Restoration Ecology and the Conservation of Biodiversity

Basic principles of ecology have practical use for solutions

to human problems

NRES 420 Restoration Ecology

Objectives

• Human transformation of landscape created need

• Illinois – a state in great need• Restoration ecology & conservation

biology• Blending science into practice• Important ecological principles for

restoration• Practice of restoration

1999Executive Order 13112

(invasive species)

1836Steel plow invented

1800 1840 1880 200019601920

1862Homestead Act

1870’sAdvent of clay drainage tile systemsDecreased rail transportation costs

Legislation to create drainage districts

1869 Transcontinental railroad

1893First gasoline automobile

1903First flight

1923First commercial hybrid

maize

1956Interstate Highway

System

1970sEnvironmental protection legislation

1850Swamp & Overflowed Lands Act

Landscape Transformation

1800 1820 1840 1860 1880 1900 1920 1940 1960 1980

Year

0

4.8

6.4

8.0

1.6

3.2

Hectares (millions) in Illinois

Pasture

Forests

Wet Prairie / MarshDry Prairie

1800 1820 1840 1860 1880 1900 1920 1940 1960 1980

EarlySettlement

Start ofAgriculture

PrairieDrainage

DiversifiedFarming Monoculture

Otter

Bobcat

Beaver

Deer

Gray Wolf

Fisher

Mountain Lion

Black Bear

Bison

Elk

Coyote

CHANGES IN MAJOR LANDSCAPE ELEMENTS IN ILLINOIS SINCE 1800 AND IMPACTS ON SELECTED MAMMALS

Fragmentation

0-0.5 0.5-2 8-204-82-4 20-40 >40

Prairie Size (ha)

Nu

mb

er o

f S

ites

0

40

80

120

NUMBER OF HIGH QUALITY PRAIRIES REMAINING IN ILLINOIS CLASSIFIED BY SIZE CATEGORY

Number of Parcels

>240

40-240

20-40

0.4-4

<0.4

4-20

1,000 1,000,00010,000 100,000100

Are

a C

ateg

ory

(h

a)

FOREST PARCELS BY AREA CATEGORY

Habitat Lss

Invasive Species

Non-Natives in the Illinois Flora*

*2004: 961 non-native of 3,074 taxa 97 of 173 families (56%) lack non-

native taxa

1846 20041950 1986

20

10

0

30

% o

f Il

lin

ois

Flo

ra

Spread of Alliaria petiolata

Illinois in Need

• Clearly a need – – Remaining habitat:

• 0.01% prairie• 9.9% wetland• 31.4% forest

– U.S. Rank:• Indiana 48• Illinois 49• Iowa 50

Restoration Ecology

Using research to better understand ecological processes

within highly disturbed ecosystems in order to enhance their complexity and long-term

persistence

LANDSCAPEECOLOGY

ECOSYSTEMECOLOGY

POPULATIONECOLOGY

COMMUNITYECOLOGY

RESTORATION ECOLOGY

van Diggelen, Grootjans & Harris (2001)

Improving the Ecology of a Disturbed Area by:

– increase diversity in highly disturbed system – reintroduce ecosystem function – reestablish characteristic species and

community structure/function

– may have to start restoration from scratch

Ecosystem What are the goals of function restoration?

A. D. Bradshaw, “Reclamation of Land and Ecology of Ecosystems”

Ecosystemstructure

Restoration Ecology

Applying ecological principles within a social context to revitalize habitats and conserve species

ECOLOGICAL RESTORATION

LANDSCAPEECOLOGY

ECOSYSTEMECOLOGY

POPULATIONECOLOGY

COMMUNITYECOLOGY

POLICY

SOCIETY

ECONOMICS

POLITICS

Ecology Theory Relevant to Restoration• Population Ecology

– Vulnerability of small populations• Genetic depression, swamping• Metapopulation theory + MVP size

• Community Ecology• Species-area relationships

– Island biogeography theory– Problems with fragmented habitats

• Intermediate disturbance hypothesis• Succession & community assembly• Diversity-stability theory; community structure• Landscape Ecology• Ecosystem Ecology

What aspects of Population Ecology are relevant to Restoration Ecology?

• Species survival depends on • maintaining minimum viable population levels

(>500).• maintaining genetic diversity.• using locally adapted genotypes.• having a metapopulation structure with strong

source subpopulations to rescue sink ones.

COMMUNITY ECOLOGY: How is the Species-Area curve relevant?

S = c + z log Alog S = log c + z log A

S = c Az

Figure 1

How is Island Biogeography Theoryrelevant?

Near

Far

LargeSmall

Immigration

Number of Species

Rat

e (s

peci

es p

er y

ear)

Extinction

Figure 2

(From Forman, 1995)

Patch relationships: What is take-home message?

