title: Experimental warming reveals positive feedbacks to climate change in the Eurasian Steppe.
abstract: Identifying soil microbial feedbacks to increasing temperatures and moisture alterations is critical for predicting how terrestrial ecosystems will respond to climate change. We performed a 5-year field experiment manipulating warming, watering and their combination in a semiarid temperate steppe in northern China. Warming stimulated the abundance of genes responsible for degrading recalcitrant soil organic matter (SOM) and reduced SOM content by 13%. Watering, and warming plus watering also increased the abundance of recalcitrant SOM catabolism pathways, but concurrently promoted plant growth and increased labile SOM content, which somewhat offset SOM loss. The treatments also increased microbial biomass, community complexity and metabolic potential for nitrogen and sulfur assimilation. Both microbial and plant community composition shifted with the treatment conditions, and the sample-to-sample compositional variations of the two communities (pairwise β-diversity distances) were significantly correlated. In particular, microbial community composition was substantially correlated with the dominant plant species (~0.54 Spearman correlation coefficient), much more than with measured soil indices, affirming a tight coupling between both biological communities. Collectively, our study revealed the direction and underlying mechanisms of microbial feedbacks to warming and suggested that semiarid regions of northern steppes could act as a net carbon source under increased temperatures, unless precipitation increases concurrently.
authors.affiliation: Key Laboratory of Dryland Agriculture, MOA, Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing, China.|School of Biology, Georgia Institute of Technology, Atlanta, GA, USA.
authors.forename: Ximei
authors.initials: X
authors.lastname: Zhang
authors.affiliation: School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA, USA.
authors.forename: Eric R
authors.initials: ER
authors.lastname: Johnston
authors.affiliation: State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China.
authors.forename: Linghao
authors.initials: L
authors.lastname: Li
authors.affiliation: School of Biology, Georgia Institute of Technology, Atlanta, GA, USA.|School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA, USA.
authors.forename: Konstantinos T
authors.initials: KT
authors.lastname: Konstantinidis
authors.affiliation: State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China.|Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China.
authors.forename: Xingguo
authors.initials: X
authors.lastname: Han
mesh_terms: D018533:Biomass; D058448:Biota; D002244:Carbon / Q000378:metabolism; D002681:China; D057231:Climate Change; D065948:Grassland; D009584:Nitrogen / Q000032:analysis; D010944:Plants / Q000378:metabolism; D012987:Soil; D012988:Soil Microbiology; D013696:Temperature; D014867:Water
chemical_list: D012987:Soil; D014867:Water; D002244:Carbon; D009584:Nitrogen