2000-2020年青海湖流域植被净初级生产力时空格局及驱动分析

Spatiotemporal Patterns of Vegetation Net Primary Productivity and Their Drivers in Qinghai Lake Basin from 2000 to 2020

[目的]明确2000—2020年青海湖流域植被净初级生产力(Net Primary Productivity,NPP)时空格局变化特征,探究影响植被NPP的主要因素及驱动比例,为青海湖流域基础科学研究提供参考。[方法]以青海湖流域为研究区域,基于2000—2020年植被NPP、气温、降水量、植被覆盖度、人类活动强度数据,采用ArcGIS空间分析、地理探测器模型等方法,分析植被NPP在子流域、海拔、微地形上的时空变化,并对流域NPP与气温、降水量和植被覆盖度的相关性及植被NPP的驱动要素进行研究。[结果](1) 21年间青海湖流域年植被NPP逐年波动上升,增速为2.22 g C·m^(2)/a,空间上自西北向东南递增。(2)年植被NPP与年均气温、年降水量、年植被覆盖度的显著相关区域占流域面积比依次为40%,9%,59%。年均气温和年降水量与年植被NPP的一级偏相关系数显著区域占流域面积比分别是59.26%和33.39%。(3)驱动分析表明气温(q=0.58)、海拔(q=0.54)、人类活动(q=0.38)是流域NPP的主要驱动因子,并且因子交互解释力强于单因子解释力。[结论]2000—2020年青海湖流域植被NPP整体逐年增长,在海拔、子流域和微地形格局上表现出显著的空间分异性,气温、海拔、人类活动的交互驱动是流域NPP的主要驱动类型。

[Objective] The primary objective of this study is to investigate the spatiotemporal variations in net primary productivity(NPP) of vegetation within Qinghai Lake Basin from 2000 to 2020.Additionally,it aims to reveal the key factors and their contributive driver of changes in vegetation NPP.The research is designed to provide a baseline scientific investigation on dynamics of NPP within Qinghai Lake Basin.[Methods] We used data on vegetation NPP,temperature,precipitation,fractional vegetation cover and human activity intensity in Qinghai Lake Basin from 2000 to 2020 to analyze the spatiotemporal changes of vegetation NPP across sub-basins,elevations,and micro-terrain in Qinghai Lake Basin.We applied spatial analysis of ArcGIS,geographic detector model to conduct these analyses.Furthermore,We also investigated the correlations of vegetation NPP with temperature,precipitation,and fractional vegetation cover,as well as the driving factors of vegetation NPP.[Results](1) In the past 21 years,the annual vegetation NPP in the Qinghai Lake Basin exhibited fluctuating increase across temporal scale,with a growth rate of 2.22 g C·m^(2)/a,and spatially increased trend from northwest to southeast.(2) The study also revealed spatially significant correlations between annual vegetation NPP and mean annual temperature,annual precipitation,and annual fractional vegetation cover,with the ratios 40%,9% and 59%,respectively.The primary partial correlation coefficients between mean annual temperature and annual precipitation with annual vegetation NPP encompassed 59.26% and 33.39% of the basin area.(3) The results of our study also revealed that temperature(q=0.58),elevations(q=0.54) and human activity intensity(q=0.38) were principal drivers of basin-scale NPP,also,interactive impact of factors were found to better explain these drives than any of single factor.[Conclusion] The NPP of vegetation in Qinghai Lake Basin increased over temporal scales from 2000 to 2020.Our study showed spatially significant differences in NPP across elevation,subwatershed and microtopographic pattern.The interactions of temperature,altitude and human activities were the main driving factors of NPP in the Qinghai Lake Basin.