青海省草地生产力变化及其驱动因素北大核心CSCD

近年来受到气候变化和人类活动的影响,青海省草地生产力发生明显的变化。本研究基于MOD17A3HGF.006数据产品,以草地净初级生产力(NPP)为指标,采用Sen-MK趋势分析、相关分析和残差分析等方法构建决策树,分析青海省2001-2017年草地NPP变化趋势,并探究其驱动因素的空间异质性。结果表明:1)近17年来青海省草地NPP发生显著(P<0.05)变化的面积为11.41×10^(4)km^(2),其中NPP极显著(P<0.01)增加、显著(0.01≤P<0.05)增加、显著减少和极显著减少的草地分别占全省草地面积的11.88%、17.25%、0.20%和0.08%;全省草地生产力明显提高。2)草地NPP显著变化的不同主导因素类型中,气温主导的区域最大,占草地NPP显著变化面积的60.66%;其次是人类活动和人类活动+气温,分别占23.45%和9.49%;气温和人类活动是引起青海省草地NPP显著变化的主要因素。3)气温、降水和人类活动对青海省草地NPP变化的作用均以促进为主;同时,人类活动又是草地退化的主要因素,其贡献了草地NPP减少趋势区域的77.49%;而在青海省主要的生态工程区内,人类活动对草地的保护和治理成效明显。

Change in grassland productivity in Qinghai Province and its driving factors

In recent years， grassland in Qinghai province has been affected by climate change and variously impacted by a range of human activities， sometimes causing degradation and sometimes facilitating restoration. Here we report a survey of the spatial and temporal variation in grassland productivity across Qinghai Province for the period from 2001-2017. To extract data on grassland net primary productivity （NPP， MOD17A3HGF.006）， Sen’s slope together with the Mann-Kendall test （Sen-MK）， correlation analysis and residual analysis were used as decision nodes of a decision tree. Then we used the tree to evaluate grassland NPP time trends and their spatial heterogeneity during the study period and identify associated factors that may be change drivers. The results were as follows： 1） There were 11.41×10⁴ km² of grassland with significant （P<0.05） NPP trends in Qinghai Province during the 2001-2017 period. The areas of extremely significant （P<0.01） increase， significant （0.01≤P<0.05） increase， significant decrease and extremely significant decrease were respectively 11.88%， 17.25%， 0.20% and 0.08% of the grassland in the province. Remarkably， the overall change is a rise in NPP. 2） For the regions where grassland NPP trends were significant， the proportion explained by temperature was the largest （60.66%）， followed by human activities （23.45%） and human activities + temperature （9.49%）. Hence， temperature and human activities were the major factors driving significant grassland NPP trends. 3） Temperature， precipitation and human activities mainly had positive impacts on NPP. Human activities were the dominant factor linked with grassland degradation and were associated with 77.49% of the grassland area with a decreasing NPP trend. However， human activities have also achieved remarkable results in grassland restoration and ecological protection projects in Qinghai Province.