Likely effects of ash dieback

disease on ash woodland

structure and ground flora.

Dominic Andrew Ranson

Faculty of Development and

Society, Sheffield Hallam

University

This Dissertation is submitted in partial

satisfaction of the requirements of the Degree of

MSc. Submitted January 2014.

(Total word length, excluding References and

Appendices: 14,923)

Statement of authorship:

I certify that this dissertation is my own unaided work, and that all sources of

reference have been acknowledged.

Signature:

Contents

Page

Abstract 1

1. Introduction (Fig 1)

1

2. Literature Review (Figs 2 - 5)

3

Ash and its ecology 3

Sycamore and its ecology 5

The relationship between the two species

7

Disease outbreak and spread 8

Threat to British woodlands 9

Disease effects

10

Canopy and understory light

11

Succession

13

Impacts on existing woodland flora

14

3. Descriptions of case study woodlands (Fig 6)

15

Oxclose Wood (Sites 1 and 3)

15

Hetchell Wood (Sites 2 and 5)

17

Horselock Dale Wood (Site 4)

17

4. Survey methodology (Figs 7 - 10)

18

Canopy survey 18

Ground flora walkover survey

19

Ground flora 2m x 2m quadrat survey

19

Conceptual models of dieback scenarios

21

5. Results, analysis and scenario predictions (Figs

11 - 17) 23

Site 1 – Oxclose Wood, sycamore woodland

23

Site 2 – Hetchell Wood, ash woodland

25

Site 3 – Oxclose Wood, mixed woodland

26

Site 4 – Horselock Dale Wood, ash plantation

woodland 27

Site 5 – Hetchell Wood, ash woodland

29

Ground flora survey analysis

30

Further analysis

33

Analysis of scenario predictions

36

6. Discussion

39

Principal outcomes

39

The future of ash woodlands in the British Isles

41

Further research

43

References

Appendices

1. Site Plans

2. Canopy Survey Plans

3. Walkover Ground Flora Survey Results

4. 2m x 2m Ground Flora Survey Results

5. Scenario Predictions

6. Canopy Survey Tree Lists

7. Risk Assessment

Acknowledgements:

The author would like to thank:

Paul Holmes and the East Keswick Wildlife Trust.

The Yorkshire Wildlife Trust.

Graham Robinson, gamekeeper at Horselock Dale Wood.

Professor Ian Rotherham at Sheffield Hallam University.

Rodney Helliwell.

Abstract.

This study examines the threat to native ash woodlands in theBritish Isles, and their associated ground flora, due to theinfection of keystone tree species Fraxinus excelsior by the newlyarrived fungal disease ash dieback (causal agent Chalarafraxinea). It is considered likely that significant ash treemortality will occur, and that Acer pseudoplatanus, sycamore, maybecome dominant. The possible effects of the heavier canopyshade of sycamore on ground flora were examined by surveyingthe structure and flora of five case study woodland sites,and forecasting possible ash mortality scenarios in each. Theeffects of reduced canopy light on woodland structure andground flora diversity were then predicted for varying ashmortality over time. It was concluded that the disease willhave significant impacts on ash woodland ecosystems. The twomain ecological issues due to such canopy changes were foundto be the effects on vernal flora reproduction fromsycamore’s earlier leafing, and a 40% reduction in summercanopy light. These factors are likely to result in areduction in the diversity of associated ground flora. Itwas also forecast that ash trees will return to the woodlandsover time.

1. Introduction.

Chalara dieback of ash is a relatively new disease of the

common or European ash tree (Fraxinus excelsior), caused by the

fungus Chalara fraxinea. The ash tree itself is a native

deciduous keystone tree species in the British Isles. It is

widely distributed, particularly on soils with high base

status, and is often dominant on calcareous soils (Wardle,

1

1961). Symptoms of the disease include damage or loss of

leaves and crown dieback (see Figure 1), and can result in

tree death (Kowalski and Holdenrieder, 2009). The disease was

first

Figure 1– Leaves from ash tree infected with Chalara fraxinea

(Forestry Commission, 2013).

recorded in Poland in 1992 (Timmermann et al, 2010), and has

since spread rapidly throughout continental Europe. The first

recorded specimens of ash trees infected with Chalara fraxinea

in the British Isles were identified in saplings in tree

nurseries in February 2012, and in woodlands in October of

that year (DEFRA, 2013).

The spread of this disease in the British Isles is serious in

ecological terms, since ash (Fraxinus excelsior) is the third most

common broadleaved tree species. Ash woodlands cover over

140,000 hectares in England alone (Forestry Commission

(2012), with an estimated further 12 million trees outside

woodland areas, where ash is an important tree of hedgerows

2

and field boundaries. Ash has a lighter canopy in comparison

with other woodland trees, and hence supports a wide range of

understorey shrub species and ground flora (Rodwell, 1991;

Woodland Trust, 2012). The disease can be lethal to ash trees

of all age classes, and mortality levels are high in mainland

Europe (Pautasso et al, 2013). Thus Fraxinus excelsior and the many

organisms dependent on these trees and the woodlands they

form are under serious threat. This potential loss of

biodiversity would compound the previous loss of many elm

trees, which occupied a similar ecological niche, in these

same UK woodlands. This loss was due to Dutch elm disease in

the 1960s and 1970s (Potter et al, 2011).

Britain has a limited native tree flora, with only thirty-

five tree and tall shrub species, perhaps due to glaciations

and its island status (Peterken, 2001). This increases the

gravity of threats to important native species such as that

posed by ash dieback. It so happens that some ecological

gaps are potentially able to be filled by new arrivals. Most

relevant in this case is sycamore, Acer pseudoplatanus, a maple

from continental Europe which is very similar to Fraxinus

excelsior in many respects. Thus should ash woodlands be

seriously affected by the spread of Chalara fraxinea, a very

likely replacement for the ash trees is sycamore. It is an

introduced but now naturalised tree which occupies a similar

ecological niche to that of F. excelsior (Okali, 1966; Waters,

1992; Waters and Savill, 1991, Binggeli, 1992).

3

Several areas of ash woodland in West Yorkshire were

investigated via desk-based studies and site visits. Three of

these were selected as being suitable case study woodlands

for survey sites, as they featured good examples of ash or

sycamore woodland (or a mixture of both), were located within

a reasonable distance, and were accessible for survey work.

These were Hetchell Wood, Ox-Close Wood and Horselock Dale

Wood. A total of five survey sites were selected from these

woodlands.

Four scenarios for the disturbance of ash woodland structure

due to Ash Dieback were considered:

A - Very little effect – virtually no impact due to high

resistance to Chalara fraxinea amongst native ash trees

(Mortality 0 - 10%).

B - The disease has a piecemeal effect on ash trees,

perhaps due to genetic resistance. Sycamore succeeds in

some areas (Mortality 10 - 50%).

C - Ash saplings and regeneration ash trees die but

veteran trees are resistant. Sycamore population rises

slowly over a long time period (Mortality 50 - 80%).

D - The disease is prevalent due to low resistance in

the native Fraxinus excelsior population. Veteran trees die

and the disease remains in the woodland long-term, so

4

ash regeneration saplings continue to be lost (Mortality

80 - 100%).

2. Literature Review.

Ash and its ecology. Common ash, Fraxinus excelsior, is a

widespread native tree species in Britain, where ash

woodlands form the typical climax community on base-rich

soils. Ash can be found in almost all woodlands with surface

soil pH greater than 4.2, and is also a significant pioneer

species in non-wooded areas (Wardle, 1958). In the National

Vegetation Classification (NVC), Fraxinus excelsior is the main

tree species in woodland types W8 and W9 (Rodwell, 1991). It

is the third most common British woodland tree species, with

only oak and birch being more numerous (Woodland Trust,

2012). Ash trees in woodlands of 0.5 hectares or more in size

cover 110,400 hectares in England - 9.2% of total woodland

(Forestry Commission , 2012) In addition to this there are a

further 32,100 hectares of ash in woodland of less than 0.5

hectares (Centre for Ecology and Hydrology, 2013). Ash is

also one of the most frequently found trees in hedgerows,

parks and gardens and along roads (DEFRA, 2013). Ash woodland

is most common in the southeast of England (West Sussex, and

Hampshire in particular), in Herefordshire and

Worcestershire, and in the upland limestone areas in the

north and west of the country (DEFRA, 2013), where mixed

5

ashwoods are amongst the richest habitats and valued at a

European level (Woodland Trust, 2012).It forms a major

component of 665 Sites of Special Scientific Interest in

England and it is integral to many other sites of high

environmental value (DEFRA, 2013).

Ash regenerates almost entirely by seed, and rapidly

colonises woodland canopy gaps by dense sapling regeneration

(Grime et al, 2007). Seedlings possess a high degree of

tolerance of the shade cast by deciduous trees such as

sycamore, but tolerate poorly the shade cast by vernal field

layer plants such as Dog’s Mercury, Mercurialis perennis, which

often dominates the ground flora of ash woodlands (Wardle,

1958). As a mature tree it is relatively light–demanding

(Woodland Trust, 2012).

Figure 2 - Ash woodland floristic diversity per m2 (Grime et

al, 2007).

6

The thin canopy of ash gives less shade compared with other

woodland trees (Grime et al, 2007). Perhaps as a result of

this, ash woodland has a diverse ground flora – see Figure 2

above. The vegetative buds of the tree’s canopy begin opening

on around the 10th of May, but some do not open till the end

of May (Wardle, 1958). Most leaves are shed during October

and the first half of November, though a few persist into

December (Wardle, 1958; Grime et al, 2007). The population of

ash trees in British woodlands has risen in recent years,

often filling gaps left by Dutch elm disease (Kirby, 2012).

Ash trees have a base-rich bark which is a vital habitat for

many species of lichens and bryophytes, many of which thrived

on ash after the elm trees were lost (Woodland Trust, 2012).

The loss of ash woodlands would have a serious impact on both

the visual landscape and the function of its ecosystems.

Sycamore and its ecology. Sycamore (Acer pseudoplatanus) is the

most common European maple (Hein et al, 2008), and is present

as a non-native naturalised species in the British Isles

(Townsend, 2008). The species was introduced in the fifteenth

and sixteenth centuries from the continent, as a quicker

growing replacement for oak, and was planted throughout

Britain from the eighteenth century onwards (Anderson and

Shimwell, 1981; Jones, 1945). Typically a tree of the

mountains of southern and central Europe (Jones, 1945),

sycamore might have been present in Britain but for the

7

barrier to migration provided by the British Channel (Grime

et al, 2007) In addition it is possible that the range of the

species may be shifting further north with climate change

(Morecroft et al, 2008). It favours soil of relatively high

base status, and is often abundant on limestone. It is often

associated with ash, with the habitat ranges of the two

species commonly overlapping, although ash prefers heavier

and wetter soils (Jones, 1945).

Acer pseudoplatanus is a weedy species with rapid and effective

regeneration (Pigott, 1969), and is one of the fastest

growing broadleaved species (Hein et al, 2008). Sycamore grows

rapidly for the first 20 – 25 years, then slows and starts

producing seed, reaching peak seed production between the

ages of 40 and 60 (Hein et al, 2008). Sycamore seeds are wind-

dispersed (Townsend, 2008; Jones, 1945). The seed is

dispersed to a range of around 50 metres from parent trees

(Hein et al, 2008; Townsend, 2008), although flights of 4 km

have been recorded (Jones, 1945). Sycamore’s leaves develop

in early summer (April to June), forming a relatively dense

canopy. Shed leaf litter is quite persistent and if dense may

result in reduced ground flora diversity (Grime et al, 2007)

There are conflicting opinions in the literature on ground

flora diversity beneath a canopy predominantly composed of

Acer pseudoplatanus. The management removal of sycamore from

woodlands has often been due to the dense shade of its canopy

8

and the impact on woodland flora, as well as its non-native

invasive status (Townsend, 2008). Grime et al (1996) stated

that sycamore’s associated floristic diversity is often low

(see Figure 3) due to its heavy shade.

Figure 3 – Sycamore woodland floristic diversity per m2

(Grime et al, 2007).

It was also stated by Worrell (2013) that a predominantly

sycamore canopy, particularly in the regeneration stage,

reduces ground flora diversity - with only the most shade-

and litter- tolerant species able to thrive. A further impact

may occur on ground flora dependent on the late spring

opening of the canopy in ash woodland for growth and

reproduction (Anderson and Shimwell, 1981; Mitchell, 1992;

Grimes and Herbert, 1988).

Other research has stated that the consensus on sycamore’s

low associated ground flora is not supported by sufficient

evidence (Waters and Savill, 1991). In his review of sycamore

9

ecology, Taylor (1985) found the number of species beneath a

sycamore canopy to be intermediate between oak and ash, and

slightly more diverse than that of ash. In a separate piece

of work, Waters (1992) stated that despite the difference

between sycamore ground flora and that of other species,

labelling such differences as negative is hard to justify. He

also went on to argue that sycamore’s low associated flora

may be due to it often being found in recent secondary

woodland, which would have poor ground flora diversity

anyway.

Taylor’s review of the species (1985) concluded that Acer

pseudoplatanus competes with and potentially replaces native

species primarily in circumstances of woodland disturbance.

Townsend (2008) suggested that sycamore does not colonise

undisturbed woodland even if surrounded by established trees

producing seed for many years, but that a major disturbance

such as the death of existing woodland canopy trees will open

up areas to rapid sycamore colonisation, providing the

required seed bank is present. This occurs due to the tree’s

ability to regenerate quickly, out-competing most other

plants (Hein et al, 2008). Other work has noted that sycamore

is rarely found in pure stands (Jones, 1945; Hein et al, 2008),

for both ecological and anthropogenic reasons (Merton, 1970).

It is not mentioned in much detail in the National Vegetation

Classification, perhaps due to the fact it is an introduced

10

species. The NVC mentions the presence of Acer pseudoplatanus

in the northwest of England mainly due to climatic conditions

and high rainfall, and the possibility that after the loss of

elm it may spread (Rodwell, 1991).

The relationship between the two species. Fraxinus excelsior and

Acer Pseudoplatanus are often closely associated, and frequently

mixed together in naturally regenerated stands (Binggeli,

1992). The two species occupy a very similar ecological

niche, showing comparable environmental requirements and

growth dynamics - work has been carried out comparing the two

and their often-complex relationship (Waters, 1992; Waters

and Savill, 1991; Okali, 1966). Following disturbance in

woodland, regeneration between the two species varies

depending on environmental factors. Light intensity and soil

type determine whether regeneration in an area will be

predominantly ash or sycamore. Sycamore is at a disadvantage

on heavy and wet clay soils, where ash regenerates freely

(Jones, 1945; Okali, 1966).

Light requirements for both species increase as the seedlings

develop into mature trees. Their comparable ecological

requirements are also reflected in similar growth rates (Hein

et al, 2008). Both species commence seed production when the

tree reaches 25 to 40 years of age, and have similar

frequencies of seed production and seed dispersal methods

11

(Okali, 1966). Further competitive differences between the

two species include the fact that sycamore is less frost

sensitive, and fewer moth larvae attack its seedlings

(Anderson and Shimwell, 1981). However ash does better in

waterlogged soils, its seedlings persist longer, and its

saplings have a competitive advantage at 3 to 4 years where

their resistance to heavy shading is better than sycamore

(Anderson and Shimwell, 1981). Areas of woodland with higher

proportions of sycamore are usually found on sites which have

experienced serious disturbance and then been left unmanaged.

These include mining spoil heaps or quarries, which can

sometimes contain pure stands of sycamore (Merton, 1970).

The study by Waters and Savill (1991) showed a significant

probability that alternation of regeneration in ash and

sycamore occurs in woodlands where both species are abundant.

