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Herbivore Assemblage as an Important Factor Modulating Grazing Effects on Ecosystem Carbon Fluxes in a Meadow Steppe in Northeast China
Author(s) -
Chang Qing,
Xu Tongtong,
Ding Shiwen,
Wang Ling,
Liu Jushan,
Wang Deli,
Wang Ying,
Li Zhiqiang,
Zhao Xuan,
Song Xuxin,
Pan Duofeng
Publication year - 2020
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
eISSN - 2169-8961
pISSN - 2169-8953
DOI - 10.1029/2020jg005652
Subject(s) - grazing , herbivore , grassland , steppe , ecosystem , ecology , plant community , productivity , growing season , conservation grazing , environmental science , biology , agronomy , species richness , economics , macroeconomics
A better understanding of how grazing by large herbivores, as the major land use worldwide, affects grassland carbon fluxes is critical for predicting future uptake of CO 2 in terrestrial ecosystem. Previous studies have focused on individual herbivore species; it remains poorly understood as to if and how herbivore assemblage (single vs. mixed species) would alter the impact of grazers on grassland carbon fluxes. Here we examined the effects of moderate grazing by different herbivore assemblages on net ecosystem CO 2 exchange (NEE), gross ecosystem productivity (GEP), and ecosystem respiration (ER) over the growing season in two types of grassland communities in a meadow steppe. We found that herbivore assemblages significantly affected NEE, and the effects varied in the two types of grassland communities. Compared to ungrazed grassland, mixed grazing of sheep and cattle increased NEE (i.e., increased CO 2 uptake) over the growing season regardless of community type, while sheep‐ or cattle‐only grazing increased NEE in the low‐diversity community and decreased it in the high‐diversity community. Herbivore assemblages altered the NEE primarily via changing GEP. The different effects of herbivore assemblages on GEP may be attributed mainly to grazing‐induced changes in soil water availability and canopy light availability. Our study indicates that mixed grazing of sheep and cattle might be an important grazing management practice to improve plant aboveground productivity and help mitigate CO 2 emissions during the growing season. It should be particularly used in diverse plant communities, where it might increase grassland carbon sequestration.