62
Table 11 Percentage of respondents who correctly identified tree species……………………..62
Table 12 Percentage of correct responses for native and non-native tree species, as well as other
urban forest topics………………………………………………………………………………..63
Table 13 Cross tabulation results based on Cramer’s V, with p-value in parentheses…………64
x
Table 14 Summary of socio-demographic and tree planting variables, shown as percentage of
all respondents………………………………………………………………………………...…82
Table 15 Principle components analysis of native tree species attitude questions……………..86
Table 16 Analysis of variance (ANOVA) with PCA components, socio-demographics, and
action variables…………………………………………………………………………………..87
Table 17 Summary of respondents’ tree planting actions………………………………………90
Table 18 Cross tabulation results of action and socio-demographic variables…………………90
Table 19 Variables retained in the logistic regression………………………………………….91
xi
List of Figures
Figure 1 – Map of the Carolinian forest zone in Canada showing the municipalities in the
study……………………………………………………………………………………..……….19
Figure 2 – Most common factors considered by municipal foresters when choosing tree species
to plant………………………………………………………………………………………...…36
Figure 3 – Reasons why non-native tree species are selected in favor of native
species………………………………………………………………………………………...….40
Figure 4 - Map of the Carolinian forest zone in Canada showing the four surveyed
municipalities...………………………………………………………………………………..…54
xii
List of Appendices
Appendix A – Written survey distributed to residents
1
Chapter 1
Introduction
1.1 Background Information
1.1.1 Dissertation Context
As global urbanization has increased over the past decades, and people’s interactions with nature
have become more contingent upon the greenery in urban areas, geographers, urban foresters and
others have increasingly acknowledged the benefits obtained from urban forests, as well as
conceived of better ways to manage the goods and services we garner from them. Nowhere is
this more relevant in Canada than in southern Ontario, where more than 90% of the population
lives in urban areas (Statistics Canada, 2011). Municipal urban forest management plans
(UFMPs) have been introduced in the past decade to guide the future structure of the urban tree
canopy, increase ecosystem services, and work towards conservation of native ecology (City of
Burlington, 2010; City of Guelph, 2012; City of London, 2014; City of Mississauga, 2014; City
of St. Catharines, 2011; City of Toronto, 2013; Town of Ajax, 2011; Town of Oakville, 2008).
However, several knowledge gaps exist in terms of the efficacy of these long-term plans given
their recent, widespread adoption; the relationship between the plans’ goals and practice by
municipal foresters; and the knowledge, attitudes, and actions of urban residents, who are
counted on to be willing partners in managing the tree canopies in their municipality.
2
1.2 Research Objectives and Dissertation Overview
The goal of this dissertation is to addresses knowledge gaps that exist in understanding the
knowledge, attitudes, and actions of urban forestry practitioners and residents regarding native
tree species and related management practices that shape urban forests. Three subsequent
chapters outlining distinct but related studies of native species and urban forest management
address this overall goal through a series of specific objectives.
Chapter 2 addresses the gaps in our understanding of the formulation and implementation of
UFMPs and on-going discussions about ecological integrity, non-native species benefits and
assisted migration. The objectives of the Chapter 2 study are to (1) examine the role of native
species in UFMPs; (2) explore municipal foresters’ attitudes and actions related to native tree
species, and (3) explore if municipalities with and without formal management plans are making
different decisions regarding native tree species planting. These objectives are addressed
through a case study of municipalities in Carolinian Canada (Ontario, Canada), by examining
UFMPs and municipal tree planting lists, and interviewing urban foresters from 16
municipalities with and without UFMPs.
Chapter 3 assesses residents’ knowledge about native species and the urban forest to provide a
better understanding of knowledge and decisions related to urban trees. The objectives of the
Chapter 3 study are to (1) explore residents’ ability to determine if common tree species are
native or exotic to the study area, (2) assess residents’ familiarity with municipal urban forest
management plans, and (3) examine the factors related to different levels of residents’ native
species knowledge. These goals are addressed through a survey of residents in four urban
municipalities in Carolinian Canada (Ontario, Canada).
3
Chapter 4 examines broader implications of the relationships present between residents and
native species in urban forests to address gaps in our understanding of urban residents’
relationship with native tree species. The main objectives of the Chapter 4 study are to (1)
explore urban residents’ attitudes and actions related to native tree species; (2) examine if the
presence of a municipal UFMP emphasizing native species is related to those attitudes or actions;
(3) determine if attitudes vary among residents with different sociodemographic characteristics;
and (4) explore if positive attitudes towards native species translates into planting native tree
species. These objectives are addressed through the same survey as utilized in Chapter 3.
While this dissertation was written following a three-paper model, with Chapters 2 through 4
prepared as stand-alone manuscripts, together they provide a comprehensive understanding of
UFMPs, municipal foresters attitudes and actions regarding native tree species and residents’
knowledge, attitudes, and actions regarding native tree species and urban forest issues. The
broader management implications and areas for future research are explored in the concluding
chapter
1.3 The Urban Forest
Urban forests consist of all the trees within a town or city, including street trees, park trees, trees
in remnant wooded areas, other public trees and all private trees (Kenney et al., 2011;
Konijnendijk et al., 2006). A tree is a woody perennial plant that is different from a shrub in that
it is larger at maturity, however, their differences are arbitrary with some sources considering
certain shrubs to be small trees and vice versa (Farrar, 1995; Waldron, 2003). Historically urban
forests have been perceived as having limited ecological value because they are heavily modified
by humans and relatively small in size, making up approximately 4% of land cover worldwide
4
(Dobbs et al., 2011). But with rates of urbanization quickly increasing, urban forests are being
recognized for their importance as ecological reservoirs, providing valuable functions and
ecosystem services for much of the world’s population (Davies et al., 2011).
The formal concept of urban forestry was first introduced at the University of Toronto in 1965
(Jorgensen 1970). Jorgensen states that urban forestry deals “with tree management in the entire
area influenced by and utilized by the urban population.” In the case where municipal boundaries
make the forest too large to manage as an urban forest, as is the case with several Canadian
municipalities, the boundaries have been set as the territory in which all homes are serviced with
municipal sewers and water (Duinker et al., 2015).
Urban forests differ from traditional forests in that urban areas are highly managed and contain
environmental stressors that do not directly affect traditional forests, including soil compaction;
limited root volume and pervious surface under the crown of the tree; soil nutrient deficiencies;
and various soil, water, and air contaminants (Day et al., 1995; Gilman, 1988; van Wassenaer
and Kenney, 2000). Trees grow differently in urban forests, often lacking the height and
longevity of their non-urban forest equivalents, and they are often valued for traits other than
ecological integrity or economic gain, e.g. low maintenance, and aesthetics (Quigley, 2004).
Genetic diversity is also different in an urban forest, as commonly planted trees are often clones
of one another, decreasing the resilience of urban forests to biological invasions and other
stressors (Pauleit et al., 2002; Sjoman et al., 2011).
Urban forests differ from the European notion of ‘town forests’ which are woodlands
surrounding a town, owned and managed by the town (Konijnendijk et al., 2006). Typically,
5
definitions of the urban forest do not take into account the numerous other biota and structures
that exist and critically interact with trees in the ecosystem. Rather, the discipline’s niche is the
focus of tree management in urban areas and the unique environmental conditions encountered.
College and university urban forestry and arboriculture programs focus on large scale and
individual tree management (Elmendorf et al., 2005), and in a professional capacity urban
foresters typically have very separate responsibilities from horticulturalists, ecologists, and
biologists.
1.3.1 Benefits of the Urban Forest
Urban forestry emerged from a desire to mitigate the negative effects of the urban environment
on trees, and more recently focused on the numerous economic, social, and ecological benefits
they can provide through their ecosystem services. While trees are associated with disservices
such as the hazard of falling limbs and fruits, allergy-inducing pollen, and blocking road
sightlines (Dobbs et al., 2011; Lyytimäki and Sipilä, 2009), trees tend to be valued by people
(Duinker et al., 2015; Ostoić and Konijnendijk, 2015), and many studies demonstrate the
plethora of ways in which trees provide ecosystem services that benefit cities.
In terms of environmental benefits, trees cool, filter, and improve air quality in the city, reducing
atmospheric carbon and particulate matter (Smith, 1990) while mitigating the urban-heat-island
effect (Livesley et al., 2016) through shading surfaces, transpiration of water vapor, respiration,
and reduction of solar radiation (Heisler, 1990). They help prevent erosion and flooding as their
roots stabilize soil and absorb ground and surface water (Neville, 1996; Sanders, 1986; Xiao et
al., 1998). Urban trees also improve water quality by reducing the flowrate of stormwater, and
staggering its’ outflow to waterbodies (Xiao et al., 2000).
6
Social benefits of urban forests include enhancing people’s sense of place (Elmendorf, 2008;
Hull et al., 1994) and community safety (Kuo et al., 2001), while providing recreational
opportunities (Bolund and Hunhammar, 1999; Gobster and Westphal, 2004). Benefits also
include mental health and wellbeing (Lee and Maheswaran, 2011; Ulrich 1981; Ulrich, 1984), as
several studies have shown that individuals have experienced shorter hospital stays and positive
physiological effects when exposed to a greener built environment (Rubin et al., 1998).
Trees are also economically beneficial. They have been found to increase property value (Anthon
et al., 2005; Kong et al., 2007; Tyrväinen, 1997), business traffic (Wolf, 2004), tourism
(Majumdar et al., 2011), longevity of infrastructure (McPherson and Muchnick, 2005), and
employment opportunities (Duinker et al., 2015). They can also reduce energy costs related to
summer cooling and/or winter heating, depending on the orientation of trees near buildings
(Akbari and Taha, 1992; Nowak and Dwyer, 2007). When cities invest in trees, they are
supporting several industries such as tree care, nursery, and urban forestry professions.
Additionally, there is a large bird-feeding economy that is dependent upon tree habitat for birds
(Degraff and Payne, 1975).
Finally, urban forests provide opportunities to learn about and conserve biodiversity and wildlife
habitat (Alvey, 2006). Cities disproportionately occur in areas of high biodiversity (Kuhn et al.,
2004), and many contain rare and endangered species for which measurable efforts have been
expended to conserve them (Alvey, 2006; Colding et al., 2003; Gustafsson, 2002). The high
visibility and complexity of many urban forest ecosystems make them excellent forums for
environmental education (Dwyer and Schroeder, 1994), and learning in a green environment has
been shown to improve children’s learning and behaviour in urban areas (Wells, 2000).
7
Though numerous studies have documented urban forests positive contribution to urban areas
and their residents, knowledge gaps remain in terms of how to develop policy that will support
the long-term sustainability of urban forests; whether ecological integrity, ecosystem services, or
adaptation to future climates should be prioritized and how that may alter practice; and the role
of native species in urban forest management. In southern Ontario, municipalities are addressing
long-term management of the urban forest through their UFMPs, though few studies have
examined the rationales and impacts of these plans given their recent adoption.
1.4 Urban Forest Theory and Concepts
1.4.1 Native Species in the Urban Forest
Prevailing ecological theory attributes the formation of ecosystems to the co-evolution of species
over millennia (Ehrlich and Ehrlich, 1981), and that large-scale patterns primarily result from,
rather than drive, evolution at lower levels (Levin, 1999). According to this view, by competition
and co-adaptation over time, species partition all available niches and produce stable
communities. Co-adapted, or native, species have increased resilience to disturbances in the
ecosystem and are generally considered more beneficial to that ecosystem (Rotherman and
Lambert, 2013). However, the native status of a species is not always agreed upon, as nativeness
is a social construct. For example, some define a native species as one that arrived in the region
before neo-lithic times, or arrived since without human agency (Kendle and Rose, 2000).
However, another commonly espoused definition of a native species in North America is a
species that was extant prior to 1492 when Christopher Columbus arrived. This definition
ignores the influence of Aboriginal peoples, who managed the composition of the forest, planting
beneficial fruit and nut trees long before 1492 (Waldron, 2003).
8
Given the various definitions of native species, people occasionally disagree as to which species
are native (Sagoff, 2005; Smout, 2000). Furthermore, Earth is not characterized by homeostasis.
It is a dynamic system whose geological, climatic, and biological make-up have fluctuated since
its genesis, and some argue that these varying degrees of change and development mean that we
should observe varying levels of nativeness, including old, naturalized, and recent non-native
species (Ordóñez and Duinker, 2012). Moreover, urban species assemblages are often
reorganized in ways that emphasize a species resilience to urban stressors as opposed to its
native status (Angermeier, 1994; Sjoman and Nielsen, 2010).
Urban ecosystems actually have some of the highest levels of tree species richness on the planet
(Alvey, 2006; Clemants and Moore, 2003; McKinney, 2002; Nowak, 1993), not only because of
naturally occurring tree diversity, but also species introductions, and native and non-native
species plantings. In some cases, urban areas that were considered species-poor prior to urban
development are now comparatively species-rich, such as North American prairie cities and parts
of California, which has notably increased from 10 native tree species to more than 350 species
in little over a century’s time (Kurz and Baudains, 2012; Nagendra and Gopal, 2011; Nowak,
1993; Nowak, 2012). Conversely, there are also examples of urban areas that have a diminished
number of species compared to pre-urbanization assemblages, such as Rio de Janeiro (Bertin et
al., 2005; dos Santos et al., 2009).
Though species assemblages in urban ecosystems contain many non-native species, urban
ecosystems are not isolated from surrounding natural ecosystems, and are in fact very diffuse
(Bolund and Hunhammar, 1999). Constant ecological interactions between urban, peri-urban,
9
rural and natural areas occur, and urban ecosystems have the potential to be, and oftentimes are
important native species strongholds (Raupp et al., 2006; Ricotta et al. 2010).
The importance of maintaining native species within urban forests is unclear (Alpert et al., 2000;
D’Antonio and Meyerson, 2002; Davis, 2012; Sagoff, 2005). The current understanding of
ecological integrity suggests that native species should be prioritized (Alvey, 2006; Ordonez and
Duinker, 2012; Raupp et al., 2006), but the benefits of planting at least some non-native species,
and the potential of assisted migration in urban forests as a response to climate change raise
questions about the value of a native-only (or native-first) approach to tree planting. These
concepts, and their relationships with native species in the urban forest are discussed below.
1.4.2 Ecosystem Services and Ecological Integrity
The literature examining urban forest management focuses on managing for ecosystem service
provision and ecological integrity. Ecosystem services are the goods or services provided by
ecosystems that contribute to human well-being (MEA, 2005). The well-documented services
provided by urban forests include storm water retention, erosion control, microclimate
regulation, and improved human physical and mental health (Ostoić and Konijnendijk, 2015).
They are correlated with biodiversity, such that higher diversity yields a greater amount of
services (Dobbs et al., 2010; Escobedo et al., 2011; Ordonez and Duinker, 2012). However,
diversity of native species may not be required for a high level of ecosystem service provision
(Morgenroth et al., 2016).
Ecological integrity is a macro-scale concept measuring the wholeness and proper functioning of
an ecosystem (Bolund and Hunhammar, 1999; Clemants and Moore, 2003; Hermoso and
10
Clavero, 2013; Landry and Chakraborty, 2009; Ordóñez and Duinker, 2012). When ecosystem
functions are lost due to an absence of native diversity, the system becomes less resilient, so the
capacity to resist damage and recover from a disturbance is reduced (Folke et al., 2004). The
current composition of species in most urban forests means that some functions (e.g. provision of
food, maintaining biodiversity, nutrient cycling, reduction of wind damage, regeneration of soils
and the maintenance of organisms within them) do not occur at the same rate as forests with a
high ratio of native species, suggesting lower resilience and reduced integrity (Ordóñez and
Duinker, 2012).
The inability of an urban ecosystem to support specialist or rare species also reflects a lack of
ecological integrity (McKinney, 2002), since certain structural components of forest ecosystems
are lost in this way. Over the past century in North America entire genera of common urban trees
have also been annihilated by invasive biota (Castanea, Ulmus, Fraxinus), which has resulted in
replanting with a low diversity of trees, continuing to leave urban forests susceptible to large-
scale pest invasions. Urban forest resilience can be theoretically heightened by planting a higher
diversity of tree families, genera, and species to lower the risk of mass tree losses (Raupp et al.,
2006).
All urban forests couple natural development processes and human processes, necessitating a
trade-off between these different processes (Ordóñez and Duinker, 2010). Urban forests are
largely engineered to provide services for society with an immediacy that natural forests do not
replicate. Furthermore, in some regions there may be a limited catalogue of native species that
can fulfill ecosystem services and are resilient to harsh urban ecosystems conditions (Sjoman et
al., 2016). As such, street trees are often chosen for attributes that contribute ecosystem services,
11
but diminish ecological integrity because trees planted to maximize immediate services tend to
lack longevity, large stature, and native status (Nowak et al., 2003).
1.4.3 Assisted Migration
In addition to ecosystem services and ecological integrity, assisted migration is emerging in the
literature as a possible management strategy. Assisted migration, also known as managed
relocation, is the intentional translocation of tree species outside of their historic ranges in order
to ameliorate actual or anticipated effects of climate change (Hewitt et al., 2011). While all
species have some natural capacity to migrate into new habitats and evolve to environmental
changes, ongoing anthropogenic climate change is occurring too rapidly for many tree species to
migrate naturally (Zhu et al., 2012). Thus, in an attempt to preserve biodiversity and maintain
coevolved species assemblages, some ecologists and practitioners have begun to assist the
dispersal of species to higher elevations and historically cooler ecozones (McLachlan et al.,
2007).
Assisted migration as a tool for addressing climate change is most commonly practiced within
the forestry sector. For example, the western Canadian provinces of British Columbia and
Alberta have modified their forestry seed transfer guidelines to allow seeds to be planted 200
metres higher in elevation and two degrees of latitude northward for most tree species (Pedlar et
al., 2012). However, the debate around assisted migration remains primarily conceptual, as many
of the anticipated aspects of climate change have yet to happen, delaying the ability to measure
the success of these practices.