The majority of sites surveyed showed that where one species

was dominant, the most likely successor was the alternate

species - both species showing poorer levels of regeneration

under their own canopy. This is supported by observations by

Merton (1970), whose records from the limestone woodlands of

Derbyshire show that where young saplings occur under

sycamore they are almost always ash, despite an abundance of

sycamore seed. The conclusion reached by Waters and Savill

(1991) was that the threat posed by sycamore to British ash

woods had been exaggerated. They stated that as the abundance

12

of sycamore in an ash wood increased, the reduction of light

levels would work against the regeneration of its own

seedlings, causing the relative abundance of the two trees to

move towards equilibrium. The balance of this relationship

seems likely to be a roughly even mix of the two species,

with sycamore becoming less abundant in areas with more

waterlogged soil (Waters, 1992). The removal of a large

proportion of healthy ash trees by previously unknown factors

such as the fungal disease Chalara fraxinea was not considered in

this analysis.

Disease outbreak and spread. Ash dieback has seriously

affected a high proportion of ash trees in continental Europe

over recent years. The disease was first recorded in Poland

in 1992 (Timmermann et al, 2010) and quickly spread to other

European countries. By the time the pathogen was identified

as a new anamorphic species, Chalara fraxinea (Kowalski, 2006),

ash tree mortality had been observed throughout Poland and in

several neighbouring countries. By November 2010, 22

countries across Europe had reported the infection in their

woodlands (Timmermann et al, 2010).

Research on the incidence of Chalara fraxinea is relatively

limited, particularly regarding its occurrence in the British

Isles, due to the recent nature of the infection. Thus the

majority of the literature to date regarding the transmission

and effects of the disease is from continental European

13

countries which experienced the outbreak of the disease

several years ago. An important paper by Pautasso et al (2013)

provides a comprehensive bibliography of the occurrence and

spread of ash dieback in Europe. Other recent work details

the incidence, spread and possible resistance to the disease

(Bengtsson et al, 2013; Skovsgaard et al, 2010).

Chalara fraxinea infection starts on the leaves, usually between

June and October, then dieback and stem lesions appear in the

next growing season (Borja et al, 2011). The disease reproduces

via spore production in fruiting bodies on infected fallen

leaves and shoots, in the growing season after infection

(Timmerman et al, 2011); trees are likely to need a high dose

of spores to become infected. The fruiting bodies form better

in moist conditions, and produce spores which are then spread

by the wind (DEFRA, 2013). Spore distribution is also thought

to have occurred through the movement of infected saplings

for trade purposes.

High rates of infection and tree death have been seen in

continental Europe. In most of the affected countries, Chalara

fraxinea has resulted in the death of around 70% of all ash

trees, although this proportion varies due to the situation

and management of individual trees (Woodland Trust, 2012).

Infection severity appears to be related to tree size, with

trees of larger girth being less affected (Bengtsson et al,

2013), but the majority of infected trees have been seen to

be dead or in severe decline within ten years. Further

14

evidence suggests that few trees older than twenty years die

directly, but are weakened and will eventually die due to a

secondary cause such as honey fungus (Skovsgaard, 2010).

Young trees especially are susceptible to Chalara fraxinea, and

succumb to infection rapidly (Kowalski, 2006).

Threat to British woodlands. Modern threats to our woodlands

from tree diseases such as those which we are currently

seeing have been discussed previously (Rackham, 2008).

Another recent and well-documented (Gibbe et al, 2004; Potter et

al, 2011; Wilkinson, 1978) example of serious tree species

loss in the British Isles has been that of Dutch elm disease.

The secondary effects on woodland structure and biodiversity

of this loss of 30 million elm trees can be compared to the

predicted outcomes of ash dieback. The most current published

work on Chalara fraxinea in the British Isles includes

government guidance (DEFRA, 2013), and a survey of the

incidence of the infection in Great Britain (Forestry

Commission, 2013). Potential impacts in England have not yet

been fully assessed, but the Forestry Commission in Scotland

have produced the Worrell Report, detailing possible

secondary effects on biodiversity (Worrell, 2013). In

addition, good practice guidelines from a conservation

perspective have been published (Woodland Trust, 2012).

In February 2012 Chalara fraxinea was discovered in a

Buckinghamshire plant nursery, the first recorded incidence

15

in the British Isles (DEFRA, 2013). Its first appearance in

the wider environment occurred in October 2012 when infected

trees were confirmed in a Norfolk woodland. Around 50% of ash

saplings planted in the United Kingdom were imported until

very recent reactive legislation was put into place (DEFRA,

2013), and it appears likely that this was the origin of the

infection. Although Chalara fraxinea was first found on infected

nursery plants, its appearance on mature trees in East Anglia

and beyond implies that it has spread through wind borne

spores (Woodland Trust, 2012) from infected nursery sites and

areas planted with infected saplings. With favourable

climatic conditions, airborne Chalara spores can survive for

days and travel tens of kilometres (DEFRA, 2013). Although

there is still some conjecture about when the disease entered

the British Isles and how it has spread, these questions are

now less important as the infection seems to be here to stay.

Disease effects. The data regarding infection of European ash

trees implies that there will be some genetic resistance

within British populations of Fraxinus excelsior. Whilst there has

been a devastating loss of ash trees in Denmark, a small

fraction of their native ash trees possessed substantial

resistance to infection (McKinney et al, 2012), and in Poland

between 10 and 25% of ash trees have exhibited natural

immunity. If trees in Britain exhibit similar resistance to

those in continental Europe, a rate of up to 90% mortality

can be anticipated (EPPO, 2010; Bakys, 2013), or perhaps even

16

as low as that of 60% recorded in Lithuania (Vasaitis and

Lygis, 2008). In the British Isles, based on the available

evidence and experience from Europe and the possibility of

some genetic resistance to the disease, around 70% of ash

trees have been predicted to succumb to ash dieback (Woodland

Trust, 2012). Important factors which can influence the rate

and extent of infection include weather conditions, location

and the presence of secondary pathogens (DEFRA, 2013). Trees

do not seem able to recover from infection, but mature and

established trees can survive for long periods of time, and

some may not succumb. This could result in the full effects

of dieback not being realised for several years to come

(Bengtsson et al, 2013; DEFRA, 2013).

According to a Forestry Commission report, the disease could

be expected to reach most parts of the British Isles within a

five year time period (Worrell, 2013). This would correspond

with a similar rate of spread via wind-blown spores across

mainland Europe (EPPO, 2010). Once infection has occurred

seedlings will succumb almost immediately; young trees will

die within 2–10 years, and mature trees may exhibit dieback

over several years before dying (Worrell, 2013; EPPO, 2010;

Bakys, 2013); the end result will be a high proportion of

seriously damaged or dead trees within approximately ten to

fifteen years.

17

As there is no efficient treatment currently available for

the disease, and due to its rapid spread, it will not be

possible to eradicate Chalara fraxinea in the British Isles

(DEFRA, 2013). Woodlands composed primarily of ash are at

particular risk, and low disease resistance could result in

major loss of canopy cover (Kirby, 2012). The probable loss

of a high percentage of ash trees will go on to have a

cascade of ecological effects on ecosystems and biodiversity,

not only in woodlands but wherever ash trees are found

(Pautasso et al, 2013).

Canopy and understory light. Canopy effects are defined as

the alteration of environmental conditions, in comparison to

those of an open field, due to the influence of woodland

stands (Bentsen, 2009). In this context, the primary

influence of the canopy is its effect on light reaching the

woodland floor. This understory light is the primary limiting

factor for woodland ground flora cover and diversity (Barbier

et al, 2008). Woodland light levels also fluctuate due to

several other factors including height of the sun, angle of

incidence and cloud cover (Helliwell, 2013), but these will

be disregarded for the purposes of this study.

During the summer months the light profile under deciduous

canopies is complex, the most obvious change coming between

spring and summer when trees gain their full canopy,

resulting in much-reduced woodland light intensity (Ovington

18

and Madgwick, 1955). The effect of different tree species on

light transmittance through the canopy varies (Barbier et al,

2008). The literature detailing comparisons in understorey

light levels between Acer pseudoplatanus and Fraxinus excelsior

specifically is not as comprehensive as would be expected.

This is unusual considering the historic debate in the

British Isles over the contrasting shade canopies of the two

tree species, and possible effects on woodland ground flora.

Figures for understorey light beneath canopies of the two

species were attained from work by Helliwell (2013), see

Figure 4 below.

Species% light under an unbroken canopy

in full leaf

Fraxinus excelsior 5

Acer pseudoplatanus 3

Figure 4 - Typical figures for the amount of light beneath

trees (Helliwell, 2013).

This corresponds with work by Legner et al (2013) which stated

that the transmitted photosynthetically active radiation

under stands of Acer pseudoplatanus canopies falls into the

approximate range of 2 – 5 %, and for Fraxinus excelsior around

5%. To put this figure in context, light reaching the ground

during the winter months in woodlands with a leafless canopy

varies between 30 and 60% (Helliwell, 2013).

19

The various woodland ground flora species which will be

examined in this study differ in their optimal light

requirements (Barbier et al, 2008). This flora shade tolerance

has been defined along a gradient of nine Ellenberg Light

Values (ELVs) which are shown in Figure 5 below:

Ellenberg LightValue

Plant DescriptionBritish

WoodlandsExample

1 Plant in deep shade N/A2 Between 1 and 3 Neottia nidus-avis

3

Shade plant, mostly less than 5% relative illumination, seldom more than 30% illumination when trees are in full leaf

Mercurialis perennis

4 Between 3 and 5 Arum maculatum

5

Semi-shade plant, rarely in full light, but generally with >10% relative illumination when trees are in leaf

Hyacinthoides non-scripta

6 Between 5 and 7 Rubus fruticosus

7Plant generally occurs in well-lit places, but also in partial shade

Calystegia sepium

8Light-loving. Rarely found where relative illumination in summer is <40%

N/A

9 Plant in full light, found mostlyin full sun. N/A

Figure 5 - Ellenberg Light Values (Hill et al, 1999, modified).

Rackham (2008) stated that woodlands in England are getting

increasingly shady on average, and that this is having a

20

negative effect on biodiversity - the majority of woodland

plants being unsuited to the increased shade levels of

unmanaged woodlands. This could mean that that a reasonably

low level of dieback (perhaps up to around 20%) may have some

conservation benefits in terms of stimulating ground flora,

birds and butterflies plus the regeneration of other tree and

shrub species (Kirby, 2012).

Succession. Woodlands are under a continuous process of

reorganisation, but disturbances to woodland structure which

originate indirectly from human activity are comparatively

new to forest ecosystems (Fischer et al, 2013). It could be

said that changes due to fungal pathogens such as Chalara

fraxinea fall into this category. Should these changes result

in widespread mortality of Fraxinus excelsior, the most obvious

ecosystem-level impact will be an increase in the frequency

and intensity of such woodland disturbances (Loo, 2009). Loss

of foundation or keystone species, such as ash in this case,

can result in changes in the fundamental nature of an

ecosystem. Ellison et al. (2005) identified several tree

species which are currently being removed from woodland

ecosystems due to non-indigenous fungal invasions such as ash

dieback.

The four scenarios of succession A to D, mentioned in Chapter

1, define possible outcomes for woodlands using varying

percentages of tree mortality due to Chalara fraxinea. If many

21

mature trees are lost due to higher levels of mortality, a

short term increase in light will result in the woodland

opening up. This is likely to lead to temporary dominance by

the most competitive species of woodland flora such as

Mercurialis perennis and Rubus fruticosus, as they would no longer be

limited by canopy shade (Kirby, 2012). In the short term

these increased light levels might also benefit some bird and

invertebrate species (Woodland Trust, 2012).

Within a relatively short time period however shrubs will

thicken and grow, and a pole crop of sycamore is likely to

begin shading out the ground flora species (Merton, 1970).

The current shrub layer could also be lost at this point

through reduced light availability (Natural England, 2009).

If the original ground flora is destroyed due to this

sycamore regeneration, the rate at which it disappears will

vary with the speed at which the canopy closes. Some of the

last ground flora species remaining could include Deschampsia

cespitosa, Brachypodium sylvaticum and Melica uniflora (Merton, 1970).

Although quick-growing and abundant when young, sycamore

thins out due to competition over time (Jones, 1945) and some

other tree species are likely to emerge. After the stand has

matured and opened out, plants will begin to re-colonise the

woodland floor (Merton, 1970). The resulting ground flora is

commonly quite uniform under mature sycamore, e.g. a carpet

of Mercurialis perennis (Natural England, 2009).

22

Impacts on existing woodland flora. The change of woodland

canopy structure from ash to sycamore will impact on woodland

flora in different ways. Semi‐natural ash woodland has thehighest number of associated tree and shrub species of any

native woodland type, with a total of sixteen native trees

and shrubs (Rodwell, 1991). Although the loss of ash would be

serious, possible replacement tree species in addition to

sycamore might constitute hazel, willow, birch, and oak

(Worrell, 2013).

Ash woodland has a very diverse ground flora of herbs,

grasses and ferns. The National Vegetation Classification

lists approximately eighty associated ground flora species,

in comparison to around sixty for oak‐birch woodlands

(Rodwell, 1991). Flowering plant communities in woodlands can

be quite robust - the appearance of canopy gaps as a result

of Chalara may not significantly affect ground flora diversity

in the long term, but would perhaps change species

composition (Worrell, 2013). Ash is also an important host

for epiphytes, on bark and deadwood and as a component of the

woodland ground flora. Its base‐rich, water-retentive barksupports different communities to other species such as oak,

birch and alder (Kirby, 2012; Worrell, 2013). The more

generalist or mobile of these may be able to find alternative

host tree species, but those more reliant on ash may face a

23

co-extinction risk, perhaps having recently suffered habitat-

loss due to the disappearance of elm trees (Woodland Trust,

2012).

3. Descriptions of case study woodlands.

When selecting woodland sites for primary data collection, it

was decided to attempt a comparison of woods with similar

topographical situations and history. Ideally two different

parts of the same woodland could be chosen, so that

comparisons could be made between the two. Five suitable case

study sites were identified, including woodlands in which

both Fraxinus excelsior and Acer pseudoplatanus were dominant, and one

with a mixture of both species. Each of the five survey sites

consisted of a square tract of woodland 30 x 30 m (900 m2) in

size. Due to the limitations on time and resources presented

by an MSc dissertation project, sites which were possibly

more suitable but further afield were excluded. The five

sites chosen were located in the three woodlands detailed

below - see Appendix 1 for plans of these woodlands. Full

descriptions of the individual sites surveyed can be found in

Chapter Five.

Oxclose Wood (Sites 1 and 3).

24

Location: A 14 hectare wood approximately 16 km northeast of

Leeds, between a curve of the river Wharfe and the A659 road.

Grid Reference: SE 36829 46376 (Centre of wood).

History: Until recently the wood was owned by the Harewood

Estate, and it was planted as a mixed conifer and broad leaf

plantation. During 1990, twenty acres of timber were

extracted. The woodland was subsequently purchased by the

East Keswick Wildlife Trust in 1993, and the felled areas

were left to regenerate naturally (EKWT, 2011).

Designation: SEGI (site of ecological and geological

importance).

Description: Underlying the woodland soil are two different

rock formations. To the north adjacent the river Wharfe is

Millstone Grit, while the southern and higher part of the

woodland is on Magnesian Limestone. Soils are acidic on the

sandstone and alkaline on the limestone, and the fertile

alluvium-based soils at the north-eastern boundary are

derived from the deposits of the River Wharfe (EKWT, 2011).

25

Figure 6 - Corner of 30m x 30m quadrat, Oxclose Wood sycamore

woodland. Site 1.

The wood is composed of mature broad-leaved woodland and

young regenerating woodland, predominantly W8 and W10

communities from the NVC (Rodwell, 1991). The area where case

study Sites 1 (see Figure 6) and 3 are located was not clear-

felled in the 1990s, and consists of mature and semi-mature

ash, sycamore, oak, small-leaved lime and alder (EKWT, 2011).

Both case study sites are on the rich alluvium based soils

adjacent to the river. It appears that Oxclose Wood may be

ancient woodland, although it has recently been used at least

partially as a plantation, and in fact may have been cleared

and replanted more than once by the Harewood Estate. There

has been woodland on the site at least as far back as the

1850s (Digimap, 2013). The name itself implies an old

woodland site, as does the fact that it is on sloping ground

near the river Wharfe. There are examples of oak trees in the

woodland which are several hundred years old. Ground flora

26

ancient woodland indicator species present include Allium

ursinum, Anenome nemorosa and Veronica montana.

