基于地形梯度的甘肃白龙江流域典型生态系统服务分布特征

白龙江流域是长江上游重要的水源涵养区和生态屏障,同时也是国家级贫困县集中连片区(秦巴山区)。基于ArcGIS软件和InVEST模型,从高程、坡度、地形起伏度、地形位指数等方面分析了甘肃白龙江流域典型生态系统服务的地形梯度特征。结果表明:(1)甘肃白龙江流域碳储量、水源涵养、生境质量、土壤保持服务功能的空间分异明显,其高值区主要分布在自然保护区、林区,低值区则在河谷、城镇、农耕地区。(2)碳储量、水源涵养和生境质量随着坡度和地形起伏度的增加而增加,土壤保持则呈先增加后降低的趋势,随地形位指数增加呈现波动变化;(3)流域综合生态系统服务供给重要区域逐渐向两极分化,多种生态系统供给服务的重要区域主要在中高梯度片区,而一般区主要分布在低梯度片。地形特征是影响流域生态系统服务梯度差异的重要因素。通过分析流域不同地形因子下分析碳储量、水源涵养、生境质量、土壤保持的空间分异特征,可为中国西部山地流域生态系统格局优化管控和生态文明建设提供科学依据。

Spatial distribution characteristics of typical ecosystem services based on terrain gradients of Bailongjiang Watershed in Gansu

The Bailongjiang watershed (BLJW) is an important water conservation area and ecological barrier of the upper Yangtze River. It also has a concentrated area of national-level poverty-stricken counties. To explore the spatial characteristics of ecosystem services in a catchment scale, we analyzed the distribution characteristics of typical ecosystem services in a terrain gradient using the ArcGIS software and InVEST model, from the perspective of elevation, slope, landform relief and terrain niche. The results indicated that there were apparent differences in the spatial distribution patterns of carbon storage, water conservation, habitat quality, and soil conservation services of the BLJW in Gansu, where the areas with a high ecosystem service value were mainly distributed in the nature reserves and forest areas, while the areas with a low service value were mainly distributed in the river valleys, towns, and farmland areas. Further, it was observed that the carbon storage, water conservation, and habitat quality increased with an increase in the slope and topographic fluctuation, while the soil conservation service increased at first and later decreased with an increase in the topographic position index. The important areas of the integrated ecosystem service gradually polarized in the BLJW, and the important areas of the multiple ecosystem service supply were located in the areas having a middle and high topographic position. The topographic features are an important factor affecting the gradient distribution of the ecosystem services. The spatial distribution characteristics and relationships of four typical services were analyzed under different topographic factors in the BLJW. This can be used to provide a scientific base for an optimal ecosystem pattern and the construction of ecological civilization for the mountainous areas in western China.