12
The risks of assisted migration include accidentally introducing new invasive species,
challenging established conservation priorities, tree mortality and investment loss, and
consuming resources addressing the symptoms of climate change, rather than causes (Hewitt et
al., 2011; McLachlan et al., 2007). However, assisted migration may also lead to healthier urban
forests and ensure that rare and endangered trees otherwise unable to migrate quickly may still
survive (Hewitt et al., 2011).
Urban ecosystems are considered suitable pilot areas for assisted migration because they already
tend to be ‘novel’ ecosystems with long histories of exotic species plantings, and non-native
species assemblages (Hobbs et al., 2006; Kowarik, 2011), and not as likely to be negatively
affected by non-native species. Additionally, the urban heat-island effect elevates the
temperature in urban areas in comparison to surrounding areas (IPCC, 2001), allowing for
species that are less tolerant of the cold to flourish (Imhoff et al., 2010). Due to the anticipated
consequences of climate change, some urban foresters are choosing to plant species that have
evolved in warmer climates in preference of native species at the southern extent of their range.
Since many species of trees have considerable longevity, and even the most conservative climate
change estimates indicate warming by at least 1.7ºC by mid-century (Meehl et al., 2007), this
will likely affect the survivability of trees evolved in cooler climates. Thus, managing for climate
conditions 20-plus years in the future, means considering planting trees that evolved in warmer
climates.
Though studies of assisted migration, ecosystem services, and ecological integrity have recently
been increasing, previous studies of assisted migration and considerations of ecological integrity
13
have lacked a practical component examining how these practices are incorporated into urban
forestry policy and practice.
1.5 Urban Forest Stakeholders
1.5.1 Municipalities and UFMPs
Urban forest structure is shaped by the many actions of different stakeholders. In North
American municipalities, municipal governments are responsible for the care and maintenance of
trees located in parks, other municipal land and along streets (City of Burlington, 2010; City of
London, 2014; City of Mississauga, 2014; City of Toronto, 2013; Town of Oakville, 2008). In
smaller municipalities, they may employ an arborist or tree-care company who will act in their
interest (Town of Oakville, 2008).
Municipal trees are a public good, and municipalities tend to select tree species to maximize
ecosystem services and minimize disservices. At the decision-level, disservices tend to outweigh
ecosystem services; if trees have thorns (Gleditsia, Crataegus), or large nuts that may damage
property (Juglans, Carya), if the tree is structurally weak (Populus), or has problematic roots
(Salix), or if the tree blocks sightlines (Thuja, Picea, Abies, Pinus) then it will not be selected for
planting as a street tree in most municipalities (Nowak et al., 2003).
Municipalities recognize that urban street trees face several adverse conditions and successfully
identifying tree species that will thrive consistently is a challenge. Given budgetary constraints,
lack of species’ suitability trials, and low odds for long-term survival, urban street trees are often
chosen from a small list of trees that are known to tolerate most urban stressors. Many of these
14
trees are non-native. In southern Ontario they have been the Gleditsia triacanthos x shademaster
(shademaster honey locust), Acer platanoides (Norway maple), Acer x freemanii (freeman
maple), Fraxinus pennsylvanica (green/red ash), Platanus x acerifolia (London planetree), Acer
saccharinum (silver maple), Pyrus calleryana (callery pear), Gingko biloba (gingko), Acer
saccharum (sugar maple), and Tilia cordata (little-leaf linden) (City of London, 2014; Town of
Oakville, 2008). Moreover, municipalities are often not involved in choosing the tree species
planted in planned developments, leaving that to developers who have traditionally bought a few
species of inexpensive trees and planted them throughout the development (Nowak et al., 2003).
An UFMP is a document purposefully created to increase urban forest management effectiveness
and efficiency, improve tree health, minimize risks to the public and maximize the ecosystem
benefits provided by the urban forest (City of Burlington, 2010). UFMPs have recently been
adopted by several North American municipalities as a way of justifying budgets and staffing for
urban forestry programs, and to increase tree cover and diversity (Kenney et al., 2011; Ordóñez
and Duinker, 2013). Typically, they are 20 year plans that are subdivided into four 5-year plans,
with objectives and targets to be met, or reassessed annually and at the end of each 5-year plan.
The content and structure of UFMPs varies depending on the municipality and its urban forest
goals, but the majority of plans include considerations of: 1) management and implementation,
2) tree health and risk management, 3) protection and preservation, 4) replenishment and
enhancement, and 5) public outreach and stewardship. Though UFMPs are drafted by the
municipality, they depend upon partnering with residents to achieve many of the urban forest
goals within them.
15
Since urban forests are also shaped by natural forces, they require forethought to manage
proactively, such that costs for maintaining and sustaining them are established in advance, to
potentially mitigate unforeseen circumstances (Kenney and Puric-Mladenovic, 2001). For
example, cost overruns for managing the emerald ash-borer infestation in eastern North America
could have been lessened had urban forests been managed to have higher tree diversity,
comprising of both evenness and greater species richness, which would have meant fewer ash
tree removals, where in some cities ash comprised nearly 50 percent of the street tree
composition (Town of Oakville, 2008). Subsequently, many municipalities have had to expend
extra money to save large trees, and remove numerous dead or dying trees. Some budgetary
stress could have been avoided by adhering to rudimentary forestry principles which can be
codified in an UFMP, like the 10:20:30 rule, that states that the street tree population of a
community should consist of no more than 10% of a single tree species, 20% of a single genus,
and 30% of a single family (Kenney et al., 2011; Sydnor et al., 2010).
In one of the few studies examining UFMPs, Ordóñez and Duinker (2013) found many
management topics in common with the majority of UFMPs, but the only topic common
amongst all UFMPs in Canada was consideration for native tree species. However, Ordóñez and
Duinker’s (2013) study did not explore the implementation impacts on municipal foresters and
residents related to these plans. Thus, notable knowledge gaps exist regarding UFMPs, including
urban forestry staff’s willingness to adopt UFMP goals, it’s influence on residents’ knowledge,
attitudes, and actions regarding urban forest issues, and other long-term impacts of managing a
municipality’s urban forest with an UFMP.
16
1.5.2 Residents and the Urban Forest
Another major stakeholder of the urban forest is residents, who have become a recent focus of
urban socio-ecological and urban forest studies. The role of urban residents in shaping and
managing the urban forest is less understood than that of the municipality, because their greenery
choices go largely undocumented, there is no mandate for landowners to plant trees, and
individual residents have unique aesthetic tastes (Conway and Urbani, 2007; Pataki et al., 2011).
However, residents are perhaps the most important variable regarding urban forest health, as it is
estimated that 75% of urban trees are on private property, and that 75% of those are planted by
residents (Nowak, 2012). This means that in order to affect large-scale change in the urban
forest, policy and law makers must be able to influence the planting actions and attitudes of
residents.
Recent research has begun to focus on where trees are located in relation to residential
characteristics, who is likely to participate in tree planting programs, and some basic attitudes
that residents have towards trees. Residents’ socioeconomic characteristics are related to the
actual distribution of the urban forest, as areas with higher percentages of owner-occupied
homes, fewer visible minorities, and residents with university degrees and higher incomes
generally have more canopy cover (Grove et al., 2006; Heynen et al., 2006; Landry &
Chakraborty, 2009; Pham et al., 2012; Tooke et al., 2010).
Additionally, there is some evidence that tree-planting actions vary among residents based on
their socioeconomic characteristics. Perkins et al. (2004) and Greene et al. (2011) both found that
participants in tree planting programs were more likely to be white homeowners, from
neighbourhoods with high socioeconomic status. People with higher income and education-
17
levels between the ages of 30 and 49 are most likely to participate in general urban forestry
activities (Fleming et al., 2006).
Given the patterns of uneven canopy cover and planting activity among different socioeconomic
groups, there are concerns that not all socioeconomic groups receive the same benefits associated
with the urban forest, potentially creating inequities within cities (Heynen et al., 2006). However,
Pham et al. (2012) determined that physical space constraints often underlie uneven distributions,
suggesting that trees in low income, renter dominated areas may be hampered by a lack of
available planting sites. While not eliminating inequalities it suggests differences are not directly
because of socioeconomic conditions themselves.
Residents’ perceptions about urban forest issues, including invasive species, canopy cover, and
biodiversity can affect planting habits on their property. In Australia, Kirkpatrick et al. (2012)
found that residents’ attitudes towards flora tend to be expressed in action on their property such
that, if residents appreciated native flora, they tended to plant native flora. In a study of residents
in Perth, Australia, the attitudinal variable with the strongest relationship to garden-type
preference was residents’ attitude toward native plants (Kurz & Baudains, 2012). Preferences
were also highly related to prevailing gardening norms in respondents’ local area.
Much of the urban forest is controlled by individual residents. Socioeconomic characteristics,
attitudes and knowledge affect residents’ planting actions and support for urban forestry efforts,
but it is unknown what residents’ knowledge, attitudes and actions towards native species in the
Eastern North America are, and whether or not UFMPs are playing a role in shaping knowledge,
attitudes and actions.
18
1.6 Study Area – Carolinian Canada
This study focuses on municipalities’ native tree species management and residents’ knowledge,
attitudes and actions regarding native trees within the Carolinian Zone of Ontario, Canada
(Figure 1). The region is Canada’s most densely populated, with greater than 8 million people
living in one-quarter of one percent of the country’s land area (Reid, 2002; Statistics Canada,
2011). Moderated by the proximity of the Great Lakes, the Carolinian Zone’s climate is
characterized as humid continental (Koppen Dfa to Dfb) with four distinct seasons (Ontario
Climate, 2011). The region’s vegetation is unique within Canada, characterized by broadleaf-
deciduous trees like Sassafrass albidum (sassafrass), Gymnocladus dioicus (Kentucky
coffeetree), Liriodendron tulipifera (tuliptree) and Magnolia acuminata (cucumber magnolia),
while also representing the southern extent of the Great Lakes-mixed boreal forest. As a result, it
is a biodiversity hotbed with the highest species richness of any ecozone in Canada (Johnson,
2007). Historically, this region’s land cover was 80% forest, which now only occupies 11% of
the landscape (Johnson, 2007). Due to the unique ecology and conditions in the Carolinian Zone
there are on-going efforts to protect the native species assemblage (Johnson, 2007; Ministry of
Natural Resources, 2000; Reid, 2002; Waldron, 2003). Specific municipalities included in the
analyses addressing each objective of the thesis are described in detail in the relevant chapter.
19
Figure 1 – Map of the Carolinian forest zone in Canada showing municipalities in the study area
.
20
Chapter 2
The Role of Native Species in Municipal Urban Forest
Planting and Practice: A Case Study of Carolinian Canada
2.1 Introduction
Throughout North America municipalities are adopting strategic plans and ambitious tree
planting goals based on the numerous ecological, social, health and economic benefits ascribed
to the urban forest. This parallels recent foci of urban environmental research exploring
sustainable management of urban forests (Clark et al., 1997; Kenney et al., 2011; Mincey et al.,
2013; Vlek and Steg, 2007; Young, 2013) and documenting their ecosystem services (Alvey,
2006; Bolund and Hunhammar, 1999; Nowak and Dwyer, 2007). With the aggressive planting
goals many municipalities are pursuing, species selection today will have a lasting impact on the
composition, health, and function of the urban forest.
Urban forests typically have relatively high species richness as compared to the surrounding
countryside (Alvey, 2006; Bertin et al., 2005; Miller and Hobbes, 2002; Stewart et al., 2004).
However, this richness is often the result of numerous non-native species while many native tree
species are not regularly planted (Clemants and Moore, 2003; Hitchmough, 2011; Kendle and
Rose, 2000; Schaeplfer et al., 2012). The importance of maintaining native species within urban
forests is unclear, as there is a knowledge gap surrounding the tolerance of many tree species to
urban stressors (Alpert et al., 2000; D’Antonio and Meyerson, 2002; Davis, 2012; Sagoff, 2005).
The current understanding of ecological integrity, measured as the wholeness and proper
functioning of an ecosystem, suggests that native species should be prioritized (Alvey, 2006;
21
Ordóñez and Duinker, 2012; Raupp et al., 2006), but the benefits of planting at least some non-
native species, and the potential of assisted migration in urban forests as a response to climate
change raise questions about the value of a native-only (or native-first) approach to tree planting.
To guide urban forestry, municipalities are increasingly adopting urban forest management plans
(UFMPs), which typically outline management goals and objectives over a 20-year timeframe.
Ordóñez and Duinker (2013) found the one commonality among all of the existing Canadian
UFMPs was an emphasis on planting native species. It is unclear if and how debates associated
with assisted migration, defined as the intentional translocation of species outside of their
historic ranges in order to ameliorate actual or anticipated biodiversity losses (Hewitt et al.,
2011; McDonald-Madden et al., 2011; McLachlan et al., 2007; Ordóñez and Duinker, 2014; Sax
et al., 2009; Zhu et al., 2012), and the potential benefits of planting non-native species, including
tolerance for urban stressors and provision of desired ecosystem services, have influenced the
goals in these plans, or the impact such debates and UFMPs themselves have on actual planting
practice.
Given the gaps in our understanding of the formulation and implementation of UFMPs and on-
going discussions about ecological integrity, non-native species benefits and assisted migration,
the objectives of this study are to (1) examine the role of native species in UFMPs; (2) explore
municipal foresters’ attitudes and actions related to native tree species, and (3) explore if
municipalities with and without formal management plans are making different decisions
regarding native tree species planting. These objectives are addressed through a case study of
municipalities in Carolinian Canada (Ontario, Canada), a region with relatively high native tree
richness, by examining UFMPs and interviewing urban foresters from municipalities with and
22
without UFMPs. The following sections outline debates around native and non-native species in
urban forests, present our methods and results, and provide a broader discussion of the
implications of current practice and recommendations for future urban forest management.
2.2 Ecological Integrity, Assisted Migration, and Non-native Trees in the
Urban Forest
The recent urban ecology and urban forestry literature debates the value of native trees in cities,
in part, because of the unique conditions associated with urban forests (Hitchmough, 2011;
Kendle and Rose, 2000; Kowarik, 1995; Rotherman and Lambert, 2013). In particular, the
importance of and potential pathway to achieve ecological integrity, the useful role of planting
non-natives trees, and the use of assisted migration as a tool to mitigate and adapt to climate
change have all been discussed (Camacho, 2010; Davis, 2012; Hewitt et al., 2011; Ordóñez and
Duinker, 2012; Zhu et al., 2012).
Ecological integrity depends upon a high ratio of native biodiversity (Bolund and Hunhammar,
1999; Clemants and Moore, 2003; Hermoso and Clavero, 2013; Landry and Chakraborty, 2009;
Ordóñez and Duinker, 2012). When ecosystem functions are lost due to an absence of native
diversity, the system becomes less resilient, so the capacity to resist damage and recover from a
disturbance is reduced (Folke et al., 2004). The current composition of species in most urban
forests means that some functions (e.g. provision of food, maintaining biodiversity, nutrient
cycling, reduction of wind damage, regeneration of soils and the maintenance of organisms
within them) do not occur at the same rate, suggesting lower resilience and reduced integrity
(Ordóñez and Duinker, 2012).
23
In order to improve the ecosystem function and resilience of urban forests, it is important to plant
not only a diverse assemblage of trees – which often already exists – but a diversity of native
trees. More specifically, native specialist and rare species must be present in order to support a
high degree of ecological integrity (Ordóñez and Duinker, 2012). However, while generalist
species can often survive the many stressors present in urban ecosystems, specialized and/or rare
native species frequently cannot (Ordóñez and Duinker, 2012). The unique challenges of
managing such a system – typically including high levels of impervious surfaces, variable
amounts of shade/sunlight, highly compacted soils, lower air quality, and other molestations –
creates complications for prioritizing native tree species, such that tree species tolerant of urban
stressors are preferred for planting even if they are not native (Escobedo et al., 2011).
Furthermore, municipalities are tasked with not only maintaining and enhancing ecological
integrity, but also typically need to reduce tree-related risks while increasing the ecosystem
services provided by the urban forest (Kenney et al., 2011). Risks are reduced, in part, by
planting trees without large fruits/nuts, avoiding the use of softwood and coniferous trees as
street trees, and using small trees to avoid utility conflicts (City of Burlington, 2010), thus
potentially excluding a number of native species.
Ecosystem services are defined as the goods or services provided by ecosystems that contribute
to human well-being (MEA, 2005). The well-documented ecosystem services provided by urban
forests include storm water retention, erosion control and microclimate regulation (Ostoić and
Konijnendijk, 2015). Managing for ecosystem service provision and risk reduction is often
achieved by planting trees that are assured to grow quickly with minimal need for maintenance
and other capital expenditures, regardless of their native status (Dobbs et al., 2011; Sjoman and
24
Nielsen, 2010). For instance, Acer platanoides (Norway maple) and Platanus x acerifolia
(London plane) have been frequently planted in urban areas outside their native ranges due to
their relatively fast growth; resistance to pests; and ability to withstand urban stressors, such as
soil compaction and particulates. In at least some cases non-native species are better at
providing desired ecosystem services in urban environments (Escobedo et al., 2011), including
providing habitat and food sources for native species (Gray and van Heezik, 2016). Given the
novel assemblages of species already present in most cities, some have argued that exotic species
should not be avoided simply because of their non-native status (Kowarik, 2011).
While some non-native trees may be more tolerant of certain urban stressors and survive better
as a result, individual trees are part of the larger urban ecosystems. The resilience of these
ecosystems to recover from disturbances, as well as the provision of food for other parts of the
food-web, nutrient cycling, and soil creation are dependent on native trees. Thus, a dilemma
exists regarding an appropriate emphasis on native species, whose planting can increase
ecological integrity, while planting select non-native species may ensure a better survival rate in
stressed situations, reduce risks to people and property, and quickly provide key ecological
services.
