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

doi:10.3969/j.issn.1000-6362.2018.01.004

Abstract

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

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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