Climate Change and Soil Microbial Processes: Secondary Effects are Hypothesised from Better Known Interacting Primary Effects

Abstract

Soil microorganisms are important processors of C and N in the biosphere, they are the dominant global sources of CH₄ and N₂O, and they are major sources of CO₂ and NO. Increased allocation of C below ground, resulting from CO₂ fertilisation, will profoundly affect microbial processes, as will increased soil temperatures and changes in soil moisture. Direct microbial responses to these changes are reasonably well known, but complex interactions, such as effects on N fixation, N mineralisation, denitrification, cation leaching, and ratios of trace gas emissions, are equally important, but are difficult to predict at present. Although the complexity of these interactions appears daunting, knowledge of primary effects can be used to develop testable hypotheses of important interactions that affect soil responses to change in climate, land use, and pollution.