Hetchell Wood (Sites 2 and 5).

Location: An 11.8 hectare woodland 11 km northeast of Leeds

and just southeast of the village of Bardsey-cum-Rigton. Grid

Reference: SE 37982 42285 (Entrance from Milner Lane,

southeast corner of site).

History: The area has been wooded since at least 1600 and the

woods are probably much older than this date (YWT, 2012).

Some parts of the woods were once used for quarrying, and

there is a mature beech plantation at the eastern end.

Designation: SSSI (Site of Special Scientific Interest) for

its ecological interest.

Description: The underlying geology of the area consists of

the boundary between the overlaying Magnesian Limestone and

Gritstone, with the woodland sited over both of the rock

types. The woodland on the limestone area is predominantly

W8e ash woodland – the Geranium robertianum sub-community (YWT,

2012; Rodwell, 1991) It is considered ancient woodland (YWT,

2012), and has ground flora that reflects this, including

Hordelymus europaeus, Sanicula europaea, and Veronica montana (Rose, F.,

1999).

27

Horselock Dale Wood (Site 4).

Location: A 12 hectare woodland lying just south of Claypit

Lane, Kippax. It is 16 km east of Leeds, near the village of

Ledsham. Grid Reference: SE 44933 29088 (Centre of wood).

History: Horselock Dale Wood has been present on the site

since at least the 1850s (Digimap, 2013). No records were

found of the area being used for any other purpose than

forestry.

Designation: No known designation for conservation purposes.

Description: This woodland is currently a commercial

plantation, on the site of what is probably ancient woodland,

as indicated by the presence of indicator species such as

Melica uniflora, Chrysosplenium oppositifolium and Primula elatior

(Anderson and Shimwell, 1981; Rose, F., 1999). It is situated

on the same Magnesian Limestone as the other woodlands

studied (Digimap, 2013).

4. Survey methodology.

In order to collect the primary data required to construct

models of dieback scenarios, canopy and ground flora surveys

were carried out at five case study sites. For each site, a

30m by 30m quadrat was plotted to record a representative

28

area. In each large quadrat, canopy and walkover ground flora

surveys were carried out. Then localised ground flora surveys

were carried out using five 2m x 2m frame quadrats per site

and standardised survey methodology (Hill et al, 2005; Rose,

2011) to determine species types and coverage. The data was

then tabulated for each site (see Appendices 2, 3, 4 and 6).

Sites with abundant A. pseudoplatanus were surveyed first, since

their earlier and heavier canopy shade may have resulted in

early disappearance of ground flora. Surveys were carried out

between 7th June and 14th July. Before embarking on any work in

the field, a full risk assessment was carried out, see

Appendix 7.

Canopy survey. A 30m squared area (900m2) was marked out

using poles and measuring tapes, and a canopy survey was

carried out (see Figure 7 below) to give an idea of tree

distribution. Within the marked tracts, each tree or shrub

over one metre in height was recorded. Tree species, diameter

at breast height (1.3 m) and tree height were noted (see

Appendix 6). Diameter at breast height was measured with a

tape. Several trees had multiple trunks below chest height,

so the thickest was recorded. Tree heights were estimated by

measuring prominent trees using a simple clinometer, and

using this data to extrapolate the heights of trees nearby.

Target notes were recorded, with photographs, of any points

of interest. Rough sketches were made of site cross-sections

29

and photographs taken along the quadrat edges to build up an

idea of the profile and structure of the woodland.

Figure 7 - Site cross-section, Hetchell Wood ash woodland.

Site 2.

Ground flora walkover survey. A rough description was made of

the overall structure of the woodland, how layered it was,

and whether there was a strong shrub layer. The diversity of

the trees was noted, and whether they were of even age. The

amount of dead wood was also documented, both standing and on

the ground, along with the general ground flora coverage.

Again, any interesting points were highlighted with target

notes and photographed. The abundance of each ground flora

species found on the site was recorded using the DAFOR scale,

which was chosen as it gives a rapid assessment (Hill et al,

2005). The entire 30m x 30m square was walked through,

ensuring the whole quadrat was covered, and an overall score

given for coverage of each ground flora species, e.g.

Mercurialis perennis: Dominant. Although this method can be quite

30

subjective, it was considered suitable in this case due to

its simplicity and functionality. Any flora initially

unidentified was photographed and in some cases sampled for

later identification. Plants found were classified using

standard identification texts (Rose, 1981; Hubbard, 1992). A

full species list was recorded for each 30m x 30m quadrat,

and this can be found in Appendix 3.

Ground flora 2m x 2m quadrat survey. The site was inspected

and different communities or stand types were visually

identified, then five 2m x 2m ground flora quadrats were

targeted within those areas, see Figure 8. Ground flora under

one metre in height was recorded using the DOMIN method (Hill

et al, 2005) as this technique gives more information than the

DAFOR method. General notes and photographs were taken of the

flora in the quadrats, and any interesting features.

Figure 8 - Sample quadrat. Oxclose Wood sycamore woodland,

Site 1.

31

Again, for any plant initially unrecognised in the quadrat,

sample photographs were taken for later identification and

flora was identified using standard texts (Rose, 1981;

Hubbard, 1992). A full species list was recorded for each 2m

x 2m quadrat, and can be found in Appendix 4. The canopy

cover above each 2m x 2m quadrat was visually assessed and

scored according to the scale in Figure 9 below.

CanopyScore % Canopy Cover0 No Cover1 0 - 10%2 10 - 20%3 20 - 30%4 30 - 40%5 40 - 50%6 60 - 70%7 60 - 70%8 70 - 80%9 80 - 90%10 90 - 100%

Figure 9: Canopy cover scoring system (Waters and Savill,

1991, modified).

Conceptual models of dieback scenarios. The survey data

recorded was used alongside information from the literature

to create conceptual models for the range of dieback effects

in ash woodlands, as presented in Figure 10. These effects

will vary with pathogen range, host susceptibility, and rates

of infection and death, as mentioned in Chapter 2. The models

32

are not designed to give specific answers, but will predict

the successional possibilities of the woodlands at different

stages.

Figure 10 – Ash Dieback scenarios (Pautasso et al, 2013).

The four scenarios chosen to represent varying ash tree

mortality in woodlands due to Chalara fraxinea infection were:

A - Very little effect – virtually no impact due to high

resistance to Chalara fraxinea amongst native ash trees

(Mortality 0 - 10 %).

B - The disease has a piecemeal effect on ash trees,

perhaps due to genetic resistance. Sycamore succeeds in

some areas (Mortality 10 - 50 %).

C - Ash saplings and regeneration ash trees die but

veteran trees are resistant. Sycamore population rises

slowly over a long time period (Mortality 50 - 80 %).

33

D - The disease is prevalent due to low resistance in

the native Fraxinus excelsior population. Veteran trees die

and the disease remains in the woodland long-term, so

ash regeneration saplings continue to be lost (Mortality

80 - 100 %).

For the purposes of calculating how many mature ash trees in

a model succumb to the disease in each scenario, the

percentage mortality used was midway between the two ends of

the range, i.e. Scenario C: 65% mortality.

In each scenario, along with the present day situation,

predictions were made regarding the future structure of the

woodlands after time periods of 50 and 150 years. The present

day, or a time period of “0”, is a representation of the

baseline data collected from surveys of the five sites. The

second time period of 50 years was chosen because both

sycamore and ash trees are considered fully mature after 40

to 50 years (Jones, 1945; Wardle 1958). The final period of

150 years was chosen since after this amount of time has

passed, the full impact of the disease will have been seen,

and the process of succession from ash woodland will be

complete. Depending on infection rates and levels of genetic

resistance, after the full 150 year time period resistant

strains of ash may have started to return.

Another factor considered when constructing these models was

the presence of a seed bank, i.e. sycamore trees on the site

34

or nearby. Seeds of A. pseudoplatanus are able to easily travel

50m and more (Jones, 1945), and are produced in large numbers

from mature trees, so even a single tree in the quadrat could

provide a sufficient seed bank. Soil moisture is also

important as sycamore is unlikely to colonise waterlogged

soils (Jones, 1945). Other tree species apart from sycamore

were also considered as possibilities for succession,

depending on environmental conditions, e.g. birch, willow,

oak and wych elm. It should be noted that the timescale of

the eventual return of ash due to genetic resistance and the

alternation process (Waters and Savill, 1991) is in no way

certain, and is only an estimate. Concerning the shrub layer,

from the survey data hazel and holly appeared to thrive under

sycamore. Blackthorn, hawthorn and elder appeared to do well

beneath an ash canopy. In addition, general observations from

the sites surveyed seemed to indicate that the shrub layer is

sparser beneath a canopy of sycamore.

Consequently a total of twelve cross-sections of woodland

structure were drawn up for each of the five sites surveyed.

The basis for this idea was that used by Jones in Sheffield’s

Woodland Heritage (1989). Each cross-section is composed of

three sections across the 30m x 30m quadrat, in order to get

a more representative idea of the woodland structure, and

these models can be found in Appendix 5.

35

Retrospective notes on methodology. The study was perhaps not

carried out at the optimal time of the year for accurate

ground flora survey work. It is likely that the surveys were

too late for the flowering of some spring species. The work

would have been better carried out a month or two earlier, in

May and June. Also, July 2013 saw a prolonged dry period

which could have affected the ground flora in the last two

sites, particularly as they were on well-draining limestone.

Data collection went reasonably well, but the speed and

accuracy of flora identification could have been improved by

having a second opinion. The useful survey data for

specifically ash woodlands was limited to Sites 2 and 5, both

at Hetchell Wood. Site 3 was a mix of the two species and

Site 4 had an incomplete canopy, so although both were useful

in some respects, they did not provide suitable ash woodland

ground flora baseline data. Therefore more sites for ash

woodland might have been useful, to provide larger data sets

for woodland ground flora diversity. A further sycamore

woodland site would have been useful for similar reasons. The

visual scoring of canopy cover above each 2m x 2m quadrat may

not have been necessary, as it was not used in the final

analysis.

5. Results, analysis and scenario predictions.

36

Site 1 – Oxclose Wood, sycamore woodland (7th and 9th of June,

2013).

The 30m x 30m canopy survey quadrat was fixed approximately

30 metres south of the river Wharfe, on an area of level

ground (see Appendix 1 for woodland area map). This location

was selected as the woodland here was predominantly composed

of Acer pseudoplatanus. It was difficult to classify this site

according to the NVC, mainly because sycamore woodland is not

included due to its non-native status (Rodwell, 1991).

Site 1 canopy survey. See Appendix 2 for the tree survey

diagram. The trees in the quadrat were mostly mature

sycamore, with some mature ash trees and a single unhealthy

oak. They appeared to be of approximately even age, and their

canopy was relatively dense (see Figure 11 below), with

complete coverage except for a small open area caused by a

recently fallen tree.

37

Figure 11 – Sycamore canopy, Oxclose Wood, Site 1.

Site 1 walkover survey. The shrub layer consisted of Ilex

aquifolium, Prunus spinosa, Crataegus monogyna, and Corylus avellana.

This layer was variable in density across the quadrat, with

some quite open areas, and a dense patch of P. spinosa where

the canopy was mainly F. excelsior. In the southeast of the

quadrat there was significant bramble coverage, possibly due

to an increase in light caused by the fallen tree. Ilex

aquifolium appeared to occur predominantly in sycamore canopy

areas. The difference between the shrub and canopy layers was

quite distinct, with few large shrubs or small trees falling

into an intermediate height category. Little significant dead

wood was recorded either on the ground or standing, except

the fallen ash tree in the southeast of the quadrat.

The site walkover ground flora survey results are available

in Appendix 3. Sixteen ground flora species were recorded in

the large quadrat: a low species diversity total in

comparison to the other sites surveyed. The general walkover

survey for ground flora showed Rubus fruticosus to be dominant

rather than Mercurialis perennis. Other ground flora species

showing significant coverage included Allium ursinum, Anenome

nemorosa and Hedera helix. There were also significant areas of

bare ground, particularly under the sycamore canopy. Anemone

nemorosa was still visible as the survey was carried out

38

relatively early - this species may not have been recorded in

later surveys as the plants are likely to have died back.

Site 1 ground flora quadrat survey. See Appendix 4 for the 2m

x 2m ground flora survey results. The smaller quadrats were

positioned to cover the dominant flora types in the 30m

squared area. Areas targeted included those dominated by

Rubus fruticosus (A and C), Mercurialis perennis (E) and Prunus spinosa

((D) along with an area of much sparser flora (B). The ground

flora diversity was reasonably high and quite consistent,

ranging between seven and nine species per quadrat. There was

little variation between the quadrats, corresponding with the

low diversity data from the walkover survey. Extremely

dominant Rubus fruticosus (quadrat C) seemed to result in

slightly less diverse ground flora. The only other notable or

unusual species was Oxalis acetosella in quadrat A.

Site 2 – Hetchell Wood, ash woodland (18th and 19th of June,

2013).

The large 30m x 30m quadrat was marked out just south of the

main path through the woodland, approximately 200 metres

south of Hetchell Crags (see Appendix 1 for woodland area

map). The site was chosen as it was the largest area of

predominantly ash woodland near the road not interrupted by

fences, walls, major paths or uneven ground. This area of

woodland was classified as W8e (Geranium robertianum sub-

39

community) in the reserve management plan (Rodwell, 1991;

YWT, 2012) but as very few examples of this species were

recorded, could be simply referred to as W8 Fraxinus excelsior –

Acer campestre –Mercurialis perennis woodland.

Site 2 canopy survey. See Appendix 2 for the tree survey

diagram. The high-level canopy was almost exclusively formed

by F. excelsior. Other mature tree species present were Acer

campestre, Ulmus glabra and several large specimens of Crataegus

monogyna. Additional single trees of Acer pseudoplatanus and

Taxus baccata were recorded. The trees forming the main canopy

were mostly mature and of even age. Canopy cover was complete

but less dense than that seen at Site 1, as would be expected

from ash woodland.

Site 2 walkover survey. The site was a characteristic example

of W8 ash woodland, with a light canopy and many mature ash

trees. The shrub layer was sparse in the eastern half of the

site where it was mainly composed of Crataegus monogyna with

some Corylus avellana, while to the western side it increased in

thickness with a high density of Prunus spinosa and some

Sambucus nigra. There was significant foliage in the

intermediate canopy layer due to a combination of smaller

trees and larger shrubs. A considerable amount of dead wood

was recorded, including both standing and fallen trees. See

Appendix 3 for the site walkover ground flora survey results.

Ground flora on this site could be considered diverse, with a

40

total of twenty three ground flora species recorded in the

large quadrat. Coverage primarily consisted of dominant

Mercurialis perennis across the survey area. Other species

recorded as frequent were Hyacinthoides non-scripta, Allium ursinum

and Hedera helix.

Site 2 ground flora quadrat survey. See Appendix 4 for the 2m

x 2m ground flora survey results. The quadrats A, B, C and E

were placed randomly using a random number generator, as

ground flora seemed uniform due to the carpet of Mercurialis

perennis. One quadrat (D) was placed in the area of dense Prunus

Spinosa. The quadrats varied wildly in their diversity, from

four species in quadrat E (possibly due to very dominant

Mercurialis perennis) to eleven species in quadrat A. Flora of

interest included the orchid Neottia ovata, Sanicula europaea,

Lamiastrum galeobdolon and the gooseberry Ribes uva-crispa, all of

which are characteristic of W8 ash woodland (Rodwell, 1991).

Site 3 – Oxclose Wood, mixed woodland (2nd and 3rd of July,

2013).

The 30m by 30m quadrat was plotted on level ground 100m south

of the river Wharfe (see Appendix 1 for woodland area map).

This specific area was selected as it featured stands of A.

pseudoplatanus (to the north) and F. excelsior (to the south), and

it was hoped that comparisons might be drawn between the 2

types of woodland in the same survey site. The woodland could

41

be described as W8 ash woodland, as A. pseudoplatanus is not

fully considered in the NVC (Rodwell, 1991), but the sub-

community was hard to determine.