Further complicating the appropriate ratio of native species in urban forests is the likely inability
of many tree species to rapidly adapt to the changing climate (Zhu et al., 2012). Given the long
life-span of trees, planting decisions today will influence urban forests’ species composition for
years to come, but some native species may not be able to survive in their current ranges in the
coming decades. Assisted migration is one way to maintain healthy urban forests into the future
25
in light of anticipated climate change (City of Halifax, 2012; Kowarik, 2011; Ordóñez and
Duinker, 2013; Peel, 2011).
The term assisted migration is discussed in the literature in a variety of ways (Hewitt et al., 2012;
Pedlar et al., 2012; Ste-Marie et al., 2011). In this study, we focused on assisted migration as the
intentional translocation of species outside their historic ranges (typically shifting northward) in
order to ameliorate actual or anticipated biodiversity losses caused by climate change, similar to
the way the term is used in the forestry sector (Pedlar et al. 2012). This may entail moving
individuals to locations with species assemblages that have coevolved with the relocated species
or to locations with non-coevolved species assemblages (Hewitt et al., 2012). In Carolinian
Zone urban forests, there is the potential for both approaches to be used to maintain the forest
over the long-term in light of climate change, by planting species from the Eastern Deciduous
Forest with ranges that do not current extend northward into Ontario. There is also the prospect
of introducing varieties or cultivars of native species that have evolved in a warmer climate.
Assisted migration as a tool for addressing climate change is perhaps most commonly practiced
within the forestry sector. For example, the western Canadian provinces of British Columbia and
Alberta have modified their forestry seed transfer guidelines to allow seeds to be planted 200
metres higher in elevation and two degrees of latitude northward for most tree species (Pedlar et
al., 2012). However, the debate around assisted migration remains primarily conceptual, as
many of the anticipated aspects of climate change have yet to happen, delaying the ability to
measure the success of these practices.
26
Assisted migration is a complex topic rife with ethical, economic, legal, political, and ecological
issues (Schwartz et al., 2012). These include the impact of the introduced species on the hosting
environment, the potential of a species becoming invasive, and mortality and investment loss if
the species is not well adapted to the local conditions. In short, it disrupts widely held
conservation objectives and paradigms (McLachlan et al., 2007). In order to ensure that assisted
migration is beneficial and that risks are minimized, decisions should be supported by scientific
findings, with migrated populations and the receiving ecosystems carefully monitored over time
(Sax et al., 2009).
Urban ecosystems are potentially good locations to apply assisted migration as a climate change
tool because the urban heat-island effect already elevates the temperature as compared to
surrounding hinterlands, potentially allowing less hardy species to acclimatize to more northerly
latitudes (Imhoff et al., 2010). Additionally, the high number of planted non-native trees means
that urban ecosystems are already ‘novel’ systems (Hobbs et al. 2006; Kowarik, 2011), with
species assemblages created through long histories of exotic species introductions.
While assisted migration is used to describe intentional management practice, in many urban
areas passive or unintentional assisted migration is already occurring as a result of the supply of
nursery stock and tradition of using exotic species as landscaping elements (Hitchmough, 2011).
However, it is unclear the extent to which municipalities are actively adopting assisted migration
as part of climate change strategies, and how active and passive assisted migration practices are
impacted by native species goals.
27
2.3 Methods
2.3.1 Study Area
As described in Chapter 1 this study focuses on municipalities’ native tree species management
within the Carolinian Zone of Ontario, Canada (Figure 1).
The nine urban municipalities within the Carolinian Zone that had an UFMP enacted by city
council as of April 2015 were included in the study (Table 1). The City of Guelph and the Town
of Ajax are on the outer boundaries of the Carolinian Zone, but were included as Carolinian
municipalities because of the numerous Carolinian tree species planted there, as well as the
anticipated northward progression of typical Carolinian species. Additionally, the 11 most
populous municipalities within the zone that lack an UFMP were included (Table 2), to provide
insight into the similarities and differences in municipal attitudes and actions between
municipalities with and without an UFMP. Collectively, these municipalities represent a variety
of urban forms and urban forest conditions. Based on the 2001 Ontario Municipal Act, the
municipalities all have the responsibility to manage street trees and other trees on municipal
land, as well as the ability to regulate trees on private property.
28
Table 1 Carolinian Zone municipalities with an Urban Forest Management Plan
Municipality (Year UFMP enacted)
Population (Statistics Canada, 2011)
Municipality Type (Municipal Act, 2001)
Ajax - (2011) 110,000 Lower-tier
Brantford - (2010) 95,000 Single-tier
Burlington - (2011) 180,000 Lower-tier
Guelph - (2012) 125,000 Single-tier
London - (2014) 370,000 Single-tier
Mississauga - (2014) 720,000 Lower-tier
Oakville - (2008) 185,000 Lower-tier
St. Catharines - (2011) 135,000 Lower-tier
Toronto - (2013) 2,650,000 Single-tier
Table 2 Carolinian Zone municipalities included in the study that were contacted for an
interview but have not enacted an Urban Forest Management Plan as of March 2015
Municipality with
no UFMP
Population (Statistics Canada, 2011)
Interviewed
Cambridge 126,748 Yes
Markham 301,709 Yes
Milton 84,362 Yes
Niagara Falls 82,997 Yes
Brampton 523,911 No
Chatham-Kent 103,671 No
Hamilton 519,949 No
Kitchener 219,153 No
Sarnia 72,366 No
Windsor 210,891 No
Woodstock 37,754 No
29
2.3.2 Urban Forest Management Plan and Planting List Review
Copies of the nine Carolinian Zone municipal UFMPs were acquired. The documents range from
46 (City of London, 2014) to 213 pages (Town of Oakville, 2008) in length and were adopted
between 2008 and 2014. Each document was analyzed for the following terms: native, non-
native, invasive, and exotic. When found, the context that the term was used in was recorded.
Additionally, municipal tree species planting lists were acquired from study municipalities with
and without UFMPs to determine the species regularly planted. The lists provide insight into
how well the urban forest goals outlined in the UFMPs are aligning with the planting practices of
the municipality or, in the case of municipalities without an UFMP, the stated goals associated
with the urban forest. Drafting and updating the lists are the responsibility of the municipalities’
Director of Forestry or equivalent, and these lists were drafted independently of the UFMP. Each
list was examined to determine the percent of native species per list and the percent of native
species that appeared on at least one municipal list was also calculated. Native status was
identified using Waldron (2003).
2.3.3 Interviews
The influence of UFMPs on urban foresters whose job it is to carry out municipal tree planting
and site-level species selection decisions has been largely unexamined. In this study, interviews
were employed to explore how municipal urban foresters view the role(s) of native species in the
urban forest in light of current debates surrounding ecological integrity, the benefits of non-
native species, assisted migration, as well as criteria used to select specific species to plant at a
given site.
30
During the first half of 2015, email and telephone outreach was conducted to contact an urban
forestry representative from each of the nine municipalities in the Carolinian Zone with an
existing UFMP, as well as the eleven most populous municipalities that lack such a plan. After
contact with the municipal representative was established, a mutually agreed upon time was set-
up for the interviews. Interviews occurred over the telephone or in-person, taking about one
hour to complete. Representatives from all municipalities with an UFMP were interviewed, but
we were only able to interview seven of the eleven contacted municipalities without an UFMP.
Of these seven municipalities, four had a draft UFMP submitted to city council. The remaining
four were contacted up to five times but expressed a lack of interest or never responded to our
requests.
All 16 interviewees had a unique job title, reflecting the size and organization of their
municipality and their specific responsibilities. These ranged from Manger of Forestry to City
Arborist to Manager of Environmental Services. However, all participants were involved in tree
planting and selection decisions, overseeing the day-to-day management of their municipality’s
urban forest. The range of employment longevity in the participants’ current position spanned
from one to 30 years, and their educational backgrounds included forestry, horticulture,
environmental science, arboriculture, and landscape architecture.
A semi-structured approach was used in the interviews, focusing on understanding the rationale
behind the treatment of native species in the UFMP and municipal planting practice. For the
municipalities that did not have an UFMP, the interviewees were asked about other forms of
forestry planning and outreach they conduct. The interviews were organized around questions
pertaining to: the value(s) each department associates with native species; the prevalence of
31
native species in municipal planting practices; where the tree species are obtained from and the
provenance of the trees (since tree suppliers can also affect what trees are planted); issues with
supply; in what case native species are preferred to non-native species (and vice-versa); whether
or not assisted migration is being taken into consideration; and if they believe recent planting is
addressing the goals and objectives of the UFMP (when applicable). At the start of the
interview, we defined several terms for the interviewees (Table 3) to ensure a basic knowledge of
each concept and consistent interpretation.
Table 3 Terms that were defined for the interviewees for ideological consistency
Term Defined for Interviewees Definition Provided
Assisted Migration
Assisted migration is the intentional
translocation of species outside of their
historic ranges in order to ameliorate actual or
anticipated biodiversity losses caused by
climatic change.
Ecological Integrity
Ecological Integrity is a measure of the
wholeness and proper functioning of an
ecosystem’s structure and natural processes.
Native Species
Native species are defined as a species that
occurs naturally within a region, either
evolving there or arriving and becoming
established without human assistance.
Tree
A tree is a woody perennial plant, having
trunk greater than 10 cm (4 inches) in
diameter.
32
We followed an informed consent process with all participants, which included giving
respondents the choice to remain anonymous. All interviews were then recorded, with
permission, and transcribed. Transcripts were coded based on an informal review of the content
of the interviews, with NVivo 10 software used to help analyze the range of responses given for
each question.
2.4 Results
2.4.1 Urban Forest Management Plans and Planting Lists
The reasons stated by the interview participants for enacting an UFMP were because it increases
the effectiveness and efficiency of managing the urban forest (five of nine respondents), it
provides clear direction for management (four of nine respondents), city council requested it
(three of nine respondents), and there was a desire to maintain natural heritage (one of nine
respondents). All representatives from the seven municipalities that lack an UFMP stated they
believe that their municipality would benefit from having an UFMP, with four of those
municipalities in the process of adopting one.
Municipal foresters communicate with residents in various ways to consult with and inform them
about urban forest issues and the goals of the UFMP. The most prevalent methods for resident
outreach are: referring residents to their website (10 of 16), social media outreach such as
facebook and twitter (nine of 16), educational booths at special events (six of 16), public
meetings (six of 16), and tree planting events (six of 16). Ten of 16 municipalities also attempt
to educate homeowners about tree selection and care when planting a street tree in front of their
residence. When drafting their UFMP only two municipalities indicated that they did not consult
33
with residents, while seven conducted community and stakeholder meetings prior to drafting
their UFMP. Every municipal forester acknowledged that resident support for urban forestry
goals is crucial for realizing the goals of the forestry department.
In terms of content, all nine UFMPs emphasized the importance of native species in the core
goals and objectives, including a desire to increase the proportion of native species in the urban
forest. For example, Mississauga’s UFMP (2014, p.88) states one of its objectives is the
“preservation and enhancement of local natural biodiversity by increasing the proportion and
population of site-appropriate native plant species through policies, guidelines, management and
stewardship,” while Guelph’s UFMP (2012, p.22) states that “the goal of good forest
management is generally to protect and expand native species diversity so that the area is
intrinsically more resilient to natural and anthropogenic stressors, such as climate change.”
While the UFMPs discuss native trees and their intrinsic benefits, they all lack specificity and
operational clarity; there is no instance of targets for native to non-native ratios for planting,
number or percent of native species that should be present, or situations where only native or
mostly native species should be planted on the streetscape. For example, Toronto’s UFMP states
that “supporting, sustaining and encouraging native biodiversity through management of natural
areas helps maintain the integrity of Toronto’s natural systems for all life forms that depend on
these areas (City of Toronto, 2013, p.24),” but concrete targets related to native biodiversity
levels are not given. While Ajax’s UFMP defines a goal to “increase native biodiversity, and
reduce the risks presented by trees on municipal lands. Species selection should always avoid
tree species known to be invasive, and include as great a diversity of native or indigenous
species as possible (Town of Ajax, 2011, p.62),” it is unclear from the UFMP what the right
34
number or frequency of native species planting is.
In addition to the absence of specific targets in the UFMPs, municipal planting lists lack native
species diversity, indicating that the stated goals are generally not being operationalized. Every
municipality interviewed had a tree species planting list, including municipalities without
UFMPs. Each planting list featured small, medium, and large stature trees with a variety of
native and non-native trees present. The number of trees on the planting lists ranged from 23 to
86 species (or varieties), while the number of native tree species on these lists ranged from 13 to
47. No list was more than 57% species native to the Carolinian Zone.
The planting lists that have the fewest native species tended to only include the most common
native species found on all lists (Acer saccharum (sugar maple), Acer rubrum (red maple),
Quercus rubra (red oak), Amelanchier (serviceberry), Gleditsia triacanthos (honey locust),
Celtis (hackberry)). The planting lists with higher diversity typically included rare native
species, more southerly species, and less common non-native species. Those municipalities with
an UFMP did have a high percentage of species native to the region on their planting lists
(averaged 49 species; 26 native species) compared to the non-UFMP municipalities whose lists
were examined (averaged 33 species; 15 species). However, of the more than 80 trees native to
Carolinian Canada, 35 do not appear on any list.
2.4.2 Planting Practice
The number of trees planted annually by the municipalities ranged from 800 to 100,000, while
the number of trees removed annually ranged from 700 to 15,000. The most commonly planted
35
trees were Acer (maple), Quercus (oak), Tilia (linden), Amelanchier (serviceberry), and Gleditsia
triacanthos (honey locust; Table 4).
Table 4 Most commonly planted tree species in Carolinian Canada
Most Commonly Planted Trees Frequency of Response (out of
13) Native Status
Acer (maple) 8 both native and non-native
varieties
Quercus (oak) 5 native
Amelanchier (serviceberry) 4 native
Tilia (linden) 4 non-native
Gleditsia triacanthos (honey
locust) 4 native
Liriodendron tulipifera
(tuliptree) 3 native
Syringa reticulata (japanese
lilac) 3 non-native
Gingko biloba 3 non-native
Celtis (hackberry) 3 native
The most common factor considered when selecting a species to plant was whether or not the
planting site has a utility conflict associated with it (11 of 16 respondents; Figure 2). One urban
forester stated that “utilities play a very big role in our species selection… So, you know
overhead wires. We are very cognizant of every site where there are overhead wires and we try
to offset the trees so they are more compatible with overhead wires.” Urban foresters were also
heavily influenced by how much growing space there is at the planting site (nine of 16
respondents), objectives of planting for street tree diversity (7 of 16 respondents, and the land
use type (five of 16 respondents).
36
Figure 2 – Most common factors considered by municipal foresters when choosing tree species
to plant
Five of nine interviewees indicated that the planting trends had changed in their municipality
since the enactment of the UFMP. Two of the nine respondents stated that the planting and tree
selection processes changed prior to the enactment of the UFMP in anticipation of the document;
while the other two respondents said that the municipality is in the midst of changing their
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planting and tree selection processes. Five of nine respondents feel that the type and number of
different species currently planted is addressing the goals of the UFMP, while four of nine
respondents felt that the municipality’s planting trends were not addressing the goals.
Tree planting authority across municipalities with and without an UFMP was largely held by the
Forestry department (or equivalent) staff members, however three of 16 respondents indicated
that tree planting selection was not centralized within a single department, but rather, several
departments who are responsible for choosing what trees are planted for their respective projects.
Thus, implementing actions to address the UFMP was not solely the responsibility of the urban
forest department, and there was not necessarily sufficient coordination between units to ensure
this occurred. For example, one municipal forester stated: “Part of the challenges that
municipalities have, is that there’s multiple departments, and there’s not only just the forestry
department, there’s also a parks department, there’s also an urban design department, there’s
also an engineering department that all plant trees, and they don’t always talk.”
All municipal interviewees indicated that the trees they plant are acquired from either a nursery
or a contractor who purchases them from a nursery. Typically, the municipality drafts a contract
that includes the number of trees of different varieties and their condition. Some of the
municipalities have strict specifications regarding tree provenance, especially when planting for
restoration programs (e.g. Guelph, Mississauga, Oakville), others request provenance (e.g. Ajax,
Burlington, Cambridge), and some do not specify. The tree contract is put to tender, and local
tree planting contractors and/or nurseries bid on the contract. Nine of 16 participants indicated
that while their municipality requests the tree species that they want to plant, it is not always
possible to acquire those exact species, and frequently the nursery will provide the municipality
38
with a comparable species instead. While some municipal forestry departments stated that they
are in the process of establishing local seed banks from which some or all of their trees will be
acquired, the majority of the trees being planted are of distant or unknown provenance. This
process of acquiring trees represents an added challenge to planting native trees and establishing
local provenance.
Species Selection: Native versus Non-Native Species
Several interview questions specifically focused on attitudes and actions pertaining to the use of
native species for tree planting. In general, municipalities that do not have an UFMP are
planting a lower ratio of native trees or do not track the relative number of natives planted.
Conversely, five of the nine municipalities that have an UFMP plant only native trees in
restoration and naturalized areas, and eight of the municipalities with an UFMP indicated a
higher proportion of native trees planted overall. The sole exception was Toronto, which has the
highest urban density in the study, where only about 40% of the street trees planted are native
species.
There was little similarity among responses about why native species are preferred or why their
use should be increased (Table 5), however, a general theme of ecological integrity exists
throughout the responses from the municipalities with an UFMP. Respondents indicated their
municipality plants native trees because the Carolinian forest is unique and should be preserved,
it creates a natural seed source, native species are less invasive, they have greater wildlife
benefits, natives fare better, and because natives are needed to increase diversity. Additionally,
four of the nine representatives from municipalities with an UFMP said native trees are planted
39
because the UFMP states that they should be planted, although additional reasons were also
given by these participants. In contrast, six of the seven responses from the municipalities that
lack an UFMP said that native species are not preferred, and their use need not be increased.
