title: Response of soil CO2 efflux to precipitation manipulation in a semiarid grassland.
abstract: Soil CO2 efflux (SCE) is an important component of ecosystem CO2 exchange and is largely temperature and moisture dependent, providing feedback between C cycling and the climate system. We used a precipitation manipulation experiment to examine the effects of precipitation treatment on SCE and its dependences on soil temperature and moisture in a semiarid grassland. Precipitation manipulation included ambient precipitation, decreased precipitation (-43%), or increased precipitation (+17%). The SCE was measured from July 2013 to December 2014, and CO2 emission during the experimental period was assessed. The response curves of SCE to soil temperature and moisture were analyzed to determine whether the dependence of SCE on soil temperature or moisture varied with precipitation manipulation. The SCE significantly varied seasonally but was not affected by precipitation treatments regardless of season. Increasing precipitation resulted in an upward shift of SCE-temperature response curves and rightward shift of SCE-moisture response curves, while decreasing precipitation resulted in opposite shifts of such response curves. These shifts in the SCE response curves suggested that increasing precipitation strengthened the dependence of SCE on temperature or moisture, and decreasing precipitation weakened such dependences. Such shifts affected the predictions in soil CO2 emissions for different precipitation treatments. When considering such shifts, decreasing or increasing precipitation resulted in 43 or 75% less change, respectively, in CO2 emission compared with changes in emissions predicted without considering such shifts. Furthermore, the effects of shifts in SCE response curves on CO2 emission prediction were greater during the growing than the non-growing season.
authors.affiliation: State Key Laboratory of Soil Erosion and Dryland Farming in the Loess Plateau, Northwest A&F University, Yangling 712100, China. Electronic address: xrwei78@163.com.
authors.forename: Xiaorong
authors.initials: X
authors.lastname: Wei
authors.affiliation: State Key Laboratory of Soil Erosion and Dryland Farming in the Loess Plateau, Northwest A&F University, Yangling 712100, China.
authors.forename: Yanjiang
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Soil Erosion and Dryland Farming in the Loess Plateau, Northwest A&F University, Yangling 712100, China; College of Animal Science and Technology, Northwest A&F University, Yangling 712100, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Soil Erosion and Dryland Farming in the Loess Plateau, Northwest A&F University, Yangling 712100, China.
authors.forename: Hailong
authors.initials: H
authors.lastname: Gao
authors.affiliation: State Key Laboratory of Soil Erosion and Dryland Farming in the Loess Plateau, Northwest A&F University, Yangling 712100, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Fan
authors.affiliation: State Key Laboratory of Soil Erosion and Dryland Farming in the Loess Plateau, Northwest A&F University, Yangling 712100, China; Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Xiaoxu
authors.initials: X
authors.lastname: Jia
authors.affiliation: State Key Laboratory of Soil Erosion and Dryland Farming in the Loess Plateau, Northwest A&F University, Yangling 712100, China.
authors.forename: Jimin
authors.initials: J
authors.lastname: Cheng
authors.affiliation: State Key Laboratory of Soil Erosion and Dryland Farming in the Loess Plateau, Northwest A&F University, Yangling 712100, China; Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Mingan
authors.initials: M
authors.lastname: Shao
authors.affiliation: State Key Laboratory of Soil Erosion and Dryland Farming in the Loess Plateau, Northwest A&F University, Yangling 712100, China.
authors.forename: Xingchang
authors.initials: X
authors.lastname: Zhang
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D002245:Carbon Dioxide / Q000032:analysis*; D002980:Climate; D004784:Environmental Monitoring; D065948:Grassland; D006109:Poaceae; D012987:Soil / Q000737:chemistry*
chemical_list: D000393:Air Pollutants; D012987:Soil; D002245:Carbon Dioxide
keywords: Precipitation regimes; Semiarid grassland; Soil CO(2) efflux; Soil CO(2) efflux response curve; Soil moisture; Soil temperature