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

doi:10.3969/j.issn.1000-6362.2018.01.004

摘要/Abstract

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。

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

Abstract: 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 N2O 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 N2O effluxes showed the “U” shape with relatively higher rate during early and late stage of growing season in alpine meadow. The N2O effluxes in fencing treatments was clearly (P＜0.01) lower than that of other three grazing gradients. There was a little positive trend between N2O effluxes and grazing density. The surface soil temperature played a predominated role in the seasonal variations of the N2O effluxes in alpine meadow and its magnitude was influenced by grazing density. The results suggested that only the magnitude, not the direction, of N2O effluxes was significantly influenced by the medium (short) -term grazing management during growing season. The fencing management could significantly reduce the N2O emission caused by improving the soil temperature.

Key words: Nitrous Oxide, Grazing density, Alpine meadow, Static closed chamber-gas chromatography method, Spearman's rank correlation coefficient

李红琴，未亚西，贺慧丹，杨永胜，李英年. 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[J]. 中国农业气象, 2018, 39(01): 27-33.

LI Hong-qin, WEI Ya-xi, HE Hui-dan, YANG Yong-sheng, LI Ying-nian. Effects of Grazing Density on Nitrous Oxide Effluxes in Alpine Kobresia Humilis Meadow on the Qinghai-Tibetan Plateau[J]. Chinese Journal of Agrometeorology, 2018, 39(01): 27-33.

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