青藏高原放牧高寒草甸主要温室气体通量及其主控因素研究

Study on flux of main greenhouse gases and its affecting factors of grazing alpine meadow under different degradation levels on the Qinghai-Tibetan Plateau

摘要:

在青藏高原高寒草地不同放牧强度区设4个试验样地,分别为原生草甸(NM)、轻度退化草甸(LM)、中度退化草甸(MM)和重度退化草甸(HM),监测草地温室气体通量。结果表明:不同放牧强度对草地温室气体通量影响显著,放牧活动对高寒草甸的影响首先表现在植被上,而土壤环境的变化比较迟滞。通过逐步回归分析和因子拆分得知,草甸甲烷通量影响较大的环境因素为土壤紧实度和有机质,分别能解释44.6%和28.4%的总变异,CO2 通量影响较大的环境因素为紧实度和生物量,分别能解释36.1%和32.8%的总变异,氧化亚氮通量影响较大的环境要素为紧实度和有机质,分别能解释50.1%和22.9%的总变异,家畜的践踏作用使退化草地紧实度增加,进而引起温室气体通量的改变,高寒草甸退化演替发展到重度退化阶段时释放大量温室气体。

Abstract:

The alpine meadow under 4 degradation stages (ND,non-degraded;lightly degraded,LD;moderatelydegraded,MD;heavily degraded,HD) were selected to measure the greenhouse gas uxes by using the staticchambers and gas chromatography.The result indicated that the grassland greenhouse gas flux were significantdifferent among 4 degradation stages (P <0.05).The important factors affecting CH4 flux were soil compactionand organic matter (44.6% and 28.4%).And they were soil compaction and biomass for CO2 flux (36.1% and32.8%).And they were still soil compaction and organic matter (50.1% and 22.9%) for N2O flux.The tramplingof animals increased the soil compaction and then changed the greenhouse gas flux.And a large amount ofgreenhouse gas was released while the alpine meadow was at severe degradation stage.