【降水量减少影响微生物群落和土壤结构】Engil Isadora Pujol Pereira Haegeun Chung Kate Scow and Johan Six. Microbial Communities and Soil Structure are Affected by Reduced Precipitation but Not by Elevated Carbon Dioxide. Soil Science Society of America Journal 2013 Vol. 77 No. 2 p. 482-488
Abstract
Elevated carbon dioxide (eCO2) concentrations in the atmosphere along with decreased precipitation regimes expected in the next decades can alter soil microbe functioning and hence soil organic matter (SOM) dynamics causing important impacts on the global C cycle. We investigated the effects of eCO2 and reduced soil moisture further referred to as reduced precipitation treatment (RP) on SOM fractions and soil microbial distribution across different soil zones (i.e. rhizosphere vs. bulk soil) and physically-separated SOM fractions (coarse particulate organic matter (cPOM; >250 mm) microaggregate (53–250 mm) and silt-and-clay fraction (<53 mm)) at the soybean free air concentration enrichment (SoyFACE) experiment in Illinois. To quantify the abundance of microorganisms we used real-time quantitative polymerase chain reaction (PCR) for the total bacterial (16S rRNA) and denitrifier (nosZ) genes. We did not detect any significant effects of eCO2 on bacterial abundance soil C and N concentrations either in the whole soil or in the SOM fractions. These findings corroborate the previously reported absence of soil C responses to eCO2. The mass of microaggregates was highest in RP treatments in both rhizosphere and bulk soil. Furthermore the abundance of 16S rRNA and nosZ genes increased in the microaggregates under RP compared to ambient conditions of soil moisture. Hence RP increased the formation of microhabitats in which the microorganisms are partly protected from the adverse effects of reduced soil moisture.
【温度对土壤微生物效率的影响极其对气候的反馈】Serita D. Frey Juhwan Lee Jerry M. Melillo & Johan Six. The temperature response of soil microbial efficiency and its feedback to climate. Nature Climate Change 3 395–398 (2013) doi:10.1038-nclimate1796
Abstract
Soils are the largest repository of organic carbon (C) in the terrestrial biosphere and represent an important source of carbon dioxide (CO2) to the atmosphere releasing 60–75 Pg C annually through microbial decomposition of organic materials