| Summary: | Although this contribution is not intended to be a comprehensive perspective on current knowledge of soil respiration, a brief overview of some pertinent research on global patterns of soil respiration is presented first to establish a context for the subsequent more focused discussion of the role of microbial communities in soil carbon budgets and net respiratory CO2 flux to the atmosphere. Major reviews, and relevant broad research studies of current knowledge about regional and global respiratory flux patterns, are available from other sources. These include reviews of terrestrial respiration in broad geographical regions (e.g. [Luo and Zhou, 2006] , [Peng and Apps, 2000] , [Raich and Schlesinger, 1992] , [Schimel, 1995] and [Schlesinger, 1997] ); in particular geographic regimes and biomes (e.g. [Anderson, 2010a] , [Bekku et al., 2003] , [Bond-Lamberty and Thomson, 2010] and [Townsend et al., 1992] ); and in relation to soil decomposition processes (e.g. [Adl, 2003] and [Tate, 1995] ). Calculated on a global scale, soil respiration releases carbon at a rate that is more than one order of magnitude larger than anthropogenic emissions (Luo and Zhou 2006, p. 24). With increasing evidence of global climate change, including increasing global temperature and likely major changes in patterns of precipitation, effects on soil microbial communities are likely to be significant, especially at higher latitudes where thawing of the permafrost may release substantial quantities of stored-up carbon compounds, thus increasing microbial respiration and efflux of CO2 to the atmosphere. In the final sections, discussion focuses on emerging evidence of the effects of climate change, especially changing precipitation patterns and soil moisture, on the dynamics of microbial communities and respiratory CO2 emissions. Some of the prospects and challenges for future inquiry on the role of soil microbial communities in terrestrial carbon budgets and CO2 efflux are discussed in relation to emerging research themes and new methodological approaches.
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