不同空间尺度的景观格局对流溪河水质的影响

为探究不同空间尺度的景观格局对流溪河水质的影响，于2020年6月和2021年1月在流溪河干流15个采样点进行了水样的采集，测定了水温、溶解氧、pH、氨氮、硝态氮、硫酸盐和氯化物等水质指标。结合遥感解译所得的土地利用数据，提取了不同空间尺度(子流域和河岸带缓冲区)的景观格局指数，采用Bioenv分析、Mantle检验、方差分解和层次分割理论等方法揭示了景观格局对水质变化的影响。研究结果表明：氨氮是流溪河的主要污染物。土地利用结构与空间格局特征对水质的影响存在空间尺度效应。在100 m河岸带缓冲区，水域是影响水质的主要贡献源；而在其他空间尺度建设用地是影响水质的主要贡献源。在子流域尺度，林地和建设用地的斑块密度(PD指数)是影响水质变化的核心特征；而在河岸带缓冲区尺度，水域和建设用地的连通性(CONTAG指数)和林地的多样性(SHDI指数)是影响水质变化的关键特征。在各个空间尺度，土地利用与空间格局的交互作用对驱动水质变化起主导作用，尤其在1000 m河岸带缓冲区对水质的贡献率最高。因此，加强1000 m缓冲区尺度土地利用的管理和减少建设用地成片建设规划等对保护流域水质具有重要意义。

Effects of landscape pattern on water quality at multi-spatial scales in the Liuxi River

To explore the impacts of landscape pattern on water quality at multi-spatial scales, water samples were taken from 15 sampling sites in the main stream of the Liuxi River in June 2020 and January 2021, respectively. The water quality indicators such as water temperature, dissolved oxygen, pH, ammonia nitrogen, nitrate, sulfate and chloride were determined. We then extracted the landscape pattern indices at different spatial scales (sub-basins and riparian buffer zones) based on interpretating Landsat remote sensing image data. Methods such as Bioenv analysis, Mantle test, Variance partitioning and Hierarchical partitioning theory were applied to reveal the influence mechanism of landscape pattern on water quality. The results showed that ammonia nitrogen was the main pollutant in the Liuxi River. The impacts of land use structure and spatial pattern characteristics on the water quality change had the spatial scale effects. Water and built-up land were the main contributor to the change of water quality in the 100 m riparian buffer zone and in other spatial scales, respectively. In the sub-basins, the patch density of forest and built-up land were the main characteristics which affected the change of water quality, while the connectivity characteristics of the water and built-up land and the richness and diversity of forest were the key features affecting the change of water quality in the riparian buffer zones. Overall, the interaction between land use and landscape pattern played a leading role in driving water quality change in the Liuxi River, especially in the 1000 m riparian buffer zone, which had the highest contribution to the water quality. Therefore, strengthening the management of land use in the 1000 m riparian buffer zone and avoiding the large area-development of built-up land are of great significant to the protection of water quality in the basin.