青藏高原东缘地质环境对植被覆盖度的影响研究:以冕宁县为例

Influence of Geological Environment on Vegetation Coverage in the Eastern Edge of Qinghai-Tibet Plateau:A case study of Mianning

研究地质环境对植被覆盖度的影响,有利于认识地质本底对生态环境的影响,促进生态保护与修复。本文选择2003-2018年的MODIS归一化植被指数(NDVI)与增强型植被指数(EVI)的多年平均值与年际变化率作为植被覆盖度的静态和动态刻画指标,应用Pearson相关性统计揭示地质因素、地形因素、气象因素和人类活动因素对植被指数的静态相关影响,使用地理加权回归模型(GWR)分析影响因子与植被覆盖度在空间尺度的回归关系。研究结果表明:高程、年均气温和年蒸散发在Pearson分析中对NDVI/EVI平均值有较强相关性,而起伏度、年均气温、年蒸散发和地质复杂度等因子对NDVI/EVI年际变化率有较好的解释作用;GWR分析显示,靠近断层的位置有利于植被发育和改善;当地质复杂度处于中等水平时,更易形成中高植被覆盖,同时利于植被覆盖度提高,当地质复杂度过高时植被覆盖度更易出现中低值;海拔较低、地势平坦和阴坡等地形条件利于植被发育和植被覆盖度升高。

Studying the influence of the geological environment on vegetation coverage is conducive to understand the effect of geological background on ecological environment and promote ecological protection and restoration.The multi-year mean of MODIS-Normalized Vegetation Index(NDVI)and Enhanced Vegetation Index(EVI)from 2003 to 2018 was selected as the static indicator of vegetation coverage,while the inter-annual variation rate was used as the dynamic index.Pearson correlation statistics were used to reveal the static correlation effects of geological factors,topographic factors,meteorological factors and human activities on vegetation index,as well as the regression relationship between influencing factors and vegetation coverage in spatial scale were obtained by geographic weighted regression(GWR).The results showed that elevation,annual average temperature and annual evapotranspiration were of great significance to the multi-year mean of NDVI/EVI,and the factors such as relief,annual average temperature,annual evapotranspiration and geological complexity performed quite well in explanation for the inter-annual variation rate of NDVI/EVI in Pearson analysis.GWR analysis indicated that the location closed to the fault is conducive to the development and improvement of vegetation.The geological complexity in the middle level was prone to form medium and high vegetation coverage,at the same time,it was in favor of increasing vegetation coverage.When the geological complexity was high,the vegetation coverage was probable to middle and low value.Low altitude,flat terrain and shady slope were favorable for vegetation development and increasing vegetation coverage.