Sunday, November 11, 2012

The threatened ash tree

click photo to enlarge
The sea that separates the British Isles from continental Europe is generally thought of, by the inhabitants of these islands at least, as a blessing, a defensive moat that kept Napoleon and Hitler at bay, has stopped rabies from becoming widespread here, and prevents European integrationism from too deeply affecting our idiosyncratic ways. However, a longer view must also record how, when the ice ages covered our islands in glaciers, sending the wildlife south to escape its deadly touch, the thaw that followed and the North Sea and English Channel that it created and which separated our islands from Europe, also prevented the return of many plants and animals. Thus, fallow deer were present before the last glaciation, but did not return after it, the present herds all being introduced animals. As many school children used to know, the adder made it back to England, Scotland and Wales, but it wasn't St Patrick who banished it from Ireland, but rather the inundation that became the Irish Sea prevented it reaching that country.

However, in these days of regular international and inter-continental travel, when goods are shipped around the world with barely a thought, and when companies source products from whoever can provide them at the lowest price, the narrow stretch of sea that was once seen as a formidable barrier, is today a mere ditch that can be stepped across at will. Ash dieback disease, the Chalara fraxinea fungus that was first seen in Eastern Europe twenty years ago, which has spread rapidly across the continent, badly affecting the ash trees of Germany, France and elsewhere, and has affected 90% of Danish ash trees, is now spreading in Britain. There is some debate over whether it was brought in solely on imported saplings or whether it also arrived on the wind from across the narrow North Sea. But, it seems widely agreed that it is here, it can't be eradicated, only slowed in its progress, and it will have a major effect on our hedgerows and woodlands, as well as on the wildlife that favours this particular species. Current thinking suggests that the best course of action is to leave trees to die naturally, to identify those individual trees that seem to be resistant, and to begin a breeding programme to produce new plants from them.

This depressing business was on my mind as I processed today's photograph. I didn't notice when I took the shot, but it features a young ash tree. Five and half percent of British woodland trees are ash, but 12 million grow elsewhere, particularly in hedgerows. It is the second most commonly seen individual tree (after the oak). I read that in Lincolnshire and East Yorkshire combined the ash accounts for 40 percent of the trees. A loss of such magnitudes would be devastating nationally and locally.

photograph and text © Tony Boughen

Camera: Canon
Mode: Aperture Priority
Focal Length: 45mm
F No: f7.1
Shutter Speed: 1/800
ISO: 100
Exposure Compensation:  -1.33 EV
Image Stabilisation: On