Abstract:

Loess Plateau of northern Shaanxi is a national key soil and water loss area and the core area of Grain for Green Program. It is more targeted and realistic to explore the temporal and spatial variation characteristics, driving factors and trade-offs of ecosystem services in county-level administrative units for the sustainable management of ecosystems. RUSLE, CASA and InVEST models were used to analyze the temporal and spatial variation of soil conservation, carbon sequestration and water supply in Zhidan County, northern Shaanxi from 2000 to 2018, respectively. The driving factors of ecosystem services and the trade-offs among ecosystem services were explored using geographic detector model and partial correlation analysis, respectively. Results showed that soil conservation, carbon sequestration (measured in carbon) and water supply increased by 199 t hm^-2 a^-1, 426 g m^-2·a^-1 and 121 mm from 2000 to 2018 in Zhidan County, respectively. The impact of natural factors such as topography, climate and vegetation on ecosystem services was stronger than that of human factors such as land use, and the interaction of multiple factors has a greater impact on ecosystem services than that of single factors. The most important factor affecting the spatial heterogeneity of soil conservation was slope, followed by NDVI. Carbon sequestration was affected by various factors such as precipitation, NDVI and soil types. The main driving factors for water supply services were precipitation and land use. There were weak synergies, weak synergies and synergies between soil conservation and carbon sequestration, soil conservation and water resources supply, and carbon sequestration and water resources supply in Zhidan Conuty, respectively, and the trade-off relationship was spatially heterogeneous. This study is helpful for further understanding the complex relationships among different ecosystem services and the differences of their driving factors, and can provide scientific reference for county-level ecosystem management and sustainable development in the Loess Plateau.

Key words: Loess Plateau, ecosystem services, geodetector, trade-off, land use/cover change, county area

摘要：

陕北黄土高原沟壑区作为全国重点水土流失区和退耕还林还草核心区，探究县域尺度生态系统服务的时空变化特征、驱动因素和权衡关系对于生态系统的可持续管理更有针对性和现实性。基于RUSLE、CASA和InVEST模型，分析了陕北志丹县2000—2018年土壤保持、碳固存和水源供给3种生态系统服务的时空变化，并运用地理探测器和偏相关分析研究了生态系统服务的驱动因子和权衡关系。结果表明：2000—2018年，志丹县土壤保持、碳固存（以C计）和水源供给都呈现增加趋势，分别增加了199 t·hm^-2·a^-1、426 g·m^-2·a^-1和122 mm。地形、气候和植被生长状况等自然因素对生态系统服务空间异质性的影响强于土地利用类型等人为因素，并且多因子的交互作用对生态系统服务的影响大于单一因子。影响土壤保持服务空间异质性最主要的因子是坡度，其次是NDVI，碳固存服务空间异质性受降雨、NDVI和土壤类型等因素的综合影响，水源供给服务空间异质性的主要驱动因素是降雨和土地利用类型。志丹县土壤保持和碳固存、土壤保持和水源供给以及碳固存和水源供给之间的关系整体上分别表现为弱协同、弱协同和协同作用，并在空间上具有异质性。该研究有助于进一步了解不同生态系统服务间的复杂关系及其驱动因子差异，可为黄土高原县域生态系统管理和可持续发展提供参考。

关键词: 黄土高原, 生态系统服务, 地理探测器, 权衡, 土地利用/覆被变化, 县域