Abstract
Agricultural production and numerous other key activities are highly dependent on suitable soil functioning and properties, and are often adapted to the present day soil conditions. Under climate change, the anticipated changes in temperature and precipitation may influence the structure and functioning of soils, making the local soil environment less suitable for some forms of activity and more suitable for others. Changes in soil conditions may also have other effects. Changes in physical structure may alter the hydrological regime, by, for example altering the water storage and transmission properties of the soil. The incidence of landslips and soil cracking may also change, with consequences to housing and infrastructure. In addition to physical change, chemical and biological processes typically respond to changes in soil moisture and temperature. Of particular interest is the possible change in the soil carbon budget, for example by increased rates of net loss through enhanced breakdown of organic matter. This has the potential to enhance global warming, so is particularly important. An understanding of the magnitude of these possible effects promotes informed decision-making. Insofar as the quantitative response of soil processes to temperature and water budget changes is known in general, we can make predictions of the effect of the specific changes expected under climate change. Our existing knowledge is built into process models which are constructed from experimental and survey measurements made under field and laboratory conditions. Models are constructed at a range of scales, depending on the process detail required or practicable for inclusion, and the amount of necessary ancillary information available. Models commonly include a causal or correlative chain relating variables, the individual links in this chain being tested by experiment and survey. Temperature and precipitation are frequently factors driving the causal mechanisms, and are included as driving variables in models. The responses down the causal chain may be such things as quantified changes in water storage in the soil, or the rate of biochemical processes such as mineralisation of organic nitrogen to ammonium. The aim of the project is to identify a range of models which are able to generate simulations of changes in important soil properties under the climate change scenarios generated by UKCP09. These scenarios will be available at a particular space and time scale, and there may be a need to modify them to suit the driver scale required by particular models. We will be seeking models which are capable of simulating changes in the following pressures and threats in response to changes in temperature and precipitation: 1. Erosion 2. Loss of soil organic matter 3. Compaction 4. Contamination 5. Salinisation 6. Sealing 7. Landslides 8. Loss of biodiversity Models of these pressures and threats will be highly diverse with a range of detail of physical and chemical processes. Changes in compaction, for example, are likely to be model by scaling up from process representation based on soil physics. Biodiversity models will be empirical and may be statistical in nature. Other processes will be represented by models with varying degrees of physical or chemical constraint. As far as possible, models will be sought which have proved capable of responding satisfactorily to past changes in temperature and precipitation. The uncertainty associated with these models will be assessed, and where possible, underlying connections between the models will be identified. Most will have particular strengths in representing the response of identified threats, but will also simulate responses to other threats for which another model is the main simulator.
United Kingdom