三江源国家公园生态功能时空分异特征及其重要性辨识

Spatial and temporal variations and the importance of hierarchy of ecosystem functions in the Three-river-source National Park

三江源国家公园的建立有利于在该区域实行最严格的生态保护,筑牢国家生态安全屏障。为摸清三江源国家公园生态本底,基于遥感数据,地理信息系统平台及生态评估模型模拟等技术手段,分析了三江源国家公园生态系统类型,2000—2015年生态功能的时空分异特征及变化趋势,辨识其重要性,并对其变化驱动因素进行初探。结果表明:(1)三江源国家公园以草地、荒漠、水体与湿地生态系统为主,面积占比达到99.8%。(2)三江源国家公园水源涵养、土壤保持及防风固沙极重要区的占比分别为15.3%、13.7%和22.4%。(3)整体呈现东部以水源涵养、中部以土壤保持、西部以防风固沙为核心生态功能的空间格局。(4)2000—2015年,水源涵养功能量总体下降,但提升区域面积占比达84.5%,极重要区呈现下降态势;土壤保持功能量总体提升,年变化趋势为987万t/a,全区超过95%的地区均呈上升趋势;防风固沙功能由于风速减小及植被覆盖度的降低,出现下降态势,为-356万t/a。(5)气候暖湿化以及三江源生态保护工程的实施是三江源国家公园生态功能总体提升的主要原因,然而草地退化态势尚未完全遏制,局部地区植被覆盖度仍有所下降。为实现国家公园和自然资源的严格保护和永续利用,需对其进行统筹规划、科学布局,在科学把握生态系统自然规律的基础上,分区、分级对其进行生态保护和修复。

The establishment of the Three-river-source National Park is beneficial because the strictest ecological protection extended to this area helps to strengthen the sustainable protection of the "Chinese water tower" and to enhance the national ecological security barrier. In order to understand the ecological background of the Three-river-source National Park, the spatial distribution of the ecosystem, the temporal and spatial variation of ecological functions from 2000 to 2015, and the importance hierarchy of the ecosystem functions were analyzed by using remote sensing data, a geographical information system, and model simulations. The results showed that:(1) Grassland, desert, water, and wetland ecosystems are the main ecosystem types in the Three-river-source National Park, and they accounted for 99.8% of the total area.(2) Areas with extremely important water regulation, soil conservation, wind prevention/sand fixation functions accounted for approximately 15.3%, 13.7%, and 22.4% of the total area in the Three-river-source National Park, respectively.(3) In the eastern, central, and western parts of the Three-river-source National Park, the core ecosystem functions were the water conservation, soil conservation, and wind prevention/sand fixation functions, respectively.(4) From 2000 to 2015, the water conservation volume decreased overall, while the increased area accounted for 84.5% of the total area, and the area of extremely important site decreased. The overall improvement of the soil conservation function was significant both in volume with a change of 9.87×10~6 t/a and in the improved area, which was more than 95%. However, the wind prevention/sand fixation function showed a declining trend, because of the decline in wind speed and vegetation coverage, with a change of-3.56×10~6 t/a.(5) A warm and wet climate and the implementation of the ecological protection project were the main reasons for the improvement of ecosystem functions in the Three-river-source National Park. However, grassland degradation was not fundamentally reversed, and vegetation coverage still declined regionally. Thus, the restoration of degraded grassland must be prioritized and the integrated capacity of ecosystem functions remains to be improved. For the strict protection and sustainable use of the Three-river-source National Park and its natural resources, overall planning and scientific layout should be scrutinized, and classifications and subarea protection should be implemented based on the natural law of the ecosystem.