基于地理探测器的甘肃省植被覆盖时空变化及驱动力分析

Spatiotemporal variation of vegetation cover and its driving forces in Gansu Province based on geodetector

准确量化人类活动和气候变化对生态环境退化的作用,探讨不同驱动因子的主次关系,是当前区域生态环境研究中的热点。本文基于1982—2015年的归一化植被指数(normalized difference vegetation index,NDVI),结合自然因素和人为因素,选取15个涵盖气候、地形地貌、社会经济等方面的因子,采用趋势分析法和地理探测器模型,对甘肃省植被NDVI的时空变化特征及驱动力进行探测。结果表明:甘肃省NDVI在空间上呈现从东南向西北递减,且低植被覆盖度区域和高植被覆盖度区域呈现“两极化”的分布规律,分别占全省植被面积的39.2%和17.8%。省内大部分地区NDVI呈现增长趋势,植被显著改善区域主要集中在陇东、陇中地区。降水量、植被类型、人均粮食占有量、土壤类型、土地利用类型是甘肃省NDVI空间分布的主要驱动因子,解释力均大于0.5,且双因子的叠加作用大于单因子的作用。本研究有助于揭示不同因子对甘肃省植被变化的驱动机制,为生态环境建设和资源利用管理提供科学参考。

Background,aim,and scope In terms of monitoring ecological environment change,regional vegetation change and its driving mechanism play an important role.Normalized difference vegetation index (NDVI) has been widely used in regional and global vegetation status studies.Taking Gansu Province as the research area,not only did this study accurately quantify the contributions of human activities and climate change to ecological degradation,but it also identified the primary and secondary relationships of different driving factors affecting NDVI spatial differentiation.Materials and methods Based on NDVI from 1982 to 2015,15 influencing factors covering climate,topography,social economy and other aspects were selected.This paper applied slope trend analysis method and geographical detector to detect the spatial-temporal variation characteristics and driving forces of vegetation NDVI in Gansu Province.Results It is shown that NDVI in Gansu Province decreased from southeast to northwest,and the distribution pattern of low vegetation coverage and high vegetation coverage was ‘‘polarized’’,accounting for 39.2% and 17.8% of the total vegetation area of Gansu Province,respectively.In most areas of Gansu Province,NDVI is on the increase.The significant improvement of vegetation is mainly concentrated in the eastern and central part of Gansu Province.Discussion According to the results,natural factors are the primary factors leading to NDVI spatial differentiation,and precipitation is the main climatic factor affecting vegetation change in Gansu Province,which is consistent with the outcomes of other research on spatial differentiation of vegetation in arid and semi-arid regions.Human activities mainly affect vegetation by changing land use types.Grain occupancy per capita,land use,number of livestock and population density are the anthropogenic factors that have great influence on spatial differentiation of NDVI.Within the province,vegetation NDVI decreased most significantly in the livestock intensive areas of Gannan Plateau,where overgrazing was the main human factor causing grassland degradation in this region.Conclusions Themain driving factors of NDVI spatial distribution are comprised of precipitation,vegetation type,per capita grain supply,soil type and land-use type.With explanatory power greater than 0.5,the superposition effect of the two factors was greater than that of the single factor.Recommendations and perspectives The results of this study present a valuable understanding of the influence of natural and human factors on vegetation change,reveal the driving mechanism of vegetation change,and provide scientific reference for rational utilization of resources and effective protection of the ecological environment.