放牧强度对青藏高原高寒矮嵩草草甸氧化亚氮释放的影响  

Effects of Grazing Density on Nitrous Oxide Effluxes in Alpine Kobresia Humilis Meadow on the Qinghai-Tibetan Plateau

作　　者：李红琴[1,2] 未亚西 贺慧丹 杨永胜[1,2] 李英年[1,2] 

机构地区：[1]中国科学院西北高原生物研究所,西宁810001 [2]中国科学院高原生物适应与进化重点实验室,西宁810001 [3]中国科学院大学,北京100049

出　　处：《中国农业气象》2018年第1期27-33,共7页Chinese Journal of Agrometeorology

基　　金：青海省国际科技合作项目(2015-HZ-804);国家自然科学基金项目(31300385;31270523)

摘　　要：依托青藏高原东北隅高寒矮嵩草草甸的5a放牧强度(禁牧、轻度放牧、中度放牧、重度放牧)试验平台,2016年在植物生长季的6-9月,基于静态暗箱-气相色谱法,测定N2O的释放特征及相应的环境、生物因子,探讨放牧强度对高寒草甸N2O释放特征的影响及其内在环境生物驱动机制。结果表明:环境、生物因子中仅表层土壤容积含水量、土壤容重及土壤有机碳含量对放牧强度响应显著(P<0.05)。高寒草甸N2O释放的季节特征表现出生长季的早期和晚期相对较高的"U"型趋势。禁牧样地N2O释放速率最小,极显著(P<0.01)低于其它3个放牧样地。高寒草甸N2O释放强度与放牧强度间表现出正相关趋势(R=0.49,P<0.01)。相关分析表明,表层土壤温度是高寒草甸N2O释放速率的主要影响因子,但放牧强度改变了土壤温度的影响程度。中短期放牧管理改变了高寒草甸植被生长季N2O释放速率,但未改变其释放的季节特征。禁牧管理提高了土壤温度,进而显著降低植被生长季N2O释放强度。Based on the experimental platform of 5 years grazing density including fencing(CK), light grazing(LG), moderate grazing(MG) and heavy grazing(HG) over the alpine Kobresia meadow on the northeastern Qinghai-Tibet Plateau, the characteristics of N_2O effluxes and its main environmental factors of different grazing density were studied by static closed chamber-gas chromatography method from June to September in 2016.The results showed that only the topsoil water content, topsoil bulk density and topsoil organic carbon content responded significantly(P<0.05) to the grazing density. The seasonal patterns of N_2O effluxes showed the "U" shape with relatively higher rate during early and late stage of growing season in alpine meadow. The N_2O effluxes in fencing treatments was clearly(P<0.01) lower than that of other three grazing gradients. There was a little positive trend between N_2O effluxes and grazing density. The surface soil temperature played a predominated role in the seasonal variations of the N_2O effluxes in alpine meadow and its magnitude was influenced by grazing density. The results suggested that only the magnitude, not the direction, of N_2O effluxes was significantly influenced by the medium(short)-term grazing management during growing season. The fencing management could significantly reduce the N_2O emission caused by improving the soil temperature.

关 键 词：氧化亚氮 放牧强度 高寒草甸 静态暗箱-气相色谱法 Spearman秩相关 

分 类 号：S812[农业科学—草业科学]