1. LAP Ash Dieback Workshop
Silviculture and management of ash:
best practice advice for woodland managers
Edward Wilson
Silviculturist
Chalara Ash Dieback Workshop
Tamar Valley AONB Helping Hands for Heritage Event
The Oak Room, Tiverton, Devon
13 August 2015
First presented: 18 06 2014
This version: v2.0, 13 08 2015
RESEARCH
I N T E R N A T I O N A L

2. Outline
• Threat to forests in Britain
• Modern Silviculture: adaptation and resilience
• Principles underlying guidance for ash
• Management options:
– Uninfected stands
– Infected stands
– Older stands
– Coppice
– Urban/parkland/hedgerow trees
• Further information
• Questions and Discussion

3. Guiding Principle
‘All our resolves and decisions are made
in a mood or frame of mind which is
certain to change.’
Proust

4. Review: Threats to UK Forests
Source: Forestry Commission England 2012
• Climate change
– Summer droughts increasingly likely, especially in South
and East
– Extreme rain and flooding events are more likely
– Ecosystem change – especially ground plants
• Pests and diseases
– Native and exotic
• Low Resilience of Existing Forest Resources
– Low number of productive species
– Monoculture stands are most common

5. United Kingdom Forestry Standard
Major Policy Documents in British Forestry
See www.forestry.gov.uk for archive of literature – technical, scientific and policy

6. Ecological Resilience
• Resilience is the capacity of an ecosystem to respond to a
disturbance by resisting damage and recovering quickly
• Not a new concept, but perhaps newly relevant to forestry
– Holling, C. S. 1973. Resilience and stability of ecological systems .
Annual Review of Ecology and Systematics 4: 1-23
– now >5800 citations (to July 2014)
• Types of disturbance
– Stochastic: fires, flooding, windstorms, insect population explosions
– Human activities: deforestation, introduced exotic plants/animals
• Disturbances and regime change
– sufficient magnitude or duration of disturbance → profound affect on
ecosystem → threshold (“tipping point”) → different regime of
processes and structures predominate

7. Rumsfeldian “Ecology”
• There are known knowns; there
are things we know we know.
• We also know there are known
unknowns; that is to say, we
know there are some things we
do not know.
• But there are also unknown
unknowns – the ones we don’t
know we don’t know. Donald Rumsfeld
US Secretary of Defense,
12 February 2002

8. The threat of climate change
Source: UK Meteorological Office
BUT!!!! Remember that our concern is not just with temperature. The predictions all point to more
instability in terms of windiness, rainfall, storm events, etc. All are aspects of global climate change
that foresters need to consider in their long-term planning.

9. What Ecological Site Classification (ESC) suggests in
terms of the dominant productive species
Effects of climate change on the identity of the most productive conifer species as predicted
by Ecological Site Classification for the UKCIP02 2050s High and Low emission scenarios.
ESC is based on
temperature, moisture
and soil physical
properties
It does not consider
Dothistroma, or any
other pests or diseases.
Source: Forestry Commission

10. Risk to woodlands on the Public Forest Estate
By the 2080s, there is a risk of 65% of the PFE being classed as ‘unsuitable’
in the absence of adaptation – a potential 35% decline in productivity
Source: Forestry Commission 2012

11. The evolution of silviculture
Summary of the major dimensions and trends
Primary Focus
Unit of Production
Tree
Ecosystem
Ecological Factors
Stand Structure
Pure, regular
Mixed, irregular
Stand Dynamics
Simple
Complex
Management Factors
Objectives/Issues
Single, discreet
Multiple, integrated
Decision-making
Professionals
Informed public
Source: Wilson 2000

12. Climate Change Action Plan for the Public Forest Estate
We will adopt the principle of anticipatory
adaptation. This offers the highest potential
gains for forest resilience, and the benefits
they provide.
We will take an approach that is ‘not risk
averse’.
Global emissions are currently tracking
close to some of the more extreme
emissions scenarios that have been
published, so it is prudent to consider
the 2050 high scenario when planning for
the future.
Diversification is the theme!

