title: Microbial lipid and amino sugar responses to long-term simulated global environmental changes in a California annual grassland.
abstract: Global environmental change is predicted to have major consequences for carbon cycling and the functioning of soil ecosystems. However, we have limited knowledge about its impacts on the microorganisms, which act as a "valve" between carbon sequestered in soils versus released into the atmosphere. In this study we examined microbial response to continuous 9-years manipulation of three global change factors (elevated CO2, warming, and nitrogen deposition), singly and in combination using two methods: lipid and amino sugar biomarkers at the Jasper Ridge Global Change Experiment (JRGCE). The two methods yielded important distinctions. There were limited microbial lipid differences, but many significant effects for microbial amino sugars. We found that CO2 was not a direct factor influencing soil carbon and major amino sugar pools, but had a positive impact on bacterial-derived muramic acid. Likewise, warming and nitrogen deposition appeared to enrich residues specific to bacteria despite an overall depletion in total amino sugars. The results indicate that elevated CO2, warming, and nitrogen deposition all appeared to increase bacterial-derived residues, but this accumulation effect was far offset by a corresponding decline in fungal residues. The sensitivity of microbial residue biomarker amino sugars to warming and nitrogen deposition may have implications for our predictions of global change impacts on soil stored carbon.
authors.affiliation: State Key Laboratory of Forest and Soil Ecology, Institute of Applied Ecology, Chinese Academy of Sciences Shenyang, China ; Department of Soil Science, University of Wisconsin-Madison Madison, WI, USA.
authors.forename: Chao
authors.initials: C
authors.lastname: Liang
authors.affiliation: Department of Soil, Water and Climate, University of Minnesota, Twin Cities MN, USA.
authors.forename: Jessica L M
authors.initials: JL
authors.lastname: Gutknecht
authors.affiliation: Department of Soil Science, University of Wisconsin-Madison Madison, WI, USA ; Department of Soil and Water Science, University of Florida, Gainesville FL, USA.
authors.forename: Teri C
authors.initials: TC
authors.lastname: Balser
keywords: amino sugar; elevated CO2; lipid; microbial biomass; microbial residue; nitrogen deposition; soil carbon stabilization; warming