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研究季节性放牧对植被耗水量、水分利用效率的影响,是探索如何提高高寒草甸水源涵养能力的重要内容之一。以青藏高原三江源高寒草甸季节性放牧样地与自然放牧样地为研究对象,分析了季节性放牧和自然放牧条件下高寒草甸植被耗水量、水分盈亏量、水分利用效率(WUE)的动态变化及其与环境因素的关系。结果表明:在植被生长季(5-9月),季节性放牧样地和自然放牧样地植被耗水量在5月开始增加,7月达最高,分别为160.94 mm和145.96 mm,季节性放牧样地植被总耗水量(395.52 mm)比自然放牧样地(348.14 mm)高13.61%。生长季平均来看,季节性放牧样地和自然放牧样地5-9月水分正盈余,分别为13.58 mm和70.96 mm,但在植物生长旺季(8月)略有亏缺。季节性放牧样地和自然放牧样地植被耗水量均与降水量呈弱的正相关关系。季节性放牧样地植被地上净初级生产量(ANPP)、地下净初级生产量(BNPP)和总的净初级生产量(NPP)比自然放牧样地分别高32.54 g·m~(-2)、5.96 g·m~(-2)、38.50 g·m~(-2),季节性放牧样地ANPP的水分利用效率(WUE)比自然放牧样地高53.85%,而BNPP、NPP的WUE比自然放牧样地分别低13.06%和9.97%。这表明,季节性放牧可提高植被生产量和耗水量,但对高寒草甸WUE的影响因放牧方式不同导致地上、地下生物量分配格局不同而有所差异。
Studying the effect of seasonal grazing on the water consumption and water use efficiency of vegetation is one of the important contents to explore how to improve the water conservation capacity of alpine meadow. Based on the seasonal herding and natural herding of alpine meadow in the Three Rivers of Qinghai-Tibet Plateau, the effects of seasonal grazing and natural grazing on the water consumption, water profit and loss, water use efficiency (WUE) Dynamic Changes and Their Relationship with Environmental Factors. The results showed that in the vegetation growing season (May-September), water consumption of seasonal herbage and natural herbage plots increased in May and reached the highest in July, reaching 160.94 mm and 145.96 mm, respectively. Seasonal grazing The total water consumption of vegetation (395.52 mm) was 13.61% higher than that of natural grazing land (348.14 mm). On average, the seasonal surplus of surplus water from May to September in the seasonal grazing plot and the natural grazing plot were 13.58 mm and 70.96 mm, respectively, but were slightly deficient in the plant growing season (August). The water consumption of vegetation in both seasonal grazing and natural grazing plots showed a weak positive correlation with precipitation. The ANPP, BNPP and NPP of seasonal grazing plot were 32.54 g · m -2 higher than that of the natural grazing plot, respectively. The average net primary production (ANPP), total net primary production (NPP) 5.96 g · m -2 and 38.50 g · m -2, respectively. The water use efficiency (WUE) of ANPP in the seasonal grazing plot was 53.85% higher than that in the natural grazing plot. However, the WUE of BNPP and NPP was higher than that of the natural grazing plot The grazing plots were 13.06% and 9.97% lower respectively. This shows that seasonal grazing can increase vegetation productivity and water consumption, but the impact on WUE in alpine meadow varies with the pattern of biomass allocation above and below ground due to different grazing ways.