Table 5 Reasons given as to why the use of native species should be increased in municipal
plantings
Reasons Why the Use of Native Species Should be
Increased
Carolinian forest is unique
They benefit wildlife
Less invasive
City council requests it
Ecological integrity
Most appropriate for site
They fair better
Sense of place
Easier to grow successfully
It is not a goal (municipalities without an UFMP)
Many species of native trees are not planted by municipalities in Carolinian Canada, for a variety
of reasons. Fraxinus (ash) trees were the most commonly avoided native trees to plant (13 of 16
respondents) because of the Agrilus planipennis (emerald ash-borer) infestation. Nine of 16
respondents indicated that they do not plant conifers and nut-bearing trees as street trees or near
roadways due to potential risks. Additionally, Platanus occidentalis (sycamores; allergen),
Ulmus (elms; Dutch elm disease vulnerability), Acer negundo (Manitoba maple; invasiveness),
and Populus (poplar) and Salix (willow; weak wood) are avoided in many of the municipalities.
Finally, a number of native species are unavailable from nurseries. Interestingly, five of the
40
study municipalities have begun species suitability trials to identify additional native species that
are suitable for use, with the municipal representatives acknowledging many native species are
avoided because it is unknown how they will fare in the urban environment.
In some situations, non-native tree species are selected in favour of native tree species by
municipal foresters. Nearly every reason was related to poor site conditions: All 16 respondents
directly referred to poor site conditions, while other factors that imply poor site conditions (salt
tolerance, compacted soil, wind resistance, utility conflicts, lack of growing space) were also
given as reasons for a non-native tree species selected in favour of a native species (Figure 3).
Figure 3 – Reasons why non-native tree species are selected in favour of native species
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2.4.3 Ecological Integrity and Assisted Migration in Practice
After being provided with the study’s definition of ecological integrity, interviewees were asked
if and how this idea factors into the municipality’s tree planting program. There was a distinct
dichotomy of responses between municipalities with and without an UFMP, as eight of the nine
municipalities that have an UFMP responded that ecological integrity factors into the
municipality’s tree planting program, while five of the seven municipalities that lack an UFMP
indicated that ecological integrity is not a factor. The most common response to how ecological
integrity is included in practice was that the municipality requests that the trees they acquire be
from the local area (five out of 16 respondents), while three respondents indicated that they
require the trees to be from local certified seed sources. Ecological integrity was also identified
as being practiced through planting a higher diversity of trees (two of 16 respondents), planting
more Carolinian and native trees (two of 16 respondents), and practicing habitat restoration (two
of 16 respondents).
We also asked respondents to indicate if and how their municipality practices assisted migration
based on the provided definition. Four of the 16 respondents indicated that they actively (i.e.
purposely) practice assisted migration through their municipal planting decisions, while 10 of 16
respondents indicated that they passively (i.e. unintentionally) practice assisted migration based
on the provided definition. One respondent indicated that they will consider assisted migration
in the future, implying that the term was new to them and that their municipality does not
actively practice assisted migration. Finally, two respondents indicated that they do not engage
in active or passive assisted migration. However, their municipal planting lists certainly contain
42
many non-native species, including those native to regions just south of Ontario, and their other
interview responses indicate these non-native trees are regularly planted.
Assisted migration was most commonly practiced by planting species that are native to a more
southerly range but still coevolved with many of the tree species in Carolinian Canada (i.e.
species from the eastern United States; 12 of 16 respondents), while assisted migration is also
practiced by planting southerly exotic species that will grow in southern Ontario’s climate. All
representatives from municipalities that actively practice assisted migration (four respondents)
do so to prepare for climate change. For example, one respondent stated, “we often choose
species from more southern climates because we know that our climate’s changing, and we are
always looking for species that grow in a more southerly climate, and we try them here in the
city to see how well they will grow, so some of those species will do well or may do very well in
this climate and in some of the growing conditions here.” In addition to practicing assisted
migration to purposely adapt to climate change, it is also practiced by some municipalities
simply because the more southerly tree species will survive and grow (three respondents), as
well as to increase the diversity of tree species in the municipality (one respondent).
2.5 Discussion and Conclusion
This study highlights the attitudes and actions of municipal urban forestry staff towards native
tree species in relation to the goals established in Carolinian Canada’s UFMPs. Municipalities
with an UFMP are emphasizing native species in planning and practice more than those
municipalities without an UFMP, typically justified as a way to increase ecological integrity.
Still, all but two municipal tree planting lists consist of a majority of non-native tree species and
many native species are not planted by any municipality in the study. Thus, a fraction of the tree
43
diversity naturally found in the Carolinian Zone of Canada is planted. Aligning the development
of planting lists with UFMPs stated goals could be a way to more easily achieve these stated
goals, at least among municipalities who have not yet adopted management plans. Most
municipalities are also passively practicing assisted migration, which is not aligned with the
UFMPs’ native emphasis, but many are not exploring the ways assisted migration can be used as
a tool to adapt to climate change.
Municipalities with an UFMP are considering more of the managerial aspects associated with
native species, which is consistent with Ordonez and Duinker’s (2013) review of UFMPs across
Canada. In addition to planning goals, the UFMP municipalities are drawing on more native tree
species than municipalities without an UFMP and planting more native tree species overall. In
contrast, municipalities that lack an UFMP are not prioritizing planting or management of native
trees, and ecological integrity is not considered when making street tree species selection
decisions. In this regard, the existence of an UFMP in a municipality indicates that some of the
higher-level goals surrounding native species have been successfully communicated to and
implemented by the forestry staff.
However, there is no discussion of targets for native ratios or the number of different native
species that should be planted. This is not surprising, given a lack of consistent guidelines from
the urban forestry literature or clear evidence from urban forestry practice. The review of the
municipal tree planting lists highlight that even in absence of clear targets, there is still a
disconnect between the stated preference for planting native trees in the UFMPs and the small
proportion of native tree species actually planted. Additionally, interviewees focused on a few
versatile native species that they knew were easy to grow, indicating that there is a preference for
44
planting the small number of native species that can grow in a variety of conditions, rather than
planting to achieve high native richness.
Research is needed to understand if and to what extent preserving native diversity is important in
achieving ecosystem service provision and other goals unrelated to ecological integrity, and
conversely, the functions and benefits that the novel assemblage of primarily non-native species
provides should be better communicated. However, if a municipality chooses to use native tree
species planting to achieve ecological integrity, they should be clear that it will require planting
less common native species to ensure high native richness, so that municipalities are not creating
a non-diverse, but native urban forest, as this would lead to diminished ecological integrity and
resilience. To support this, more native species suitability trials must occur to determine these
species tolerance to common urban tree stressors. While several interviewees commented on the
high cost of species suitability trials, others suggested coordinating and sharing this research
amongst all Carolinian Zone municipalities through existing forestry councils to ease the cost
burden.
Another challenge associated with operationalizing ecological integrity through native species
planting is the limited availability of native species and difficulty of establishing the provenance
of the trees acquired. In Carolinian Canada, tree nurseries are often not able to meet the requests
of municipalities, limiting the species that can be planted. This is consistent with the findings of
Sydnor et al. (2010), who examined municipal urban foresters’ planting needs in relation to
nursery supply and identified a mismatch between species urban foresters want and those
available from suppliers. While nurseries said they respond to demand, the need to substitute
species due to lack of availability was not necessarily recorded, masking the unmet demand in
45
many cases. In a related study examining wholesale nurseries in Washington State, there was
general support for increasing the diversity of tree species available, but many nursery
representatives surveyed did not know why higher species diversity was important (Polakowski
et al., 2011). The limited availability of native trees in retail and wholesale nurseries, as well as
the aesthetic and economic considerations that dominate their supply decisions, has received
recent attention (Kenney et al., 2011; Pincetl et al., 2013; Conway and Vander Vecht, 2015) and
represents an added challenge to planting native trees and establishing local provenance.
Finally, assisted migration of tree species to ameliorate the anticipated effects of climate change
provides another wrinkle in the decision to manage for high native diversity. While assisted
migration can potentially be used to build an urban forest that will thrive in future climates, as
well as for species restoration, economic gain and/or ecosystem benefits, the risks of introducing
invasive species, failure of plantings that may not be able to survive local conditions or climate
conditions over the short-term, and loss of time and money on failing species need to be taken
into account.
Although a minority of municipalities indicated that they are actively practicing assisted
migration, the majority of Carolinian Zone municipalities in this study are passively practicing it.
In particular, they are planting species from a more southerly zone because they are available and
will grow. Given that there are several risks associated with assisted migration, if municipalities
are practicing it then their actions should be managed thoughtfully by actively choosing which
species to translocate and monitoring their progress, rather than the more passive version that
currently dominates in the region. Keeping in mind that municipalities are bound by strict
financial and temporal budgets, this may best be achieved by partnering with colleges and
46
universities in the region to provide species suitability trial research and development.
Additionally, creating a municipal network that communicates the successes and failures of
planting experimental species under various growing conditions in Carolinian Canada would
eliminate the time and monetary cost of each municipality independently conducting these trials,
and as such, would be an efficient tool for operationalizing assisted migration across the region.
By doing so, municipalities could adaptively manage their urban forest, while also striving to
mitigate the effects of climate change.
While the goals of Carolinian Canada’s UFMPs clearly emphasize native species as a way to
protect and improve ecological integrity, there are an absence of specific targets, due to a lack of
knowledge about many native tree species’ tolerances to urban stressors and no consideration of
the ways other UFMP goals, like ecosystem service provision, may be met with non-native
species. Similarly, though the municipal representatives were generally supportive of native tree
planting, there are many planting scenarios in which non-native species are preferred and
typically more non-native species to choose from, based on official planting lists. Thus, practice
is not fully supporting native species goals. While careful consideration of actively practicing
assisted migration and/or planting non-native species for other reasons would benefit many
municipalities, those that do want to plant primarily native species must address issues of supply
and species suitability to ensure a diversity of native species are represented.
47
Chapter 3
Residential Knowledge of Native Tree Species: A Case Study
of Residents in Four Southern Ontario Municipalities
3.1 Introduction
In our urbanizing world, with finite natural resources that are ever more in demand, urban forests
are increasingly important areas for producing life sustaining ecosystem services and
maintaining ecosystem processes (Collins et al., 2000; Grimm et al., 2013; UNPD, 2010; Wu,
2014). Municipalities throughout North America are adopting strategic plans to manage the
urban forest based on the numerous ecological, social, health and economic benefits ascribed to
them, including storm water retention, filtration of air, shading, urban heat island mitigation,
habitat provision, retention of biodiversity, aesthetic appeal, and food production (Alvey, 2006;
Bolund and Hunhammar, 1999; Nowak and Dwyer, 2007). Recent research has explored how to
sustainably manage urban forests (Clark et al., 1997; Kenney et al., 2011; Mincey et al., 2013;
van Wassenaer and Kenney, 2000; Vlek and Steg, 2007; Young, 2013), with most authors
agreeing that protection of native species is an important component (Alvey, 2006; Clark et al.,
1997; McKinney, 2002; Ordóñez and Duinker, 2012).
Urban forests typically have relatively high species richness, as compared to the surrounding
countryside (Alvey, 2006; Bertin et al., 2005; Miller and Hobbs, 2002; Stewart et al., 2004).
However, this richness is often the result of numerous non-native species being planted, while
many native tree species are absent (Clemants and Moore, 2003; Hitchmough, 2011; Kendle and
Rose, 2000; Schaeplfer et al., 2012). The value of maintaining native species within urban
forests is debated (Alpert et al., 2000; D’Antonio and Meyerson, 2002; Davis, 2012; Sagoff,
48
2005). Goals of ecological integrity suggest that native species should be prioritized (Alvey,
2006; Raupp et al., 2006), but the unique stressors of urban ecosystems, potential ecosystem
services provided by non-native species, and on-going climate change raise questions about the
benefits of a native-only approach (D’Antonio and Meyerson, 2002; Davis, 2012; Hewitt et al.,
2011). While this debate occurs, many municipalities are adopting native-only or native-first
planting goals. For example, Ordóñez and Duinker (2013) found that the one commonality
among all of the existing Canadian urban forest management plans was an objective of
increasing native species.
Recent research has also begun to examine the role of key actors involved with tree planting and
species selection, including NGOs, community groups, and residents (e.g. Avolio, 2015; Conway
et al., 2011; Watkins et al., 2016). Residential support for urban forestry initiatives is crucial,
since the majority of urban trees are planted on residential property (McPherson, 1998; Nowak,
2012), though there is little understanding of how to activate residential support for municipal
urban forest goals. Additionally, while municipalities are depending on residents to be urban
forest partners, it is unclear what residents’ knowledge-level is regarding common species and
key management goals, or if identifying residents as partners in urban forest plans has actually
increased knowledge (through education programs and other outreach).
Studies suggest that knowledge of species, along with an interest in and experiences with nature,
are the factors that best promote an understanding of environmental issues, biodiversity and
sustainable lifestyle (Chawla, 1999; Corcoran, 1999; Lindemann-Matthies, 2006; Martin, Sorice,
and Kreuter, 2013; Palmberg and Kuru, 2000; Palmberg et al., 2015; Palmer et al., 1999). Thus,
assessing residents’ current knowledge about urban forests is important to provide a better
49
understanding of residents’ decisions related to urban forest management, as well as to assess if
they have the basic knowledge necessary to be good partners with their municipality on urban
forest initiatives.
The goals of this study are to determine if: 1) residents in municipalities with an UFMP are more
knowledgeable about the native status of common street trees; 2) residents who have lived in the
area longer have greater knowledge; 3) knowledge level is correlated with education level,
ethnicity, or income; and 4) residents’ knowledge is related to having planted trees on their
property. These goals are addressed through a case study of four urban municipalities in
Carolinian Canada (Ontario, Canada), a region with relatively high native species richness.
3.2 Residents and the Urban Forest
The role of residents in shaping the urban forest is far less clear than that of the municipality.
This is largely because residents’ greenery choices on their own property go widely
undocumented. There are typically no legally enforceable mandates for residents to plant
specific species of trees, much less any trees, on their property (with the exception of
replacement trees when removing existing trees in some cases; Conway and Urbani, 2007) and
residents have varied decision-making processes related to residential landscaping (Kirkpatrick
et al., 2012). However, residents collectively are perhaps the most important actor regarding
urban forest composition and health as approximately 75% of all urban trees are located on
private property and 75% of those are estimated to have been planted by residents (Nowak,
2012). This means that in order to effectively manage the urban forest, policy and practitioners
must influence the actions and perceptions of residents through various forms of engagement,
including education.
50
Not surprisingly, knowledge of urban trees appears to be related to attitudes and actions towards
the urban forest, including tree planting decisions. Generally, people who are knowledgeable
about urban tree programs and forestry services are more likely to donate money and support the
goals of tree planting programs (Zhang and Zheng, 2011). Additionally, positive attitudes
towards urban biodiversity, native species, and a general concern for the environment are
correlated with knowledge of common native species (Kurz and Baudains, 2012). This is
important because if residents’ actions are guided by their knowledge and attitudes, then
educating residents about municipal urban forestry plans should help achieve the long-term goals
laid out in those plans.
Kirkpatrick et al. (2012) examined residents’ tree planting motives in eastern Australian cities
and found a positive correlation between people’s willingness to plant native trees and their
knowledge of common tree species. Kaplan and Herbert (1987) measured landscape preferences
amongst students from Western Australia and Michigan, as well as from a group of
conservationists in Western Australia, and found that landscape preferences differed more
between the conservationists and the Western Australian students than they did between the
Western Australian and Michigan students. They ultimately concluded that species knowledge-
levels have an effect on preference.
While studies researching residents’ native tree species knowledge have been conducted in
Australia, where the threat of exotic-invasive species is highly publicized due to their unique
species assemblages and the influence of global trade (Kirkpatrick et al., 2012; Kurz and
Baudains, 2012), and in Arizona, where the arid climate inhibits many would be invaders
(Larson et al., 2010), residents’ knowledge of native species and urban forestry issues in the
51
North American temperate forest has been largely unstudied. Similarly, there are few published
studies that examine knowledge of common tree species, though it is clear that a variety of
factors can influence knowledge-levels associated with the environment, and urban forestry more
specifically.
Not surprisingly, exposure to environmental information and specific knowledge sources leads to
greater understandings of the environment. Martin et al. (2013) found that environmental
education of residents increased their knowledge of all environmental knowledge domains, while
Arbuthnot (1977) concluded that environmental knowledge was directly correlated with having
been exposed to detailed sources of information about it. Similarly, students gained a modest
increase in overall knowledge of environmental issues when exposed to environmental programs
(Armstrong and Impara, 1991). More specifically, Luckmann (2014) noted that educational
programs motivate and evoke an interest in students regarding knowledge of species. Other
studies link knowledge and awareness of environmental issues to attitudes and ultimately support
for specific policy initiatives (Slimak and Dietz, 2006; Zahran et al., 2006). Thus, municipalities
with goals of residential engagement and action should be exposing residents to information that
would increase their ability to identify common trees.
Others have focused on sense of place, local knowledge acquisition, and childhood experiences
being related to knowledge about the local environment. Several studies have emphasized a
sense of place as being an important driver of local action and planning initiatives, which may
become operationalized through knowledge of place (Davenport and Anderson, 2005; Gobster et
al., 2007; Larson et al., 2009; Romig, 2010; Williams and Stewart, 1998). For example, a
resident survey in Austin, Texas found a strong correlation between local newspaper readership
52
and knowledge of the city’s wildland management program (Martin et al., 2013). Formal and
informal childhood education also provides a venue to gain knowledge about local environments.
