There are an estimated 80 million Ash trees in the UK (the third most populous species after Birch and Larch). However, recent findings from environmental organisations suggest that 90% of the current Ash population will be eradicated within the next decade.
A shadow is looming - the fungal disease Chalara fraxiena has made its way across mainland Europe to the shores of the British Isles. The changing season makes it more difficult to spot for signs of disease, but if you look closely - in certain parts of the country - you will be able to spot trees with dark lesions, dying leaves. The disease affects mature trees by reducing the numbers of twigs and branches at the crown, giving them a strange spiky-topped appearance.
The loss of Ash Trees on our landscape will have a severe and long-lasting impact. In some areas of the country, Ash Trees dominate as 'hedgerow trees'. They are the main species of tree planted in hedgerow's along our farmland. Such trees provide a valuable habitat for plants and animals. In particular, it is thought that certain species of Ash-dependent Lichen (an organism consisting of fungus and algae) could disappear altogether. These impacts, of course, would deeply hamper the government's post-2010 targets of conserving and enhancing the UK's biodiversity.
On a positive note: scientists in Denmark and the UK have found that not all Ash Trees succumb to the disease. In fact, 2% of the British Ash Tree population are estimated to be genetically resistant to the strain. At present, scientists in Denmark are collecting the seeds of trees which have not been infected and are hoping to plant new, disease-resistant trees.
Regardless, the disease is spreading fast within the UK, with incidences having increased rapidly since the outbreak was first discovered in areas of East Anglia in October 2012. As of the 15th November, there have been 200 confirmed cases of Chalara fraxiena reported to the Forestry Commission. Of this total, 116 were cases of the disease occurring in natural woodland. Moreover, the disease is thought to have spread not just from infected imports but also through wind-borne spores; which can survive for extended periods of time and move up to 20-30 km per year (Forestry Commission, 2012).
The rapid pace and character of the disease could mean that, despite the best efforts of the government and environmental bodies to control and stop the spread of the disease, many Ash Trees (particularly younger trees) will leave a large, empty space in our countryside. It will likely be many years before woodland and Ash-dependant plant, animal and insect populations are able to recover.
If you want to know more about the disease and what solutions are being put forward then please head to The Woodland Trust's specialist prevention website- www.treedisease.co.uk.
There is also information available from The Forestry Commission: http://www.forestry.gov.uk/chalara.
No comments:
Post a Comment