流域景观破碎化对土壤保持服务的影响研究——以甘肃白龙江流域为例

Impact of landscape fragmentation on watershed soil conservation service——a case study on Bailongjiang Watershed of Gansu

甘肃白龙江流域是中国四大滑坡和泥石流灾害高发区之一,也是长江上游重要的水源涵养区和生态脆弱区,土壤保持服务尤为重要,近几十年来日益增强的人类活动不仅加重了土壤侵蚀,也加剧了景观破碎化,因此开展景观破碎化对土壤保持服务的影响研究可以明晰两者间的空间关联,旨在为流域生态系统的可持续发展提供科学依据。本文综合运用景观格局指数、网格分析和双变量空间自相关等方法,揭示了1990—2014年甘肃白龙江流域景观破碎化与土壤保持服务的时空格局,并从数理统计和空间统计两个角度探讨了两者间的相关关系。结果表明:(1)1990—2014年甘肃白龙江流域景观破碎化程度和土壤保持服务分别呈现先增后减、先降后升的变化趋势;(2)1990—2014年间,甘肃白龙江流域土壤保持服务与景观破碎化的空间负相关关系从无到有,且两者间的空间关联性逐渐增强;(3)2014年宕昌北部、武都中南部及最南端、文县南部和宕昌-舟曲-武都交汇处的景观破碎化程度对该区土壤保持服务产生显著负影响,可通过减弱景观破碎化以达到提升土壤保持服务的目的。

Bailongjiang watershed of Gansu, a vital water conservation area and environmental fragile area in the upper Yangtze River, is one of the four major landslides and debris flow disaster areas in China. Here, soil conservation service is particularly important. However, the highfrequency and high-intensity human activities have deepened the degree of landscape fragmenta tion and soil erosion in recent decades. Therefore, the research on the impact of landscape fragmentation on soil conservation service can clarify their spatial correlation and provide scientific basis for the watershed ecosystem sustainability. Taking Bailongjiang watershed of Gansu as an example, the spatio-temporal dynamic of landscape fragmentation and soil conservation service was quantitatively characterized from 1990 to 2014 via landscape pattern index, grid analysis, and In VEST model. Meanwhile, the relationship between the two issues was also discussed from the perspectives of mathematical and spatial statistics. The results showed that：（1）Initially, the degree of landscape fragmentation increased and then decreased in the Bailongjiang watershed in Gansu from 1990 to 2014. Soil conservation service documented a changing trend of descending firstly then ascending.（2） In 1990~2014, the spatial negative correlation between soil conservation service and landscape fragmentation developed from nothing to increase gradually.（3） By 2014, the degree of landscape fragmentation illustrated a significant negative impact on soil conservation service in the following areas： the northern part of Tanchang County, the middle and the southern part of Wudu District, the southern part of Wen County, and the boundary belts of Tanchang-Zhouqu-Wudu. It is essential to obtain a better soil conservation service through the decrease of the landscape fragmentation in the above areas.