Assessing the impact of ash dieback on biodiversity
The Tree Council is highlighting a five-step plan for assessing the impact of ash dieback on woodland biodiversity.
Also known as chalara, ash dieback is spreading through the UK and is expected to destroy up to 90 per cent of the country’s ash population. The widespread death of ash trees has the potential to impact on the populations of many other plant and animal species that use ash trees for feeding, breeding or as a habitat, including birds, mammals, lichens, fungi, and invertebrates.
The five-step plan was discussed by Ruth Mitchell from the James Hutton Institute during a recent meeting of the England Woodland Biodiversity Group (EWBG), of which The Tree Council is a member.
The plan consists of the following five steps:
- Step 1: Assess the potential biodiversity of the site
- Step 2: short list priority species for conservation
- Step 3: Identify the alternative tree and shrub species needed to maintain these species
- Step 4: Assess the site
- Step 5: Determine management.
The plan is based on a report published by Defra in 2014 and subsequent research led by Ruth Mitchell, which found that no single tree species offers a suitable alternative to ash on its own in terms of its benefits to biodiversity. Out of 22 tree species studied, the research identified the top five alternative tree species as oak, beech, sycamore, hazel and birch.
During the presentation based on her work, Ruth told members of the EWBG that establishing a mix of tree species to replace ash would support a much greater number and variety of ash-associated species than a single alternative tree species. For example, a mixture of oak and beech could support 74% of ash-associated species identified, while a combination of field maple, sycamore, birch, hazel, hawthorn, beech, poplar, bird cherry, oak, goat willow and small-leaved lime could support 84% of species that can be found depending on ash.
The research also highlighted the benefits of leaving ash (living and dead) within ash woodlands, rather than removing it, for ash associated biodiversity as this will give wildlife more time to colonise alternative hosts.
The full report can be viewed here
A user-friendly database for woodland managers to assess the impact of ash dieback on biodiversity and to plan interventions accordingly can be downloaded from Natural England.
The next meeting of the EWBG is scheduled for 5th December 2016. If there are any issues that you would like us to discuss with the group, then please send an email to: firstname.lastname@example.org