Heavy grazing reduces grassland soil greenhouse gas fluxes: A global meta-analysis.
Heavy grazing reduces grassland soil greenhouse gas fluxes: A global meta-analysis.
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DOI：
10.1016/j.scitotenv.2018.11.082
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发表时间：
2019-03
期刊：
影响因子：
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通讯作者：
Shiming Tang;Kun Wang;Yangzhou Xiang;Dashuan Tian;Jinsong Wang;Yanshu Liu;B. Cao;D. Guo;S. Niu
中科院分区：
文献类型：
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作者：
Shiming Tang;Kun Wang;Yangzhou Xiang;Dashuan Tian;Jinsong Wang;Yanshu Liu;B. Cao;D. Guo;S. Niu
放牧使全球草原退化，并可能抑制土壤温室气体(温室气体：CO2、CH4和N2O)的排放。然而，这三种气体通量对放牧的全球模式和一般机制仍然知之甚少。在这里，我们对63项独立的放牧研究进行了荟萃分析，这些研究测量了全球草原上的土壤温室气体通量。结果表明，轻、中度放牧对土壤CH4吸收、N2O和CO2排放无显著影响，但重度放牧持续降低土壤CH4吸收、N2O和CO2排放。它们对放牧的反应大小受放牧持续时间和降雨量的影响。与CO2排放相比，重度放牧、放牧持续时间较长或降水较少时，土壤CH4吸收和N2O排放的减少幅度较大。土壤CO2排放的下降可能是由于放牧引起的根系生物量和土壤水分的减少，而土壤CH4吸收和N2O排放的下降则是由于土壤水分和基质有效性的下降。总体而言，这项研究首次对放牧对三种主要土壤温室气体通量的响应进行了大规模评估，强调放牧对温室气体排放的抑制，但代价是植物生产力和土壤肥力。我们呼吁今后作出努力，确定最佳放牧强度，以平衡这些复杂的影响。
Grazing degrades worldwide grasslands and possibly suppresses soil greenhouse gas (GHG: CO2, CH4and N2O) fluxes. However, the global patterns of these three gas fluxes in response to grazing and the general mechanisms remain poorly understood. Here, we performed a meta-analysis of 63 independent grazing studies that measured soil GHG fluxes across global grasslands. Our results revealed that light and moderate grazing had no significant effect on soil CH4uptake, N2O and CO2emission, but heavy grazing consistently reduced them. The magnitudes of their responses to grazing were regulated by grazing duration and precipitation. In comparison with CO2emission, soil CH4uptake and N2O emission were reduced much more under heavier grazing, longer grazing duration or less precipitation. The decrease in soil CO2emission was possibly caused by grazing-induced reduction in root biomass and soil moisture, while the decline in soil CH4uptake and N2O emission was due to decreased soil moisture and substrate availability. Overall, this study provides the first large-scale evaluation on three main soil GHG fluxes in response to grazing, highlighting grazing inhibition of GHG emission but at the cost of plant productivity and soil fertility. We call for future efforts to identify an appropriate grazing intensity that is optimal to balance these complicated impacts.