Monday, August 3, 2009

Neglect is casting Britain's once bright woodlands into darkness

Damian Carrington in the Guardian (UK): The gentle pleasures of a summer's woodland walk have become darker and duller, thanks to fertiliser from farms and the ancient art of coppicing dying out.

The discovery came after botanist Sally Keith retraced the steps of the pioneering ecologist Professor Ronald Good, who cycled the lanes of Dorset in the 1930s, recording in great detail the plants he found. Of the 1,500 woodland sites Good noted, Keith revisited almost 100, as close to the day and month of the original survey as possible.

She found that the unique character of each wood had vanished, and that the canopy of leaves was more dense. …"It's both fascinating and disturbing," said Professor James Bullock at the Centre for Ecology and Hydrology in Wallingford, Oxfordshire, who worked with Keith. "It's likely to be going on undetected elsewhere, but as we have Good's maps we can see it here. We are losing diversity on a large scale…."

…Keith believes there are two key reasons for woodlands becoming less distinctive. First is the end of coppicing, in which wood was harvested from different parts of a forest in rotation, creating bright clearings and letting in light to favour less common plants, such as red bartsia. In her study, 117 species had vanished, while only 47 new plants had arrived. "Traditionally, woodlands had glades, meadows and ponds, giving many more habitats and so many different things to see, rather than wall-to-wall trees," said Hetherington.

The other key reason is the increased run-off of nitrogen from farms, due to increased fertiliser use and intensive livestock rearing. Some plants, such as holly, thrive on high nitrogen levels; others do not….

A coppiced alder stool after one year's growth. Image by Naturenet, Wikimedia Commons, under the Creative Commons Attribution ShareAlike 3.0 License.


Mark Fisher said...

I just wonder why the researchers assume that managed woodland and the opportunistic species it attracts is necessarily the natural ideal. Thus the conclusion of greater shade as a detractor just seems to be aping that of the English Nature Research Report 653 - "Long-term ecological change in British woodlands (1971-2001). That study noted it was a value judgement that favoured open habitat species in woodlands. They wondered whether it is feasible to return to the high levels of species richness shown in their 1971 baseline survey for plants if this was a consequence of a one-off set of circumstances around the specific management of woodland in the mid-twentieth century? They say the same argument might also apply to butterflies and birds in woodland, as it does to plants. I would say that argument also applies to this study of Dorset woodland! If the trend is to a "homogenisation" then this surely is a reflection that it is woodland species that are occupying woodland spaces. England has one of the lowest woodland covers in Europe, and consequently one of the smallest amounts of interior woodland habitat. To impose open habitat species sets on such extant woodland through "management" seems onerous, and does not admit other realities for our wild nature.

Brian Thomas said...

What an interesting point -- the downside of the old-style management. Thanks for this thoughtful comment.