Soil

 

Climate change will greatly affect forest soils in Britain and around the world. A combination of rising atmospheric carbon dioxide levels and consequent changes in temperature, precipitation, windiness and solar radiation will lead directly to changes in soil functioning. Soils will also be affected indirectly via the effect of climate change on the trees and ground vegetation.

Research is focussed on improving understanding in three key areas:

• The net effect of climate change on the organic matter in woodland soils. There is a consensus that decomposition will be faster because of the higher temperatures which, in the absence of other trends, will decrease soil organic matter. On the other hand, increases in soil moisture will tend to increase organic matter content. The direct effects of elevated carbon dioxide concentrations and temperatures will generally increase plant growth and litter input to the soil although some of the indirect effects, such as the effects of pest and diseases, are much more difficult to predict with any certainty; where water availability becomes limiting, growth rates and survival are likely to fall and therefore predictions of the effects of climate change on soil organic matter are especially uncertain.

  This research is viewed as high priority, to help explain observations of large losses of soil organic matter in England and Wales over the past 25 years, as reported in Nature in 2005.

• The role of forest soils as both a source of and a sink for the greenhouse gases carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O). Forest soils in the UK are, at present, a net sink for carbon dioxide and methane. However, forest soils in the UK as a whole tend to have a higher organic matter content a potential source of carbon dioxide and methane than most agricultural soils so careful management is needed to minimise their release. Net release of N₂O also represents a minor loss of site fertility and a small contribution to atmospheric pollution.
• The changes in forest operations required to safeguard soil properties.

The following research questions are currently being investigated:

• Examination of existing models that predict the status of soil carbon and other nutrient pools as influenced by changes in atmospheric carbon dioxide concentration and climate.
• In order to gain a better understanding of the effects of air pollution and other stress factors affecting UK forest ecosystems, long-term intensive monitoring plots covering five tree species have been established. Plots have been established in working forests under normal forest management. These plots form part of a European wide network established under European Union Regulations. Use of long-term Level II data-sets and/or other environmental data sources such as the Environmental Change Network (ECN) are being used to investigate relationships between climate and soil nutrient and carbon dynamics.
• Testing models of carbon sequestration in forest soils.
• Measuring and modelling below ground carbon allocation.
• Research on peat soils as sinks or sources of carbon, methane and nitrous oxide.