13. Succession stages in a natural forest
initial stage intermediate stage
open
ground
final stage
Strategies for Enhancing Resilience
Modify thinning regimes Extend “rotations”
Diversify Structure
- CCF
Species choice
- genetics/provenance
Mixed species
Assisted migration of native species
New species introduced
Wider use of “minor” species
Diagram: Jens Haufe

14. Alternative Species
Chinese mahogany
(Toona sinensis)
After 2 growing seasons
Westonbirt Arboretum
Photo: E. R. Wilson

15. Prolific ash natural regeneration
in a small canopy clearing – lots
of competition and selection
Photo: Sharon Rodhouse

16. New native oak plantation.
Note close spacing to promote form,
competition and natural selection. Photo: E. R. Wilson

17. Continuous Cover Forestry
• “...the use of silvicultural systems whereby the forest
canopy is maintained at one or more levels without clear
felling.”
Mason et al. 1999
It has 4 main guiding principles:
1. Managing the forest ecosystem
2. Using natural processes
3. Working within site limitations
4. Diversifying stand structure
Prime movers: ProSilva Europe (1989) and CCFG (1991)

18. final harvest
and
regeneration
young
growth
stage
H<1.3m
pole stage
DBH>10cm
DBH<20cm
small timber
stage
DBH>20cm
DBH<35cm
medium
timber stage
DBH>35cm
DBH<50cm
DBH>50cm
large timber
stagethinning
thicket stage
H>1.3m
DBH<10cm
respacing
fallow stage 
restocking
final harvestBeat up,
tending
In order to transform a planted forest we have to:
• develop adequate tree stability (Frame Trees).
• promote the best trees as likely source for Natural Regeneration (NR)
• get the species composition right
• create optimal conditions for NR (ground vegetation, seedbed, browsing)
Stand development and transformation
Source: Jens Haufe

19. Modified first thinning in Douglas fir
Wythop Wood, Cumbria
Photo: G. Browning

20. Frame tree and natural regeneration
Douglas fir stand, Wythop Wood, Cumbria
Photo: G. Browning

21. Light demand of conifer seedlings
Species
Overstorey BA for
seedling stablishment
[m2
/ha]
Overstorey BA for
seedling growth
[m2
/ha]
Shade tolerance
of seedlings
JL/EL 20-25 15-20 Intolerant
SP/LP/CP 25-30 20-25
SS 30-35 25-30 Intermediate
DF 35-40 30-35
NS
40-45 35-40
Tolerant
WH
leader/lateral
shoot ratio > 1
Management of Seedling Establishment and Growth
Note: Light demand for seedling
establishment may be considerably
lower than for seedling growth.
 management of light level is
important
(Source: Forestry Commission Operational Guidance OGB 7)

22. Single and group tree selection in Douglas fir
Mixed-species regeneration
Photo: E. R. Wilson

23. Lowland broadleaved shelterwood
Sharon Rodhouse 2007

24. Management Guidance and Advice for Ash

25. Ash Silviculture and Management Principles
• Maintain the values and benefits associated with ash
woodlands and iconic trees;
• Secure an economic return where timber production is an
important objective;
• Reduce the presence and rate of spread of Chalara dieback;
• Maintain as much genetic diversity in ash trees as possible
with the aim of ensuring the presence of ash in the long term;
and
• Minimise impacts on associated species and wider
biodiversity
Source: Forestry Commission 2013, Royal Forestry Society 2014

26. Reporting suspected cases of Chalara ash dieback (1)
• Check ash plantations and
woodlands regularly during the
growing season for signs of
Chalara ash dieback disease
• Look for:
– leaf wilting and premature
browning in the growing
season
– Shoot dieback and epicormic
sprouting
– Characteristic diamond-
shaped lesions on stems at
branch unions
• Check current guidance for
disease signs and symptoms – see
www.forestry.gov.uk/chalara
Photo: E. R. Wilson 2014
Photo: E. R. Wilson 2014Photo: Forest Research

27. Reporting suspected cases of Chalara ash dieback (2)
• Three ways to report suspected cases of ash dieback:
1. Forestry Commission’s Tree Alert app – see
www.forestry.gov.uk/treealert, Google Play or App Store
2. Forestry Commission on-line reporting form -
www.forestry.gov.uk/treealert
3. Defra hotline on 08459 33 55 77
• Respondents are asked to enter the code '6/20' in the
'Additional notes' field of the app or online reporting form or
to mention this when reporting through the hotline.
• Removal of infected trees. See latest Forestry Commission
guidance - http://www.forestry.gov.uk/forestry/INFD-979BZJ
Source: Forestry Commission 2013