Lohr and Pearson-Mims (2005) found that children’s interactions with plants influence their
knowledge and attitudes towards trees and gardening as adults, while Olive (2014) indicated that
residents’ knowledge of endangered species in Canada would benefit from eco-literacy school
programs, based on the success of these programs to inform pupils. Thus, location of residency
during childhood, or length of residency in a place, may influence knowledge about local tree
species.
On the other hand, residents’ interactions with common tree species likely reflects social,
demographic, or cultural factors like income, education-level, and ethnicity (Cilliers et al., 2012;
Kendal et al., 2012; Marco et al., 2010), which may affect their knowledge of the native status of
common tree species. Past studies have shown that low-income populations lack access to urban
greenery and high-levels of canopy cover (Grove et al., 2014; Landry and Chakraborty, 2009;
Pham et al., 2012). Whereas other studies have found that education-level, rather than income, is
a better predictor of vegetation characteristics in urban areas (Heynen and Lindsey, 2003, Luck
et al., 2009). This relationship has been attributed to greater knowledge about the benefits of
vegetation (Luck et al., 2009) or a higher value placed on vegetation by the more educated (Lohr
et al., 2004). Additionally, several studies correlate ethnicity with uneven distributions of urban
trees, as well as interest level in urban forestry activities (Heynen et al., 2006; Perkins et al.,
2006; Perkins and Heynen, 2004; Zhang and Zheng, 2011), likely due to cultural preferences
(Fraser and Kenney, 2000). As a result of these relationships, people from varied socio-
demographic groups may have different knowledge-levels about common species.
53
Finally, knowledge of the native status of common trees may also be accrued via hands-on
experiences. Sommer et al. (1994) noted that residents involved in tree planting had a greater
sense of ownership and pride in the urban forest. Exposure to traditions of gardening, tree
planting, and landscaping have also been shown to have an influence on residents’ knowledge of
urban forestry issues (Jones et al., 2013). Summit and Sommer (1998) found that tree-planting
programs can show residents how easy it is to plant trees, demonstrate their benefits, create
opportunity for people to work together, and make environmental values and behaviour more
appealing, which leads to greater knowledge of trees and nurtures environmental protection and
sustainability values. This study explores residents’ species knowledge to better understand
residents’ role in urban forest dynamics and, more specifically, their potential to help
municipalities address native species goals.
3.3 Methods
3.3.1 Study Area
As described in Chapter 1 this study focuses on residents’ knowledge of native tree species in
four municipalities within the Carolinian Zone of Ontario, Canada (Figure 4).
54
Figure 4 - Map of the Carolinian forest zone in Canada showing the four surveyed
municipalities
Four municipalities within the Carolinian Zone were chosen as case studies: London, Hamilton,
Oakville, and Markham (Table 6). These municipalities were selected because they are
relatively large cities, two of which are characterized by new urban growth with higher average
incomes and immigrant populations (Markham and Oakville) and two municipalities that are
characterized by older urban growth, lower incomes and smaller immigrant populations
(Hamilton and London). Oakville and London have active UFMPs that emphasize both native
species and resident engagement (City of London, 2012; Town of Oakville, 2008), while
Markham and Hamilton do not. These municipal factors (population, income, immigration,
55
presence of an UFMP) were considered because they are related to the distribution of the urban
forest (Heynen and Lindsey, 2003; Pham et al., 2012), as well as influence basic knowledge of
one’s environment (Williams and Stewart, 1998).
Table 6 Municipal demographics (Statistics Canada, 2011)
Municipality Area
(km2) Population
Population
density
(people/km2)
Median
household
income
Percentage
immigrants
Survey
response
rate (%)
London 421 366,151 871 $73,107 21 44
Hamilton 1,117 519,949 465 $76,742 25 34
Oakville 139 182,520 1,314 $159,724 31 33
Markham 213 301,709 1,417 $108,520 58 29
3.3.2 Resident Surveys
Residents’ knowledge of the native-status of common tree species, municipal urban forestry
goals, and related topics such as their location in the Carolinian Zone, were explored through a
survey. Sixteen hundred residents were sent surveys (400 in each municipality) in the summer of
2015 using a spatially stratified random sample to capture a range of socio-demographics within
each municipality. A multiple contact approach was employed, with up to four attempts at
contacting the residents (Dillman, 2007). Initially, a recruitment postcard was mailed to all
possible participating households, alerting them to the coming survey and letting them know they
had the option to respond online. The survey was mailed a week later, followed by a reminder
56
letter, and then a second copy of the survey, if needed. Informed consent was obtained from all
individual participants included in the survey.
At the start of the survey we defined several terms (Table 7) to ensure a basic knowledge of each
concept and consistent interpretation. The survey contained a list of 12 tree species (6 common
native species, and 6 commonly planted non-native species) that residents were asked to label as
native, non-native, or “do not know”. Common native and commonly planted non-native trees
were chosen based on Waldron (2003) and southern Ontario municipal inventory and planting
lists. Native-status is based on Farrar (1995) and Waldron (2003), with common names used in
the survey. Participants were also asked to indicate if they had ever knowingly planted a native
tree on their property, the total number of trees they have planted on their property, and if they
knew their municipality was located in the Carolinian Forest zone. Basic socio-demographic
data was also collected. Residents from the two municipalities that had enacted an UFMP
(London and Oakville) were asked three additional questions regarding their UFMPs: if they
were aware of their municipality having an UFMP, if they had read any of the UFMP, and did
they believe that the municipality had effectively communicated the goals of the UFMP to
residents. Residents in the municipalities that lack an UFMP (Hamilton and Markham) were
asked if they believe their municipality should enact one.
Table 7 Terms that were defined for the survey respondents for ideological consistency
Term defined on survey Definition provided
Native species
Native species are defined as a species that occurs naturally
within a region, either evolving there or arriving and becoming
established without human assistance.
Tree A tree is a woody perennial plant, having a trunk greater than 10
cm (4 inches) in diameter.
57
After the first round of survey mailings, the survey question sections were rearranged to make
the survey more approachable. Specifically, residents were initially asked to identify which trees
are native and then asked property specific questions about their trees. In the revised survey,
these sections were reversed as it was thought that these knowledge testing questions may be less
appealing, and therefore dissuade some from completing the surveys. We found no statistically
significant differences between responses from the original survey and the revised survey, thus,
we do not differentiate these groups in the analysis.
Basic summaries of knowledge-levels and socio-demographics of respondents were calculated,
with survey socio-demographics compared with municipal characteristics. Based on the
literature, we propose four possible hypotheses for why residents may have different levels of
knowledge about species’ native-status. The hypotheses are:
H1: Respondents’ knowledge will be correlated with the presence or absence of an UFMP in
their municipality, based on the plans’ emphasis on native species and resident engagement.
H2: Respondents’ knowledge will be correlated with length of residency (in Ontario; in their
home) associated with local knowledge acquisition.
H3: Respondents’ knowledge will be correlated with education-level, ethnicity, and income
associated with preferences and access to knowledge, trees, and experts.
58
H4: Respondents’ knowledge will be correlated with having planted trees on their current
property associated with experiential knowledge.
These hypotheses were tested through a series of cross tabulations using Cramer’s V as the test
statistic. In order to meet the assumptions of Cramer’s V, some categories were combined to
meet the minimum sample requirements. Knowledge-level was represented as a categorical
variable (0-3 correct, 4-6 correct, 7-9 correct, or 10-12 correct) reflecting the number of species a
respondent correctly identified as native or exotic.
3.4 Results
Of the 1600 possible respondents, 90 surveys were not successfully delivered, and 552 surveys
were completed, representing a 37% response rate. London had the highest response rate at
44%, and Markham had the lowest at 29% (Table 6). The average age of the respondents was 58
years, and 55% were male. On average, respondents had lived at their current residence for
between 15 and 19 years and 59% were born in Ontario (Table 8). The average annual
household income was $117 650, with 96% homeownership. At least a university bachelor’s
degree was completed by 45% of survey participants, while 81% of respondents indicated either
a British Isles or European ethnicity.
In comparison to the most recent census data (Statistics Canada, 2011), the percentage of
university-educated participants and average household income was higher for survey
respondents than the corresponding municipal-level (Table 9), possibly as a result of limiting
participants to non-apartment dwellers. With the exception of London, the number of Ontario
born survey participants reflects the proportion of the municipality born in the province.
59
However, the accuracy of the 2011 census is unclear (Statistics Canada, 2015), making the cause
of divergences (census issues, survey representativeness, or temporal differences) uncertain.
60
Table 8 Summary of socio-demographic and tree planting variables, shown as percentage of all
respondents
Combined London Hamilton Oakville Markham
Born
Ontario 59 50 67 73 49
Outside of Ontario 41 50 33 27 51
Years at this current address
1 year or less 4 4 5 3 6
2 to 4 years 10 10 12 10 10
5 to 9 years 16 17 17 15 12
10 to 14 years 15 17 8 13 20
15 to 19 years 13 13 13 10 18
20 or more years 42 40 45 49 34
Education
No certificate, diploma or degree 3 2 8 1 3
High school certificate or equivalent 19 23 24 13 12
Apprenticeship, College, CEGEP 30 35 36 20 25
University Bachelor’s degree 33 22 24 49 46
Masters or Doctorate degree 15 19 8 18 15
Household Income
0 to 29 000 5 6 7 5 1
30 000 to 59 000 22 24 30 16 17
60 000 to 89 000 23 21 24 29 18
90 000 to 119 000 16 17 10 23 11
120 000 to 149 000 9 6 16 10 5
150 000 to 179 000 9 12 4 8 11
Over 180 000 16 14 9 10 37
Ethnicity
British Isles 51 64 45 67 19
European 30 30 42 19 26
Other 19 5 13 14 55
Planted a tree on your property
Yes 71 80 62 76 59
No 29 20 38 24 41
Planted a native tree on your property
Yes 36 43 31 38 26
No 64 57 69 62 74
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Table 9 Comparison between survey participant demographics and municipal demographics
(Statistics Canada, 2011)
Survey Respondents, 2015 Statistics Canada, 2011
Municipality At least a
bachelor’s
degree
Born in
Ontario
Median
household
income
At least
bachelor’s
degree
Born in
Ontario
Median
household
income
London 38% 47% $108,450 28% 70% $73,107
Hamilton 30% 67% $104,000 23.5% 68% $76,742
Oakville 62% 51% $145,050 46% 56% $159,724
Markham 56% 30% $119,220 40% 37% $108,520
3.4.1 Knowledge
When asked to indicate the native-status of the 12 tree species, overall knowledge was low
(Table 10), while the correct status was given most frequently for Acer saccharum (native –
82%), Juglans nigra (native – 65%), and Quercus rubra (native – 64%). Respondents were least
likely to know the native-status of Catalpa speciose (exotic – 17%), Tilia cordata (exotic –
20%), and Liriodendron tulipifera (native – 24%; Table 11). Five of the six most correctly
identified trees were native species, while responses for non-native species were more frequently
incorrect or ‘do not know’. Knowledge of the native status of common tree species was highest
amongst London respondents (44%) and lowest for Oakville (35%), although correct
identification of native trees was higher than that for non-native trees across all four
municipalities.
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Table 10 Number and percentage of all survey participants in each category of knowledge of the
native-status of common tree species
Number of Correct Answers to
Native Status of Tree Questions
Number of
Respondents
Percentage of
Respondents
0 93 17%
1 to 3 117 21%
4 to 6 175 32%
7 to 9 118 21%
10 to 12 50 9%
Table 11 Percentage of respondents who correctly identified tree species (* denotes native
species)
Combined London Hamilton Oakville Markham
Acer saccharum* 82 89 88 82 72
Juglans nigra* 65 80 76 57 49
Quercus rubra* 64 65 70 66 63
Gingko biloba 46 58 50 36 47
Fraxinus pennsylvanica* 45 49 46 42 47
Platanus occidentalis* 35 41 42 33 27
Acer platanoides 34 40 31 34 36
Cercidiphyllum 33 35 33 28 40
Syringa reticulata 24 25 24 21 33
Liriodendron tulipifera* 24 33 25 19 16
Tilia cordata 20 26 18 15 24
Catalpa speciosa 17 18 17 13 13
With regard to activity and urban forest issues in southern Ontario, 34% of respondents indicated
that they had knowingly planted a native tree on their property, with 71% planting at least one
tree on their property. Twenty-eight percent of respondents were aware that their municipality
lies within the Carolinian Zone of Canada. There were, however, large differences in having
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knowingly planted a native tree between municipalities (26% - 44%), and knowledge of being
located in the Carolinian Zone (10% -47%) that mirrored the pattern of correctly identifying
native-status (Table 12).
Table 12 Percentage of correct responses for native and non-native tree species, as well as other
urban forest topics
Native
correct
Non-
native
correct
Carolinian
awareness
UFMP
awareness
Read
UFMP
UFMP goals
communicated
effectively
London 29% 16% 47% 53% 8% 19%
Hamilton 27% 13% 25% N/A N/A N/A
Oakville 23% 12% 21% 50% 13% 17%
Markham 22% 16% 10% N/A N/A N/A
Fifty-one percent of respondents from the municipalities that have an UFMP were aware that
their municipality has a management plan, but only 10% of respondents said that they had read
any part of it (Table 11). Thirty-four percent of respondents indicated that they did not feel as
though their municipality had meaningfully communicated the goals of the UFMP, while 48% of
respondents were indifferent about goal communication. In the municipalities without an UFMP
only 2% of respondents were not in favour of their municipality drafting one.
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3.4.2 Factors related to knowledge-level
The results of the hypothesis testing are shown in Table 13. Respondents’ knowledge was not
significantly related to the presence or absence of an UFMP in their municipality, providing no
support for the first hypothesis that survey participants in municipalities with an UFMP would be
more knowledgeable. In relation to H2, knowledge-level was positively related to length of
residency at current address (p-value = 0.011), but there was no significant relationship between
knowledge of the native status of common tree species and location of birth in or outside
Ontario.
Table 13 Cross tabulation results based on Cramer’s V, with p-value in parentheses. See Table 8
for variable categories
Variable
Correctly
identified
species
Carolinian
awareness
UFMP
awareness1 Read UFMP1
UFMP goals
communicated
effectively1
UFMP
adopted 0.052 (0.831) 0.187 (0.001) N/A N/A N/A
Place of birth 0.096 (0.590) 0.138 (0.757) 0.079 (0.573) 0.063 (0.637) 0.105 (0.583)
Length of
residency 0.244 (0.011) 0.16 (0.523) 0.123 (0.410) 0.150 (0.096) 0.213 (0.594)
Education 0.143 (0.596) 0.363 (0.007) 0.207 (0.016) 0.194 (0.167) 0.289 (0.018)
Income 0.176 (0.829) 0.172 (0.113) 0.13 (0.156) 0.174 (0.683) 0.285 (0.578)
Ethnicity 0.125 (0.291) 0.335 (0.001) 0.366 (0.039) 0.339 (0.836) 0.382 (0.227)
Planted a tree 0.232 (0.034) 0.144 (0.222) 0.207 (0.054) 0.214 (0.200) 0.234 (0.104)
Planted a
native tree 0.311 (0.001) 0.087 (0.380) 0.128 (0.062) 0.150 (0.140) 0.197 (0.018)
1 These cross-tabulations were only completed for respondents in the two municipalities with an
UFMP (London and Oakville).
65
Education-level, income, and ethnicity (H3) were not significantly related to knowledge of the
native status of common tree species. However, socio-demographics were significantly related to
other urban forest topics. Respondents with higher education levels were more likely to know
that their municipality had an UFMP (p-value = 0.016) and that they lived in the Carolinian zone
(p-value = 0.007). However, the higher the level of education of the respondent, the more likely
they felt that the goals of the UFMP had not been effectively communicated (p-value =0.018).
Ethnicity also played a role in general knowledge, as 56% of respondents who indicated a British
Isles or European ethnicity were aware of their municipality having an UFMP, but only 27% of
other ethnicities were aware of their municipality having an UFMP (p-value = 0.039). Thirty-
seven percent of respondents who identified as British and 29% of respondents who are
ethnically European were aware that their municipality lies in the Carolinian Zone, while only
5% of respondents who indicated another ethnicity knew they lived in the Carolinian Zone (p-
value = 0.001). Income showed no significant relationship to knowledge of native species,
municipal policy, or Carolinian Canada.
Finally, native species knowledge-level was significantly related to having planted trees on one’s
current property (H4), as respondents correctly identified more tree species’ status the higher the
number of trees they had planted (p-value = 0.034). Similarly, having planted a native tree on
your property also increased the likelihood of being knowledgeable about the trees’ native status:
of those participants who correctly identified at least nine of the 12 species, 56% had knowingly
planted a native tree, as compared to 34% of all participants (p-value = 0.001).
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3.5 Discussion
This study explores residents’ knowledge of common tree species and urban forestry issues in
southern Ontario municipalities. Overall, native tree species in the urban forest are more
identifiable by residents than common non-native tree species, but knowledge-levels are
generally low: only three of the 12 common species could be correctly identified by more than
half of the participants. Other studies have similarly found that residents’ knowledge of native
species is lacking (Brzuszek et al., 2007; Meyer, 2005), and that there is a general societal
knowledge deficiency regarding local ecology (Arbuthnot, 1977; Armstrong and Impara, 1991;
Brzuszck et al., 2007; Carrier, 2009; Chipeniuk, 1995; Corcoran, 1999; Lindemann-Matthies,
2006; Luckmann and Menzel, 2014).
The results from the survey indicate that respondents did not avail themselves of digital or print
information when they filled out the survey, skewing the number of species they correctly
identified, as less than two percent (10 of 552) of respondents correctly answered all 12
knowledge questions. It was communicated to the survey respondents that the data being
collected was exploratory, there was no incentive to have a higher knowledge score, and
individual results would not be published. While “cheating” about tree knowledge was an option
for respondents, it seems that if any cheating occurred it was minimal.
