RESEARCHERS have unlocked secrets buried in the earth for 6,000 years to predict how woodlands in the British Isles could be transformed due to disease and climate change. 

Woodlands account for 13 per cent of the total land area in the UK, providing habitat for a huge ranges of animal species. However, outbreaks of disease and pests, as well as droughts caused by climate change, could have a dramatic effect on their composition.  

With UK woodlands under increasing threat, University of Gloucestershire ecologists Dr Julia Webb and Professor Anne Goodenough studied 6,000-year-old pollen grains that had been preserved in sediment to shed light on how a catastrophic decline in one species within the canopy – due to some tree species being affected by disease or drought – impacts wider woodland ecology.  

Professor Anne Goodenough Professor Anne Goodenough (Image: Supplied)

Dr Webb and Professor Goodenough’s research found that when a particular stressor directly affects only one tree species, gaps are created in the woodland canopy.  

The amount of light reaching the woodland floor increases and there is then a battle to see which tree species will fill each gap, with those species that are quick growing, highly competitive or already abundant locally, most likely to win.  

This means that change in one tree species causes woodlands to change dramatically, which impacts on the insects, amphibians, birds and mammals that are especially adapted for specific woodland types. 

Dr Webb, senior lecturer in biology, said: “From studying pollen preserved in sediment at 10 sites across the British Isles, we found that during a decline in elm nearly 6,000 years ago, there was considerable turnover in tree species as the community changed.  In many cases, different gaps in the same woodland were being filled by different species.

“This created a patchwork-style effect, rather than a single tree species dominating the area and filling all the gaps. There was a notable decline in climbing plants such as ivy and an increase in shrubs such as holly and hawthorn, as well as heather suggesting a more open canopy. Weed species that could tolerate soil disturbance also increased rapidly.”  

Anne Goodenough, professor in applied ecology, said: “Looking to the past to help predict future changes is vital. When species such as ash are lost, we can expect shrubs, including non-native species such as rhododendron, to increase, at least until gaps refill with trees. 

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“These changes will affect many important aspects of woodland sites, including how many species they support, and whether rare species increase or are lost. Rare plant species that need dark conditions are especially at risk.

“As the woodland recovers with new trees filling the gaps, woodland canopies could be more varied than before, so having specific ‘ash woodlands’ and ‘beech woodlands’ and ‘oak woodlands’ could gradually become consigned to history.”