Figure 3

(D.T. Krohne, ‘General Ecology’)

Ecological Disturbance: What are its dimensions? How relate to restoration?

12

3

Figure 4

Intermediate Disturbance Hypothesis:at which level does disturbance aidrestoration?

Disturbance Rate

Smallspecies

pool

Num

ber

of S

peci

es

Competitive exclusion

Figure 5

** Entries in italics connote reversible disturbances; others represent long-term or permanent conversion of habitat.

Selected Natural & Anthropogenic Disturbances: reversible vs. permanent change?• Natural Events**

– Fire– Disease epidemic– Flood– Herbivory– Drought– Hurricane, tornado, windstorm

– Avalanche, landslide– Volcanic eruption– Ice storm

• Anthropogenic Events**– Residential development– Road, trail, railroad line– Telephone line, electrical

power line– Dam, water diversion, canal– Commercial development – Modern agriculture – Mining– Logging – Grazing

Succession• an orderly change in relative abundances of

dominant species in a community following a disturbance until a stable community (‘climax’- like predisturbance) results

1° succession begins on mineral soils 2° succession begins on soils with seeds

Succession: Species-Species Interactions How do these interactions influence community

development?– Facilitation – early species make environment less

suitable for themselves, but more suitable for later species -- nurse crops

- Tolerance - early species make environment less suitable for recruitment of similar early species, but they neither help nor hinder later species

- Inhibition - early species make environment inhospitable to later-arriving species

Early prairie reconstructions overly dominated by warm season grasses

Community Assembly• development of the ecological community• is determined by random variation in

species' colonization of a disturbed area & subsequent species interactions

Which orientation to follow?Succession vs. Community Assembly

• Succession– Deterministic– Internal interactions & environment determine

outcome

• Assembly– Stochastic– Supply of propagules determines outcome– Multiple stable assemblies

How can succession be managed to aid restoration?

General causes Contributing processes Modifying factors

Site availability Disturbance Size, severity, time, dispersion

Species availability Dispersal Landscape configuration, dispersal agents

Propagules Land use, time since last disturbance

Resources Soil, topography, site history

Species performance

Ecophysiology Germination requirements, assimilation rates, growth rates, genetic differentiation

Life history Allocation, reproductive timing & mode

Stress Climate, site history, prior occupants

Competition Competition, herbivory, resource availability

Allelopathy Soil chemistry, microbes, neighboring species

Herbivory Climate, predators, plant defenses & vigor, community patchiness

Restoration: Managing Succession

ManagingSuccession

Designed Disturbance

Controlled SpeciesPerformance

ControlledColonization

Managing Succession: in PracticeDesigned Disturbance Controlled Colonization Controlled Species Performance

Burning Burning Burning

Bulldozing, Scraping, Topsoil Mixing

Broadcast seeding, Drill seeding, Direct planting Cabling

Cabling Cutting Grazing, Excluding grazers

Chopping, Clipping Grazing Fertilization, Reducing soil fertility

Flooding & draining Fertilization, Herbicide spraying Herbicide application

Herbicide application Irrigation, Water level change Mowing, Selective cutting

Plowing Topsoiling & live soiling Irrigation, Water level change

Solarization (thermal shock) Rotovating

Soil compaction Scraping

Soil fabrics

How can community structure influence stability of restored community?

• Top-down control of trophic abundances

• Cascade effects: indirect effects extended

through multiple levels

• Can have chain of extinctions if highly

dependent

• Keystone organisms must be preserved

• Non-redundant species, key species

that maintain stability/diversity

How can Diversity Complexity Stability be enhanced?

• An increase in the structural diversity of

vegetation increases species diversity.

• Full restoration of native plant communities

sustains diverse wildlife populations.

• A high diversity of plant species assures a

year-round food supply for the greatest

diversity of wildlife

Landscape Ecology• How does the landscape context of the restoration

influence everything discussed earlier?

Spatial Principles• Large areas sustain more species than small areas. • Many small patches in an area will help sustain regional diversity.• Patch shape is as important as size.• Fragmentation of habitats, communities, and ecosystems reduces diversity.• Isolated patches sustain fewer species than closely associated patches.• Species diversity in patches connected by corridors > than for disconnected patches.• A heterogeneous mosaic of community types sustains more species & is more likely to support rare species than a single homogeneous community.• Ecotones between natural communities support a variety of species from both communities & species specific to the ecotone.

Largest patch size

Patch longevity

Disturbance frequency

Habitat requirements

Minimum Dynamic Area in Restoration Design

Ecosystem Ecology: how is it relevant?

Interactions between the biotic

& abiotic components of the

ecosystem