高寒草甸植被生产量年际变化及水分利用率状况

分析了海北地区高寒草甸植被2001-2011年11 a耗水量、 生物现存量、 净初级生产量、 水分利用率及其相关性, 结果表明: 植物生长期5-9月耗水量416.30 mm, 植被地上净初级生产量(ANPP)、 地下净初级生产量(BNPP)以及总的净初级生产量(NPP=ANPP+BNPP)分别为393.07 g·m^-2、 945.26 g·m^-2、 1 338.33 g·m^-2, BNPP与ANPP之比为2.404. 8月底植被现存生物量达3 422.92 g·m^-2, 其中地上和地下现存量分别为411.07 g·m^-2、 3 011.85 g·m^-2, BNPP与ANPP之比高达7.327, 说明植被现存量巨大, 归还土壤碳能力强. NPP与5-9月植被耗水量相关性很差, 但与5-9月平均气温具有显著的正相关关系, 表明高寒草甸地区水分条件可满足植物生长的基本需求, 而同期温度是影响NPP提高的重要因素. 11 a来BNPP、 ANPP和NPP平均水分利用率分别为0.958 g·m^-2·mm^-1、 2.326 g·m^-2·mm^-1和3.284 g·m^-2·mm^-1, 表明高寒草甸植被净初级生产具有较高的水分利用率.

Interannual Variations of Production and Water Use Efficiency of the Vegetation in Alpine Meadow

Statistical analysis on the water consumption, standing biomass, net primary production, water use efficiency and their correlations with the vegetation in Haibei alpine meadow from 2001 to 2011 showed that the water consumption from May to September was 416.30 mm, the aboveground net primary production (ANPP) was 393.07 g·m^-2, the belowground net primary production (BNPP) was 945.26 g·m^-2and the total net primary production (NPP) was 1 338.33 g·m^-2, and the ratio of BNPP to ANPP was 2.404, the standing crop biomass at the end of Augustreached 3 422.92 g·m^-2, of which the ANPP and BNPP was 411.07 g·m^-2and 3 011.85 g·m^-2, respectively, with the ratio of BNPP to ANPP of 7.327. This demonstrates that the current vegetation had huge standing stock and great ability to return the soil carbon. NPP had a poor correlation with the water consumption but had a significantly positive correlation with the air temperature averaged from May to September, indicating that water condition in the alpine meadow could meet the demand for the plant growth, and the synchronous air temperature was the principal factor to improve the NPP. Water consumption averaged over the 11 years shows that the water use efficiency for BNPP, ANPP and NPP was 0.958 g·m^-2mm^-1, 2.326 g·m^-2mm^-1and 3.284 g·m^-2mm^-1, respectively, indicating that the vegetation in alpine meadow had a higher water use efficiency.