京津风沙源区防风固沙功能的时空变化及其区域差异

防风固沙功能是京津风沙源治理成效的关键监测指标。以往研究注重局地防风固沙功能的评估,对全区防风固沙功能的时空变化与内部差异揭示不足。基于京津风沙源区多期遥感数据,采用修正风蚀方程与GIS空间统计技术,评估分析了2000-2015年防风固沙功能的整体变化及其区域差异。结果表明:(1)京津风沙源区年均防风固沙量为28.98亿t,防风固沙能力为68.24 t/hm^2,且均随年份变化波动增加,年均增速分别为1.10%和0.71%;(2)京津风沙源区防风固沙能力呈西北高、东南低趋势,有49.06%的区域防风固沙能力高于70 t/hm^2,评估期内有54%的区域防风固沙能力明显提高;(3)浑善达克沙地亚区、典型草原亚区和荒漠草原亚区的防风固沙量累计为全区防风固沙总量的88%,燕山丘陵山地水源保护亚区和晋北山地丘陵亚区的防风固沙能力提升最显著;(4)锡林郭勒盟、赤峰市和乌兰察布市的防风固沙量合计占全区防风固沙量的77%,朔州市与包头市防风固沙能力较高,北京市与天津市防风固沙能力增速较高。因此,未来应重视分区施策治理与西部和北部防风固沙功能提升。

Spatial-temporal changes and regional differences of the sand-fixing service in the Beijing-Tianjin sandstorm source region

Wind erosion is an important soil degradation process that takes place in arid and semiarid environments, and the sand-fixing service has been used as one of the key indicators of the ecological restoration effects in the Beijing-Tianjin sandstorm source region. Over the past few decades, some studies have focused on the sand-fixing service at local areas in the Beijing-Tianjin sandstorm source region, but few researchers explored the entire changes and regional differences of sand-fixing service. The inadequate information on the sand-fixing service heterogeneity has hindered the implementation of the diversified measures for land management. This paper investigated the dynamic changes and regional differences of the sand-fixing service in the Beijing-Tianjin sandstorm source region from 2000 to 2015 through multi-period RS data and GIS spatial statistical technologies. The annual amount of fixed sand and average amount of fixed sand per hectare of land served as two indicators for the changes and differences of sand-fixing service. The results indicated that, the annual amount of fixed sand nearly reached 2.90 billion tons in the study region, the average capacity of sand-fixing was 68.24 t/hm², and the two indexes annually increased by 1.10% and 0.71%, respectively. The average sand-fixing ability in the northwest of sandstorm source region has a significantly higher level than the southeast part. Approximately 49.06% of the Beijing-Tianjin sandstorm source region generated the sand-fixing capacity higher than 70 t/hm², and nearly 54% presented an obvious increase in the sand-fixing ability from 2000 to 2015. The Hunshadake sand subzone, the typical grassland subzone and the desert grassland subzone provided 88% of the total amount of fixed sand in the sandstorm source region, whereas the sand-fixing ability in the Jinbei mountain-hill subzone and the Yanshan mountain-hill-water source protection subzone showed higher annual increase rates. In addition, the accumulated amount of fixed sand in Xilin Gol, Chifeng and Ulanqab exceeded 77% of the total amount of sand-fixing service, however, those regions with higher sand-fixing ability are mainly located in Shuozhou and Baotou, and the lands in Beijing and Tianjin showed higher increase rates in sand-fixing abilities. Therefore, we should take differential strategies in different sand-fixing service restoration zones, and pay more attention to the improvement of sand-fixing service in the western and northern parts of the Beijing-Tianjin sandstorm source region.