Levine, U.Y., G.P. Robertson, and T.M. Schmidt
Presented at the All Scientist and GLBRC Sustainability Meeting (2009-05-05 to 2009-05-07 )
The relationship between the rates of carbon dioxide production and the consumption of methane by upland soils, and the diversity of microbes that catalyze these ecosystem processes was determined across a range of land uses at the Kellogg Biological Station Long Term Ecological Research. We conducted molecular surveys of methane–oxidizing bacteria (methanotrophs) and total microbial diversity, and measured in situ rates of methane consumption and carbon dioxide production. We show that converting native lands at the Kellogg Biological Station Long Term Ecological Research site to row-crop agricultural use leads to a 7-fold reduction in methane consumption and a proportional decrease in methanotroph diversity. The trajectory of recovery of both methanotroph diversity and methane consumption in fields abandoned from agriculture for up to 50 years supports the complementarity hypothesis, and links methane consumption to the additive activity of methanotroph species in complementary niches. The results indicate that managing land to conserve or restore methanotroph diversity would enhance the capacity of soil as a methane sink, and help mitigate the increasing abundance of this potent greenhouse gas. Conversely, total bacterial diversity was not correlated to changes in the flux of carbon dioxide, and is not linked to rates of carbon dioxide emissions. These results are consistent with the expectation that diversity is a better predictor of the magnitude of ecosystem processes catalyzed by specialized microbes like methanotrophs, as compared to processes driven by highly redundant types of metabolism such as the production of carbon dioxide.
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