论文部分内容阅读
为了探讨植被指数、地上生物量和总初级生产力对增温的响应是否会随着增温幅度而发生变化,2013年6月底在藏北高原高寒草甸进行了两个梯度的野外增温试验。2013–2014年的生长季节(6–9月)利用农业多光谱相机获取归一化植被指数(normalized difference vegetation index,NDVI)、归一化绿波段差值植被指数(normalized green difference vegetation index,GNDVI)和土壤调节植被指数(soil adjusted vegetation index,SAVI)三种植被指数。基于NDVI和气象数据模拟了地上生物量(aboveground plant biomass,AGB)和总初级生产力(gross primary production,GPP)。结果表明:1、2013–2014年低幅度和高幅度的增温分别显著增加了空气温度(air temperature,T_a)1.54℃和4℃,同时分别显著增加了饱和水汽压亏缺(vapor pressure deficit,VPD)0.13和0.31 k Pa;2、在三个增温处理间,GNDVI,AGB和ANPP并没有显著差异;3、高幅度的增温显著减少了23.3%(–0.06)的NDVI,而较低增温幅度并没有影响NDVI。低幅度和高幅度增温分别显著减少了19%(–0.04)和27.4%(–0.05)的SAVI,同时分别减少了24.2%(0.21 g C m~(–2) d~(–1))和44%(0.39 C m~(–2) d~(–1))的GPP。低幅度和高幅度增温两处理间的平均NDVI,SAVI和GPP并无显著差异;4、增温引起的NDVI,GNDVI,SAVI,AGB,ANPP和GPP的绝对变化量与增温引起的土壤和空气温度的绝对变化量呈不显著相关。因此,在藏北高寒草甸,生产力和植被指数对增温的响应与增温幅度并不呈简单线性变化趋势,这可能归因于较高的增温导致了更高的干旱,进而抑制了温度升高对高寒草甸植被的生长。
In order to investigate whether the response of vegetation index, aboveground biomass and total primary productivity to temperature increase will change with increasing temperature, two gradient field experiments were conducted in the alpine meadow of northern Tibet Plateau in late June 2013. The growing season of 2013-2014 (June-September) obtained the normalized difference vegetation index (NDVI) using the agricultural multispectral camera, and the normalized green difference vegetation index (GNDVI ) And soil adjusted vegetation index (SAVI). Aboveground plant biomass (AGB) and gross primary production (GPP) were simulated based on NDVI and meteorological data. The results showed that: 1. The low and high temperature increases significantly increased the air temperature (T_a) 1.54 ℃ and 4 ℃ from 2013 to 2014 respectively, and significantly increased the vapor pressure deficit VPD) of 0.13 and 0.31 kPa; 2. There was no significant difference in GNDVI, AGB and ANPP among the three warming treatments; 3. High temperature warming significantly reduced NDVI by 23.3% (-0.06), while lower The warming rate did not affect the NDVI. Low and high amplitude warming reduced SAVI by 19% (-0.04) and 27.4% (-0.05), respectively, while decreased by 24.2% (0.21 g C m -2 d -1) And 44% (0.39 C m -2 d -1) of GPP. There was no significant difference between the average NDVI, SAVI and GPP between low and high temperature warming treatments; 4, The absolute change of NDVI, GNDVI, SAVI, AGB, ANPP and GPP caused by warming was positively correlated with the soil temperature and Absolute changes in air temperature were not significantly correlated. Therefore, in the alpine meadow of northern Tibet, productivity and vegetation index did not show a simple linear trend of response to temperature increase and temperature increase, which may be attributed to the higher drought resulted in higher drought and further inhibited Increasing temperature on the growth of alpine meadow vegetation.