title: Grazing effects on ecosystem CO2 fluxes differ among temperate steppe types in Eurasia.
abstract: Grassland ecosystems play a critical role in regulating CO2 fluxes into and out of the Earth's surface. Whereas previous studies have often addressed single fluxes of CO2 separately, few have addressed the relation among and controls of multiple CO2 sub-fluxes simultaneously. In this study, we examined the relation among and controls of individual CO2 fluxes (i.e., GEP, NEP, SR, ER, CR) in three contrasting temperate steppes of north China, as affected by livestock grazing. Our findings show that climatic controls of the seasonal patterns in CO2 fluxes were both individual flux- and steppe type-specific, with significant grazing impacts observed for canopy respiration only. In contrast, climatic controls of the annual patterns were only individual flux-specific, with minor grazing impacts on the individual fluxes. Grazing significantly reduced the mean annual soil respiration rate in the typical and desert steppes, but significantly enhanced both soil and canopy respiration in the meadow steppe. Our study suggests that a reassessment of the role of livestock grazing in regulating GHG exchanges is imperative in future studies.
authors.affiliation: Forage Seed Lab, China Agricultural University, Beijing Key Laboratory of Grassland Science, Beijing 100193, China.
authors.forename: Longyu
authors.initials: L
authors.lastname: Hou
authors.affiliation: State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Institute of Grassland Research, Chinese Academy of Agricultural Sciences, Hohhot 010010, China.
authors.forename: Jiancai
authors.initials: J
authors.lastname: Du
authors.affiliation: Forage Seed Lab, China Agricultural University, Beijing Key Laboratory of Grassland Science, Beijing 100193, China.
authors.forename: Mingya
authors.initials: M
authors.lastname: Wang
authors.affiliation: Forage Seed Lab, China Agricultural University, Beijing Key Laboratory of Grassland Science, Beijing 100193, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Wang
authors.affiliation: Forage Seed Lab, China Agricultural University, Beijing Key Laboratory of Grassland Science, Beijing 100193, China.
authors.forename: Peisheng
authors.initials: P
authors.lastname: Mao