Drier conditions at the edges of forest patches slow down the decay of dead wood and significantly alter the cycling of carbon and nutrients in woodland ecosystems, according to a new study.
Forests around the world have become increasingly fragmented, and in the UK three quarters of woodland area lie within 100 metres of the forest edge. It has long been known that so-called 'edge effects' influence temperature and moisture (the 'microclimate') in woodlands, but the influence on the carbon cycle is largely unknown.
Researchers from the University of Exeter and Earthwatch in the UK combined experiments with mathematical modelling to fill this knowledge gap. Wood blocks were placed in Wytham Woods near Oxford at various distances from the forest edge, and left to decay over two years. The measured decay rates were applied to a model of the surrounding landscape, to allow comparison between the current fragmented woodland cover and decay rates in continuous forest.
The research, published today in the journal Global Change Biology, shows that wood decay rates in the southern UK are reduced by around one quarter due to fragmentation. This effect is much larger than expected due to variation in temperatures and rainfall among years.
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