More Rain, Less Decay

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Science  07 Dec 2001:
Vol. 294, Issue 5549, pp. 2055
DOI: 10.1126/science.294.5549.2055c

The amount of carbon stored in soils is an important component of the global carbon cycle and therefore is relevant to calculations of the effects of climate change on the biosphere. There is a correlation between increased rainfall and increased carbon storage in forest soils, but the search for how these parameters are linked has proved inconclusive.

Schuur et al. have examined soil ecology across a gradient of precipitation in a montane forest system in Maui, Hawaii, a natural laboratory where variation in complicating factors such as geology and vegetation history is minimized. In this system, soil carbon storage nearly doubled as the annual precipitation doubled. Of the various processes examined, such as primary productivity (biotic) and soil mineralization (abiotic), a reduced rate of decomposition of organic matter appeared to be the key determinant of increased carbon storage. Reduced oxygen availability to microbes in the wetter soils is the most likely agent of reduced decomposition, which would lead to greater accumulation of soil carbon and slower carbon cycling.—AMS

Ecology82, 3182 (2001).

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