1998-2018年新疆伊犁河谷植被覆盖度时空变化及驱动力

Spatial-temporal Variation and Driving Force Analysis of Vegetation Coverage in the Ili River Valley of Xinjiang from 1998 to 2018

根据1998—2018年的MODND1M 500m植被指数(NDVI)数据,利用像元二分模型、趋势分析法、变异系数及地理探测器模型,探究了新疆伊犁河谷植被覆盖度变化特征及其驱动因子。结果表明:(1)新疆伊犁河谷多年平均植被覆盖度为0.687。研究时段内植被覆盖度平均最高值位于新源县,为0.86,最低值位于可克达拉及霍尔果斯,仅为0.53。(2)1998—2018年,研究区1500 m以下低海拔地区植被覆盖增长显著,1500~3000 m中海拔区域植被覆盖呈下降趋势,3000~4000 m高海拔区域植被覆盖也呈上升趋势。(3)研究时段内伊犁河谷植被覆盖度整体呈低波动趋势。3000 m以上高海拔地区及荒漠等低植被覆盖区域波动较大,森林及农田等高植被覆盖区域波动较小。(4)新疆伊犁河谷植被覆盖度主要受气温、植被分类、海拔等3个因子的影响,其解释力在40%以上。双因子交互方面,坡向与所有其他因子双交互作用均为非线性增强,而坡度∩土壤类型及土壤类型∩地貌类型的探测解释也呈现非线性增强。海拔梯度上,1500 m以下低海拔地区植被覆盖分布主要受植被类型影响,3000 m以上高海拔地区植被覆盖分布主要受气温影响。

With the MODND1M 500 m NDVI data from 1998 to 2018,the characteristics and driving factors of vegetation cover change in the Ili River Valley of Xinjiang were explored by using pixel dichotomous model,trend analysis method,coefficient of variation and geographic detector model.The results showed that:(1)The average vegetation coverage of the Ili River Valley in Xinjiang was 0.687.During the study period,the highest average value of vegetation cover was 0.86 in Xinyuan County,and the lowest value was only 0.53 in Kokdala and Khorgos.(2)From 1998 to 2018,vegetation cover increased significantly in low-altitude areas below 1500 m in the study area,decreasing in medium-altitude areas of 1500-3000 m,and increasing in high-altitude areas of 3000-4000 m.(3)The vegetation coverage of the Ili River Valley showed a low fluctuation trend during the study period.Low vegetation coverage areas such as high altitudes above 3000 m and deserts fluctuate greatly,while high vegetation coverage areas such as forests and farmland fluctuate less.(4)The vegetation coverage of the Ili River Valley in Xinjiang is mainly affected by three factors,such as temperature,vegetation classification and altitude,and its explanatory power is more than 40%.In terms of two-factor interactions,the double interaction between aspect and all other factors was nonlinear enhancement,while the detection and interpretation of slope∩soil type and soil type∩landform type also showed nonlinear enhancement.On the altitude gradient,the distribution of vegetation cover in low-altitude areas below 1500 m was mainly affected by vegetation type,and the distribution of vegetation cover in high-altitude areas above 3000 m was mainly affected by temperature.