2001—2015年间我国陆地植被覆盖度时空变化及驱动力分析

Spatial-temporal variation and its driving forces of vegetation coverage in China from 2001 to 2015

基于MODIS-NDVI遥感数据反演计算了我国陆地2001—2015年地表植被覆盖度的空间分布,讨论了植被覆盖度的时空变化规律,分析了影响植被覆盖度近十几年来动态变化的主要驱动因素。研究结果表明:我国陆地植被覆盖度从2001—2015年,植被覆盖度总体上呈增加趋势,其中淮河流域、华北平原地区、以及黄土高原地区增加趋势显著。根据植被覆盖度在时间序列上的变化特征,可将其变化类型分为持续增长型、先减小后增长等六种类型,其中农业种植区基本为一直增长型,而主要森林覆盖区,特别是西南地区的植被覆盖度在研究时段内表现出波动性的变化特征。降水是驱动华北平原北部、内蒙古、以及西北大部分区域植被覆盖度动态变化的重要因素,东北、青藏高原等地区植被覆盖度受温度的影响较大,而在中国东南沿海地区,光照条件是影响该区域植被覆盖度的主要因素。

Vegetation coverage is a quantitative index to reflect the surface condition of plant communities, and it can indicate the regional environmental change,which has important significance for the regional hydrological,ecological conditions and the regional response of the global change. In this study,based on the MODIS-NDVI data during the period from 2001 to 2015,the mean values of vegetation coverage were Firstly calculated every three years,and the differences of distribution during each period were investigated;Secondly,the variation rate of vegetation coverage was computed at the national scale during the study period,and six variation types were defined and the distribution of different types was analyzed in order to understand the variation characteristics;Finally,the drivers of the vegetation coverage change in different areas were analyzed by computing the correlation between vegetation coverage and typical climatic factors,such as annual mean temperature,annual precipitation and annual average sunshine percentage.The results were summarized as follows:(1) The spatial distribution of vegetation coverage in China is gradually reduced from the southeast coast to the northwest inland.From 2001 to 2015,there were regional variations of the vegetation coverage which caused little difference in terms of the overall distribution trend.(2) Over the past 15 years,the vegetation coverage in China had shown an increasing trend,in particular,in the Huaihe River Basin,the North China Plain area and the Loess Plateau region it was increased significantly.While the vegetation coverage of Qinghai Tibet Plateau and Inner Mongolia plateau had little change.(3) According to the time series analysis of the vegetation coverage,the variation type can be divided into six categories,such as continuous growth,reduced-after-initially-increase,and so on.The vegetation coverage in most plain areas showed a continuous growth,while most of the forest-covered area,especially in the southwest,the vegetation coverage showed the variation characteristics of volatility during the study period.(4) By calculating the correlation coefficient between vegetation coverage and the selected climatic factors,it can be found that the vegetation coverage and precipitation were significantly and positively correlated in the Northern China Plain,Inner Mongolia,and most of the northwest area,which indicated that precipitation is the main climatic factor that affects vegetation coverage in those areas.Climate factors such as temperature,sunshine have a significant positive correlation with vegetation coverage in humid climate region,while there is a significant negative correlation in arid climate region.