浑太河上游流域河岸缓冲区景观格局对水质的影响

摘要

以浑太河上游流域31个采样点上游水系为中心，生成5种尺度的河岸缓冲区，采用Fragstats软件计算类型水平和景观水平上的8个景观指数。分别从景观数量组成和景观空间格局2个方面，采用空间分析、相关分析和冗余分析等方法，识别不同宽度河岸缓冲区景观格局与水质的相关关系。结果表明：景观格局在不同宽度缓冲区内对河流水质具有不同的效应。300 m宽度河岸缓冲区景观格局具有最大的水质空间分异解释能力，可解释48�5％的水质变异。对于50和100 m宽度河岸缓冲区，景观数量组成指标较景观空间格局指标对水质空间分异的解释能力强，景观数量组成指标分别解释水质空间分异的16％和18％，景观空间格局指标分别解释水质空间分异的11％和6％。其中，旱地的解释能力最强，分别为13％和12％，因为≤100 m宽度河岸缓冲区内旱地是优势景观类型。对于300、500和1000 m宽度河岸缓冲区，景观空间格局指标较景观数量组成指标对水质空间分异的解释能力强，景观空间格局指标可分别解释水质空间分异的25％、20％和23％，景观数量组成指标分别解释水质空间分异的10％、11�3％和14�3％。当缓冲区宽度≥300 m时，景观空间格局指标对水质的解释能力随缓冲区宽度的增加而逐渐增强，解释能力显著的景观空间格局指标包括景观尺度上的斑块密度、蔓延度指数、多样性指数和均匀性指数以及类型水平上的林地破碎度指数。%Out of the upper reaches water system of the Huntai River, encompassing 31 water quality monitoring stations, riparian buffer zones of 5 different scales were delineated with ArcGIS, and 8 landscape indices of the buffer zones at the type and landscape levels were calculated using the FRACSTATS software. Spatial analysis, correlation analysis and redun⁃dancy analysis were performed to define relationships of landscape patterns of the riparian buffer zones different in width with water quality from the aspects of number of landscapes in composition and space pattern of the landscape. Results show that the impact of a landscape pattern on water quality varied with the width of the riparian buffer zone. Landscape pattern of a riparian buffer zone 300 m in width can well explain 48�5% of the variation of water quality. In riparian buffer zones 50 and 100 m in width, the landscape number composition indices could better explain spatial variation of water quality than the landscape space pattern indices, and the former could explain 16% and 18% of the variation of water qual⁃ity, while the latter could do 11% and 6%, and up to 13% and 12% in the case of upland field, because upland field was the dominant landscape in riparian buffer zones ≤100 m in width. However, in riparian buffer zones, 300, 500 or 1 000 m in width, things went reversely, with the latter exceeding the former in explaining the variation of water quality. The lat⁃ter could explain 25%, 20% and 23%, while the former 10%, 11�3% and 14�3%. While width of the riparian buffer zone was ≥300 m, the impacts of landscape space pattern indices on water quality increased with width of the riparian buffer zone. Dominant landscape space pattern indices include PD, CONTAG, SHDI and SHEI at landscape level, and forest fragmentation at the type level.