28. Reporting suspected cases of Chalara ash dieback (3)
• Grant Aid. Death of ash trees on sites currently within an
active grant or farm woodland scheme should also be
reported to the office administering the scheme
www.forestry.gov.uk/england-areas
• Re-planting. Financial support available for removal of
diseased trees and re-planting with alternative species on
sites planted under the English Woodland Grant Scheme and
now subject to Chalara dieback (in counties designated as
high and medium risk only). Work can only commence
following approval of grants.
Source: Forestry Commission 2013

29. Silviculture and management options for ash
1. Uninfected stands
1. Planning
Before taking any action, owners/managers need to review
their management objectives and local circumstances.
2. Silviculture
Carry on with planned work and thin to promote fast, healthy
growth in selected trees.
3. Biosecurity
Adhere to guidance on biosecurity, ensure tools are
disinfected, boots and clothes cleaned and ash leaves are not
moved from the wood
4. Monitoring
Regularly monitor trees for signs of Chalara and, if found,
report to the Forestry Commission (see earlier guidance).
Source: Forestry Commission 2013, Royal Forestry Society 2014

30. Silviculture and management options for ash
2. Infected stands (<25 years)
1. Where there are low levels of disease
– Young Plantations
Remove recently planted trees and natural regeneration if
small numbers are infected and burn or bury them on site.
– Pole-Stage Stands
Thin woodland as usual. Select diseased trees for thinning
which show symptoms of Chalara, preferably when in full
leaf to ensure the right tree is felled, and where possible
burn the brash.
– Coppice
Do not bring forward coppicing of ash as this will make
stools and new growth more vulnerable to Chalara.
Source: Forestry Commission 2013, Royal Forestry Society 2014

31. Silviculture and management options for ash
2. Infected stands (<25 years)
2. Where there are high levels of disease (>50% stand infected)
– Support Research
Do not rush to remove recently planted or mature trees, or
ash coppice. This will prevent identification of resistant trees.
– Realise Timber Value
Consider felling ash to realise the value before timber
condition deteriorates or thin to favour alternative species.
– Biodiversity
Consider leaving some trees close to dying for deadwood and
biodiversity. Restock with alternative species suitable for
local site conditions and to emulate the ecological value of
ash (see Natural England guidance). Validate the provenance
of any new stock with your nursery prior to purchase.
Source: Forestry Commission 2013, Royal Forestry Society 2014

32. Natural England Guidance for management of
woodlands of conservation importance
• Assessing and addressing
the impacts of ash dieback
on UK woodlands and trees
of conservation importance
• Published on 30 April 2014
• http://publications.naturale
ngland.org.uk/publication/5
273931279761408

33. Silviculture and management options for ash
2. Infected stands (<25 years)
3. Where timber production is not a consideration
– Habitat Conservation
The aim here is to retain ash in the wood for as long as
possible to provide habitat for species dependent on ash
and to allow time to identify trees that may be resistant.
– Commitment to Management
Continuing to manage the wood will ensure less spore
production and more light on the woodland floor to
encourage regeneration and structural diversity.
Source: Forestry Commission 2013, Royal Forestry Society 2014

34. Silviculture and management options for ash
3. Infected older stands
• Adopt an individual tree approach
– There should be a presumption against the felling of
ancient, veteran or mature ash trees, whether or not they
are infected with Chalara.
– Where less than 50% of the crown is infected the tree
should be regularly monitored and symptoms of honey
fungus (Armillaria) – often it is this secondary infection that
kills the tree.
– Where more than 50% of the crown is infected consider
felling.
– Health and Safety around Dead and Declining Trees
Take special care and appropriate measures where trees are
in areas close to public access.
Source: Forestry Commission 2013, Royal Forestry Society 2014

35. Ash and oak planted mixture, Suffolk
Photo: Gary Battell

36. Ash being managed for firewood, Suffolk
Photo: Gary Battell

37. Silviculture and management options for ash
4. Coppice Woods
• Coppice
– Where there are low numbers of infected coppice stools in
the wood consider killing them.
– Attempting to regenerate a wood from coppice stools is not
recommended as coppice re-growth is likely to be infected.
– Avoid carrying out traditional coppice operations where ash
forms >30% of the canopy.
Source: Forestry Commission 2013, Royal Forestry Society 2014

