基于地理探测器的长株潭“绿心”植被演变及影响因素分析

Influencing Factors of Vegetation Change in Green Heart of Changsha-Zhuzhou-Xiangtan Based on Geographical Detector

为研究绿心地区的植被变化和影响因素,对长株潭绿心地区2000年—2020年归一化植被指数(Normalized Difference Vegetation Index,NDVI)的最大值进行数据处理、等级划分和面积统计,结合Theil-Sen Median和Mann-Kendall研究绿心地区植被长时间序列NDVI的变化趋势,使用地理探测器探究NDVI的影响因素、影响过程和影响机制.研究结果表明:(1)NDVI总体呈上升趋势,各年份NDVI呈现分级镶嵌分布,高等级在研究区中部,低等级聚集在河流附近,其他等级分散分布;(2)人口密度是影响NDVI变化的主要因素,解释力高达40%,其次是高程、降水和最低气温;(3)对NDVI变化的影响不是单个因子独立作用的结果,而是人文因子和自然因子之间交互作用的结果,且交互作用影响较大的因子组合对NDVI的空间分布均存在显著性差异.研究结果可为长株潭绿心地区的规划建设及生态环境监测提供决策参考,为该区域生态环境的保护与可持续发展提供理论与方法依据.

As a policy protected green space in the rapidly developing Changsha-Zhuzhou-Xiangtan urban agglomeration,the study of vegetation change and influencing factors in the Green Heart area has important practical value.The maximum value of normalized difference vegetation index(NDVI)from 2000 to 2020 in the Changsha-Zhuzhou-Xiangtan Green Heart is data-processed,rank-classified and area-counted.The change trend of NDVI in the long time series of vegetation in the Green Heart is studied in combination with Theil-Sen Median and Mann-Kendall,and the influencing factors,processes and mechanisms of NDVI are explored by using geographical detectors.The results show that firstly the spatial distribution characteristics of NDVI in the study area are high in the middle and inlaid transition between adjacent grades.Except for low grades,the distribution of NDVI in other grades is scattered,and the overall trend of NDVI change is upward.Secondly,population density is the main factor affecting NDVI changes,with the explanatory power up to 40%,then is elevation,precipitation and minimum temperature.Thirdly,the impact on NDVI change is not the result of the independent action of a single factor,but the result of the interaction between human factors and natural factors,and the combination of factors with greater interaction has significant differences on the spatial distribution of NDVI.This research result has an important guiding role in the planning and construction and ecological environment monitoring of the Green Heart.It provides a theoretical basis for decision-making on the sustainable development and protection of the regional ecological environment.