Site 3 canopy survey. See Appendix 2 for the tree survey

diagram. The major trees on the site were of young to medium

maturity, with only ash and sycamore being present. The

canopy was even and complete, although denser to the north of

the quadrat due to the presence of A. pseudoplatanus, including

some slightly older trees.

Site 3 walkover survey. A footpath ran north to south on the

eastern side of the quadrat, and this was where some of the

ground flora less-characteristic of woodlands, such as Lamium

album and Galium aparine, were recorded. There was a newly

created ride to the south, around five metres from the

quadrat’s southern edge. The shrub layer was quite sparse,

comprised mainly of F. excelsior saplings, Crataegus monogyna and

Corylus avellana. The intermediate layer of foliage formed from

young trees and large shrubs was relatively thick. The more

mature A. pseudoplatanus trees and widespread F. Excelsior saplings

present supported the theory of alternation between the two

species - no sycamore saplings were recorded, and the ash

seemed to be regenerating under the sycamore canopy (Waters

and Savill, 1991). Significant amounts of fallen dead wood

were recorded in the quadrat area. The ground flora to the

south of the quadrat adjacent to the ride was dominated by

42

Rubus fruticosus. Mercurialis perennis was abundant, but not dominant

as in other sites surveyed. Other common species noted

included Hyacinthoides non- scripta, Allium ursinum, Hedera helix and Geum

urbanum. See Appendix 3 for the site walkover ground flora

survey results. A total of nineteen ground flora species

were recorded in the large quadrat, indicating somewhat low

overall diversity. There were some bare patches in the

northern half of the quadrat, possibly due to badger activity

or the heavy shade caused by the dense sycamore canopy with

hazel understorey. The ground was quite uneven in places, and

there was a dense overall canopy effect due to thick

understorey layers.

Site 3 ground flora quadrat survey. See Appendix 4 for the 2m

x 2m ground flora survey results. The quadrats were placed

roughly evenly around the site, while attempting to gain a

representative picture of the different flora present in the

area. One was placed in the centre of the sycamore canopy

area (quadrat B), one by the footpath (quadrat C), two in the

ash canopy area (quadrats A and D) and one in an area of

dense ash sapling regeneration (Quadrat E). In terms of

number of species per 2m x 2m quadrat, Site 3 had the lowest

diversity of all five surveys, ranging from four to nine

species. The high frequency of Galium aparine was unusual when

compared to the other sites surveyed.

43

Site 4 – Horselock Dale Wood, ash plantation woodland (9th and

10th of July, 2013). The large 30m x 30m quadrat was placed

just to the north of the main footpath through the wood (see

Appendix 1 for woodland area map). This particular location

was chosen as it was a uniform ash woodland with easy access

for survey work. The woodland appeared to be a commercial

plantation, half the trees having been recently felled

resulting in an incomplete canopy. In terms of NVC

classification, this site conformed to the W8c Deschampsia

cespitosa sub-community (Rodwell, 1991).

Site 4 canopy survey. See Appendix 2 for the tree survey

diagram. All the ash trees present were of equal age and

approximately equal spacing, as might be expected in a

plantation woodland (see Figure 12 below). No other mature

trees were recorded in the quadrat. The canopy coverage was

only around sixty to seventy percent, with many large gaps

where trees had been recently felled.

44

Figure 12 – Ash plantation with incomplete canopy. Horselock

Dale Wood, Site 4.

Site 4 walkover survey. This site was quite waterlogged in

places, especially in the southern half of the quadrat. The

ground towards the northern edge of the quadrat sloped up

quite steeply, while the southern edge was located just north

of a footpath running east to west. There were no large

shrubs present, the majority of the sparse shrub layer being

composed of F. Excelsior saplings, particularly to the eastern

side of the quadrat. Otherwise there were only a few

scattered Crataegus monogyna, Corylus avellana and Sambucus nigra, as

the succession process post-felling had only just recently

begun. There was very little dead wood present in the

quadrat. See Appendix 3 for the site walkover ground flora

survey. General ground flora coverage again consisted of

45

abundant Mercurialis perennis, although this species was not

completely dominant due to competition with Deschampsia cespitosa.

A very diverse total of 26 ground flora species was recorded

in the large quadrat, several of the species being plants

suited to more open conditions which had sprung up due to

canopy gaps. Examples of these included Geranium sanguineum,

Prunella vulgaris and Chamerion angustifolium.

Site 4 ground flora quadrat survey. See Appendix 4 for the 2m

x 2m ground flora survey results. Quadrat E was placed on the

sloping area of ground to the north of the area. The other

four quadrats were positioned randomly using a random number

generator, due to the apparent uniformity of the ground flora

cover on initial inspection. These quadrats were the most

diverse of the five sites studied in terms of species

numbers, ranging from nine to twelve species per quadrat.

Apart from those mentioned above, other species of interest

included Chrysosplenium oppositifolium and Lysimachia vulgaris, both of

which are adapted to wetter soil conditions in addition to

lower levels of woodland canopy shade (Rose, 1981).

Site 5 – Hetchell Wood, ash woodland (13th and 14th of July,

2013).

The 30m squared canopy and walkover survey quadrat was placed

approximately 100 metres west of the eastern car park

entrance to the wood (see Appendix 1 for woodland area map).

46

This location was selected as it was clearly W8 ash woodland

and within easy access of the main point of entry to the

wood. Again, the site management plan lists the area as

belonging to the W8e Geranium robertianum sub-community

(Rodwell, 1991; YWT, 2012) but as very few examples of this

species were recorded, it can be referred to simply as W8 ash

woodland.

Site 5 canopy survey. See Appendix 2 for the tree survey

diagram. Tree species commonly characteristic to W8 woodland

were present, i.e. Ulmus glabra and Acer campestre, and there

were three specimens of Acer pseudoplatanus to the eastern edge

of the survey area. Most of the trees present were mature and

of comparatively even age, as could be expected from an area

of ancient woodland (YWT, 2012).

Site 5 walkover survey. The ground on this site was quite

uneven, perhaps due to prolonged badger activity. There was

an old badger sett in the northwest of the quadrat and

several paths in the area. A footpath ran east to west just

south of the southern edge of the quadrat. There were several

fallen trees, with corresponding gaps in the canopy -

possibly due to Dutch elm disease. Areas of mature beech

plantation were noted just to the north and east of the

quadrat. The shrub layer was diverse with widespread Crataegus

monogyna of varying ages, as well as several Sambuca nigra and

slightly fewer Corylus avellana present. A comparatively diverse

47

total of 21 ground flora species was recorded in the large

quadrat - see Appendix 3 for the walkover ground flora survey

results. Once again the characteristic carpet of Mercurialis

perennis was dominant, other common species on this site being

Rubus fruticosus, Hyacinthoides non-scripta, Allium ursinum, Geum urbanum and

Brachypodium sylvaticum. Less shade-loving species such as

Anthriscus sylvestris and Rumex acetosa were found adjacent to the

main footpath where there were some gaps in the canopy.

Site 5 ground flora quadrat survey. See Appendix 4 for the 2m

x 2m ground flora survey results. These smaller quadrats were

placed roughly evenly around the Site 5 survey area, with

quadrat E in a shaded low-lying ditch, D adjacent to the main

footpath, and A, B and C targeting areas of ground flora away

from any recognisable features. Species diversity was

relatively low in these quadrats in relation to the other

sites surveyed – ranging between five and nine species per

quadrat. No ground flora of special interest was recorded.

Ground flora survey analysis.

Figure 13 below summarises the 30m x 30m walkover species

diversity results for the five sites, along with the five

individual flora quadrats for each, and the averages for the

quadrat diversity by site for these smaller quadrats:

Site

TotalSpecies per30m x 30mQuadrat

Species per 2m x 2mQuadrat

Mean Speciesper

2m x 2mQuadratA B C D E

48

1 16 8 8 7 8 9 82 23 11 6 9 7 4 7.43 19 7 4 9 5 6 6.24 26 12 12 11 10 9 10.85 21 5 6 6 9 6 6.4

Figure 13 – Ground Flora Diversity by Quadrat.

The results for walkover survey species diversity for the

different woodlands are as could be expected. The ash

woodland Sites 2 and 5 have relatively high total species

numbers of twenty three and twenty one respectively. The

sycamore woodland in Site 1 has the lowest total, with

sixteen species, while the mixed ash and sycamore woodland in

Site 3 has slightly higher with nineteen species. The highest

score for total number of ground flora species is the

plantation woodland Site 4 with twenty six, perhaps due to

the sudden flush of growth after half of the trees in the

woodland had been felled.

The data from the five 2m x 2m ground flora quadrats for each

site was slightly more varied. The mean of the five quadrats

was taken for each site. Site 1 - the sycamore woodland - had

a surprisingly high mean in comparison with the ash woodlands

of Sites 2 and 5. Site 3 was quite low as might be expected

due to the influence of the sycamore canopy. Again, the

highest diversity of species was that found in Site 4, which

had a mean number of species per 2m x 2m quadrat of 10.8.

49

To predict the effects of increased woodland shade on ground

flora, the shade tolerance, or Ellenberg Light Value (ELV)

for each species was considered. For the ELVs for all flora

recorded, see Appendix 3. Figure 14 below summarises the ELVs

for all species recorded by site:

Ellenberg LightValue(ELV)

Number of species in 30x30mquadrat

Site1

Site2

Site3

Site4

Site5

3 1 1 1 1 14 7 7 6 5 65 2 6 2 5 36 5 8 8 9 107 1 1 2 6 1

Total Ground Flora Species 16 23 19 26 21

Mean ELV 4.88 5.04 5.21 5.54 5.19

Figure 14 – Ellenberg Light Values for ground flora species

by site.

From these figures, it can be estimated that a full sycamore

canopy (Site 1) creates light conditions favourable to ground

flora averaging 4.5 to 5 on the Ellenberg scale. For ash

(Sites 2 and 5) this may be 5 to 5.5. Gaps in the canopy

could increase these scores (e.g. Site 4).

50

3 4 5 6 70

1

2

3

4

5

6

7

8

9

10

Sycamore woodland ground flora diversity (Site 1)

Figure 15 – Distribution of species across ELV range in

different woodland types.

Figure 15 above compares the incidence of species across the

range of ELVs in the pure sycamore and ash woodlands

surveyed. Shade-tolerant flora, with ELV 4, were seen to be

common in sycamore woodland and slightly less common in the

ash woodlands. However, species of flora with Ellenberg Light

Value of 5 and 6 were much less common in the sycamore

woodland than in the two examples of ash woodland. This is

consistent with the figures mentioned in Chapter 2 for the

difference in percentage light under a full canopy, from 5%

for ash to 3% for sycamore (Helliwell, 2013). Thus such

species (with ELVs of 5 and 6) in ash woodland are likely to

be adversely affected by an increase in canopy shade. Species

with an ELV of 7 cannot be classified as true woodland flora,

as according to the Ellenberg scale they occur in well-lit

51

Numberof

specie

ELV

places or partial shade (Hill et al, 1999). These species may

occur under areas of incomplete canopy or adjacent to open

areas, and so are not as relevant when comparing the two

types of woodland canopy. The recurring species with an ELV

of 3 is Mercurialis perennis.

Further analysis.

Another aspect of the change from ash to sycamore as the main

tree of the woodland canopy is the differing time at which

the two species of canopy tree come into leaf, or their

“seasonality”. Sycamore’s leaves start to develop in early-

to mid- April (Jones, 1945), while the canopy of ash trees

does not emerge until mid- to late- May (Wardle, 1958). This

difference of 5 to 6 weeks occurs at a critical time of year

for the growth of many species of woodland ground flora. For

A. pseudoplatanus, an average of 22 days elapses between first

leafing and completion of leafing of old trees (Jones, 1945.)

No such data was available for F. excelsior, although a similar

time period can be assumed, if not slightly faster as the ash

trees are ”catching up” with other canopy species due to

their late first leafing.

Tree leaf fall varies from season to season depending on

environmental conditions, but most leaves are shed during

October and the first half of November (Wardle, 1958; Jones,

1945; Grime, 2007). The slightly later drop of sycamore

52

leaves in relation to ash is not considered significant in

this study, as most growth and reproduction occurs in spring

and early summer. It may however effect the regeneration of

tree seedlings as they grow all year round. It should also be

noted that for some evergreen woodland flora such as Mercurialis

perennis this seasonality might not be as significant, due to

their extended growth period. A graphical representation of

this difference between the two tree species can be seen in

Figure 16 below, which shows that not only is canopy shade

deeper under sycamore, it also occurs for a significantly

longer period of time. The dark green line represents the

coming into leaf of A. pseudoplatanus, while the light green line

signifies that of F. excelsior.

53

Figure 16 - Relationship between vernal canopy development

and canopy light transmittance.

In ash woodlands there is an important window of opportunity

from late February through to late May, before the canopy

appears. This spring growth period is vital for the growth

and reproductive processes, i.e. flowering, of the majority

of ash woodland ground flora. Thus an earlier onset of canopy

shade due to replacement of ash with sycamore may have

detrimental effects on these “vernal” species, e.g.

Hyacinthoides non-scripta. The time period representing this earlier

onset of shade is shown between the two green lines in Figure

16, and could be defined as the Critical Canopy Period (CCP).

From the literature it can be estimated to last from the 10th

of April to the 20th of May.

For each species recorded in the site surveys, the common

months of flowering were noted (Rose, 1981; Grime et al, 2007;

Hubbard, 1992). This information is found in the walkover

survey results in Appendix 3. If this flowering period

overlaps with the Critical Canopy Period from Figure 16, then

that species may be affected by sycamore’s earlier canopy

emergence. The magnitude of this effect depends on the

overlap of the two periods, if any.

The combined effects of these two impacts - shade tolerance

and whether flowering overlaps with the Critical Canopy

Period - will have consequences for each of the ground flora

54

species present. Looking at the sites surveyed, some plants

are likely to thrive in these more shady conditions, while

some could be reduced in number or lost completely.

ELV Flowering periodnot in CCP

Floweringperiod

slightly inCCP

Floweringperiod

mostly inCCP

Floweringperiodtotally

within CCP

7

Calystegia sepiumSenecio jacobaea

Geranium sanguineumPrunella vulgaris

Lysimachia vulgaris

Lamium albumTaraxacum

officinale Rumexacetosa

 - -

6

Neottia ovataHordelymus europaeus

Brachypodiumsylvaticum Arctium

minusStachys sylvaticaGalium aparine

Deschampsia cespitosaChamerion

angustifolium(Viola riviniana)

Rubus fruticosusViola riviniana

Anthriscussylvestris

 -

5  -

Anenomenemorosa

Alliaria petiolataGeranium

robertianum

Hyacinthoidesnon-scriptaRibes uva-

crispa

Chrysosplenium

oppositifoliumRibes rubrum

4 Hedera helixCircaea lutetiana

Geum urbanumSanicula europaeaVeronica montana

Lamiastrumgaleobdolon

Melica uniflora

Primula elatiorAllium ursinum

Arummaculatum

Oxalisacetosella

3 - Mercurialisperennis -  -

55

Figure 17 – Relationship between Shade Tolerance (ELV) and

Seasonality.

The relationship between these two variables of shade

tolerance (Ellenberg Light Value) and seasonality is shown in

Figure 17 above. Essentially, the further to the top and to

the right of the chart a species is found, the more likely it

is to be detrimentally effected by the change in canopy from

ash to sycamore.

Analysis of scenario predictions.

After considering each scenario logically, predictions for

the future structure of each woodland site were made, in the

form of cross-sectional models. The diagrammatic

representations of these can be found in Appendix 5. It

should be noted that these models are a “best guess” attempt

at forecasting what will happen, informed by the literature

and site surveys (see Methodology in Chapter 4). These

predictions assume no woodland management by groups such as

the East Keswick Wildlife Trust or Yorkshire Wildlife Trust.

