Potential impact of climate change

The impact of climate change is difficult to predict but effects are already being noticed in our woods.

First into leaf

Of all our large trees, sycamore is responding fastest to climate change. Hawthorn and hornbeam are also coming into leaf earlier, while others such as ash, beech or maple are only showing a small change. This is likely to alter the competitive advantage of some species resulting in changes in composition of our woods over the next 50 to 100 years. The large leaves of the introduced sycamore all too often shade out our later-leafing, native species. In the future it could have an even more dominating influence on our woods.

In the same way oak could come to dominate most ash-oak woodland, as this species appears to be responding more to climate change. More on oak and ash. Other species such as small-leaved lime, once a major component of our woodland, may make a comeback as the climate warms up, as in the warmer climate it once again produces fertile seeds.

Battle of the flowers

Spring flowers such as snowdrops and bluebells start the process of growth for the next year in late summer and autumn and overwinter as bulbs. This strategy, in the past, has given them a head start.

By contrast plants such as garlic mustard and cow parsley are more temperature sensitive and delay their leaf formation until the following spring. Warmer winters have allowed these plants to begin leaf growth much earlier, and the bluebells and snowdrops are losing their advantage. This could seriously change the composition of our woodland flora.

In contrast some plants actually require a certain quantity of winter chill hours (hours when temperature falls to below a certain point) in order to break dormancy. Research is just beginning into the effect of warmer winters (and therefore a reduction in the number of winter chill hours) on commercially grown fruits such as blackcurrants, where it is thought that yields may be quite strongly affected. It is hoped that the research will also cover wild fruit.

Keeping in tune

Species in woodland communities are interdependent and it is important that animals and plants remain in synchrony. At present insects seem to be responding to temperature changes at the same rate as their food-plants. For example orange tip butterflies and garlic mustard and winter moth and oak trees.

However in a wood in Oxfordshire, there is evidence that the hatching of blue tits may no longer coincide with the peak of caterpillar numbers in the wood. Also the arrival dates of some summer migrant birds are already lagging behind the rest of the woodland community. More information on trends in bird populations.

As climate change accelerates, more species may no longer be synchronised with the species on which they depend and in turn this could have serious implications for their survival.

What is the Woodland Trust aiming to do about climate change?

Ask the Prime Minister to take action to cut greenhouse gas emissions.
Switch to green energy and support the Woodland Trust.
Stop Climate Chaos Campaign - vision and manifesto 

 
What is the Environment Agency aiming to do about climate change?

The UKPN is specifically mentioned as one of the programmes for action in the Government’s new Biodiversity Strategy for England (Working with the Grain of Nature) launched in 2002 by the RT Hon Margaret Beckett MP.

Environment Agency climate change pages.

Wondering what you can do to make a difference?

Find out more about taking personal action for a better world by downloading our combat climate change PDF