基于遥感监测的天山新疆段草地退化时空特征及其与气候因子的关系

Temporal and spatial characteristics of grassland degradation in Xinjiang Section of Tianshan Mountains based on remote sensing monitoring and its relationship with climate factors

以植被覆盖度作为草地退化的遥感监测指标,基于2001-2020年天山新疆段MODIS NDVI和气象遥感资料,采用像元二分模型、草地退化指数、冷/热点分析、变异系数和相关性分析等方法,分析草地退化时空特征及其与气候因子的关系,结果表明:1)2001-2020年平均草地退化面积占总面积的34.04%,草地退化指数为1.67,处于轻度退化水平。2)空间上,轻度退化草地空间分异特征明显,主要集中分布在天山西部和中段山区,中度退化和重度退化草地面积较小且不集中,95%以上的区域草地植被覆盖度变异系数小于0.2,总体上覆盖度的年际波动小,变化相对稳定。3)2001-2020年草地植被覆盖度受气候因子驱动的区域占总面积的44.23%,主要分布在天山西部和东部,受非气候因子驱动的区域占总面积的55.77%,在山区和南北两侧地势较平缓的区域均有分布,说明非气候因子在天山新疆段草地的变化中起到主导作用。该研究结论可为当地草地资源保护与利用提供科学依据。

Grassland plays an important role in environmental protection in Xinjiang.Understanding the temporal and spatial characteristics of grassland degradation and revealing the degradation mechanism would be beneficial for promoting and constructing the ecological civilization of Xinjiang.MODIS NDVI data and remote sensing data of the Xinjiang section of the Tianshan Mountains from 2001 to 2020 were used to analyze the relationship between the temporal and spatial characteristics of grassland degradation and climate factors.Vegetation coverage was used as the remote sensing monitoring index for detecting grassland degradation,and analyses were conducted using methods such as the dimidiate pixel model(DPM),grassland degradation index(GDI),cold/hot spot analysis method,coefficient of variation(COV),and correlation analyses.The results showed the following:1)The average area of degraded grassland was 34.04%of the total area from 2001 to 2020,and this was categorized as being lightly degraded(with a GDI of 1.67).2)Slightly-degraded grassland had obvious spatial differentiation characteristics,and they were mainly distributed in the western and central areas of the Tianshan Mountains.Areas of moderately and heavily degraded grasslands were small and not concentrated in a particular region.More than 95%of the regional grassland vegetation coverage had a COV of less than 0.2.The variation in overall coverage was relatively steady,with a small inter-annual fluctuation.3)From 2001 to 2020,the areas of grassland vegetation coverage affected by climate factors accounted for 44.23%of the total area and were mainly distributed in the west and east of the Tianshan Mountains.Areas of grassland vegetation coverage driven by non-climatic factors accounted for 55.77%of the total area,and these were distributed on relatively flat terrain in the central,northern,and southern sections of the Tianshan Mountains.The results show that non-climate factors play a leading role in grassland changes within the Xinjiang section of the Tianshan Mountains,and they provide a scientific basis for planning the protection and utilization of local grassland resources.