长江流域生态系统水文调节服务空间特征及影响因素:基于子流域尺度分析

Spatial patterns of ecosystem hydrological regulation services and factors affecting them in the Yangtze River Basin: sub-watershed scale analysis

水文调节服务是流域生态系统所提供的重要服务之一,认识流域生态系统水文调节服务空间变异规律及其驱动力,对于流域生态系统保护与恢复、合理开发利用水资源具有重要意义。以洪涝灾害频发的长江流域为对象,运用变异系数法和多元统计方法,在子流域尺度上研究了长江流域生态系统水文调节服务空间特征及影响因素。结果表明,长江流域子流域生态系统水文调节服务呈现出明显的空间异质性,水利工程密集、自然植被覆盖率高达71%的金沙江和汉江水系各子流域水文调节服务最强,降雨与径流变异系数差为0.477;农田和人口密集的嘉陵江水系各子流域水文调节服务最弱,降雨与径流变异系数差为-0.474,其他子流域水文调节服务作用不明显。影响水文调节服务的主要因素是:水库库容、自然植被面积比例、农田面积比例、单位面积人口数,其中:水库库容和自然植被面积比例对水文调节服务具有正向促进作用,农田面积比例和单位面积人口对水文调节服务的作用正好相反。水库库容对子流域生态系统水文调节服务空间异质性的贡献最大(58.85%)。上述结果有助于科学认识长江流域生态系统水文调节服务空间分异规律,可为制定不同子流域生态保护与恢复措施、提升子流域生态系统水文调节服务提供科学依据。

Hydrological regulation is one of the services provided by watershed ecosystems. For watershed ecosystem conservation and restoration and reasonable development of watershed water resources,it is important to identify the spatial pattern of watershed ecosystem hydrological regulation service and its driving forces. Many studies have been conducted at the ecosystem and landscape scale on the influence of different vegetation types and landscape patterns on hydrological regulation; such studies have played an important role in furthering the understanding of the processes and mechanisms of the hydrological regulation service in the ecosystem. At the basin scale,hydrological regulation services were affected comprehensively by many factors,including ecosystem characteristics,water conservancy facilities,water used by humans,and so on,and these influences have scale effects. Presently,owing to the lack of comprehensive studies of the systematicecosystem at the river scale,it is still difficult to evaluate ecosystem effects on regional hydrological processes from a macro perspective. In addition,few studies have explored how to represent and understand ecosystem water regulation services at the river scale as well as to identify influential factors that have differing effects on the water regulation service of the ecosystem at the river scale. Thus,a study on the space variation regularity of hydrological regulation services and its diving force is necessary. We used as a case study the Yangtze River Basin,where flooding occurs frequently,as to study the spatial patterns of ecosystem hydrological regulation services and factors affecting it,by using the variation coefficient method and multi-variable statistics methods. The results showed that,in the Yangtze River Basin,ecosystem hydrological regulation services presented significant spatial heterogeneity at the sub-watershed scale. The sub-watersheds in Jinshajiang and Hanjiang watersheds,where dense hydropower engineering facilities are located and the coverage of natural vegetation is 71%,had the highest regulating capacity of hydrology. The difference between the coefficients of variance of precipitation and runoff was 0. 477. In contrast,sub-watersheds with high population density and high proportion of cropland in Jialingjiang watershed had the lowest regulating capacity of hydrology and the difference between the coefficients of variance of precipitation and runoff was -0.474. The factors primarily affecting sub-watershed ecosystem hydrological services include reservoir volume,natural vegetation proportion,cropland proportion,and population density. Reservoir volume and natural vegetation proportion had positive effects on sub-watershed ecosystem hydrological services,while cropland proportion and population density had negative effects. Reservoir volume had the highest contribution to the heterogeneity of sub-watershed ecosystem hydrological services（ 58.85%）. Our results facilitate a better understanding of the spatial heterogeneity of subwatershed ecosystem hydrological services in Yangtze River Basin,and could also provide a scientific basis for sub-water ecosystem conservation and restoration,as well as the improvement of sub-watershed ecosystem hydrological regulation services.