2000-2020年黄土高原植被覆盖度时空格局变化分析

以2000—2020年MODIS-NDVI植被指数为数据源,反演计算黄土高原植被覆盖度,通过转移矩阵和重心迁移等方法分析黄土高原植被覆盖度时空格局变化及其与降水、气温、坡度和土壤类型等因素的关系。结果表明:(1)2000—2020年黄土高原植被覆盖度由0.39提高到0.61,整体呈上升趋势,2017年后实现快速提升;(2)近20年,黄土高原植被覆盖度显著好转类型与极显著好转类型改善面积比例达到37.93%,2009年前以低覆盖和中低覆盖植被为主,2010年后以中覆盖及更高等级覆盖植被为主,2019年以后中高覆盖植被所占比例最高;(3)从2000年到2020年,黄土高原低覆盖、中低覆盖、中覆盖和中高覆盖植被向更高等级覆盖植被转化比例分别为93.10%,96.57%,82.99%,43.34%,中低覆盖、中覆盖、中高覆盖和高覆盖植被向更低等级覆盖植被转化比例分别为0.30%,2.21%,7.83%,12.47%;(4)近20年黄土高原植被覆盖度变化与气温和降水的变化表现敏感,斜坡地和陡坡地植被覆盖度较高,淋溶土类型下的植被覆盖度较高,国家政策和措施实施等人为因素对植被覆盖度改善发挥重要作用。

Change of Vegetation Coverage in the Loess Plateau from 2000 to 2020 and Its Spatiotemporal Pattern Analysis

This research calculated vegetation coverage on the Loess Plateau from 2000 to 2020 by using the MODIS-NDVI vegetation index, analyzed its relationship with rainfall, temperature, slope and soil by using the transfer matrix and other methods. The results showed that:(1) The vegetation coverage increased from 0.39 to 0.61, and increased rapidly after 2017. (2) The area ratio of significantly improved and extremely significantly improved reached 37.93%. The coverage was dominated by low and middle-low before 2009, and dominated by medium and higher coverage after 2010. The proportion of middle-high coverage was the highest after 2019. (3) The conversion ratios of low, medium-low, medium and medium-high cover to the higher cover were 93.10%, 96.57%, 82.99%, 43.34% respectively. The conversion ratios of medium-low, medium, medium-high and high cover to the lower cover were 0.30%, 2.21%, 7.83%, 12.47% respectively. (4) The changes of vegetation coverage were sensitive to the changes of temperature and rainfall. The vegetation coverages of slope, steep slope and leached soil were higher. Human interventions, such as policies and soil conservation measures, played an important role in vegetation coverage improvement.