2000-2019年重庆市植被覆盖时空变化特征及其驱动因素

基于MODIS-NDVI数据、气象数据、地形数据和人类活动数据,采用趋势分析等方法,应用地理探测器模型,全面分析2000-2019年重庆市植被覆盖时空变化特征,并探究各地理因子及其交互作用对重庆市植被覆盖的影响程度与作用机制。研究发现:(1)2000-2019年,重庆市植被覆盖整体呈波动上升趋势,增长率为4.4%/10a,NDVI偏差值呈先减小后增加趋势。(2)2000-2019年,重庆市植被覆盖高值区主要分布于渝东北和渝东南,低值区则主要分布于三峡库区消落带及渝西、主城地区;植被覆盖空间格局在东西方向上由"一字型"向"斜线型"演化,南北方向上由"浅U型"向"深U型"演化。(3)2000-2019年,各地理因子对重庆市植被覆盖空间分异性解释力大小依次为:年均温(0.3459)>高程(0.3281)>年均降水量(0.2305)>人类活动强度指数(0.1747)>坡度(0.1008)>总辐射(0.0552)>坡向(0.0034);年均温、坡向、人类活动强度指数解释力总体呈增加趋势,年均降水量、总辐射、高程、坡度解释力总体呈减小趋势。(4)2000-2019年,各地理因子对重庆市植被覆盖变化存在交互作用,且呈双因子增强和非线性增强两种类型,而不存在相互独立作用或对植被覆盖变化解释力减弱的交互因子。

Spatiotemporal variation characteristics and driving factors of vegetation cover in Chongqing from 2000 to 2019

Based on MODIS-NDVI data, meteorological data, terrain data and human activity data, using trend analysis and other methods, the spatial-temporal change characteristics of vegetation cover in Chongqing from 2000 to 2019 were comprehensively analyzed by using geographic detector model. The influence degree and mechanism of each geographical factor and its interaction on vegetation cover in Chongqing were explored. The study finds that from 2000 to 2019:(1) The overall vegetation cover in Chongqing showed a fluctuating upward trend, with a growth rate of 4.4%/10A. The deviation value of NDVI first decreased and then increased. The change characteristics of vegetation cover were obvious and showed three stages. In the early stage, the average annual value of NDVI showed a downward trend; In the medium term, the average annual value of NDVI shows a slight growth trend; In the later stage, the average annual value of NDVI showed a rapid growth trend. (2) The vegetation cover in Chongqing is in the spatial distribution pattern of high in the East and low in the west. The high value areas are mainly distributed in the continuous area of Daba Mountains in Northeast Chongqing and the edge area of Wuling Mountain in Southeast Chongqing; Low value areas are mainly distributed in the fluctuating zone of the Three Gorges Reservoir area, Western Chongqing and the main urban areas. The spatial pattern of vegetation cover evolves from one-sided to diagonal in the east-west direction and from shallow U to deep U in the north-south direction, but the high-low concentration pattern of vegetation cover is basically stable. (3) The explanatory power of various geographical factors on the spatial differentiation of vegetation cover in Chongqing is as follows:annual average temperature (0.3459)>elevation (0.3281)>annual precipitation (0.2305)>human activity intensity index (0.1747)>slope (0.1008)>total radiation (0.0552)>slope direction (0.0034); the explanatory power of annual average temperature, slope direction and human activity intensity index generally increases, and the explanatory power of annual average precipitation, total radiation, elevation and slope generally decreases. (4) Each geographical factor interacted with vegetation cover change in Chongqing, and showed two types of double factor enhancement and nonlinear enhancement, but there was no interaction factor that interacted independently or weakened the explanatory power of vegetation cover change. The first dominant interactive factor of vegetation cover change in Chongqing is annual mean temperature and human activity intensity index, the second dominant interactive factor is elevation and human activity intensity index, and the third dominant interactive factor is annual mean temperature and total radiation.