Environmental and stoichiometric controls on microbial carbon‐use efficiency in soils
Tóm tắt
Carbon (C) metabolism is at the core of ecosystem function. Decomposers play a critical role in this metabolism as they drive soil C cycle by mineralizing organic matter to CO2. Their growth depends on the carbon‐use efficiency (CUE), defined as the ratio of growth over C uptake. By definition, high CUE promotes growth and possibly C stabilization in soils, while low CUE favors respiration. Despite the importance of this variable, flexibility in CUE for terrestrial decomposers is still poorly characterized and is not represented in most biogeochemical models. Here, we synthesize the theoretical and empirical basis of changes in CUE across aquatic and terrestrial ecosystems, highlighting common patterns and hypothesizing changes in CUE under future climates. Both theoretical considerations and empirical evidence from aquatic organisms indicate that CUE decreases as temperature increases and nutrient availability decreases. More limited evidence shows a similar sensitivity of CUE to temperature and nutrient availability in terrestrial decomposers. Increasing CUE with improved nutrient availability might explain observed declines in respiration from fertilized stands, while decreased CUE with increasing temperature and plant C : N ratios might decrease soil C storage. Current biogeochemical models could be improved by accounting for these CUE responses along environmental and stoichiometric gradients.
Từ khóa
Tài liệu tham khảo
Ågren GI, 1998, Theoretical ecosystem ecology. Understanding element cycles
IPCC.2007.SolomonS QinD ManningM ChenZ MarquisM AverytKB TignorM MillerHL eds.Climate change 2007: the physical science basis. Contribution of Working Group I to the fourth assessment report of the Intergovernmental Panel on Climate Change. Cambridge UK & New York NY USA:Cambridge University Press.
Panikov NS, 1995, Microbial growth kinetics
Sterner RW, 2002, Ecological stoichiometry. The biology of elements from molecules to the biosphere