1992-2019年阿拉尔市植被覆盖时空变化分析

Spatio-temporal changes analysis of vegetation coverage in Alar City in 1992-2019 years

以阿拉尔市为研究区,采用1992、1997、2002、2008、2013和2019年6个时期的Landsat系列影像数据作为数据源,运用NDVI、像元二分模型和重心迁移模型等方法和模型分析阿拉尔市植被覆盖时空变化和影响驱动因素。结果表明:阿拉尔市的植被覆盖分布总体上以塔里木河和阿克苏河为轴线,从高植被覆盖向低植被覆盖由内向外展布。近28年,阿拉尔市NDVI、植被覆盖面积和植被覆盖度均呈增加趋势。2019年比1992年总植被覆盖面积增加了1476.7 km^(2),增长率为110.3%。阿拉尔市植被覆盖时间尺度变化存在时段性和区域性差异。在时段变化上,2002-2008年植被覆盖面积增加最显著;区域上,幸福农场、8团和10团北部区植被覆盖度大幅度增加,增加较显著。过去28年期间,总、高、中和低植被覆盖度重心都向东北方向迁移,极低植被覆盖度重心都向东南方向迁移。气候变暖对植被覆盖度有一定的影响,也间接体现在因冰雪融水流域径流不断增大,但是短期内的人类活动因素对区域植被覆盖度影响更为直接。其中耕地开垦、农作物种植是阿拉尔市植被覆盖增加的主要因素。

Taking Alar City as the research area,Landsat series image data of six periods from 1992 to 2019 as the data source,NDVI,pixel binary model and center of gravity migration model were used to analyze the spatiotemporal changes of vegetation cover and its influencing factors in Alar City.The results showed as follows:(1)The distribution of vegetation coverage in Alar City generally took the Tarim River and Aksu River as the axis,spreading from high vegetation coverage to low vegetation coverage from the inside to the outside.(2)In recent 28 years,while the average NDVI in Alar City showed an increasing trend,the vegetation coverage area and vegetation coverage also showed an increasing trend.Compared with 1992,the total vegetation coverage in 2019 increased by 1476.7 km~2,representing a growth rate of 110.3%.(3)There were temporal and regional differences in the time scale of vegetation coverage in Alar City.During the period of change,the vegetation coverage area increased most significantly from 2002 to 2008.Regionally,the vegetation coverage in the northern area of Xingfu Farm,No.8 and No.10 Regiment increased significantly.(4)During the past 28 years,the center of gravity of total,high,medium and low vegetation coverage had all moved to the northeast,and the center of gravity of very low vegetation coverage had all moved to the southeast.(5)Climate warming had a certain impact on the change of vegetation cover,which was also indirectly reflected in the continuous increase of snow and ice meltwater on watershed runoff.However,human activities in the short term had a more direct impact on regional vegetation coverage.Among them,cultivated land reclamation and crop planting were the main factors for the increase in vegetation coverage in Alar City.