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Silviculture and management of ash: best practice advice for woodland managers (v1.1). Living Ash Project, 18 June 2014

This presentation was prepared for the Living Ash Project Chalara Ash Dieback Workshop at Lawshall, Suffolk on 18 June 2014.

The talk aims to provide an overview of the silviculture and management of ash woodlands in Britain, where Chalara ash dieback is currently a major threat. The lecture starts with an overview of the key drivers in forestry at the present time, including the need to adapt and enhance the ecological resilience of woodlands in the face of many threats (climate change, pests, diseases). A major theme is the need to diversify the range of genotypes, species and structures of woodlands so that the risk of major damage is minimised. A large number of silvicultural practices are reviewed, and several, including planting alternative species and continuous cover forestry, are presented in more detail.

With respect to ash, a number of silvicultural and management measures have been introduced to slow the rate of infection, minimise environmental impacts and realise the value of ash timber. Practical guidance is provided, based on information from the Forestry Commission and Royal Forestry Society. In addition, there is greater need for monitoring forest conditions so that infected trees can be located as quickly as possible.

Finally, the presentation highlights the role of research and the need to identify ash trees that demonstrate a degree of tolerance or resistance to infection. These trees are an important priority for the Living Ash Project and for future ash tree breeding programmes.

The presentation includes many photographs taken in the field and supplied with acknowledgement by colleagues.

Further information on the Living Ash Project is available at Also at the Future Trees Trust, General information about the biology and management of Chalara ash dieback is available from the Forestry Commission,

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Silviculture and management of ash: best practice advice for woodland managers (v1.1). Living Ash Project, 18 June 2014

  1. 1. LAP Ash Dieback Workshop Silviculture and management of ash: best practice advice for woodland managers Edward Wilson Silviculturist Chalara Ash Dieback Workshop Lawshall Village Hall, Lawshall, Suffolk 18 June 2014 First presented: 18 06 2014 This version: v1.1, 05 07 2014 RESEARCH I N T E R N A T I O N A L
  2. 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. 3. Guiding Principle ‘All our resolves and decisions are made in a mood or frame of mind which is certain to change.’ Proust
  4. 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. 5. United Kingdom Forestry Standard Major Policy Documents in British Forestry See for archive of literature – technical, scientific and policy
  6. 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. 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. 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. 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. 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. 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. 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. 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. 14. Alternative Species Chinese mahogany (Toona sinensis) After 2 growing seasons Westonbirt Arboretum Photo: E. R. Wilson
  15. 15. Prolific ash natural regeneration in a small canopy clearing – lots of competition and selection Photo: Sharon Rodhouse
  16. 16. New native oak plantation. Note close spacing to promote form, competition and natural selection. Photo: E. R. Wilson
  17. 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. 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. 19. Modified first thinning in Douglas fir Wythop Wood, Cumbria Photo: G. Browning
  20. 20. Frame tree and natural regeneration Douglas fir stand, Wythop Wood, Cumbria Photo: G. Browning
  21. 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. 22. Single and group tree selection in Douglas fir Mixed-species regeneration Photo: E. R. Wilson
  23. 23. Lowland broadleaved shelterwood Sharon Rodhouse 2007
  24. 24. Management Guidance and Advice for Ash
  25. 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. 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 Photo: E. R. Wilson 2014 Photo: E. R. Wilson 2014Photo: Forest Research
  27. 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, Google Play or App Store 2. Forestry Commission on-line reporting form - 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 - Source: Forestry Commission 2013
  28. 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 • 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. 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. 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. 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. 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 273931279761408
  33. 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. 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. 35. Ash and oak planted mixture, Suffolk Photo: Gary Battell
  36. 36. Ash being managed for firewood, Suffolk Photo: Gary Battell
  37. 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. 38. Ash coppice, Suffolk Photo: Gary Battell
  39. 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. 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. 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. 42. Wider Environment: A mature ash tree with Signs of ash dieback disease (Chalara fraxinea) Photo: Sharon Rodhouse 2012 Be vigilant! Early identification of infected trees will give more options for management and conservation of woodlands
  43. 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. 44. Supporting Forestry Research is Vital Become an Applied Scientist Ash Genetics Trial Photo: Jo Clark, Earth Trust
  45. 45. 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
  46. 46. "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.
  47. 47. Silviculture Rediscovered ‘Everything has been thought of before, but the problem is to think of it again’ Goethe
  48. 48. References, Further Information and Guidance • Forestry Commission – – 08459 33 55 77 (Defra hotline - open 8am - 6pm every day) – • Natural England – Assessing and addressing the impacts of ash dieback on UK woodlands and trees of conservation importance: • Royal Forestry Society – Managing Chalara fraxinea (Ash Dieback): Guidance for woodland owners and managers (May 2014) – • Kent Downs AONB – Guidance on Ash Management – • Future Trees Trust –
  49. 49. Project partners:
  50. 50. 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: Web: First presented: 18 06 2014 This version: v1.1, 05 07 2014 RESEARCH I N T E R N A T I O N A L