Friday, 26 October 2012

Ash to ashes...

Posted by Dr Trevor Dines, botanist and Plantlife Cymru Conservation Manager.

With the confirmation of ash dieback disease (Chalara fraxinea) in Scotland and Wales as well as England, what will the future hold, not just for this familiar native tree, but also for the other plants and wildlife it supports?

The humble ash tree (our fourth most common tree in Britain) turns out to be a rather important part of the landscape.  A handsome species, it flourishes on base rich soils where its open canopy encourages a diverse flora on the woodland floor. It supports a vast array of native wildlife from the animal, plant and fungi kingdoms, is an excellent coppice tree with fast growth rates, and is great for woodfuel, making it an important tree in terms of managing woodland for the benefit of our woodland flora.

Lady orchid. © Andrew Gagg/Plantlife 
Whilst the floor beech woodlands can be bare, ash woods abound with primroses, ferns, anemones and early purple orchids. In some areas, ash woodlands are home to some very special plants indeed. Native wild daffodils and fragrant lily-of-the-valley prefer to grow in ash woodlands, as do the arching stems of Solomon's-seal and rarities such as lady orchid, Suffolk lungwort and the exotic lady’s-slipper orchid. Spiked Star-of-Bethlehem, a bulb that produces a flower spike once harvested as a substitute for asparagus, has already declined following the loss of elm woods and is now largely confined to the shade of ash trees. Similarly, toothwort, a remarkable plant that lives entirely underground on the roots of trees, its presence only belied when the fat pink flower spikes emerge in spring as if by magic, prefers to grow on the roots of elm, hazel and ash and is already declining across Britain.

Not only important for the plants that grow around it, ash is vital to those plants that grow on it.  As well as a wide range of fungi, mosses and liverworts, 255 species of lichen are recorded as finding a home on the trunks, branches and twigs of ash, a figure second only to oak. Of particular importance are the highly threatened group of lichens known as lungworts, which thrive on the base-rich bark of ash trees in western parts of Britain. Groups of these large, leafy lichens often grow closely together on the same tree, forming a spectacular tapestry of colour and texture.

Lobaria pulmonaria, a lungwort lichen.  © Ray Woods
In addition, ash is renowned for the insects that it supports – over 120 species including gall midges, bark beetles, leaf miners and sawflies - and its fruit are a valuable source of food for many birds and mammals, such as bullfinches and wood mice.

Ash dieback was first recorded in Britain in February 2012, when the fungus was found on trees at a nursery in Buckinghamshire. These had come from a nursery in the Netherlands and since then five other outbreaks in England and Scotland have all been found on nursery stock planted within the last five years.

Plantlife welcomes the ban on imported ash but, with the disease now present in the wild, this measure may be too late. The impact of large stands of ash dying will be considerable. In their place, we’ll probably see a sprouting of other trees - sycamore most likely - to replace the ash, with a completely different bark and leaf shading pattern. This in turn will alter the woodland floor flowers as well as the lichens, mosses and liverworts living on the trees.

Plantlife is keen to ensure the continuity of our woodland – both trees and flora - by encouraging a greater emphasis on woodland management and the natural regeneration of native stock rather than being reliant on planting non-native imports.  As part of Plant Link UK, we have submitted a response to the Food and Environment Research Agency (FERA) consultation on how to tackle the problem. But you can play your part too: if you know of any ash trees planted over the last 5-7 years, do keep a close eye on them and please report any dying ash to FERA or the Forestry Commission.

For more on Plantlife’s call for more sustainable woodland management to revitalise our dark and overgrown woodlands, click here (here for Scotland and here for Wales).