These scenarios can be used in conjunction with the data in

Figure 17 to predict the likely effects of any changes in

canopy and structure on individual ground flora species.

Site 1 – Oxclose Wood sycamore woodland. This site is around

90% sycamore, although the several mature ash trees present

will certainly be affected by ash dieback. The many sycamore

trees ensure a strong seed bank. In Scenario A (0 – 10%

56

mortality) the alternation discussed by Waters and Savill

(1991) is likely to take place over the 150 year time period,

the final state of the woodland being more ash-dominated with

a corresponding slight increase in number of understorey

shrubs. Scenario B (0 – 50% mortality) might see the death of

some of the existing ash trees, but due to resistance in the

population these would be replaced and the alternation

process would still occur, although at a much slower pace

than in Scenario A. This eventual regeneration of ash and

slowed alternation process is also likely to occur in

Scenario C (50 – 80% mortality), although at an even slower

rate. Scenario D (80 – 100% mortality) would result in the

woodland remaining as predominantly A. pseudoplatanus for an

extremely long time period, although after 150 years some

resistant specimens of F. excelsior might spread back to the site

owing to the species’ long range seed dispersal methods.

Site 2 – Hetchell Wood ash woodland. The single sycamore tree

on the northern edge of the site is likely to provide a

sufficient seed bank for the purposes of sycamore succession

due to the prolific seeding of the species, and its dispersal

range of 50 metres (Jones, 1945; Hein et al, 2008). In Scenario

A, even the 0 – 10% mortality of ash trees may have a visible

effect in the woodland due to the dominance of F. excelsior in

this case. The presence of a sycamore seed bank might thus

result in a slow increase in sycamore to replace the fallen

ash after 50 years or so. After 150 years, this rise in

57

sycamore numbers would likely have become more pronounced,

due to the cycling phenomenon between the species.

The Scenario B forecast for 10 – 50% ash mortality may see

this trend for sycamore replacing the ash increasing, as more

gaps left by dead or dying ash trees will encourage more

sycamore trees to replace them. This would be a slow process

however as many mature ash would remain, and the woodland may

become an even mix of the two species. Scenario C (50 – 80%

mortality) could result in most of the ash being gone after

50 years, but after the full 150 years some disease-resistant

ash might return in areas heavily shaded by sycamore.

Finally, Scenario D with 80 – 100% mortality would mean after

50 years perhaps only one or two resistant ash trees might

remain, with sycamore having taken over in the area and one

or two other species such as wych elm or field maple having

also taken advantage of the gaps. One hundred and fifty years

after the disease onset, the sycamore may have shaded these

other trees out. However, a slow return of genetically

resistant ash might also have begun. In all cases an increase

in sycamore canopy is likely to see a slight reduction in

numbers of shrubs present in the area, relative to the

percentage of sycamore canopy.

Site 3 – Oxclose Wood mixed woodland. There are many sycamore

trees present in the northern half of the quadrat, so a

source of seeds is available. Scenario A might see one or two

58

of the ash trees die and be replaced by sycamore over 50

years. However as the site appears to be in transition from

sycamore to ash woodland, this effect would be reversed after

150 years as the species alternation cycle proceeded.

Scenario B would be a very similar picture, at the 50-year

mark the effects of the disease and the alternation cycle

might cancel each other out, but after 150 years the effects

of the disease would have worn off and the transition to ash

woodland continued, although at a slower rate, with

corresponding increase in understorey shrub numbers.

In Scenario C, with over 50% mortality after 50 years only a

few ash trees would remain, having been replaced by sycamore.

After 150 years the woodland might end up looking similar to

its original state, with the return of ash after the effects

of the disease ended. In the final Scenario D, after 50 years

all the ash trees are likely to have been replaced by

sycamore, and thus the understorey shrub layer might be

sparser due to the increase in summer canopy shade. After 150

years, some young resistant ash may have begun a slow return

to the site.

Site 4 – Horselock Dale Wood ash plantation. There are no

sycamore trees within the 30m squared quadrat, however there

are likely to be viable trees within the dispersal range of

the seeds. Colonisation by sycamore will thus be possible,

but at a slower rate than if a strong seed bank was already

59

present. Over the 150-year period, the waterlogged area may

possibly dry out. In Scenario A, with negligible effect from

the disease, the ash saplings already present will become a

mature ash woodland within 50 years. The shrub understorey

will also thrive. After 150 years some sycamore may have

taken a foothold on the raised, non-waterlogged area of

ground. The situation in Scenario B may be quite different,

as many saplings and young ash will be susceptible to Chalara

infection, giving opportunity to Salix cinerea (Grey Willow) and

Betula pubescens (Downy Birch) on the waterlogged areas of the

site. After 150 years, resistant ash is likely to do better,

with again perhaps some sycamore on the dryer high ground.

In Scenario C, with most of the ash dead, birch and willow

could be even more successful in colonising the waterlogged

area, and again sycamore would favour the high ground. At the

end of the 150 years, ash trees will have returned,

particularly on the lower ground level. Finally in Scenario

D, with all the plantation ash trees likely to be dead after

50 years, the site could become an example of W2 Salix cinerea –

Betula pubescens – Phragmites australis woodland (Rodwell, 1991), with

sycamore on the raised ground. The sycamore might spread by

the end of the 150 year period, with some resistant ash then

also slowly returning.

Site 5 – Hetchell Wood ash woodland. There are some sycamore

trees present in the quadrat, so a seed bank will be readily

60

available. In Scenario A with very low ash tree mortality,

the 150-year period will likely see a slow transition from

ash to sycamore woodland, with a slight decrease in density

of the understory shrub layer. As mortality increases to 10 –

50% in Scenario B, any gaps due to ash tree death are likely

to be filled by sycamore, which will also continue growing

under areas of ash canopy resulting in an almost complete

alternation in species by the end of 150 years. Scenario C

will see a faster replacement process than in B, although

some resistant ash may emerge under the sycamore canopy by

the end of the 150 year period. In Scenario D after 50 years

the entire ash woodland is likely to have been replaced by a

sycamore canopy, with some wych elm and field maple

remaining, and again after 150 years some resistant ash may

have returned.

6. Discussion

Principal outcomes. The main findings of this study have been

the identification of two variables which determine the

different light environments beneath woodland canopies of F.

excelsior and A. pseudoplatanus. These are:

1. The time difference between ash and sycamore first

coming into leaf in the spring, or the “Critical

Canopy Period”. For each ground flora species, the

61

proportion of its reproductive (flowering) process

which overlaps with this period is crucial.

2. The likely reduction in summer canopy light

transmittance from 5% to 3% if sycamore replaces ash

in woodlands. This reduction can then be linked to

shade tolerance in ground flora species in terms of

Ellenberg Light Values.

The combination of these two factors is fundamental to

understanding how the replacement of ash by sycamore will

affect the woodland ground flora. Using Figure 17 as a

guide, broad conclusions can be made about changes in species

composition in ash woodland ecosystems, as they attempt to

adapt to a denser sycamore canopy. By analysing each ground

flora species from the surveys using these variables, impacts

on individual species can be predicted, examples of which are

mentioned below. If only a partial change to sycamore occurs,

then the scale of these effects will be proportionally less.

Mercurialis perennis can be expected to thrive in such conditions,

as it is adapted to survive in the shadiest of woodlands. In

fact this species is likely to out-compete much of the other

ground flora. In addition to its high shade tolerance it is

green all year round, so its overlap with the CCP may not be

as important as for other species. Arum maculatum is another

species which could do well in increased shade, as it is

already present in ash woodlands but is more adapted to those

62

of sycamore, as can be seen by its ELV of 4 and the fact that

it flowers under such conditions. Bryophytes such as

Rhytidiadelphus sp. could be a further type of flora to do well

in increasingly shaded conditions. Also shade-tolerant shrub

species such as Corylus avellana and Ilex aquifolium might find such

an environment more favourable.

Little change might be expected in species such as wood

anemone, Anenome nemorosa, which flowers early (before the

Critical Canopy Period), and is often finished by April.

Another important species which may experience low levels of

impact from a change to a sycamore canopy is Allium ursinum,

which although its flowering period of April to June overlaps

with the CCP, is highly shade tolerant, with an ELV of 4.

Reductions should be expected in the populations of species

such as Hyacinthoides non-scripta, whose flowering period is

relatively late and so overlaps with the CCP. Thus bluebell

may survive reasonably well until canopy shade gets below a

certain level, but then be unable to reproduce under the

dense sycamore canopy. Also the gooseberry, Ribes uva-crispa,

might not do well under denser shade: it flowers in March so

could possibly survive, although it would probably decline

over time.

The complete loss of some of the less shade-tolerant species

with higher ELVs is also to be expected under a sycamore

canopy. Ground flora such as Anthriscus sylvestris and Geranium

63

robertianum would probably disappear soon after the first

sycamore saplings appeared in the woodland, as they are

simply not adapted to a heavily-shaded woodland environment.

Additionally, grasses characteristic to ash woodland such as

Brachypodium sylvaticum and bryophytes with lower shade tolerance

such as Eurhynchium praelongum are likely to be lost.

Alongside this species-specific information are the models of

canopy structure - predictions of how woodlands might be

affected by ash dieback over time. To test whether the

predictive models for woodland succession were robust, the

model depicting present day sycamore woodland - the Site 1

case study (model 1A0) - was compared with those of ash

woodlands after almost complete replacement of ash with

sycamore (Scenario D). Thus when comparing scenario 1A0 with

scenarios 2D150 and 5D150 (See Appendix 5) the models can be

seen to be very similar if not virtually identical. Hence the

ground flora in these latter two scenarios could be similar

to that found in the survey of Site 1.

The future of ash woodlands in the British Isles. From the

literature it seems likely that the overall effects of Chalara

fraxinea in the British Isles will be approximately 70% tree

death, corresponding roughly with Scenario C from the

predictive models. Apart from the behaviour of the disease

itself, the rate and extent of sycamore succession will vary

according to soil type, possible waterlogging, seed bank

64

availability and management of woodlands if any. Supposing

that the tree mortality in Scenario C is roughly correct, and

that resistant ash trees emerge after several years, this

will result in a slow return of F. excelsior to woodlands due to

its nature as a pioneer species. Surviving resistant trees

will act as a source of seeds for the redistribution of ash,

aided by its long range distribution method and rapid

regeneration capability. Thus, the long-term consequences may

be that the ash population drops to around a quarter of its

current level for around 50 to 100 years, before gradually

returning to its current status.

The information gained in this study could be useful when

highlighting woodland communities of particular ecological

value which may be threatened by the loss of ash trees due to

dieback, e.g. those with populations of locally important or

rare ground flora. Any mitigation of the disease’s effects

should be prioritised to such woodlands, as resources may be

limited. This work can also also assist in understanding the

likely effects of sycamore shading on ash woodlands and their

ecosystems, and the time periods involved. For example a

modified version of the model in Figure 17 could be used to

evaluate the threat to various different ground flora

species. It is also possible that the predictive woodland

structure models could be used in other woodlands to forecast

the effects of the disease.

65

Comparisons can be drawn between the upcoming effects of ash

dieback on British woodlands and the decline of the elm 30 to

40 years ago, which seriously affected what were then called

ash-elm woodlands. If sycamore can be considered to cast a

similar shade to that of elm, and ash has replaced elm, then

an unexpected result of ash dieback might be that shade

returns to parts of woodlands that were previously ash-elm

woodlands. With ash perhaps expected to return in 100 years

from now, these woodlands might then become termed ash-

sycamore woodlands, with alternation between species being

likely to occur. Should ash woodlands lose a serious

proportion of their primary foundation species Fraxinus excelsior,

sycamore can be considered ecologically to be the best

available replacement to fill the niche due to the many

similarities between the two species. Without sycamore to

replace ash in these woodlands there would perhaps be an even

greater problem. Thus due to the likelihood of sycamore at

least partially replacing ash in this way, sycamore’s non-

native status seems set to become increasingly irrelevant.

The characteristic tree species associated with ash woodland,

i.e. wych elm, field maple and hawthorn, may thrive for

several years after the ash trees are gone. However they are

likely to exhibit overall decline in the woodlands affected,

as they are shaded out by the larger sycamore. Other possible

replacements for ash apart from sycamore are species with

good wind-borne seed dispersal such as birch, wych elm and to

66

a lesser extent field maple. In waterlogged conditions,

willows such as Salix cinerea are likely. Oak is a further

potential replacement if gaps are of sufficient size.

Succession will vary across different scenarios and

environmental conditions. Under a sycamore canopy it is

likely there will be less sapling regeneration, and light

demanding shrub species will not succeed. Referring to the

ELVs of species in the walkover surveys (see Appendix 3),

populations of elder, hawthorn and blackthorn may be reduced,

with a possible increase of hazel and holly populations.

In addition to the main analysis of ground flora species

survivability from Figure 17, some species may disappear as

they are outcompeted by dominant Mercurialis perennis, or where

there are canopy gaps, Rubus fruticosus. Where environmental

conditions are suitable for these species, their over-

dominance can reduce general ground flora diversity, e.g. as

seen in quadrat E in Site 2. An overall reduction in ground

flora diversity will probably occur under sycamore, at least

until the woodland has had opportunity to develop its own

shade-tolerant ground flora over time. However this is

unlikely due to the alternation with ash, unless ash

populations are unable to fully recover from the effects of

Chalara fraxinea.

Another possible result of greater canopy shade will be an

increase in populations and diversity of bryophytes. Shady

67

and damp woodland conditions and possibly reduced ground

flora diversity might create an opportunity for bryophytes

which can tolerate low light levels. Species of rare or

specialised lichens may suffer due to loss of habitat,

although some more common species may prefer sycamore’s base-

rich bark to that of other native trees.

It is always important when considering woodland ecosystems

and models such as those mentioned, not to fall into the trap

of thinking that woodlands are static. They are dynamic and

constantly evolving systems, with a wide range of different

factors at work. It should also be remembered that ash

dieback disease is just one of many factors currently

affecting woodland biodiversity in Britain. These include

climate change, poor management, pollution, and many other

tree diseases and invasive species.

Further research.

As mentioned earlier, the rate of sycamore succession in ash

woodlands will depend not only on the environmental

conditions present in each case, but also on the behaviour of

the disease itself. The range and rate at which the fungal

spores acting as a vector for the disease spread, and which

environmental factors may influence this, still need to be

defined. Now that the disease has become reasonably

widespread in the British Isles, work should be done to

categorise resistance levels across F. excelsior populations in

68

different areas, along with what conditions might influence

such resistance.

The time taken for mature trees take to die after initial

infection, along with the duration for which Chalara fraxinea is

likely to remain in woodlands, could also be the subject of

additional further research. The former is particularly

important since if mature trees remain alive for several

years they could help to mitigate effects on the rest of the

woodland ecosystem. Mechanisms and types of secondary

infection also require further investigation, as some of

these could be preventable. Work could be done on the effects

of lone trees or those in hedgerows, which are likely to be

under different conditions from those in woodlands, and thus

may react differently to the disease and its spread. If

intervention to conserve woodlands of high ecological value

is being planned, e.g. the planting and encouragement of

other shade tree species to mitigate the short term effects

of the disease, further work on the light transmittance

figures for alternative tree species would be useful.

It may be that sycamore woodland’s low diversity is simply

due to its usual status as secondary woodland. To test this

hypothesis it could be useful to study the diversity of

established sycamore woodlands in continental Europe, and

compare them to those found in the British Isles.

69

Finally, with respect to the models described in Figures 16

and 17 (showing the relationships between vernal canopy

development and canopy light transmittance, and also shade

tolerance and seasonality), it would be possible to examine

these relationships in more depth, perhaps in more detailed

multi-dimensional models. The predictive models shown in

Appendix 5 are fairly limited due to incomplete data in

several areas, including the severity and rate of disease

infection. Should these data become available, there could be

scope for more accurate predictions using this technique to

forecast the future structure of ash woodlands.

70

References.

Anderson, P. and Shimwell, D., 1981. Wild flowers and other plants

of the Peak District – an ecological study. Ashbourne: Moorland

Publishing.