Hypothesis 1, that respondents’ knowledge would be correlated with the presence or absence of
an UFMP in their municipality, is rejected based on the survey responses. This may be related to
the short period of time that the UFMPs have been in place (Oakville, 2008; London, 2012). But
the poor communication of the plans’ goals, as expressed by many survey participants, suggests
that little education has occurred. Resident engagement in the region is often limited to
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encouraging residents to help meet tree planting targets, such as London’s Million Tree
Challenge (http://www.reforestlondon.ca/), or allowing homeowners requesting a city-tree in
front of their house to choose from a short list of site-appropriate tree species (Almas and
Conway, 2016). Furthermore, the much higher knowledge of one’s municipality having an
UFMP and living in the Carolinian Zone among participants with British or European
background as compared to participants who identify as other ethnicities, who are typically more
recent immigrants to Canada, suggests that engagement is uneven among different ethnic
communities in the study area.
The limited and uneven awareness that is reflected by study participants illustrates a broader
issue of uncertainty about how to engage with residents, particularly those who are not already
interested in urban forestry issues. Summit and Sommer (1998) outlined basic steps for public
engagement in urban forestry programs, including making the desired behavior easy and clearly
communicating the threat and ways that residents can help address it. While the study area
municipalities and other cities are taking some of these steps in tree planting programs,
communicating the importance of native species, when there is still debate about their value
(D’Antonio and Meyerson, 2002; Davis, 2012; Kendle and Rose, 2000; Sagoff, 2005; Schaeplfer
et al., 2012) and many instances where municipalities are choosing to plant non-native trees
(Almas and Conway, 2016), requires messaging that is not as simple as ‘plant more trees’.
Moreover, Johnston and Shimada (2004) argue that terms like ‘native’ and ‘alien’ can be
offensive, discouraging further interest among immigrant populations. Thus, cities like Oakville
and Markham, with sizable immigrant populations, may face additional challenges about how to
communicate information in a way that will be inclusive. Alternatively, a strategy to engage
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newcomers and residents of minority ethnic groups is to highlight the multicultural nature of the
urban forest itself, as common urban species originate from many parts of the world (Johnston
and Shimada, 2004). However, this is at odds with management goals that emphasize native
trees.
Residents’ length of residency was related to correctly identifying the native-status of tree
species (H2). Similarly, the longer residents lived in their house, the more likely they were to
have read some of the UFMP, which is in line with previous findings that people who have lived
in a community for a long period of time tend to be more knowledgeable about and engage in
their community’s activities (Romig, 2010; Williams and Stewart, 1998). An explanation for
this is that the longer a person has lived at their current location the more likely they are to have
had reasons to interact with the native ecology (Martin et al., 2013), whether by reading the
newspaper, engaging in community activities, social media, or physically walking amongst it.
The role of residential length in relation to knowledge about a place suggests that increasing use
of traditional and social-media may help educate residents about native tree species.
Furthermore, Lindgren (2015) argues that social media can be effective in reaching new
residents, who we found to be less knowledgeable about native tree species. However, a survey
of 463 municipalities across the United States indicates that social media communications are
under-utilized by municipal governments (Graham and Avery, 2013), suggesting its potential of
is not being fulfilled.
Somewhat surprisingly, there was no statistically significant relationship between correctly
identifying tree species and being born in Ontario, perhaps because there has not been exposure
69
to native trees through formal or informal childhood education. This is at odds with other studies
that suggest being born and educated in your place of residence is a good predictor of knowledge
of flora and fauna (Corcoran, 1999; Olive, 2014; Palmer et al., 1999). However, Palmberg et al.
(2015) found that students are not exposed to native species in their local environment, and argue
that experiential methods should be mandatory for learning about native ecology.
The lack of formal education about native tree species was further highlighted through the
rejection of H3, that respondents’ knowledge would be correlated with education-level, income,
and ethnicity. However, we did find that those with higher levels of education were more likely
to know that their municipality is located in Carolinian Canada and that their municipality has an
UFMP, suggesting that acquisition of knowledge about native tree species is different and
perhaps less easily obtained.
In an attempt to increase knowledge of local environments, several schools across the globe
(including in Ontario) have created an outdoor-based curriculum. These ‘forest schools’
acknowledge society’s lack of connection with the natural world and base their curricula on
nature immersion as the primary form of education (Forest School Canada, 2014). Since
municipalities have prioritized the use of native species in UFMPs, residents require some basic
knowledge of native ecology if they are to be helpful urban forest partners. Though entire school
curricula devoted to outdoor education may not be necessary to fulfill basic knowledge criteria,
primary school programs that introduce students to common urban tree species using a variety of
learning methods would likely help prepare children to be good partners in municipal urban
forestry initiatives.
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Finally, Hypothesis 4, that respondents’ knowledge is correlated with having planted trees on
their current property, was supported by the survey results. However, it is unclear whether
residents who have planted a tree were more knowledgeable about trees’ native-status before
planting their tree(s), or if the experience provided the learning opportunity. As several studies
suggest that experiential learning is linked to strong memory retention (Carrier, 2009; Dunphy
and Spellman, 2009; Kolb, 1984), it is possible that information gained from researching what
type of tree to plant would be retained. On the other hand, those with prior knowledge of tree
species native-status may have a proclivity towards trees that would result in them being more
likely to plant tree(s).
This study explores a particular aspect of native tree knowledge: ability to identify locally native
and non-native tree species based on their common name. We did not examine if this type of
knowledge is related to being able to physically identify species in one’s local environment or
understanding the role native species play in ecological integrity. However, we chose to focus
on this aspect of native species knowledge because residents who decide to plant a tree are
typically buying them from nurseries (Conway, 2016), but many nurseries are not interested in or
knowledgeable about native tree diversity (Brzuszck et al., 2007; Sydnor et al., 2010;
Polakowski et al., 2011; Conway and Vander Vecht, 2015). Thus, the ability of residents to ask
for native trees by name may be equally or more important than being able to physically identify
species when the objective is having residents’ planting species that will support municipalities’
native species objectives.
Undoubtedly, urban forestry programs have the potential to determine the forest structure and
species diversity in a municipality (Summit and Sommer, 1998), but additional public education
71
needs to provide basic knowledge in order for residents to have the tools needed to support
municipal management goals. Since all Carolinian Zone UFMPs emphasize the planting and
maintenance of native tree species over non-native species (Almas and Conway, 2016), assessing
residents’ knowledge of native species is crucial to establish a baseline for understanding how
much community education needs to occur in order to have residents function as knowledgeable
tree planting partners. This study indicated a lack of effective education in the two
municipalities with UFMPs, and the particular need to reach newer residents and those who have
not previously planted trees. To this end, there are opportunities to include native species in
school curricula, as well as provide learning opportunities for all residents. However, remaining
challenges include communicating native species objectives in an inclusive way that will
encourage supportive actions by all residents and reaching new residents to facilitate their
knowledge acquisition about the local environment.
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Chapter 4
Resident Attitudes and Actions Towards Native Tree Species:
A Case Study of Residents in Four Southern Ontario
Municipalities
4.1 Introduction
As more of the world’s finite land area is used for urban development and agriculture, urban
forests are increasingly becoming important areas for producing life sustaining ecosystem
services (Dobbs et al., 2011; Mincey et al., 2013). As a result, urban forests are now often
managed to maximize societal benefits through a focus on ecosystem service provision,
including microclimate regulation, stormwater mitigation, erosion control, shading, carbon
sequestration, and human stress reduction (Alvey, 2006; Bolund and Hunhammar, 1999; Dobbs
et al., 2011). In addition, maintaining natural species assemblages can increase ecological
integrity and provide resilience against disturbances (Alvey, 2006; Alberti, 2010; Ordóñez and
Duinker, 2012; Raupp et al., 2006).
Recent research has focused on the role of key actors involved with planting and maintaining the
urban forest to better understand the socio-ecological dynamics contributing to urban forest
conditions and support effective management (e.g. Avolio 2015; Conway et al. 2011; Watkins et
al. 2016). Of these actors, residents may be the least understood but perhaps the most important,
as the majority of trees in the urban forest are located on private property (Nowak, 2012). Thus,
many of the decisions regarding urban tree planting, species selection, maintenance and removal
are being made by residents. Yet we know little about residents’ attitudes and actions regarding
73
specific urban forest topics or level of support for common municipal urban forest management
goals.
An expansive literature has documented the relationship between residents’ socio-demographic
characteristics and urban forest characteristics at the property and neighbourhood-scale, planting
activities, and general support for municipal urban forestry (Kendal et al., 2012; Fraser and
Kenney, 2000; Grove et al., 2006; Heynen et al., 2006; Landry and Chakraborty, 2009; Pham et
al., 2012; Sommer et al., 1994; Tooke et al., 2010; Troy et al., 2007; Zhang and Zheng, 2011).
Additionally, several studies have shown that residents’ attitudes towards urban greenery are
typically expressed through planting and maintenance actions (Conway and Shakeel, 2014;
Finger, 1994; Fishbein and Ajzin, 2010; Zagorski et al., 2004), though it is unclear if residents
are interested in including native species on their property.
The major objectives of this study are to (1) explore urban residents’ attitudes and actions related
to native tree species; (2) examine if the presence of a municipal urban forest management plan
(UFMP) emphasizing native species is related to those attitudes or actions; (3) determine if
attitudes vary among residents with different socio-demographic characteristics; and (4) explore
if positive attitudes towards native species translates into planting native tree species. These
objectives are addressed through a case study of four municipalities, two with an UFMP
emphasizing native species planting, and two without, in Carolinian Canada (Ontario, Canada).
The following sections outline recent research considering native species in urban forests and
resident interactions with the urban forest, our methods and results, and the broader implications
of the relationships present between residents and native tree species.
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4.2 Native Species and Residential Actors in the Urban Forest
Typically, urban forests contain higher tree species richness than neighboring natural forests,
primarily because of the numerous non-native species regularly planted by municipalities,
residents, and other actors (Alvey, 2006; Bertin et al., 2005; Miller and Hobbs, 2002; Stewart et
al., 2004). This richness is not indicative of an even species distribution, as a few species often
dominate, some native species are not planted, and many native and non-native species are quite
rare within a given city (Clemants and Moore, 2003; Hitchmough, 2011; Kendle and Rose, 2000;
Schaeplfer et al., 2012).
The benefit of maintaining native species diversity within urban forests is contested throughout
the academic literature (Alpert et al., 2000; D’Antonio and Meyerson, 2002; Davis, 2012;
Sagoff, 2005; Sjöman et al., 2016); the multiple stressors within urban ecosystems, potential
ecosystem service benefits of planting non-native species, having a limited catalogue of native
species to fulfill ecosystem services and resilient to harsh urban ecosystems, and the uncertainty
of added environmental stressors from a changing climate raise questions about the benefits of a
native-first approach. In any case, as many municipalities are pursuing aggressive tree planting
goals alongside adoption of native species goals - often in response to loss of natural cover
(Bardekjian, Kenney, and Rosen, 2016), there is a push for all urban forest actors to plant more
native tree species in many North American cities.
Across Canada, the planting and maintenance of native tree species is the only management topic
that every existing municipalities’ UFMP has in common (Ordóñez and Duinker, 2013). The
promotion of native species in these plans is based on their contribution to ecological integrity,
75
ability to grow well in the local climate, and the known risks associated with invasive non-native
species (Almas and Conway, 2016). Though many municipalities in Canada and elsewhere are
emphasizing native species planting in their urban forests, it is unclear whether residents are
supportive of these goals or taking actions that help meet them.
Residents’ role in shaping the structure and function of the urban forest is not fully understood,
in part, because residents’ planting choices and motivations typically go undocumented.
Collectively, residents manage much of the distribution and condition of the urban forest through
the cumulative effects of many individual property-level decisions (Conway and Shakeel, 2014).
This is particularly true for municipalities that have adopted ambitious long-term management
plans to grow the urban forest, as residential planting is often explicitly needed to achieve plan
goals (e.g. City of London, 2014; Town of Oakville, 2008). Given the short history and lack of
research regarding the influence of UFMPs, it is unclear if their adoption has altered the
likelihood of residents planting a tree, much less a native tree. North American municipalities
typically do not regulate tree plantings by residents (outside of the initial development process),
or dictate which species of trees to plant. So if municipalities are going to affect the actions of
residents, they must do so through education and outreach that influence residents` attitudes and
ultimately impacts their actions. As a result, it is critical to establish a better understanding of
residential planting attitudes and actions in relation to native species, and the factors that are
related to those attitudes.
Attitude is a complex construct, formed and affected by socioeconomic, cultural and biophysical
interactions (Balram and Dragićević, 2004). Knowledge of species, interest in nature, and nature
experiences are the factors that best promote positive attitudes towards environmental issues,
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biodiversity and sustainable life style (Baur and Haase, 2015; Chawla, 1999; Corcoran, 1999;
Lindemann-Matthies, 2006; Martin, Sorice, and Kreuter, 2013; Palmberg and Kuru, 2000;
Palmberg et al., 2015; Palmer et al., 1999); these likely play a role in residents’ attitudes towards
native species in the urban forest. Residents generally express a positive attitude toward trees
(Barro et al., 1997; Jones et al., 2012; Lohr et al., 2004; Schroeder, Flannigan, and Coles, 2006;
Zhang et al., 2007), although Kirkpatrick et al (2012) documented a variety of attitudes towards
urban trees among residents in Australia. Moreover, desire for specific vegetated land covers
varies among ethno-cultural communities and ‘lifestyle groups’, and is not uniform within
income classes (Fraser and Kenney, 2000; Grove et al., 2006).
Education about urban forestry programs can affect the attitudes and actions of residents, with
people who know more about urban forestry programs (measured by the total number of forestry
services the respondent could name) more likely to support the goals of tree planting programs
by donating money (Zhang and Zheng 2011). However, efforts to increase native species
plantings that focus on consciousness-raising and attitude change are not always effective
(Summit and Sommer, 1998). Thus, residents’ native species attitudes are likely a result of
multiple factors, but may not be easy to modify.
Like attitudes, residents’ tree planting decisions are affected by a variety of factors, including
existence of tree planting policy and programs, the availability of trees from nurseries and garden
centres, preferences of influential gardeners and landscape designers, as well as residents’
attitudes (Conway and Vander Vecht, 2015; Kendal et al., 2012). For example, Kirkpatrick et al.
(2012) found residents’ attitudes about urban forest issues, including invasive species, canopy
cover and biodiversity, can affect planting actions on their property in eastern Australia.
77
Additionally, residents’ who appreciate native flora, tend to plant native flora. In a study of
residents in Perth, Australia, the attitudinal variable with the strongest relationship to garden-type
preference was residents’ attitude toward native plants (Kurz and Baudains, 2012). Preferences
were also highly related to prevailing gardening norms in respondents’ local area.
Studies regarding residential urban forest native species attitudes and actions have not been
conducted in the Eastern Deciduous Forest of North America, so it is unclear if residents will
have the same attitudes and related actions towards planting native species that residents in
Australia demonstrated.
Recent North American studies have compared residential characteristics, such as participation
in tree planting programs in relation to tree or canopy abundance (Zhang and Zheng, 2011).
Additionally, there is evidence that tree-planting actions vary among residents based on their
socio-demographic characteristics. Locke and Grove, (2016) found that municipal street tree
requests are most likely to come from relatively highly-treed neighbourhoods. Participants in
backyard tree planting programs are more likely to be white homeowners from neighbourhoods
with high socioeconomic status (Greene et al. 2011; Perkins et al. 2004), while people with
higher income and education-levels between the ages of 30 and 49 are most likely to participate
in general urban forestry activities (Fleming et al., 2006).
While attitudes, knowledge, and sociodemographic characteristics affect residents’ planting
actions and support for urban forestry efforts, it is unclear what residents’ attitudes towards
native species in the Carolinian Canada forest are, and whether or not the presence of an UFMP
and/or positive attitudes are associated with actually planting native trees.
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4.3 Methods
4.3.1 Study Area
This study was conducted in four large municipalities in the part of southern Ontario known as
the Carolinian Zone of Canada (Figures 1 and 4), which is described in detail in Chapter 1.
Residents from the municipalities of London, Hamilton, Oakville, and Markham were surveyed
to better understand attitudes and actions towards native tree species (Table 6). These
municipalities were chosen because they are relatively large urban municipalities that have
experienced two distinct patterns of growth. London and Hamilton are characterized by older
urban development, and have been among Canada’s largest municipalities since the inception of
the Canadian Census in 1871. These older municipalities have similar demographics, with
relatively low average household incomes and smaller immigrant populations than the two newer
study areas of Oakville and Markham. The Cities of Oakville and Markham have both
experienced exponential population growth in the past few decades and are two of the most
ethnically diverse municipalities in North America, primarily because of large immigrant
populations. One older (London) and one newer growth municipality (Oakville) have adopted
UFMPs (City of London, 2012; Town of Oakville, 2008), while Hamilton and Markham have
not, allowing for examination of the impacts of the UFMPs and differing demographics on
residential attitudes and actions regarding native tree species in urban forests.
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4.3.2 Resident Surveys
For this study, we used the same survey employed in the Chapter 3 study in which we surveyed
1600 residents (400 in each municipality) in the summer of 2015 about their attitudes and actions
towards native tree species. For details regarding the survey methods see Section 3.3.2. At the
beginning of the survey we defined “tree” as a woody perennial plant having a trunk greater than
10cm in diameter, and “native species” as occurring naturally within the region, either evolving
there or arriving and becoming established without human assistance, to ensure a basic
knowledge of each concept and consistent interpretation. The survey asked residents to indicate
the factors they would consider when deciding to plant a tree on their property, the current
number of trees present, recent actions related to tree planting and removal, and their knowledge
and actions related to their municipality’s UFMP if applicable. Attitude related to respondents’
level of support for native tree species in urban areas was assessed using a five-point Likert scale
for 16 statements related to the planting and maintenance of native species by individuals and
municipalities (See Appendix A). Additionally, residents’ knowledge of native tree species was
gauged, with knowledge based on the number of common street tree species’ native status the
respondent could correctly identify (Almas and Conway, in press).
