Grazing amplifies the stimulating effects of N addition on N2O emissions in a temperate meadow steppe
Grazing amplifies the stimulating effects of N addition on N2O emissions in a temperate meadow steppe
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放牧放大了温带草甸草原氮添加对 N2O 排放的刺激作用
DOI：
10.1016/j.agee.2022.108143
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Wei Sun
中科院分区：
文献类型：
--
作者：
Wanling Xu;Mingming Zhao;Rongrong Ren;Wenzheng Song;Weifeng Gao;Hugh A.L. Henry;Wei Sun
氮（N）的添加通常会增加一氧化二氮（N 2 O）的排放，但这种影响的大小取决于土地利用类型和强度。放牧对草地N动态有重要影响，但在影响草地N 2 O排放方面，放牧与N添加在多大程度上可能相互作用尚不清楚。2017年10月至2018年9月，通过测定N2 O通量、气象因子、植被参数和土壤性质，研究了氮添加和放牧（对照（CK）、氮添加（N）、放牧（G）和氮添加+放牧（N + G）处理）对温带草甸草原N2 O排放的个体效应和交互效应。研究的温带草甸草原是实验期间N2 O排放的一个来源.在植物生长季节，每年约有80%的N2 O排放量被释放出来. N + G处理的N2 O排放量最高，说明放牧处理放大了N处理对N2 O排放的刺激效应。结构方程模型（SEM）结果表明，施氮通过增加NH 4 + -N浓度和土壤潜在净硝化速率（Nnitri）促进N2 O排放;放牧通过直接通过排泄物增加基质有效性或通过践踏破坏土壤团聚体和释放基质间接促进N2 O排放。由于动物践踏、动物排泄物和有效氮对硝化和反硝化过程的协同作用，施氮和放牧使N2 O排放量增加最大。总的来说，我们的研究结果表明，草地管理和全球变化因素对N 2 O排放的交互影响需要被考虑，以便准确评估草地温室气体排放。·所研究的温带草甸草原是N2 O排放的一个来源。施氮和放牧没有改变N2 O排放的季节分布格局.放牧通过践踏和排泄促进了N2 O的排放.放牧放大了施氮对N2 O排放的刺激作用.·N2 O通量与土壤容重、无机氮含量和pH值相关。
Nitrogen (N) addition typically increases nitrous oxide (N 2 O) emissions, but the magnitude of this effect depends on land use type and intensity. Grazing has an important influence on grassland N dynamics, but it is not clear to what extent grazing may interact with N addition in affecting grassland N 2 O emissions. We investigated the mechanisms underlying the individual and interactive effects of N addition and cattle grazing (control (CK), N addition (N), grazing (G), and N addition plus grazing (N + G) treatments) on N 2 O emissions in a temperate meadow steppe by measuring N 2 O fluxes, weather factors, vegetation parameters and soil properties from October 2017 to September 2018. The studied temperate meadow steppe was a source of N 2 O emissions during the experimental period. Approximately 80 % of the annual N 2 O emissions were released during the plant growing season. The highest N 2 O emission was detected in the N + G plots, which indicated the grazing treatment amplified the stimulating effects of N addition on N 2 O emissions. The results from structural equation model (SEM) suggested that N addition enhanced N 2 O emission through increases in NH 4 + -N concentration and soil potential net nitrification rate (N nitri ); grazing promoted N 2 O emissions by increasing substrate availability directly via excreta or indirectly through trampling-associated soil aggregate disruption and substrate release. N 2 O emissions increased most strongly with N addition and grazing due to the synergetic effects between animal trampling, animal excreta and available N on the processes of nitrification and denitrification. Overall, our results suggest that the interactive effects of grassland management and global change factors on N 2 O emissions need to be considered for the accurate assessment of grassland greenhouse gas emissions. • The studied temperate meadow steppe was a source of N 2 O emissions. • N addition and grazing did not change the seasonal distribution pattern of N 2 O emissions. • Grazing promoted N 2 O emissions through trampling and excretion. • Grazing amplified the stimulating effect of N addition on N 2 O emissions. • N 2 O fluxes were correlated with soil bulk density, inorganic N content and pH.