Bakys, R., 2013. Dieback of Fraxinus excelsior in the Baltic Sea Region.

Uppsala: University of Agricultural Science.

Barbier, S., Gosselin, F., Balandier, P., 2008. Influence of

tree species on understory vegetation diversity and

mechanisms involved - a critical review for temperate and

boreal forests. Forest Ecology and Management, 254, pp. 1–15.

Bengtsson, V., Stenström, A. and Finsberg, C., 2013. The

impact of ash dieback on veteran and pollarded trees in

Sweden. Quarterly Journal of Forestry, 107 (1), pp. 27 – 33.

Binggeli, P. (1992) Patterns of invasion of sycamore (Acer pseudoplatanus

L.) in relation to species and ecosystem attributes. D.Phil. Thesis, The

University of Ulster.

Børja, I., Hietaka, A.M., Kirisits, T. and Solheim, H., 2011.

Ash dieback: pathogen spread and diurnal patterns of

ascospore dispersal, with special emphasis on Norway. EPPO

Bulletin, 41, pp. 14-20.

Centre for Ecology and Hydrology, 2013. Countryside Survey:

Distribution of ash trees (Fraxinus excelsior) in Countryside Survey data.

Wallingford: Centre for Ecology and Hydrology.

COST (European Cooperation in Science and Technology), 2009.

35th COST conference on forest and landscape: Forest vegetation management –

towards environmental sustainability. Vejle, Denmark, 5-7 May 2009.

Copenhagen: COST.

Department for Environment, Food and Rural Affairs (DEFRA),

2013. Chalara Management Plan. London: Department for

Environment, Food and Rural Affairs.

Digimap, 2013. Digimap Ordnance Survey website. [online]

<http://digimap.edina.ac.uk/digimap/home> [Accessed 31

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Appendix 2 - Canopy Survey Plans

Canopy Survey Key.

Fraxinus excelsior

Acer pseudoplatanus

Acer campestre

Crataegus monogyna

Quercus robur

Pinus sylvestris

Ulmus glabra

Taxus baccata

Site 1 Canopy Diagram (30m by 30m quadrat).

North

Fraxinus excelsior

Prunus spinosa

Crataegus monogyna

Corylus avellana

Sambucus nigra

Ilex aquifolium

Rosa canina

Target Note

Target Notes.

1 – Very high ash canopy above sycamore 5 – Fallen ash tree, still alive

2 – Diseased, branches snapped off 6 – Heavy bramble area

3 – Very high ash canopies 7 – Heavy bramble area

South

4 – Blackthorn. Saplings 1 to 2.5m height 8 – Area ofbare ground

Site 2 Canopy Diagram (30m by 30m quadrat).

North

Target Notes.

1 – Dead ash tree 5 – Fallen tree

2 – Patch of hedge woundwort 6 - Gap in canopy

South

3 – Deadwood with ivy 7 - Dead hawthorn with ivy

4 – Clear floor with paths 8 - Fallen tree

Site 3 Canopy Diagram (30m by 30m quadrat).

North

Target Notes.

South

1 – Unusual grass – Wood Brome 5 – Bare patchesof earth

2 – Footpath

3 – Thick bramble

4 – Bare patches of earth

Site 4 Canopy Diagram (30m by 30m quadrat).

North

South

Target Notes

1. Burdock 6. Selfheal

2. Opposite-leaved Golden Saxifrage 7. Oxlip

3. Ragwort 8. Gap in canopy

4. Thistle 9. Brambles under canopy gap

5. Nettles

Site 5 Canopy Diagram (30m by 30m quadrat).

North

Target Notes.

1 - Fallen tree 5 – Old badger sett

2 - Fallen tree 6 – Active badger sett

3 – Large gap in canopy 7 – Diseased elm – nofoliage

South

4 – Large gap in canopy

Appendix 3 - Walkover Ground

Flora

Survey Results

Site 1 ground flora walkover survey.

Latin Name Common NameCover(ROFAD

)

Ellenberg LightValue

Monthof

Flowering

Fraxinus excelsior Ash O 5 N/ACorylus avellana Hazel O 4 N/ACrataegus monogyna Hawthorn O 6 N/ASambucus nigra Elder R 6 N/AAcer pseudoplatanus Sycamore D 4 N/APrunus spinosa Blackthorn O 6 N/AIlex aquifolium Holly O 5 N/A

Mercurialis perennis Dog's Mercury O 3 2 – 4Rubus fruticosus Bramble D 6 5 – 9Pteridium aquilinium Bracken O 6 N/A

Hyacinthoides non-scripta Bluebell O 5 4 - 6

Allium ursinum Ramson F 4 4 – 6Urtica dioica Nettles O 6 6 – 8Anenome nemorosa Wood Anenome F 5 3 – 4Hedera helix Ivy F 4 9 – 11

Stellaria nemorumWood Stitchwort R 4 5 – 6

Lamium album White Dead R 7 5 – 12

Nettle

Veronica montanaWood Speedwell R 4 4 – 7

Arum maculatumLords and Ladies R 4 4 – 5

Oxalis acetosella Wood Sorrel R 4 4 – 5Geum urbanum Wood Avens O 4 5 – 8

Viola riviniana Common Dog Violet

R 63 – 5(8 –10)

Rhytidiadelphus sp. Shaggy Moss O 6 N/A

Site 2 ground flora walkover survey.

Latin Name Common NameCover(ROFAD

)

Ellenberg LightValue

Monthof

Flowering

Fraxinus excelsior Ash D 5 N/AAcer campestre Field Maple R 5 N/ACorylus avellana Hazel F 4 N/ACrataegus monogyna Hawthorn F 6 N/ASambucus nigra Elder R 6 N/AUlmus glabra Wych Elm R 4 N/AAcer pseudoplatanus Sycamore R 4 N/APrunus spinosa Blackthorn F 6 N/AIlex aquifolium Holly R 5 N/ATaxus baccata Yew R 4 N/A

Mercurialis perennis Dog's Mercury D 3 2 – 4Rubus fruticosus Bramble R 6 5 – 9Pteridium aquilinium Bracken R 6 N/AHyacinthoides non-scripta Bluebell F 5 4 – 6

Allium ursinum Ramson F 4 4 – 6Anenome nemorosa Wood Anenome R 5 3 – 4Hedera helix Ivy F 4 9 – 11

Arum maculatumLords and Ladies R 4 4 – 5

Geum urbanum Wood Avens R 4 5 – 8

Viola riviniana Common Dog Violet R 6

3 – 5(8 –10)

Eurhynchium praelongum

Common Feather Moss O 5 N/A

Neottia ovata Twayblade R 6 6 – 7

Calystegia sepiumHedge Bindweed R 7 7 – 9

Hordelymus europaeus Wood Barley R 6 6 - 7Sanicula europaea Sanicle R 4 5 – 8Brachypodium sylvaticum False Brome R 6 7 - 8

Arctium minusCommon Burdock R 6 7 – 9

Stachys sylvaticaHedge Woundwort R 6 7 – 9

Ribes uva-crispa Gooseberry R 5 3 – 5

Alliaria petiolataGarlic Mustard R 5

4 – 7

Veronica montanaWood Speedwell R 4

4 – 7

Geranium robertianum Herb Robert R 5 4 – 9

Lamiastrum galeobdolon

Yellow Archangel R 4

5 – 6

Site 3 ground flora walkover survey.

Latin Name Common NameCover(ROFAD)

Ellenberg LightValue

Monthof

Flowering

Fraxinus excelsior Ash A 5 N/ACorylus avellana Hazel R 4 N/ACrataegus monogyna Hawthorn O 6 N/AUlmus glabra Wych Elm R 4 N/AAcer pseudoplatanus Sycamore F 4 N/APrunus spinosa Blackthorn R 6 N/AIlex aquifolium Holly R 5 N/A

Mercurialis perennisDog's Mercury A 3 2 – 4

Rubus fruticosus Bramble O 6 5 – 9Pteridium aquilinium Bracken R 6 N/AHyacinthoides non-scripta Bluebell O 5 4 – 6

Allium ursinum Ramson O 4 4 – 6Urtica dioica Nettles R 6 6 – 8Galium aparine Goosegrass O 6 6 – 8Anenome nemorosa Wood Anenome R 5 3 – 4Hedera helix Ivy O 4 9 – 11

Lamium albumWhite Dead Nettle R 7 5 – 12

Veronica montanaWood Speedwell R 4 4 – 7

Arum maculatumLords and Ladies R 4 4 – 5

Geum urbanum Wood Avens O 4 5 – 8

Viola riviniana Common Dog Violet

R 63 – 5(8 –10)

Rhytidiadelphus sp. Shaggy Moss F 6 N/ABrachypodium sylvaticum False Brome R 6 7 - 8

Stachys sylvaticaHedge Woundwort R 6 7 – 9

Calystegia sepiumHedge Bindweed R 7 7 - 9

Site 4 ground flora walkover survey.

Latin Name Common Name

Cover(ROFAD

)

Ellenberg LightValue

Monthof

Flowering

Fraxinus excelsior Ash F 5 N/ACorylus avellana Hazel R 4 N/ACrataegus monogyna Hawthorn R 6 N/ASambucus nigra Elder R 6 N/A

Mercurialis perennis Dog's Mercury A 3 2 – 4Rubus fruticosus Bramble O 6 5 – 9Hyacinthoides non-scripta Bluebell R 5 4 – 6

Urtica dioica Nettles R 6 6 – 8Anenome nemorosa Wood Anenome O 5 3 – 4Galium aparine Goosegrass O 6 6 – 8Hedera helix Ivy R 4 9 – 11Geum urbanum Wood Avens O 4 5 – 8

Viola riviniana Common Dog Violet R 6

3 – 5(8 –10)

Brachypodium sylvaticum False Brome R 6 7 - 8

Deschampsia cespitosaTufted Hair-grass F 6 6 - 8

Stachys sylvaticaHedge Woundwort R 6 7 – 9

Arctium minusCommon Burdock R 6 7 – 9

Chrysosplenium oppositifolium

Opposite-leaved GoldenSaxifrage

O 5 4 – 5

Senecio jacobaeaCommon Ragwort R 7 6 – 10

Geranium sanguineumBloody Cranesbill R 7 7 – 8

Prunella vulgarisCommon Selfheal R 7 6 – 10

Melica uniflora Wood Melick R 4 5 - 7

Calystegia sepiumHedge Bindweed R 7 7 – 9

Chamerion angustifolium

Rosebay Willowherb R 6 7 – 9

Lysimachia vulgarisYellow loosestrife R 7 7 – 8

Arum maculatumLords and Ladies R 4 4 – 5

Eurhynchium praelongum

Common Feather Moss F 5 N/A

Ribes rubrum Red Currant R 5 4 – 5

Taraxacum officinaleCommon Dandelion R 7 3 – 10

Primula elatior Oxlip R 4 3 – 5

Site 5 ground flora walkover survey.

Latin Name Common Name Cover Ellenberg Month

(ROFAD)

LightValues

of Flowering

Fraxinus excelsior Ash A 5 N/AAcer campestre Field Maple R 5 N/ACorylus avellana Hazel R 4 N/ACrataegus monogyna Hawthorn F 6 N/ASambucus nigra Elder O 6 N/ARosa canina Dog Rose R 6 N/AUlmus glabra Wych Elm R 4 N/AAcer pseudoplatanus Sycamore O 4 N/A

Mercurialis perennisDog's Mercury D 3 2 – 4

Rubus fruticosus Bramble O 6 5 – 9Pteridium aquilinium Bracken R 6 N/AHyacinthoides non-scripta Bluebell O 5 4 – 6

Allium ursinum Ramson O 4 4 – 6Urtica dioica Nettles R 6 6 – 8Galium aparine Goosegrass R 6 6 – 8Hedera helix Ivy R 4 9 – 11Geum urbanum Wood Avens O 4 5 – 8

Viola riviniana Common Dog Violet

R 63 – 5(8 –10)

Brachypodium sylvaticum False Brome O 6 7 - 8

Hordelymus europeaus Wood Barley R 6 6 - 7

Arctium minus Common Burdock R 6 7 - 9

Rumex acetosaCommon Sorrel R 7 5 - 6

Circaea lutetiana Enchanters Nightshade R 4 6 – 8

Eurhynchiumpraelongum

Common Feather Moss F 5 N/A

Arum maculatum Lords and R 4 4 – 5

LadiesGeranium robertianum Herb Robert R 5 4 – 9

Stachys sylvatica Hedge Woundwort R 6 7 – 9

Anthriscus sylvestris Cow parsley R 6 4 - 6

Veronica montanaWood speedwell R 4 4 - 7

Appendix 4 - 2m x 2m Ground Flora

Survey Results

Site 1, Oxclose Wood. Ground Flora Quadrat A (Grid square N5).

Latin Name Common NameCover

(DOMIN)

Ellenberg LightValue Notes

Fraxinus excelsior Ash + 5 Tiny sapling

Prunus spinosa Blackthorn + 6 Tiny sapling

Rubus fruticosus Bramble 9 6 80% coverHyacinthoides non-scripta Bluebell 5 5

Urtica dioica Nettles 2 6Hedera helix Ivy 4 4Geum urbanum Wood Avens 2 4Rhytidiadelphus sp. Shaggy Moss 7 6

Lamium albumWhite Dead Nettle 1 7

Oxalis acetosella Wood Sorrel 2 4

Canopy Score: 8 (70 - 80 % Cover)

Notes.

5 north-facing photographs taken.

No trees in the quadrat, only tiny saplings under brambles.

Quadrat is in the shade of sycamore and partial ash canopy. Alarge gap in the canopy to south gives a lot of light (out ofquadrat).

Quadrat is just south of a large fallen tree.

Site 1, Oxclose Wood. Ground Flora Quadrat B (Grid Square H12).

Latin Name Common Name

Cover(DOMIN

)

Ellenberg LightValue Notes

Fraxinus excelsior Ash + 5  10cm sapling x1

Prunus spinosa Blackthorn + 6  10cm sapling x1

Rubus fruticosus Bramble 1 6Hyacinthoides non-scripta Bluebell 5 5

Anenome nemorosa Wood Anenome 2 5

Geum urbanum Wood Avens 2 4Hedera helix Ivy 5 4

Viola riviniana Common Dog Violet 1 6

Rhytidiadelphus sp. Shaggy Moss 7 6

Veronica montana

Wood Speedwell 2 4

Canopy Score: 10 (90 - 100 % Cover)

Notes.

5 north-facing photographs.

Heavy shade, adjacent to large ash but with a sycamore understory.

Many large sycamore surrounding quadrat area.

Site 1, Oxclose Wood. Ground Flora Quadrat C (Grid Square K6).

Latin Name Common Name

Cover(DOMIN

)

EllenbergLightValue Notes

Rubus fruticosus Bramble 8 6Pteridium aquilinium Bracken 6 6Hyacinthoides non-scripta Bluebell 4 5

Anenome nemorosaWood Anenome 5 5

Geum urbanum Wood Avens 3 4Hedera helix Ivy 6 4Rhytidiadelphus sp. Shaggy Moss 8 6

Canopy Score: 9 (80 - 90 % Cover)

Notes.

5 north-facing photographs taken,

Canopy is mainly sycamore.

The quadrat area receives light from a gap in canopy to the south, and from the ash canopy to the northwest.

Site 1, Oxclose Wood. Ground Flora Quadrat D (Grid square B4).

Latin Name Common Name

Cover(DOMIN

)

Ellenberg LightValue Notes

Prunus spinosa Blackthorn 1 6 3x 1m saplings

Mercurialis perennis

Dog's Mercury 9 3

Allium ursinum Ramson 5 4Anenome nemorosa Wood Anenome 8 5

Hedera helix Ivy 5 4Geum urbanum Wood Avens 2 4

Viola riviniana Common Dog Violet 1 6

Rhytidiadelphus sp. Shaggy Moss 8 6

Arum maculatumLords and Ladies + 4

Canopy Score: 9 (80 - 90 % Cover)

Notes.

5 north-facing photographs.

Quadrat is under a slight gap in the canopy, which is a mix of ash and sycamore.

