Fraxinus excelsior (Common Ash)
In Toll Wood:
This section includes our strategy for future management. Where possible, ash in all stages of life, infection, death, and regeneration will be retained in situ. Only demonstrably sick trees, adjacent public rights of way (Red Zone), should be considered for felling or reduction to manage hazards.
Most of our ash trees sit in the southern 'toe' of Toll Wood. They are mixed with many sycamore that appear to be struggling with the dry, shallow soil over chalk. Removal of sycamore offers scope for planting drought-tolerant tree species. There is some evidence coming out of France (Grosdidier et al 2020) that serious disease is less likely where the canopy is less crowded. The southern part of the wood shows the clearest suggestion of relatively recent clear-felling as the trees are of similar age to each other except at the woodland edges.
Ash die-back watch: Caused by Hymenoscyphus fraxineus fungus that arrived around 2004 - used to be called Chalara fraxinea. Things to look for include raggedy "witches broomsticks" at the extreme ends of boughs at the crown of the tree - in full-leaf, a diseased ash gradually loses its leaves; bleeding lesions on the trunk. Infection is generally airborne - often incubated in leaf-litter.
It is important to keep an eye on the health of our ash trees. Unlike Elm, Ash may not need to be felled after infection. Felling and/or removal of boughs only needs to take place where there is busy traffic (pavements, public footpaths and busy roads) - so-called "red zones" for monitoring and regular risk assessment.
The Trust reviewed the conditions for ash in Toll Wood (2024). Our policy follows official advice - one sick tree is absolutely not a reason to fell that tree unless it presents a danger to public spaces (Toll Lane and public path ZR269, or "Granny Stiles' Path"). Nearly all the ash trees can mostly be left alone as stumps for their habitat importance. There is also potential for epicormic regrowth (from what appear as small bumps on the trunk) or "suckering" from their roots. Not all ash trees are equally vulnerable to 'ash die-back'. There may be scope for limited planting of disease-resistant ash varieties (unless, of course, we already have disease-resistant ash).
Succession planting strategy. If the UK loses 90% of all its ashes, the impact on biodiversity is serious. For example, if "ash dependent" species of invertebrates are to survive the shock, it makes sense to get in early with planting and protecting a multitude of native species to fill the gap. The many native species across Toll Wood is encouraging for the future of the wood and its inhabitants.
Based on research in 2016, 2019 and a literature survey in February 2023, ash habitat restoration can be (nearly) achieved by using a mix of native species. For Toll Wood conditions, that list includes field maple, copper beech, aspen, sessile oak and hornbeamfn1. Two species often included in this context are sycamore (over-abundant in Toll Wood and struggles amongst the ash trees) and silver birch (a pioneer species that can be invasive).
Biodiversity value: HIGH
Ash is a European "keystone" species for its important niche biodiversity in hedgerows, woods and forests.
They are particularly important for leaf-litter, lichens, fungi, mycorrhizal networks and invertebrates. As such, it is important to about 41 invertebrate "chewer" species and 23 sap-feeders.
Flowering in spring, ash trees can carry both male and female flowers on different branches, pollinated by wind. Seeds hang in clusters that can stay on the tree into the winter as a valuable food source - e.g. bullfinch. The leaves drop early, which is important for the understory plants, including dog's mercury that is abundant in Toll Wood.
Footnotes
fn1. Percentage of species diversity shared between ash and other trees - Acer campestre - Field maple (88%), Acer platinoides - Norway maple (60%), Acer pseudoplatanus - Sycamore (88%), Alnus glutinosa - Black alder (89%), Betula pendula - Silver birch (90%), Betula pubescens - Downy birch (90%), Carpinus betulus - Hornbeam (88%), Fagus sylvaticus - Copper beech (92%), Juglans regia - English walnut (81%), Populus tremula - Aspen (89%), Prunus avium - Wild cherry (88%), Quercus petraea - Sessile oak (94%), Quercus robur - Pedunculate oak (94%), Tilia cordata - Small-leaved Lime (31%).