4.3.3 Analysis
Basic summaries of each survey question were calculated to understand prevailing attitudes and
actions, current property-level tree conditions, and respondents’ socio-demographics. A
principal component analysis (PCA) was completed to analyze relationships among the 16
statements assessing attitudes towards native species. Given the exploratory nature of this study,
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a PCA was chosen in favour of calculating an index that would reflect the various attitudes of
residents regarding native trees, as PCA explores the discrete differences amongst the attitudinal
variables, which should be known prior to calculating an index of attitudes.
Components with eigenvalues greater than 1 were retained (Kim and Mueller, 1978), and used in
an Analysis of Variance (ANOVA) to examine the relationship between native species attitudes,
and categorical variables representing socio-demographics, presence of an UFMP, and residents’
actions. Bonferroni’s post-hoc test was used to determine significant differences between groups
when a significant relationship existed.
The relationship between planting native species, UFMP presence and sociodemographic
variables was initially examined through a series of cross tabulations using Cramer’s V as the
test statistic. In order to meet the assumptions of Cramer’s V some categories were combined to
meet the minimum sample assumptions.
Binary logistic regression was then used to further examine the factors related to having
knowingly planted a native tree. A stepwise analysis was conducted with all possible explanatory
variables, including attitudinal and knowledge based variables. It was expected that the presence
of an UFMP in a municipality would be correlated with more positive attitudes towards native
species and greater likelihood of planting a native species. It was also expected that residents
with higher household incomes would be more likely to plant native species given that wealthier
areas tend to have larger properties with larger planting areas (Gorman, 2004; Landry and
Chakraborty, 2009; Lohr et al., 2004; Zhang and Zheng, 2011) and residents with more
disposable income have more choices when it comes to planting practices, which in turn can also
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lead to opinions being formed about what constitutes “better practice” (Kirkpatrick et al., 2012).
Finally, we expected higher native species knowledge-levels and positive attitudes towards
native species would be related to actually planting native species.
4.4 Results
Of the 1600 possible respondents, 90 surveys were not successfully delivered, and 552 surveys
were completed, representing a 37% response rate. London had the highest response rate at 44%,
while Markham had the lowest response rate at 29% (Table 14). The demographic results
collected in the survey and their overall representativeness are discussed in detail in Section 3.4.
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Table 14 Summary of socio-demographic and tree planting variables, shown as percentage of
all respondents
Combined London Hamilton Oakville Markham
Education
No certificate, diploma or degree 3 2 8 1 3
High school certificate or equivalent 19 23 24 13 12
Apprenticeship, College, CEGEP 30 35 36 20 25
University Bachelor’s degree 33 22 24 49 46
Masters or Doctorate degree 15 19 8 18 15
Ethnicity
British Isles 51 64 45 67 19
European 30 30 42 19 26
Other 19 5 13 14 55
Born
Ontario 59 50 67 73 49
Outside of Ontario 41 50 33 27 51
Years at this current address
1 year or less 4 4 5 3 6
2 to 4 years 10 10 12 10 10
5 to 9 years 16 17 17 15 12
10 to 14 years 15 17 8 13 20
15 to 19 years 13 13 13 10 18
20 or more years 42 40 45 49 34
Household Income
0 to 29 000 5 6 7 5 1
30 000 to 59 000 22 24 30 16 17
60 000 to 89 000 23 21 24 29 18
90 000 to 119 000 16 17 10 23 11
120 000 to 149 000 9 6 16 10 5
150 000 to 179 000 9 12 4 8 11
Over 180 000 16 14 9 10 37
Planted a tree on your property
Yes 71 80 62 76 59
No 29 20 38 24 41
Planted a native tree on your property
Yes 36 43 31 38 26
No 64 57 69 62 74
Knowledge of native trees (correctly
identified native status)
Yes 40 44 40 35 38
No 60 56 60 65 62
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4.4.1 Native Species Attitudes
In general, respondents believe that native species are more beneficial than non-native species in
urban areas: 85% said that native species are or may be more beneficial, while only 15% did not
believe that native species are more beneficial. Based on coding of an open-ended question, the
most common reasons stated as to why native species are more beneficial are: they grow better,
better suited to climate, better chance of survival, they are resilient, they contribute to the native
ecosystem, they are healthier, and non-native trees can become invasive. In contrast, the most
common reasons given as to why native species are not more beneficial in urban areas were:
urban areas are not native, trees are trees, and variety is helpful to adapt to climate change.
While there was widespread recognition of the value of native species in urban areas, only 20%
of respondents said native status of the tree was a primary consideration when choosing a tree to
plant on their property. The most common factors were: shade provision (58% of respondents),
size and shape of tree species (54% of respondents), suits the aesthetic of their home (48% of
respondents), and maintenance requirements of the tree (36% of respondents).
Most respondents (64%) agreed or strongly agreed that their municipality should be planting
more trees, planting more native trees (65%), and that other homeowners should also plant more
native trees (52%). In contrast, only 9% thought that their municipality should plant more non-
native trees. These results are reinforced by the finding that 73% of respondents believe that
their municipality is responsible for maintaining their natural heritage, with more respondents
from municipalities with an UFMP believing (81%) that it is the responsibility of the
municipality to maintain natural heritage. However, only 19% of respondents thought that all
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varieties of native trees should be planted by municipalities if they could lead to added costs or
hazards, and 57% thought that municipalities should not plant native trees if they require extra
maintenance.
Four components were retained from the PCA (Table 15). Component 1 (general attitudes) was
associated with statements that captured attitude towards native tree species issues, with more
positive values related to preference for selecting native species and considering them beneficial.
The statements associated with municipalities and homeowners not needing to plant more trees
were most highly, positively loaded on component 2 (no tree planting). Component 3 (reduced
hazards and future conditions) is associated with statements about tree hazards and practicing
assisted migration. The fourth component (plant all natives) represents the statement: all
varieties of native trees should be planted by the municipality, even if this leads to greater
hazards and/or maintenance costs. It is interesting that this statement was only weakly
associated with the first component, which is most strongly correlated to all other statements
related to valuing and planting native species; support to plant all species of native trees
regardless of hazards and costs differs from generally appreciating native species and believing
that homeowners and municipalities should plant them.
Based on the ANOVA (Table 16), general attitudes towards native species (Component 1) is
strongly related to education and place of birth. Specifically, respondents with higher education-
levels, and those who still live in their municipality of birth or those born in Ontario are more
likely to have positive native species attitudes. Additionally, place of birth is positively related
to the idea that homeowners and municipalities should be planting more trees (Component 2).
Immigrants were more likely to feel that homeowners and municipalities do not need to plant
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more trees (Component 2), but were also more likely to be in favour of planting all varieties of
native trees (Component 4), even if it leads to greater hazards and maintenance costs. Results
from Component 3 (reduced hazards and future conditions) were not significantly related to
place of birth. Importantly, the ANOVA indicated no significant relationships between the
presence of an UFMP and attitudes towards native tree species.
Knowledge of native tree species had a mixed relationship with being in favor of planting all
natives (Component 4). Those who correctly identified the native status of 1 to 3 (out of 12) tree
species were more likely than those who could not correctly identify any species to support the
planting of all native species, while respondents who were able to correctly identify more than
three native tree species did not strongly support planting all natives. Finally, residents who
were aware that their municipality is located in Carolinian Canada were more likely to have
positive attitudes towards native species (Component 1), and believe that more trees should be
planted by homeowners and the municipality (Component 2).
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Table 15 Principle components analysis of native tree species attitude questions
Components
Statements
General
attitudes
1
No tree
planting
2
Reduce
hazards and
future
conditions
3
Plant all
natives
4
Natives are more beneficial in urban areas 0.65 -0.03 -0.192 -0.123
I do not consider nativeness when
planting -0.476 -0.062 0.418 0.365
I want my neighbours to plant native 0.706 0.088 -0.09 -0.059
Two similar trees: native over non-native 0.697 0.151 0.031 -0.071
I Prefer native 0.751 0.306 -0.01 0.014
I prefer a native street tree 0.792 0.213 0.009 -0.003
City should plant more natives 0.728 -0.057 0.084 0.125
Homeowners should plant more natives 0.766 -0.069 0.032 0.118
City should plant more non-native -0.563 -0.008 0.216 0.319
City doesn’t need to plant more trees -0.352 0.767 0.138 0.034
Homeowners don't need to plant more
trees -0.337 0.788 0.091 0.046
Only plant natives that grow well 0.545 0.273 0.323 0.023
City is responsible for natural heritage 0.587 -0.07 0.287 0.312
Plant all native species 0.21 0.053 -0.237 0.784
Don’t plant native trees that have hazards 0.083 -0.023 0.707 -0.388
Practice assisted migration 0.217 -0.31 0.595 0.154
Initial Eigenvalues 5.236 1.570 1.398 1.179
% of Variance 32.725 9.811 8.739 7.368
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Table 16 Analysis of variance (ANOVA) with PCA components, socio-demographics, and action variables
Component 1 Component 2 Component 3 Component 4
Socio-demographics df F P df F P df F P df F P
Gender 1 2.499 0.115 1 1.211 0.272 1 0.120 0.730 1 0.165 0.685
Education 4 5.795 0.001 4 0.791 0.531 4 1.452 0.216 4 2.461 0.045
Ethnicity 2 1.488 0.227 2 2.113 0.122 2 2.485 0.084 2 2.543 0.080
Where born 3 3.133 0.025 3 3.075 0.027 3 2.542 0.056 3 4.773 0.003
Length of time at current residence 5 0.361 0.875 5 0.580 0.715 5 2.133 0.060 5 0.791 0.557
Own or rent home 1 2.381 0.123 1 0.277 0.559 1 0.366 0.545 1 0.021 0.884
Income 6 0.952 0.458 6 1.841 0.090 6 0.289 0.942 6 1.319 0.247
Number of people over 65 4 0.174 0.951 4 2.183 0.070 4 1.144 0.335 4 0.612 0.654
Number of people 45 to 64 3 0.236 0.871 3 1.269 0.285 3 0.602 0.614 3 1.047 0.371
Number of people 18 to 44 4 2.756 0.028 4 0.975 0.421 4 1.406 0.231 4 0.435 0.784
Number of people under 18 4 0.425 0.790 4 1.734 0.141 4 0.856 0.490 4 2.333 0.055
By municipality 3 1.909 0.127 3 1.108 0.346 3 2.091 0.101 3 0.050 0.985
Presence of UFMP 1 1.053 0.305 1 1.029 0.311 1 0.118 0.731 1 0.111 0.739
Knowledge and action variables
Knowledge of native species 4 1.964 0.099 4 0.313 0.870 4 1.252 0.288 4 2.841 0.024
Carolinian Canada awareness 1 28.327 0.001 1 6.980 0.009 1 0.055 0.814 1 3.785 0.052
Participated in UF activity 2 0.091 0.913 2 0.051 0.951 2 0.844 0.433 2 1.072 0.346
Knowingly planted native 1 2.175 0.141 1 0.084 0.772 1 0.382 0.537 1 0.306 0.581
Trees removed since moving 5 0.609 0.693 5 0.546 0.741 5 1.009 0.412 5 0.338 0.890
Trees planted since moving 4 0.488 0.744 4 1.938 0.103 4 1.162 0.327 4 1.999 0.094
Number of trees on property 4 0.410 0.801 4 0.514 0.725 4 0.137 0.969 4 1.051 0.380
Number of native trees on property 4 1.049 0.381 4 2.598 0.036 4 0.623 0.647 4 1.194 0.313
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4.4.2 Native Species Actions
The vast majority of respondents had planted trees on their property since moving there (72%;
Table 17). Additionally, 34% of respondents had knowingly planted a native tree on their
property, meaning that nearly half of the people who had planted trees had knowingly planted at
least one native species.
Not surprisingly, only 6% of respondents indicated that they had planted a tree with the goals of
an UFMP or forestry department in mind. However, respondents who live in municipalities with
an UFMP (London and Oakville) are more actively engaged in planting native trees, planting and
removing of trees on their property in general, and had more trees currently on their property, as
compared to Hamilton and Markham (Table 17).
Through a series of cross-tabulations (Table 18) the relationship between socio-demographic
variables and native species planting actions was explored. There was no significant relationship
between having a native species and planting with forestry goals in mind. However, having
knowingly planted a native species was related to the presence of an UFMP. Respondents’
immediate plans to plant a tree, and plans to plant a native tree were both related to their income
level, with the middle-income respondents most likely to have planting plans. Similarly, plans to
plant a tree and plant a native tree were also related to respondents’ age, with younger (18-40
year-olds) respondents most likely to have plans to plant a tree and plans to plant a native tree.
Results from the logistic regression (Table 19) indicate that knowingly planting native trees is
related to higher levels of knowledge of native trees, awareness of living in the Carolinian zone,
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and presence of an UFMP, while sociodemographics and attitudes towards native trees were not
included in the model. However, the Nagelkerke R Square value was not high (0.152), meaning
there is considerable variation in the planting variable that is not captured by the explanatory
variables.
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Table 17 Summary of respondents’ tree planting actions
Trees Planted and Removed
Number of trees planted 1 to 4 5 to 10 10+ Total:
Percentage of respondents 43% 17% 12% 72%
Number of trees removed 1 2 3 to 5 Total:
Percentage of respondents 22% 14% 24% 60%
Future Actions
Plans to plant a
tree
Plans to plant
native
May plant a
tree
May plant a native
tree
Percentage of respondents 11% 7% 31% 36%
Table 18 Cross tabulation results of action and socio-demographic variables
Age Category Gender
Highest
education Ethnicity
Where
born
Length of
residence Ownership Income
Presence
of UFMP
Knowingly planted
a native tree
Cramer's V 0.069 0.088 0.118 0.014 0.069 0.044 0.034 0.071 0.129
P-value 0.311 0.051 0.146 0.956 0.497 0.964 0.442 0.926 0.003
Plan to plant a tree Cramer's V 0.100 0.04 0.096 0.058 0.052 0.070 0.030 0.181 0.043
P-value 0.039 0.672 0.317 0.490 0.832 0.890 0.788 0.009 0.611
Plan to plant a
native tree
Cramer's V 0.109 0.034 0.100 0.053 0.051 0.073 0.012 0.188 0.044
P-value 0.018 0.753 0.262 0.593 0.843 0.853 0.966 0.005 0.589 Planted with
forestry goals in
mind
Cramer's V 0.029 0.060 0.053 0.044 0.072 0.069 0.020 0.139 0.039
P-value 0.811 0.174 0.836 0.611 0.441 0.780 0.651 0.255 0.364
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Table 19 Variables retained in the step-wise logistic regression (dependent variable =
knowingly planted a native tree)
Variable B Wald Sig.
No UFMP -0.883 11.924 0.001
Carolinian Aware 0.627 5.284 0.022
Knowledge of Trees 19.602 0.001
Knowledge of Trees (0) -2.559 18.863 0.000
Knowledge of Trees (1-3) -1.293 6.136 0.013
Knowledge of Trees (4-6) -1.370 8.032 0.005
Knowledge of Trees (7-9) -1.140 5.252 0.022
Constant 0.729 2.257 0.133
4.5 Discussion and Implications
This study examines the role of residents’ attitudes and actions towards native tree species in
light of recent urban forestry goals to increase their presence. The survey results highlight the
need for municipalities to more actively engage residents regarding the goals and targets of their
UFMPs, and to reinforce the property-level value of planting native trees and achieve resident
buy-in for these initiatives. Most residents expressed generally positive attitudes towards native
species and were overwhelmingly in favour of their neighbours and the municipality planting
more native trees, and most respondents indicated that if given the choice between two trees with
similar attributes they would choose the native tree. These positive attitudes did not relate to
having native trees on their property or to a desire to plant native species regardless of costs.
Additionally, in the event that the native trees could cause hazards or had higher maintenance
costs, then residents tended not to support them.
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There was a strong relationship between respondent’s level of education and positive attitudes
towards native tree species. This relationship between education-level and participation in urban
forest activities has been noted by others (Conway and Shakeel, 2014; Grove et al., 2006;
Heynen et al., 2006; Landry and Chakraborty, 2009; Pham et al., 2012; Tooke et al., 2010;
Zhang and Zheng, 2011; Zhang et al., 2007). Interestingly, other sociodemographic factors
commonly related to urban forest extent and participation (such as income) were not found to be
significantly related to native species attitudes in this study.
One explanation for the significance of education is that public campaigns in Carolinian Canada
against invasive species like Acer platanoides (Norway maple) and Rhamnus cathartica
(common buckthorn) have swayed opinions in favour of native trees. Similarly, the outreach,
including posted signage in the remnant Carolinian forest areas that praise the existing diversity
of native species, likely also have garnered support for native species. People with a higher
education-level are possibly more likely to have been exposed to this literature and/or understand
the broader implications.
In fact, while residents tend to believe that native species are more beneficial in urban areas, the
motivations that drive their tree planting actions are dominated by pragmatic, property-level
concerns such as the size and shape of the tree, amount of maintenance required, shade
provision, and aesthetic-value placed on the tree. This is mirrored by others’ findings that
homeowner planting is primarily motivated by aesthetics and maintenance requirements of trees
(Avolio et al., 2015; Camacho-Cervantes et al., 2014; Conway, 2016; Summit and McPherson,
1998). This dichotomy between attitudes and actions was also observed in relation to municipal
planting. Only 9% of respondents believe the municipality should plant more non-native trees,
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but surveyed residents did not prioritize native species when given the opportunity to choose the
species of tree that the municipality planted on their boulevard. This also helps explain why the
majority of residents have positive attitudes towards native trees, but do not support planting
certain species that may cause additional hazards or maintenance costs.
