The role of the physical properties of soil in determining biogeochemical responses to soil warming

Warmer air temperatures projected for the coming centuries are expected to increase soil temperature and accelerate the rate of biogeochemical processes. Currently, there is limited data on the expected response of soil temperature to the projected increase in atmospheric temperature, and the implications of warming on soil physicochemical properties. The primary objective of this chapter is to determine if changes in air temperature with projected warming are likely to cause important shifts in the physical properties of soil. We discuss the relationship between atmospheric and soil temperatures, synthesize our current knowledge of the physical basis of soil temperature changes and responses to anticipated warming, and review current knowledge on how warming impacts the physical and biogeochemical processes in soil. The synthesis of available data discussed in this chapter shows that many of the biogeochemical flux- and stock-related responses to warming are mediated by the effects of warming on the physical conditions of soil. Further improvements to our understanding of the mechanistic connections between the physical processes in soil and the biogeochemical cycling of essential elements in soil will undoubtedly improve our ability to predict the response of the soil system to changing environmental conditions.