Site 1, Oxclose Wood. Ground Flora Quadrat E (Grid Square F7).

Latin Name Common Name Cover(DOMIN)

EllenbergLightValue

Notes

Ilex aquifolium Holly + 5 10cm saplingx1

Mercurialis perennis Dog's Mercury 7 3

Rubus fruticosus Bramble 5 6Pteridium aquilinium

Bracken 3 6

Hyacinthoides non-scripta Bluebell 4 5

Anenome nemorosa Wood Anenome 6 5Hedera helix Ivy 7 4Geum urbanum Wood Avens 2 4Viola riviniana Common Dog 1 6

VioletRhytidiadelphus sp. Shaggy Moss 8 6

Canopy Score: 10 (90 - 100 % Cover)

Notes.

5 south-facing photographs.

Heavy shade from a large holly tree to the south of the quadrat area.

Other surrounding trees are mainly sycamore with some ash, hawthorn and holly.

Site 2, Hetchell Wood. Ground Flora Quadrat A (Grid square N2).

Latin Name Common Name

Cover(DOMIN

)

Ellenberg LightValue Notes

Acer campestre Field Maple 1 5 1x 50cm sapling

Prunus spinosa Blackthorn 1 6Ilex aquifolium Holly 1 5

Mercurialis perennis Dog's Mercury 9 3

Rubus fruticosus Bramble 2 6Hyacinthoides non-scripta Bluebell 2 5

Geum urbanum Wood Avens 5 4Lamiastrum galeobdolon

Yellow Archangel + 4

Hedera helix Ivy 4 4

Viola riviniana Common Dog Violet 1 6

Arum maculatum Lords and Ladies + 4

Ribes uva-crispa Gooseberry + 5

Alliaria petiolata Garlic Mustard + 5 Adjacent path

Eurhynchium praelongum

Common FeatherMoss 6 5

Canopy Score: 10 (90 - 100 % Cover)

Notes.

5 north-facing photographs taken.

The canopy above the quadrat mainly consists of ash, with a hawthorn and field maple understorey.

Site 2, Hetchell Wood. Ground Flora Quadrat B (Grid square N8).

Latin Name Common NameCover(DOMIN)

Ellenberg LightValue Notes

Prunus spinosa Blackthorn 1 6

Mercurialis perennis Dog's Mercury 9 3Hedera helix Ivy 8 4Geum urbanum Wood Avens 3 4

Viola rivinianaCommon Dog Violet 2 6

Geranium robertianum Herb Robert + 5

Veronica montana Wood Speedwell 2 4

Canopy Score: 9 (80 - 90 % Cover)

Notes.

5 north-facing photographs taken.

Thick layer of Ivy under Dog’s Mercury.

The canopy above the quadrat is mainly ash, with hawthorn andwych elm understorey.

Site 2, Hetchell Wood. Ground Flora Quadrat C (Grid square J15).

Latin NameCommon Name

Cover(DOMIN

)

Ellenberg LightValue Notes

Fraxinus excelsior Ash 3 5 Tiny saplings

Crataegus monogyna Hawthorn 2 6 Tiny saplings

Prunus spinosaBlackthorn 3 6 Tiny

saplings

Mercurialis perennis Dog's Mercury 9 3

Rubus fruticosus Bramble 7 6Hedera helix Ivy 6 4

Geum urbanumWood Avens 4 4

Sanicula europea Sanicle + 4

Viola rivinianaCommon Dog Violet

4 6

Brachypodium sylvaticum

False Brome 3 6

Calystegia sepium Hedge Bindweed 2 7

Neottia ovata Twayblad 1 6

e

Canopy Score: 9 (80 - 90 % Cover)

Notes.

5 north-facing photographs taken.

Light mainly ash canopy.

Adjacent to footpath.

Site 2, Hetchell Wood. Ground Flora Quadrat D (Grid square I5).

Latin Name Common Name

Cover(DOMIN

)

Ellenberg LightValue

Notes

Prunus spinosa Blackthorn 3 6

Mercurialis perennis Dog's Mercury 7 3Rubus fruticosus Bramble 5 6Allium ursinum Ramson 7 4Geum urbanum Wood Avens 1 4Hedera helix Ivy 5 4Eurhynchium Common Feather 4 5

praelongum MossCalystegia sepium Hedge Bindweed 1 7

Canopy Score: 8 (70 - 80 % Cover)

Notes.

5 north-facing photographs taken.

Elm and hawthorn understorey.

Quadrat is just south of a large hawthorn.

Large gap in canopy to the south due to a fallen tree.

Dense leaf cover.

Site 2, Hetchell Wood. Ground Flora Quadrat E (Grid square D12).

Latin Name Common Name

Cover(DOMIN

)

EllenbergLightValue Notes

Fraxinus excelsior Ash 3 5 Small

saplings

Prunus spinosa Blackthorn 3 6 Small saplings

Mercurialis perennis

Dog's Mercury 10 3

Hedera helix Ivy 7 4

Viola riviniana Common Dog Violet 1 6

Eurhynchium praelongum

Common Feather Moss

4 5

Canopy Score: 9 (80 - 90 % Cover)

Notes.

5 north-facing photographs taken.

Yew to northeast.

Dense canopy to the north of quadrat, less dense to south.

Site 3, Oxclose Wood. Ground Flora Quadrat A (Grid Square H1).

Latin Name Common Name

Cover(DOMIN

)

EllenbergLightValue Notes

Fraxinus excelsior Ash 3 5 Tiny saplings

Mercurialis perennis

Dog's Mercury 9 3

Rubus fruticosus Bramble 8 6Hyacinthoides non-scripta Bluebell 2 5

Galium aparine Goosegrass 2 6Hedera helix Ivy 2 4Geum urbanum Wood Avens 4 4 Rhytidiadelphus sp. Shaggy Moss 8 6

Canopy Score: 9 (80 - 90 % Cover)

Notes.

5 north-facing photographs.

Canopy comprising ash to the south of the quadrat, and sycamore to the north.

Quadrat is well-shaded, with some small gaps in canopy to thesouth.

Some fallen logs in quadrat along with some bare patches of earth.

Site 3, Oxclose Wood. Ground Flora Quadrat B (Grid Square D8).

Latin NameCommon Name

Cover(DOMIN

)

Ellenberg LightValue Notes

Fraxinus excelsior Ash 3 5 Tiny saplings

Mercurialis perennis

Dog's Mercury 5 3

Rubus fruticosus Bramble 4 6Geum urbanum Wood Avens 4 4 Rhytidiadelphus sp.

Shaggy Moss 8 6

Canopy Score: 10 (90 - 100 % Cover)

Notes.

5 north-facing photographs.

Large patches of bare ground

The quadrat is well shaded. The main canopy is sycamore, withsome ash. The understorey is comprised of hazel.

Small gap in canopy to southwest

Site 3, Oxclose Wood. Ground Flora Quadrat C (Grid Square F14).

Latin Name Common NameCover

(DOMIN)

Ellenberg LightValue Notes

Fraxinus excelsior Ash 2 5 Tiny saplings

Mercurialis perennisDog's Mercury 8 3

Rubus fruticosus Bramble 5 6Pteridium aquilinium Bracken 3 6

Hyacinthoides non-scripta Bluebell 4 5

Galium aparine Goosegrass 3 6Hedera helix Ivy 2 4Geum urbanum Wood Avens 4 4

Arum maculatumLords and Ladies 1 4

 Rhytidiadelphus sp. Shaggy Moss 6 6

Canopy Score: 9 (80 - 90 % Cover)

Notes.

The canopy is mainly ash with some sycamore, there’s a gap inthe canopy slightly to the south of the quadrat.

Fallen logs in quadrat.

Interesting that no sycamore saplings found!!!

Site 3, Oxclose Wood. Ground Flora Quadrat D, Grid Square L4.

Latin Name Common Name

Cover(DOMIN

)

EllenbergLightValues Notes

Mercurialis perennis

Dog's Mercury 10 3

Rubus fruticosus Bramble 6 6Galium aparine Goosegrass 2 6Geum urbanum Wood Avens 2 4 Rhytidiadelphus sp. Shaggy Moss 8 6

Canopy Score: 9 (80 - 90 % Cover)

Notes.

5 north-facing photographs taken.

Canopy is mainly ash with a thick understorey of hazel and hawthorn, giving heavy shade. There are some gaps to the south of the quadrat.

Some bare areas without vegetation. Possibly due to badger activity.

Site 3, Oxclose Wood. Ground Flora Quadrat E (Grid Square N15).

Latin NameCommon Name

Cover(DOMIN

)

EllenbergLightValues Notes

Fraxinus excelsior Ash 3 5 Tiny saplings

Mercurialis perennisDog's Mercury 8 3

Rubus fruticosus Bramble 4 6Galium aparine Goosegrass 1 6Geum urbanum Wood Avens 1 4 Brachypodium sylvaticum

False Brome 5 6

 Rhytidiadelphus sp.Shaggy Moss 5 6 Mainly on

logs

Canopy Score: 8 (70 - 80 % Cover)

Notes.

5 north-facing photographs taken.

Canopy is predominantly ash, although quadrat is adjacent to a large sycamore.

A large log in the quadrat from a recent tree fall might be the cause of the gap in the canopy to the southwest.

Quadrat is adjacent path (2m away).

Substantial leaf litter.

Site 4, Horselock Dale Wood. Ground Flora Quadrat A (Grid Square N4).

Latin Name Common NameCover (DOMIN)

Ellenberg Light Value Notes

Fraxinus excelsior Ash 15 Saplin

gs

Mercurialis perennis Dog's Mercury 5 3Rubus fruticosus Bramble 8 6Hyacinthoides non-scripta Bluebell 1

5

Galium aparine Goosegrass 5 6Geum urbanum Wood Avens 4 4

Viola riviniana Common Dog Violet 1 6

Deschampsia cespitosaTufted Hair-grass 5

6

Stachys sylvatica Hedge 2 6

Woundwort

Arum maculatumLords and Ladies +

4

Melica uniflora Wood Melick 2 4Brachypodium sylvaticum False Brome 3

6

Eurhynchium praelongum

Common Feather Moss 6 5

Canopy Score: 7 (60 - 70 % Cover)

Notes.

5 north-facing photographs.

Very thin canopy of ash with many gaps.

Dense layer of 20/30cm high ground flora.

Site 4, Horselock Dale Wood. Ground Flora Quadrat B (Grid Square I4).

Latin Name Common Name

Cover (DOMIN)

Ellenberg LightValue Notes

Fraxinus excelsior Ash 1 5 Sapli

ngs

Mercurialis perennis Dog's Mercury 9 3Galium aparine Goosegrass 4 6Hedera helix Ivy 1 4Geum urbanum Wood Avens 4 4

Viola rivinianaCommon Dog Violet 7 6

Lysimachia vulgarisYellow Loosestrife 1 7

Chamerion angustifolium

Rosebay Willowherb + 6

Deschampsia cespitosaTufted Hair-grass 5 6

Brachypodium sylvaticum False Brome 1 6

Eurhynchium praelongum

Common FeatherMoss 7 5

Taraxacum officinaleCommon Dandelion + 7

Stachys sylvaticaHedge Woundwort + 6

Canopy Score: 6 (50 - 60 % Cover)

Notes.

Very thin canopy composed of ash trees, 50% gaps.

High and thick ground flora layer 20/30cm high.

Site 4, Horselock Dale Wood. Ground Flora Quadrat C (Grid Square L10).

Latin Name Common Name

Cover(DOMIN

)

Ellenberg LightValue Notes

Fraxinus excelsior Ash 3 5 Tiny saplings

Mercurialis perennis Dog's Mercury 6 3Rubus fruticosus Bramble 7 6Hyacinthoides non-scripta Bluebell 1 5

Galium aparine Goosegrass 4 6Geum urbanum Wood Avens 4 4

Viola riviniana Common Dog Violet 5 6

Arctium minusCommon Burdock + 6

Deschampsia cespitosaTufted Hair-grass 6 6

Chrysosplenium oppositifolium

Opposite-leaved G. Saxifrage

7 5

Brachypodium sylvaticum False Brome 4 6

Eurhynchium praelongum

Common Feather Moss 6 5

Canopy Score: 6 (50 - 60 % Cover)

Notes.

5 north-facing photographs.

Thick ground flora - 20/30cm.

Substantial gaps in ash canopy - 50/50.

Site 4, Horselock Dale Wood. Ground Flora Quadrat D (Grid Square F8).

Latin NameCommon Name

Cover (DOMIN)

Ellenberg LightValue Notes

Fraxinus excelsior Ash 4 5 Tiny saplings

Mercurialis perennisDog's Mercury 9 3

Rubus fruticosus Bramble 4 6Hyacinthoides non-scripta Bluebell 1 5

Galium aparine Goosegrass 4 6Geum urbanum Wood Avens 6 4

Viola riviniana Common DogViolet 6 6 Some very

large

Deschampsia cespitosa Tufted Hair-grass 5 6

Eurhynchium praelongum

Common Feather Moss

5 5

Brachypodium sylvaticum

False Brome 2 6

Ribes rubrumRed Currant + 5

Canopy Score: 7 (60 - 70 % Cover)

Notes.

5 north-facing photographs taken.

Quadrat is on a steep slope.

Slightly sparser ground flora, 20cm high, on dryer soil.

Site 4, Horselock Dale Wood. Ground Flora Quadrat E (Grid Square D1).

Latin Name Common Name Cover Ellenber Notes

(DOMIN)

g Light Value

Fraxinus excelsior Ash 2 5 Tiny saplings

Crataegus monogyna Hawthorn 3 6 Tiny saplings

Mercurialis perennisDog's Mercury 10 3

Hyacinthoides non-scripta Bluebell 2 5

Galium aparine Goosegrass + 6Geum urbanum Wood Avens 2 4

Viola riviniana Common Dog Violet 5 6

Deschampsia cespitosaTufted Hair-grass 2 6

Eurhynchium praelongum

Common Feather Moss 5 5

Brachypodium sylvaticum False Brome 2 6

Taraxacum officinale Common Dandelion + 7

Canopy Score: 8 (70 - 80 % Cover)

Notes.

5 north-facing photographs taken.

80% ash canopy, 20% gap.

Quadrat is on a slight slope.

Site 5, Hetchell Wood. Ground Flora Quadrat A (Grid Square D11).

Latin Name Common Name

Cover(DOMIN

)

EllenbergLightValues Notes

Fraxinus excelsior Ash + 5 10cm sapling

Mercurialis perennis Dog's Mercury 10 3

Allium ursinum Ramson 1 4

Viola rivinianaCommon Dog Violet 1 6

Eurhynchium praelongum

Common FeatherMoss 9 5

Circaea lutetiana Enchanter’s Nightshade 1 4

Canopy Score: 8 (70 - 80 % Cover)

Notes.

5 north-facing photographs.

Predominantly high-level ash canopy.

Large gap in canopy above quadrat.

Adjacent diseased elm.

Very dense Dog’s Mercury crowds out other species.

Site 5, Hetchell Wood. Ground Flora Quadrat B (Grid Square E3).

Latin Name Common Name

Cover(DOMIN

)

EllenbergLightValues Notes

Crataegus monogyna Hawthorn 1 6 Tiny

saplings

Mercurialis perennis

Dog's Mercury 9 3

Hyacinthoides non-scripta Bluebell 2 5

Geum urbanum Wood Avens 1 4

Viola riviniana Common Dog Violet 1 6

Eurhynchium praelongum

Common Feather Moss 6 5

 Arum maculatum Lords and 1 4

Ladies

Canopy Score: 10 (90 - 100 % Cover)

Notes.

5 north-facing photographs.

High badger activity - paths may affect ground flora distribution.

Canopy predominantly ash, with a dense understorey of sycamore/hawthorn.

Site 5, Hetchell Wood. Ground Flora Quadrat C (Grid Square I6).