This pragmatic relationship residents have with native tree species reinforces others’ findings
that suggest factors such as native tree availability from nurseries and garden centres may play a
significant role in the make-up of the urban forest canopy (Brzuszck et al., 2007; Conway and
Vander Vecht, 2015; Polakowski et al., 2011; Sydnor et al., 2010). Since the majority of urban
residents acquire the trees planted on their property directly or indirectly (through contractor
sourcing) from nurseries and garden centres, their choice of tree is limited to what is in stock
(Sydnor et al., 2010), and considering the specific motivations that drive residents’ tree planting
decisions (ie: shade provision, size, shape, aesthetic), it is likely that a native tree may not be
available that meets the specific planting motivations of the resident. It is also noted that garden
centre and nursery employees are often not advocates of native tree species, and may not be able
to recommend a suitable native tree to meet residents stated requirements (Polakowski et al.,
2011).
Residents born outside of Canada indicated less support for native trees as compared to those
who live in the municipality where they were born. This relates to Almas and Conway’s (in
press) findings that immigrants are less knowledgeable about urban forest issues, while residents
who had lived at their house for over 15 years were more knowledgeable about native tree
species in particular. Johnston and Shimada (2004) argue that municipalities often lack the tools
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to meaningfully communicate with immigrants, and that terms like ‘native’ and ‘alien’ can be
offensive, discouraging further interest among immigrant populations.
Based on this study, UFMPs appear to have had some relationship to residents` planting habits,
such that they are more likely to have knowingly planted a native tree. It is unclear if this is a
result of the UFMP, a result of Oakville and London (who have UFMPs) properties having more
available planting space, or if legacy effects from historic socio-economic conditions have
affected current canopy cover patterns (Boone et al., 2010; Luck et al., 2009).
The presence of an UFMP and the availability of resources it takes to enact a plan indicate that
there is some residential buy-in to managing the urban forest in London and Oakville, though
that has not translated into a deeper appreciation for native tree species. Thus, making a
management plan is not enough to achieve a representative native tree canopy. Since the
majority of residents` actions appear to be guided by pragmatic decision-making that prioritizes
aesthetics and tree functions over nativeness, a systemic approach that involves changing the
species availability at the point of purchase (nurseries and garden centres) to represent a wider
diversity of native trees would likely alter residents` actions in favor of native species diversity,
and the pragmatic benefits of native species. A first step that municipalities can take is to require
more native species diversity and quantity in their tree-planting request for tenders from
nurseries, as municipalities are very large contracts, and this requirement should cause the
supply-side to adjust. In some instances, this type of supply-chain influence has been found to
be more effective than educating residents (Summit and Sommer, 1998). Though residents may
still choose trees based on their aesthetic and functional value, if the available nursery stock
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represents a higher number of native tree species, the ratio of native to non-native trees will
likely increase through residential plantings.
Most residents expressed generally positive attitudes towards native tree species in their yards
and in public spaces. However, if costs and risks were greater with native species, fewer
respondents were supportive of native tree planting. Moreover, having a positive attitude
towards native species did not necessarily translate into action. Given that presence of an UFMP
was not significantly related to native species attitudes, municipalities with native species
planting goals should be doing more education and outreach to ensure that residents do not just
express support for native species, but are willing to prioritize them when making species-
selection decisions. Since knowledge of native trees was related to planting native trees,
educating residents about local ecology is a good place to start. Another way of doing this is to
work with nurseries to ensure a diverse supply of native trees, so that residents can meet their
pragmatic species criteria while also selecting a native species.
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Chapter 5
Summary and Recommendations
5.1 Dissertation Summary
Municipalities are managing urban forests to provide ecosystem services, as well as to maintain
ecological integrity. Native species are prioritized in urban forest management planning in order
to meet both of these goals. The first chapter of this dissertation introduced the context, common
themes, study area, and research objectives of this study. The subsequent chapters examined the
role of native species in urban forest planning, municipal foresters’ actions regarding native
trees, and residents’ knowledge, attitudes, and actions regarding native trees and urban forest
topics. Several study methods were employed, including: interviews with municipal foresters,
coding of responses using NVivo software, examination of primary documents, a survey of
residents in four Carolinian Zone (Ontario, Canada) municipalities, and statistical analysis of
responses using SPSS and Microsoft Excel to complete the primary research in this study.
5.1.1 UFMPs, Municipalities, and the Attitudes and Actions of Municipal
Foresters Regarding Native Tree Species
Chapter 2 describes the methods and results related to municipal foresters interviews, and
UFMPs and municipal tree planting lists to establish the role of native species in recent policy
and the relationship between native species policy and practice. While academic discussions
have debated the importance of native species, it was not clear how these debates influenced
municipal policy rationales or practice. Through the case study of Carolina Canada, it was found
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that municipalities with an UFMP are emphasizing native species in planning and practice, and
considering more of the managerial aspects associated with native trees than those municipalities
without an UFMP. UFMP municipalities are also utilizing more native species than
municipalities without an UFMP and planting more native trees overall. In this regard, the
existence of an UFMP in a municipality indicates that some of the higher-level goals surrounding
native species have been successfully communicated to municipal forestry staff, who have then
implemented them. Still, most municipal tree planting lists consist of a majority of non-native
tree species with many native species not being planted by any municipality in the study. As
such, not all of the tree diversity naturally found in the Carolinian Zone of Canada is planted,
potentially leading to a high native ratio but low species richness.
Review of municipal tree planting lists shows that there is still a disconnect between the stated
preference for planting native trees in the UFMPs, and municipal foresters practice of favouring
a few versatile native species that they can depend on to survive urban stressors, rather than
planting to achieve high native richness.
While the goals of UFMPs clearly emphasize native species as a way to protect and improve
ecological integrity, there are a lack of specific targets and no formal consideration of the ways
other UFMP goals, like ecosystem service provision, may be better met with non-native species.
Similarly, though the municipal foresters generally support native tree planting, non-native
species are preferred in a variety of planting scenarios and there are more non-native species to
choose from, based on official planting lists. Thus, practice is not fully supporting native species
goals.
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5.1.2 Residents’ Level of Knowledge of Native Tree Species and Urban Forest
Issues
Chapter 3 explores residents’ knowledge of the native-status of common street tree species and
urban forestry issues in southern Ontario municipalities, to address a gap in our understanding of
residents’ relationship with urban trees. Residents are central actors in urban forest management,
yet research has only recently begun to focus on their knowledge, attitudes, and actions. The
objective was achieved through a survey of residents in four Carolinian Zone municipalities, two
with an UFMP.
Overall, native tree species are more identifiable by residents compared to commonly planted
non-native tree species, but knowledge-levels are low, with only one-quarter of the commonly
planted species correctly identified by more than half of the participants. Respondents’
knowledge was not correlated with the presence or absence of an UFMP in their municipality,
which is likely because of the short period of time that the UFMPs have been in place and poor
communication of the plans’ goals, as expressed by several survey participants, indicating a lack
of engagement. Additionally, residents of British or European origin demonstrated a higher
knowledge of urban forest topics, and residents’ length of residency was related to knowledge of
the native-status of tree species, suggesting that engagement is uneven among different
communities in the study area and that people living in a community for a long period of time
tend to be knowledgeable about and engage in community activities (Romig, 2010; Williams and
Stewart, 1998). However, there was no relationship between knowledge of tree species and place
of birth, likely due to a failure in childhood education to expose children to forest and ecosystem
issues (Palmberg et al., 2015). Finally, it was found that respondents’ knowledge is correlated
with having planted trees on their property, though it is unclear whether they were
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knowledgeable about trees’ native-status before planting, or if the experience offered the
learning opportunity.
This chapter highlights the need for better outreach to all members of the community, to ensure
basic knowledge about urban forestry topics and goals, especially if municipalities require
residents to actively support policy goals. Additionally, the findings raised questions about
communicating the importance of native species to diverse communities, including those with
high immigrant populations who may feel slighted by the terminology.
5.1.3 Resident Attitudes and Actions Regarding Native Tree Species and
Urban Forest Issues
The study conducted in Chapter 4 uses the same survey of Carolinian Zone residents as Chapter
3, to examine residents’ attitudes and actions towards native tree species to further illuminate the
role of this key actor in urban forest management. The survey results accentuate the need for
municipalities to more actively engage residents regarding the goals of their UFMPs to achieve
resident buy-in for these goals. Most residents expressed positive attitudes towards native species
and were vastly in favour of their neighbours and the municipality planting more native trees.
Additionally, most respondents indicated that if given the choice between trees with similar
attributes they would choose the native tree. However, positive attitudes did not relate to having
native trees on their property or to support for the planting of native species regardless of costs,
and in the event that native trees could cause hazards or had higher maintenance costs, then
residents showed little support for them.
100
There was a strong relationship between respondent’s level of education and positive attitudes
towards native tree species, which is similar to other urban forest studies that have noted a
relationship between education-level and participation in urban forest activities (Conway and
Shakeel, 2014; Grove et al., 2006; Heynen et al., 2006; Landry and Chakraborty, 2009; Pham et
al., 2012; Tooke et al., 2010; Zhang and Zheng, 2011; Zhang et al., 2007). Residents born
outside of Canada indicated less support for native trees as compared to those who live in the
municipality where they were born, which relates to findings in Chapter 3 that immigrants are
less knowledgeable about urban forest issues.
While the vast majority of residents believed that native species are more beneficial in urban
areas, the motivations that drive their tree planting actions are dominated by pragmatic, property-
level concerns such as the size and shape of the tree, amount of maintenance required, shade
provision, and aesthetic-value placed on the tree. This difference between attitudes and actions
was also observed in relation to municipal planting, as few respondents thought the municipality
should plant more non-native trees, but residents did not prioritize native species when given the
opportunity to choose their municipal boulevard tree. This also explains why the majority of
residents have positive native tree attitudes, but do not support planting species that could cause
additional maintenance costs or hazards.
This pragmatic relationship between residents and native trees supports findings that native tree
availability from nurseries and garden centres may play a large role in the structure of the urban
forest (Brzuszck et al., 2007; Conway and Vander Vecht, 2015; Polakowski et al., 2011; Sydnor
et al., 2010). Since the majority of urban residents acquire the trees planted on their property
from nurseries and garden centres, their choice of tree is limited to what is in stock (Sydnor et
101
al., 2010). Furthermore, nursery employees are not necessarily advocates of native tree species,
and may not have the knowledge to recommend a suitable native tree to meet residents stated
requirements (Polakowski et al., 2011).
By examining municipal planning documents, interviewing municipal foresters, and surveying
urban residents, this original research has addressed several gaps in the existing literature,
including: municipal considerations of native tree species in UFMPs, ecosystem services,
ecological integrity, and assisted migration; willingness of urban foresters to adopt the goals of
UFMPs; the role of residents in managing the urban forest and their knowledge, attitudes, and
actions regarding native tree species and urban forest issues; and, the impact of residents’ socio-
demographics on their urban forest knowledge, attitudes, and actions. By addressing these
knowledge gaps this dissertation is contributing a deeper understanding of the effects of urban
forest policy and outreach on municipal actors and residents in urban areas, while also
considering managing native species for ecosystem services and improved ecological integrity.
5.2 Recommendations for Management and Future Research
5.2.1 Management Recommendations
While this research has contributed to filling many knowledge gaps, several management and
future research recommendations have also emerged that could further contribute to
understanding native species management and urban forest policy interactions. Firstly, there is an
opportunity for municipalities to align the development of their planting lists with UFMPs stated
goals of increased native species presence to more easily achieve these goals, especially among
municipalities who have not yet adopted a management plan. Moreover, if a municipality
102
chooses to use native tree species planting to achieve ecological integrity, they should be clear
that it will require planting less common native species to ensure high native richness, so that
they are not creating a non-diverse, but a native urban forest; this may not be the same as
maximizing ecosystem services.
Another challenge associated with operationalizing ecological integrity through native species
planting is the limited availability of native species and difficulty of establishing the provenance
of the trees acquired. In Carolinian Canada, tree nurseries are often not able to meet the requests
of municipalities, limiting the species that can be planted. This is consistent with the findings of
Sydnor et al. (2010), who identified a mismatch between species urban foresters request and
those available from suppliers. This limited availability of native trees in nurseries represents an
added challenge to planting native trees and establishing local provenance. Municipalities should
explore development of local seed sources from the extant forest networks within their
community to improve their access to low-cost native trees.
Second, since the majority of residents` actions appear to be guided by pragmatic decision-
making that prioritizes aesthetics and tree functions over nativeness, a systemic approach that
involves altering the species availability at the place of purchase (nurseries and garden centres)
to represent a richer diversity of native trees would likely alter residents` actions in support of
native species diversity. A first step that municipalities can take is to require more native species
diversity and quantity in their tree-planting request for tenders from nurseries, as municipalities
are very large contracts, and this request should cause the nurseries to adjust their supply of
native trees. In some instances, this type of supply-chain influence has been found to be more
effective than educating residents (Summit and Sommer, 1998). Though residents may still
103
choose trees based on their aesthetic and functional value, if a higher number of native tree
species are available at the nursery, then the ratio of native to non-native trees will likely
increase through residential plantings.
Third, most Carolinian Zone municipalities in this study are passively practicing assisted
migration, by planting species from a more southerly zone because they are available and will
grow. Given that there are several risks associated with assisted migration, if municipalities are
practicing it then their actions should be managed thoughtfully by actively choosing which
species to translocate and monitoring their progress, rather than the more passive version that has
been widespread throughout the region.
Fourth, this study indicated a lack of effective urban forestry education and the particular need to
reach newer residents and those who have not previously planted trees. Fulfilling basic
knowledge criteria could be achieved through primary school programs that introduce students to
common urban tree species using a variety of learning methods that would likely help prepare
children to be good partners in municipal urban forestry initiatives. In addition to school
programs, municipalities should increase their use of traditional and social-media to help educate
residents about native tree species, as it can be a very effective tool for reaching new residents
(Lindgren, 2015), who it was found tend to be less knowledgeable about native tree species.
Unsurprisingly, a large-scale survey of American municipalities found that social media
communications are under-utilized by municipal governments (Graham and Avery, 2013),
suggesting its potential is not being realized. Given that presence of an UFMP was not
significantly related to native species attitudes, municipalities with native species planting goals
104
should be doing more education and outreach to ensure that residents are willing to prioritize
them when making species-selection decisions.
5.2.2 Future Research Recommendations
Future research studies are needed to understand if and to what extent preserving native diversity
is important for achieving ecosystem service provision and other goals unrelated to ecological
integrity, as well as understanding the functions and benefits that the novel assemblage of
primarily non-native species can provide to the municipality. At the same time, more native
species suitability trials must occur to determine these species’ tolerance to common urban tree
stressors and increase the usability of native trees as urban street trees. While several
interviewees commented on the high cost of species suitability trials, others suggested
coordinating and sharing this research amongst all Carolinian Zone municipalities through
existing forestry councils to reduce the burden of cost.
Similarly, municipalities lack species suitability information regarding assisted migration of
species from a more southerly zone. Keeping in mind that municipalities are bound by strict
financial and temporal budgets, this may best be achieved by partnering with colleges and
universities in the region to provide species suitability trial research and development.
Additionally, creating and investing in a municipal network that communicates the successes and
failures of planting experimental species under various growing conditions in Carolinian Canada
would eliminate the time and monetary cost of each municipality independently conducting these
trials, and as such, would be an efficient tool for operationalizing assisted migration across the
region. By doing so, municipalities could adaptively manage their urban forest, while also taking
steps to mitigate the anticipated effects of climate change.
105
The limited and uneven awareness that is reflected by survey participants in this study illustrates
a broader issue of uncertainty about how to engage with residents, particularly those who are not
already interested in urban forestry issues. Summit and Sommer (1998) described some basic
steps for engaging the public in urban forestry programs, including making the desired behavior
easy and clearly communicating the threat and actions that residents can take to address it.
While the study area municipalities are communicating with residents using tree planting
programs, the value of planting native species is still debated (D’Antonio and Meyerson, 2002;
Davis, 2012; Kendle and Rose, 2000; Sagoff, 2005; Schaeplfer et al., 2012) and there are many
instances where municipalities are choosing to plant non-native trees, making the desired
behaviour unclear, and not as simple as “plant more trees”. Thus, there is a need for consistent
messaging and future research that indicates different scenarios and methods to achieve an
effective partnership between municipal and resident actors, outlining successful methods of
municipal outreach.
In particular, reaching new residents, especially immigrant populations to facilitate their
knowledge acquisition about the local environment is a challenge. In addition, there is a need to
facilitate more positive attitudes towards native ecology amongst immigrants. Thus, cities like
Oakville and Markham, with sizable immigrant populations, may face additional challenges
about how to effectively communicate information in a way that will be inclusive. One strategy
to engage newcomers and residents of minority ethnic groups is to highlight the multicultural
nature of the urban forest itself, as common urban species originate from many parts of the world
(Johnston and Shimada 2004). However, this is at odds with management goals that emphasize
native trees. Thus, future research could help our understanding of how to effectively engage
with new residents, minority ethnic groups, and immigrant populations.
106
Future research action should also consider inclusion of apartment dwellers, as they were
purposefully excluded from this study given that they do not have space to plant trees on their
property, and as a result their knowledge, attitudes, and actions regarding native trees remain
unexamined. Similarly, to build upon the findings in this dissertation future research should
include case studies that investigate the meaning and influence of local and familiar places on
residents’ knowledge, attitudes, and actions related to native tree species, as this has been shown
to have an effect on local environmental decision-making in previous studies (Davenport and
Anderson, 2005; Gobster et al., 2007; Larson et al., 2009; Romig, 2010; Williams and Stewart,
1998). This would aid in the understanding of the complex motivations and reasoning behind
attitudes and actions as shown in this and other’s work surrounding local environmental issues.
107
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Appendices
Appendix A – Written survey distributed to residents
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