38. Ash coppice, Suffolk
Photo: Gary Battell

39. Silviculture and management options for ash
5. Urban/parkland/hedgerow trees
• Litter Removal
There is evidence that removal of leaf litter combined with the
lower humidity in urban and parkland environments can
significantly reduce and slow the impact of Chalara.
• Wider Benefits
There should not be a presumption to fell infected trees in
these environments as these trees can continue to provide
benefits even when dead.
• Health and Safety
Carry out a full risk assessment before taking action. Public
safety is of paramount importance in this assessment.
Source: Forestry Commission 2013, Royal Forestry Society 2014

40. New Woodland Considerations:
- Management objectives
- Site-based silviculture
- Diversify species choice
- Consider ecological alternatives
(Natural England Guidance)
- Consider mixtures
Mixed native woodland
Golden Wood (Green Light Trust)
Lawshall, Suffolk
Photo: E. R. Wilson 2014

41. Principles of ESC are well-established
ESC is a knowledge-based model; productivity
distribution data are used to inform decisions
ESC was developed to support commercial
species selection
Also analysis of National Vegetation
Classification community types
Detailed species information, including some
provenance guidance
ESC does not consider rising CO2 levels or plant
health issues
Ecological Site Classification (ESC)
A Cornerstone of site-based silviculture

42. Wider Environment: A mature ash tree with
Signs of Chalara ash dieback disease
Photo: Sharon Rodhouse 2012
Be vigilant!
Early identification of infected trees will give more
options for management and conservation of woodlands

43. Early signs of Chalara ash dieback
on current year leaves
Frithy Wood (Green Light trust)
Lawshall, Suffolk. 17 June 2014
Photo: E. R. Wilson 2014

44. Supporting Forestry Research is Vital
Become an Applied Scientist
Ash Genetics Trial
Photo: Jo Clark, Earth Trust

45. The Forest Research Site at Pound Farm, Woodland Trust, Suffolk. Photo: E. R. Wilson 11 August 2015

46. The Forest Research Site at Pound Farm, Woodland Trust, Suffolk. Photo: E. R. Wilson 11 August 2015

47. Conclusions
• Resilience - theoretical framework within which we
can ensure sustainable management of natural
resources
• Working with Uncertainty – in all future decisions
and actions
• Implications for forestry in the UK
– Diversification of genotypes, species and structures
– Site-based decision making
• Global issues require local, site-specific solutions

48. "A gentleman takes as much
trouble to discover what is
right as lesser men will take
to discover what will pay."
K'ung Fu-tzu (Confucius),
quoted by M.L. Anderson 1951
Decision making
Reference:
Anderson, M.L. 1951. The Selection of tree species: an
ecological basis of site classifications for conditions found in
Great Britain and Ireland. Oliver and Boyd, Edinburgh. 151 pp.

49. References, Further Information and Guidance
• Forestry Commission
– www.forestry.gov.uk/chalara
– 08459 33 55 77 (Defra hotline - open 8am - 6pm every day)
– plant.health@forestry.gsi.gov.uk
• Natural England
– Assessing and addressing the impacts of ash dieback on UK woodlands and
trees of conservation importance:
http://publications.naturalengland.org.uk/publication/5273931279761408
• Royal Forestry Society – Managing Chalara fraxinea (Ash Dieback): Guidance
for woodland owners and managers (May 2014)
– http://www.rfs.org.uk/files/Managing-chalara-ash-dieback_May2014.pdf
• Kent Downs AONB – Guidance on Ash Management
– www.kentdowns.org.uk
• Future Trees Trust
– www.futuretrees.org

50. livingashproject.org.uk
Project partners:

51. LAP Ash Dieback Workshop
Acknowledgements
My thanks to the following colleagues and organisations: Jo Clark, Earth Trust; Tom
Brown, Green Light Trust; Sharon Rodhouse, Sylvatic Ltd; Gary Battell, Suffolk County
Council; Jens Haufe, Forestry Commission; Gareth Browning, John Weir and Barnaby
Wylder, Forestry Commission England; Forest Research; Royal Forestry Society
Contact Information
Edward Wilson
Email: ted.wilson@silviculture.org.uk
Web: www.silviculture.org.uk
First presented: 18 06 2014
This version: v2.0, 13 08 2015
RESEARCH
I N T E R N A T I O N A L