河北省张承地区2001—2020年植被动态变化及驱动因素分析

Vegetation Dynamics and Driving Factors in Zhangjiakou-Chengde Area of Hebei Province from 2001 to 2020

张承地区(张家口—承德)作为京津冀的水源涵养功能区,植被动态对其生态环境建设和保护有重要意义。本文以MODIS-NDVI、气温降水、土地利用、地下水位埋深和实测土壤湿度数据为基础,利用Sen+Mann-Kendall趋势分析和偏相关性分析等方法,分析张承地区2001—2020年植被时空变化特征及其与气温降水、土地利用、地下水位埋深和土壤湿度响应特征。结果表明,研究区NDVI年均值为波动上升趋势。植被覆盖率空间分布呈“西北低,东南高”的特点。植被显著改善地区主要分布在坝下大部分区域,占研究区85.79%的面积。降水、气温与植被指数的偏相关性较好,皆呈正相关。研究区人类活动导致用地类型发生的变化与植被变化有响应联系。区内地下水位埋深在6.2 m的地方植被长势最好。土壤湿度空间分布为坝上低、坝下高,植被指数在整体趋势上随实测土壤湿度的增大而增大。

As a water conservation function area in the Beijing-Tianjin-Hebei region,the vegetation dynamics of Zhangjiakou-Chengde(Zhang-Cheng)area is of great significance for the ecological/environmental construction and protection.Based on MODIS-NDVI,temperature and precipitation,land use,groundwater depth and measured soil moisture data,Sen+Mann-Kendall trend analysis,partial correlation analysis and other methods,we analyze the spatial-temporal variation characteristics of vegetation and the response characteristics of temperature and precipitation,land use,groundwater depth and soil moisture in Zhang-Cheng area from 2001 to 2020.The results show that the annual mean NDVI value shows an upward fluctuation trend.The vegetation coverage is characterized by being low in the northwest and high in the southeast.Significant vegetation improvement areas were mainly distributed across most of Baxia,accounting for 85.79%of the study area.There are positive correlations between precipitation,temperature,and the vegetation index.Furthermore,the vegetation variation agrees well with the land-use change.The vegetation growth is best when the groundwater depth is around 6.2 m.The spatial distribution of soil moisture is low at Bashang and high at Baxia.The NDVI increases with increasing measured soil moisture.