生态工程背景下黄土高原植被变化时空特征及其驱动力

Analysis of Spatial-temporal Change and Driving Forces of Vegetation in Loess Plateau Under Background of Ecological Engineering

[目的]分析1990—2015年黄土高原植被的时空演变规律,并从气候变化和人类活动两个方面分析该地区植被变化的驱动力,以期为生态环境保护相关政策的制定和区域可持续发展提供理论依据。[方法]基于GIMMS NDVI和MODIS NDVI建立长时间序列NDVI数据集,采用线性趋势分析、多元线性回归和改进的人类残差等分析方法,以NDVI为指标,辅助土地利用数据,对黄土高原地区1990—2015年期间植被时空变化特征及其影响因素进行了定量分析。[结果]①在1990到2015年期间,黄土高原地区植被的NDVI总体表现为上升趋势,且变化趋势较明显的分为两个时期,其中2000年以后NDVI上升速率较快;②2000年以后,黄土高原植被NDVI迅速上升,上升区域面积达到总面积的91.90%,其中NDVI显著上升面积比为65.78%;③黄土高原地区植被面积总体表现为增加,且主要来自于耕地的转入;④人类活动促使的植被恢复区域占黄土高原总面积的21.74%,主要分布在内蒙古的东部和北部、甘肃和宁夏的南部,以及陕西和山西的中部地区。[结论]随着退耕还林还草政策的实施,黄土高原地区植被面积持续增加,且植被生长状况持续变好,黄土高原植被恢复的原因主要是气候和人类共同影响,其中人类影响的程度较大。

[Objective]The spatial and temporal evolution of vegetation on the Loess Plateau from 1990 to 2015 was studied,and the driving forces of vegetation change in this region were analyzed from the aspects of climate change and human activities in order to provide a theoretical basis for formulating policies related to ecological environmental protection and regional sustainable development.[Methods]Based on GIMMS NDVI and MODIS NDVI,long-term sequence NDVI datasets were established.During the period of 1990—2015,the linear trend analysis,multiple linear regression and improved human residuals were used to analyze the spatial and temporal variation of vegetation with NDVI and land use data in the Loess Plateau.The characteristics and their influencing factors were quantitatively analyzed.[Result]①Between 1990 and 2015,the NDVI of the Loess Plateau showed an upward trend,and the trend of change was more clearly divided into two periods,of which the rate of NDVI increased faster after 2000.②After 2000,the NDVI of the Loess Plateau increased rapidly,and the rising area reached 91.90%of the total area,of which the NDVI significantly increased area ratio was 65.78%.③The overall area of vegetation in the Loess Plateau increased,and it mainly came from the transfer of cultivated land.④The vegetation restoration area promoted by human activities accounted for 21.74%of the total area,mainly distributed in the eastern and northern parts of Inner Mongolia,southern area of Gansu and Ningxia Region,as well as the central areas of Shaanxi and Shanxi Province.[Conclusion]With the implementation of the policy of returning farmland to forest and grass land,the vegetation area in the Loess Plateau continued to increase,and the vegetation growth continued to improve.The main reason for the restoration of vegetation on the Loess Plateau was the combination of climate and humans,and the degree of human influence was relatively larger.