2001—2020年川西高原植被EVI时空变化特征及气候因子驱动力分析

为了了解川西高原植被EVI的时空变化特征,以MODIS-EVI数据、DEM数据和气象格点数据为基础,基于相关性分析、趋势分析和最大值合成等方法,探讨了川西高原2001—2020年植被EVI时空变化特征及不同海拔高程下植被EVI分布和变化规律。在此基础上,对研究区植被EVI时空变化的气候因子驱动力进行了分析研究。结果表明:(1)川西高原20年间植被EVI均值介于0～0.88,空间分布具有明显的地域分异。(2)近20 a来,川西高原植被EVI整体增长趋势,速率为1.0%/10 a,植被EVI的相对年际变化率介于-4.26%～13.58%。有13.09%的地区植被EVI变化通过显著性检验,其中约10.18%的区域植被EVI呈增加趋势。(3)川西高原近20 a不同海拔高程下植被EVI都呈波动增加趋势,变化速率以及增加趋势的显著性都有明显的差异。在<2 500 m,2 500～3 000 m,4 500～5 000 m 3个海拔高程区间内,植被EVI增加趋势显著。(4)川西高原植被EVI与气温和降水呈正向相关的区域面积占比分别为56.42%,64.09%。在0.05显著性水平下,川西高原植被EVI变化受气候因子驱动的地区约占研究区总面积的21.87%。整体而言,近20 a来川西高原植被EVI呈增加趋势,且具有明显空间差异,EVI与气温和降水整体呈正向相关。川西高原大部分地区的植被EVI变化受非气候因子驱动。

Spatiotemporal Variation Characteristics of Vegetation EVI and Driving Forces of Climate Factors in Western Sichuan Plateau from 2001 to 2020

In order to understand the temporal and spatial variation characteristics of vegetation EVI in western Sichuan Plateau, based on MODIS-EVI, DEM and meteorological grid data, the temporal and spatial variation characteristics of vegetation EVI and the distribution and variation processes of vegetation EVI at different altitudes in western Sichuan Plateau from 2001 to 2020 were discussed by using the methods of maximum synthesis, trend analysis and correlation analysis. On this basis, the response of vegetation EVI change to climate change in western Sichuan Plateau was studied. The results showed that:(1)the average EVI of vegetation in the western Sichuan Plateau ranged from 0 to 0.88 in 20 years, and the spatial distribution showed obvious regional differentiation;(2)in the past 20 years, vegetation EVI increased at a rate of 1.0%/decade, and the relative interannual variation rate of vegetation EVI ranged from -4.26 to 13.58; in 13.09% of the areas, vegetation EVI changed through significant test, and about 10.18% of the regional vegetation EVI showed an increasing trend;(3)in the past 20 years, vegetation EVI at different altitudes in western Sichuan Plateau showed a fluctuating increasing trend, and the change rate and the significance of the increasing trend were significantly different; in the three altitudes of <2 500 m, 2 500～3 000 m and 4 500～5 000 m, the vegetation EVI increased significantly;(4)the proportions of EVI positively correlated with temperature and precipitation were 56.4% and 64.1%, respectively; at 0.05 significance level, about 21.87% of vegetation EVI changes in western Sichuan Plateau were driven by climate factors. Overall, the vegetation EVI in western Sichuan Plateau had been increasing in the past 20 years, and there was obvious spatial difference. EVI was positively correlated with temperature and precipitation. The variation of vegetation EVI in western Sichuan Plateau was driven by non-climatic factors.