近20年黄土高原土地利用/植被覆盖变化特征及其成因

近20年来黄土高原土地利用结构发生了显著变化,生态环境取得举世瞩目的成效,揭示黄土高原土地利用/植被覆盖的变化特征及成因是促进区域土地利用空间格局优化的关键环节。运用GIS技术,对黄土高原2000年、2010年、2017年的遥感数据进行转移矩阵,系统研究了黄土高原地区、各省份和生态分区的变化特征并定性分析了造成土地利用变化的主要驱动力。结果表明:(1)黄土高原的土地利用类型主要以耕地、林地和草地为主。2000—2017年,耕地、草地和水域都呈减少趋势,分别减少了19 860 km²,42 410 km²和5 630 km²,而林地、建设用地和未利用地面积有所增加,分别增加30 650 km²,9 840 km²和27 410 km²; 草地为主要的转入与转出地类。(2)黄土高原7个省域主要土地类型与区域变化规律基本一致,草地退化现象在甘肃与宁夏的不同时间段较为严重,具体表现为甘肃省在2000—2010年有7 830 km²草地转移为未利用地,而宁夏在2010—2017年有8 900 km²草地转入未利用地。(3)黄土高塬沟壑区、丘陵沟壑区、风沙区和土石山区及河谷平原区水域面积持续减少,且主要向耕地发生转移,同时生态区土地利用主要发生耕地与草地的动态转移。(4)黄土高原土地利用/植被覆盖变化的主要驱动力是社会因子,其中国家政策的实施起到了主要的推动和促进作用,而人类活动等的影响相对小一些。研究结果可为黄土高原土地利用规划提供科学支撑,也为该区生态保护和高质量发展服务。

Characteristics and Causes of Land Use/Vegetation Coverage of the Loess Plateau in the Past 20 Years

In the past 20 years, the land utilization structure of the Loess Plateau has undergone significant changes, and the ecological environment has achieved remarkable results. Revealing the characteristics and causes of land utilization/vegetation coverage on the Loess Plateau are the key link to promote the optimization of the spatial pattern of regional land use. We used GIS technology to transfer matrix of remote sensing data in 2000, 2010 and 2017, systematically studied the land change/characteristics of vegetation coverage in Loess Plateau region, provinces and ecological zones and qualitatively analyzed the main driving force of land use changes. The results showed that:(1)the land use types in Loess Plateau were mainly cultivated land, woodland and grassland; between 2000 and 2017, farmland, grassland and water decreased by 19 860 km², 42 410 km², 5 630 km², while woodland, construction land and unused land area increased by 30 650 km², 9 840 km², 27 410 km², respectively; grassland was the main transfer-in or transfer-out category;(2)the main land types in the seven provinces of the Loess Plateau are basically consistent with the rules of regional changes; the grassland degradation was serious in different periods between Gansu and Ningxia, specifically 7 830 km² grassland was transferred to unused land in Gansu Province from 2000 to 2010, and 8 900 km² grassland to unused land in Ningxia from 2010 to 2017;(3)the water areas of each ecological area in Gaoyuan gully area, hilly gully area, wind sand area and earth-rock mountain area and valley plain area had been continuously reduced, and mainly transferred into cultivated land, while the land use in ecological area mainly occurred the dynamic transfer of cultivated land and grassland;(4)social factors were the main driving force for the change of land use/vegetation coverage on the Loess Plateau, among which the implementation of national policies had played a main role in pushing and promoting, while the impact of human activities was relatively small. The results of this research can provide scientific support for the land use planning of the Loess Plateau and serve the ecological protection and high-quality development of the Loess Plateau.