Modelling blanket peat erosion under environmental change
报告人： 李朋飞 博士
Peatlands, a subset of wetlands, cover over 4 million km2 of the Earth’s surface and store between one third to one-half of the world’s soil carbon pool. Many peatlands across the world have undergone erosion exacerbated by human disturbances, resulting in depleted soil carbon stocks. Blanket peatlands are a type of precipitation-fed peatlands. They often occur on sloping terrain and may be more susceptible to fluvial erosion than other peatland types which are more typical in very gentle gradient basins. Bioclimatic modelling suggested that some marginal regions, which were currently suitable for active peat growth, may be no longer under a climate supporting the accumulation of peat by the end of 21st century. However, it remained unknown whether blanket peatland will degrade via erosion in these marginal areas. In order to understand and map the impacts of environment change on blanket peat erosion it was essential to model mechanisms and rates of blanket peat erosion and test different scenarios.
The first fluvial erosion model for blanket peatlands, PESERA-PEAT, was developed through substantially modifying the PESERA model to include dominant blanket peat erosion processes (i.e. freeze-thaw and desiccation). Land management practices (prescribed burning, grazing and artificial drainage) were parameterized for their influence on vegetation cover, biomass and soil moisture condition. PESERA-PEAT was numerically evaluated using available field data from four blanket peat-covered catchments with different erosion conditions and management intensity, and it was found to be robust in modelling fluvial erosion in blanket peat.
PESERA-PEAT has been applied to a blanket peatland region in Northern England (i.e. North Pennines), ten blanket peat-covered sites across Great Britain, and the whole of Northern Hemisphere blanket peatlands to examine the response of blanket peat erosion to possible changes in climate change and land management practices. Climate change scenarios were established and climate data were compiled to 2100, while land management scenarios were established based on outputs from earlier published investigations. Modelling results suggested that the response of blanket peat erosion to climate change was spatially very variable. Areas with high precipitation and low temperature were predicted to have low sediment yield. Temperature was found to be more dominant than precipitation in controlling long-term blanket peat erosion. Land management change was shown to be useful in mitigating the impact of 21st century climate change on the amount and spatial pattern of blanket peat erosion. The results can be used within blanket peatland regions to inform spatially-targeted management strategies.