Latin Name Common Name

Cover(DOMIN

)

EllenbergLightValues Notes

Fraxinus excelsior Ash 15 Tiny

saplings

Mercurialis perennis Dog's Mercury 10 3

Hyacinthoides non-scripta Bluebell 2 5

Geum urbanum Wood Avens 2 4

Viola riviniana Common Dog Violet 1 6

Allium ursinum Ramson 1 4Eurhynchium praelongum

Common FeatherMoss 8 5

Canopy Score: 10 (90 - 100 % Cover)

Notes.

5 north-facing photographs taken.

Quite dense canopy under field maple with ash above, and an elder and hawthorn understorey

Minor badger activity has some effect on ground flora distribution.

Site 5, Hetchell Wood. Ground Flora Quadrat D (Grid Square N4).

Latin Name Common NameCover(DOMIN)

EllenbergLightValues

Notes

Mercurialis perennisDog's Mercury 8

3

Rubus fruticosus Bramble 5 6Hyacinthoides non-scripta Bluebell 2

5

Allium ursinum Ramson 2 4Hedera helix Ivy 2 4Geum urbanum Wood Avens 1 4

Viola riviniana Common Dog Violet 2 6

Eurhynchiumpraelongum

CommonFeather Moss 7 5

Brachypodium sylvaticum False Brome 4

6

Canopy Score: 10 (90 - 100 % Cover)

Notes.

Even ash canopy with a dense wych elm understorey.

Site 5, Hetchell Wood. Ground Flora Quadrat E (Grid Square L13).

Latin Name Common Name

Cover(DOMIN

)

EllenbergLightValues Notes

Fraxinus excelsior Ash +5 Tiny

sapling

Mercurialis perennisDog's Mercury 9

3

Rubus fruticosus Bramble 6 6Hyacinthoides non-scripta Bluebell 2 5

Allium ursinum Ramson 3 4

Viola riviniana Common Dog Violet 1 6

 Eurhynchium praelongum

Common Feather Moss

7 5

Canopy Score: 10 (90 - 100 % Cover)

Notes.

5 north-facing photographs taken.

Even ash canopy, with a dense wych elm and sycamore understorey.

Patches of bare ground, with significant-sized logs from fallen trees.

Appendix 5 – Scenario Predictions

Key to Tree and Shrub Species.

- Acer pseudoplatanus

pubescens

- Fraxinus excelsior -Crataegus

monogyna

- Quercus robur -

avellana

- Ulmus glabra -Sambucus nigra

Site 1 – Oxclose Wood Sycamore Woodland – Scenario A (0 – 10 % ash mortality).

Present Day

50 years

150 years

Site 1 – Oxclose Wood Sycamore Woodland – Scenario B (10 - 50% ash mortality).

Present Day

50 years

150 years

Site 1 – Oxclose Wood Sycamore Woodland – Scenario C (50 - 80% ash mortality).

Present Day

Site 1 – Oxclose Wood Sycamore Woodland – Scenario D (80 - 100 % ash mortality).

50 years

150 years

Present Day

Site 2 – Hetchell Wood Ash Woodland – Scenario A (0 - 10 % ash mortality).

50 years

150 years

Present Day

50 years

150 years

Site 2 – Hetchell Wood Ash Woodland – Scenario B (10 - 50 % ash mortality).

50 years

Present Day

150 years

Site 2 – Hetchell Wood Ash Woodland – Scenario C (50 - 80 % ash mortality).

Present Day

Site 2 – Hetchell Wood Ash Woodland – Scenario D (80 - 100 % ash mortality).

50 years

Present Day

150 years

Present Day

Site 3 – Oxclose Wood Mixed Woodland – Scenario A (0 – 10 % ash mortality).

50 years

150 years

Present Day

Site 3 – Oxclose Wood Mixed Woodland – Scenario B (10 – 50 % ash mortality).

50 years

150 years

50 years

Present Day

150 years

Site 3 – Oxclose Wood Mixed Woodland – Scenario C (50 – 80 % ash mortality).

50 years

Present Day

150 years

Site 3 – Oxclose Wood Mixed Woodland – Scenario D (80 – 100 %ash mortality).

Present Day

50 years

Site 4 – Horselock Dale Wood Ash Woodland – Scenario A (0 – 10 % ash mortality).

150 years

Present Day

Site 4 – Horselock Dale Wood Ash Woodland – Scenario B (10 – 50 % ash mortality).

50 years

150 years

Present Day

50 years

150 years

Site 4 – Horselock Dale Wood Ash Woodland – Scenario C (50 – 80 % ash mortality).

Present Day

150 years

Site 4 – Horselock Dale Wood Ash Woodland – Scenario D (80 - 100 % ash mortality).

Present Day

Site 5 – Hetchell Wood Ash Woodland – Scenario A (0 – 10 % ash mortality).

50 years

150 years

Present Day

50 years

150 years

Site 5 – Hetchell Wood Ash Woodland – Scenario B (10 – 50 % ash mortality).

Present Day

Site 5 – Hetchell Wood Ash Woodland – Scenario C (50 – 80 % ash mortality).

150 years

Present Day

Site 5 – Hetchell Wood Ash Woodland – Scenario D (80 – 100 % ash mortality).

50 years

150 years

Present Day

50 years

150 years

Appendix 6 – Canopy Survey TreeLists

Site 1 Canopy survey (Trees above 5m).

GridNumber Tree Species

Approximate Height

(m)Girth (cm) Not

es

B8 Acer pseudoplatanus 21 40 - 45  Iv

y

B10 Acer pseudoplatanus 21 50 - 55  Iv

y

B11 Acer pseudoplatanus 20 35 - 40  Iv

yD3 Fraxinus excelsior 21 45 – 50

D6 Acer pseudoplatanus 16 30 – 35

E5 Fraxinus excelsior 20 35 – 40F4 Fraxinus excelsior 21 40 – 45

G10 Acer pseudoplatanus 21 20 – 25

G13 Acer pseudoplatanus 21 35 – 40

H3 Acer pseudoplatanus 19 35 – 40

I6 Acer pseudoplatanus 21 35 – 40

I10 Acer pseudoplatanus 20 30 – 35

I10 Acer pseudoplatanus 20 35 – 40

I10 Acer pseudoplatanus 20 35 – 40

I12 Acer pseudoplatanus 20 35 – 40

I14 Acer 20 30 – 35

pseudoplatanus

I14 Acer pseudoplatanus 20 30 – 35

I15 Acer pseudoplatanus 20 25 – 30

J12 Fraxinus excelsior 21 55 – 60  Ivy

K4 Acer pseudoplatanus 21 60 – 65  Iv

yL3 Fraxinus excelsior 21 40 – 45L9 Quercus robur 14 35 – 40

M15 Acer pseudoplatanus 22 70 – 75

N14 Acer pseudoplatanus 20 25 - 30

Site 2 Canopy survey (Trees above 5m).

GridNumber Tree Species

Approximate Height

(m)

Girth(cm) Notes

A3 Crataegus monogyna 9 20 – 25  Ivy

A5 Acer pseudoplatanus 19 25 – 30

A7 Fraxinus excelsior 15 25 – 30A10 Fraxinus excelsior 14 20 – 25B1 Fraxinus excelsior 13 25 – 30  IvyB7 Acer campestre 8 15 – 20C10 Fraxinus excelsior 8 10 – 15C12 Fraxinus excelsior 19 30 – 35C15 Fraxinus excelsior 21 40 – 45

C15 Taxus baccata 10 30 – 35D4 Fraxinus excelsior 6 15 – 20D11 Fraxinus excelsior 15 30 – 35D11 Acer campestre 7 15 – 20E3 Ulmus glabra 13 15 – 20E8 Ulmus glabra 12 25 – 30  IvyE8 Ulmus glabra 10 20 – 25E10 Fraxinus excelsior 12 20 – 25

E12 Crataegus monogyna 6 25 – 30

E13 Crataegus monogyna 7 25 – 30

E14 Ulmus glabra 6 10 – 15

F6 Crataegus monogyna 6 35 – 40

G7 Fraxinus excelsior 17 35 – 40G12 Fraxinus excelsior 20 35 – 40H8 Fraxinus excelsior 6 10 – 15H14 Fraxinus excelsior 6 10 - 15

I4 Crataegus monogyna 7 15 – 20  Dead

K4 Crataegus monogyna 8 35 – 40

K10 Crataegus monogyna 5 20 – 25

K11 Fraxinus excelsior 6 10 – 15

L5 Crataegus monogyna 7 20 – 25

L7 Ulmus glabra 6 15 – 20L7 Fraxinus excelsior 7 15 – 20L10 Fraxinus excelsior 16 25 – 30L10 Fraxinus excelsior 15 25 – 30L14 Fraxinus excelsior 9 20 – 25L15 Fraxinus excelsior 11 20 – 25M1 Ulmus glabra 11 20 – 25M2 Fraxinus excelsior 22 40 – 45M10 Acer campestre 6 10 – 15M12 Acer campestre 9 15 – 20

N2 Fraxinus excelsior 6 20 – 25N5 Acer campestre 8 15 – 20N9 Fraxinus excelsior 9 20 – 25N13 Fraxinus excelsior 6 10 - 15

Site 3 Canopy survey (Trees above 5m).

GridNumbe

r

Tree Species Approximate Height

(m)

Girth(cm) Notes

A7 Acer Pseudoplatanus 21 40 – 45

A9 Acer Pseudoplatanus 20 30 – 35

B2 Acer Pseudoplatanus 20 30 – 35

B3 Acer Pseudoplatanus 18 25 – 30

B11 Acer Pseudoplatanus 20 35 – 40

C7 Acer Pseudoplatanus 19 30 – 35

C11 Acer Pseudoplatanus 20 30 – 35

D3 Acer Pseudoplatanus 14 25 – 30

D9 Acer Pseudoplatanus 19 30 – 35

D13 Acer Pseudoplatanus 18 25 – 30

F4 Fraxinus Excelsior 17 25 – 30

F8 Acer Pseudoplatanus 20 30 – 35

F11 Acer Pseudoplatanus 21 35 – 40

G2 Fraxinus Excelsior 19 30 – 35G6 Fraxinus Excelsior 21 30 – 35G13 Fraxinus Excelsior 15 20 – 25H2 Fraxinus Excelsior 20 30 – 35H4 Fraxinus Excelsior 19 30 – 35H9 Acer 19 30 – 35

Pseudoplatanus

I4 Acer Pseudoplatanus 20 30 – 35

I6 Acer Pseudoplatanus 20 30 – 35

J4 Fraxinus Excelsior 18 30 – 35

J8 Acer Pseudoplatanus 19 30 – 35

J14 Fraxinus Excelsior 13 15 – 20K3 Fraxinus Excelsior 17 25 – 30

K10 Acer Pseudoplatanus 19 30 – 35

K12 Fraxinus Excelsior 9 15 – 20K14 Fraxinus Excelsior 11 20 – 25L13 Fraxinus Excelsior 9 15 – 20M1 Fraxinus Excelsior 17 30 – 35M3 Fraxinus Excelsior 19 40 – 45M12 Fraxinus Excelsior 12 15 – 20M12 Fraxinus Excelsior 13 15 – 20M12 Fraxinus Excelsior 11 15 – 20N15 Fraxinus Excelsior 12 15 – 2001 Fraxinus Excelsior 19 30 – 35

014 Acer Pseudoplatanus 19 30 – 35

Site 4 Canopy survey (Trees above 5m).

GridNumbe

r

Tree Species Approximate

Height(m)

Girth(cm) Notes

A1 Fraxinus excelsior 20 30 – 35B5 Fraxinus excelsior 21 35 – 40B13 Fraxinus excelsior 20 30 – 35C6 Fraxinus excelsior 16 20 – 25

E3 Fraxinus excelsior 21 40 – 45E5 Fraxinus excelsior 21 35 – 40E7 Fraxinus excelsior 21 35 – 40E10 Fraxinus excelsior 19 25 – 30E15 Fraxinus excelsior 18 25 – 30G10 Fraxinus excelsior 16 20 – 25G13 Fraxinus excelsior 18 25 – 30I9 Fraxinus excelsior 20 30 – 35K5 Fraxinus excelsior 21 35 – 40M11 Fraxinus excelsior 21 40 – 45M14 Fraxinus excelsior 21 45 – 50O12 Fraxinus excelsior 21 40 - 45

Site 5 Canopy survey (Trees above 5m).

GridNumbe

Tree Species Approximate

Girth(cm)

Notes

r Height(m)

A7 Fraxinus excelsior 19 30 – 35

B1 Crataegus monogyna 6 25 – 30

B3 Fraxinus excelsior 12 20 – 25

B4 Crataegus monogyna 6 20 – 25

B13 Fraxinus excelsior 17 40 – 45

C15 Crataegus monogyna 6 20 – 25

D12 Ulmus glabra 7 25 – 30 Dutch elm disease

E1 Crataegus monogyna 6 15 – 20

E4 Crataegus monogyna 7 20 – 25

E6 Fraxinus excelsior 18 35 – 40

E10 Crataegus monogyna 6 20 – 25  Dead

F14 Fraxinus excelsior 18 30 – 35

G4 Acer pseudoplatanus 9 15 – 20

G6 Fraxinus excelsior 21 40 – 45G6 Ulmus glabra 13 20 – 25

G9 Ulmus glabra 8 20 – 25 Dutch elm disease

G10 Crataegus monogyna 7 20 – 25

G11 Ulmus glabra 10 25 – 30H5 Acer campestre 14 25 – 30H5 Fraxinus excelsior 19 35 – 40H7 Fraxinus excelsior 20 40 – 45H12 Fraxinus excelsior 7 10 – 15

J1 Crataegus monogyna 7 25 – 30

J7 Fraxinus excelsior 16 25 – 30K2 Crataegus 9 40 – 45

monogynaK8 Fraxinus excelsior 11 25 – 30L6 Fraxinus excelsior 18 30 – 35M5 Ulmus glabra 12 25 – 30M6 Fraxinus excelsior 20 35 – 40M8 Fraxinus excelsior 21 40 – 45  IvyM13 Fraxinus excelsior 21 40 – 45M13 Acer campestre 12 25 – 30

N1 Acer pseudoplatanus 6 15 – 20

N3 Fraxinus excelsior 21 45 – 50N7 Fraxinus excelsior 20 40 – 45N8 Fraxinus excelsior 20 40 – 45

O2 Acer pseudoplatanus 6 10 – 15

O12 Acer campestre 7 15 – 20

Appendix 7 - Risk Assessment

Step 1: Define the Scope of the Risk Assessment

Process: MSc Environmental Management, dissertation fieldwork – Woodland flora surveys

Place(s): Ox-Close Wood, Bluebell Wood, Hetchell Woods, Leeds

Type of assessment:

Generic / Specific assessment

New / Existing process

RA Ref: - Frequency of review: N/A

Step 2: Identify the Hazards

Step 3: Identify who might be Harmed

Step 4: Identify Existing Controls and their Reliability

Step 5: Level of Risk

Ref

Hazard

1 Traffic safety when crossing busy road

Student / Assistant

Due care Low

2 Accident or illness when on-site

Student / Assistant

Due care Low

3 Ditches & rough terrain

Student / Assistant

Due care Low

4 Trees, fallen branchesetc

Student / Assistant

Due care, do not climbtrees.

Low

5 Ticks / Insect bites Student / Assistant

Appropriate clothing and insect repellent.

Low

Continue on an additional sheet if more than 6 hazards have been identified.

Step 6: Decide if Risks are Tolerable

Are all risks identified at step5 tolerable?

Yes / No Are additional safety measures available?

Yes /No

(Give details below)

Ref

Additional safety measures to be taken

Carry a mobile phone. Inform someone when I will be arriving on-site and leaving site. Work in the company of an assistant. Wear appropriate footwear. Avoid unnecessary risks.

If the additional safety measures are implemented are all risks identified now tolerable?

Yes / No

Step 7: Define Management Actions

Management Action Required Person Responsible

Target Date

N/A

Step 8: Authorisation

Risk assessment carried out by:

Name: Dominic Ranson

Student Signature:

14.06.2013

Risk assessment authorised by:

Name: Professor Ian D. Rotherham

Supervisor

Signature:

14.6.2013