长江流域景观格局与生态系统水质净化服务的关系

流域景观格局通过影响生态过程,改变进入河流污染物的数量,进而对水质净化服务产生重要影响,探讨流域景观格局对水质净化服务的影响对于流域景观规划、生态系统保护和生态系统服务提升具有重要意义。以长江流域为研究区域,在分析45个子流域景观格局特征、应用In VEST模型评估流域水质净化服务基础上,探讨了两者的关系,结果表明:①景观组成上,长江流域农田和城镇面积比例分别与生态系统水质净化服务存在显著对数关系(P0.01),森林面积比例则与之呈极显著正相关关系(P0.01);②流域景观配置上,斑块密度和景观破碎度与水质净化服务呈显著负相关(P0.01),而平均斑块面积和形状规律相反(P0.01);③斑块类型水平上,森林平均斑块面积、灌丛/湿地平均斑块形状与生态系统水质净化服务呈显著正相关(P0.01),而农田平均斑块面积/边缘密度、城镇斑块密度则与之呈显著负相关(P0.01);④森林主导景观的子流域,仅有景观破碎度与生态系统水质净化服务呈显著负相关,而农田主导景观的子流域,景观蔓延度、香农多样性与其分别呈正相关(P0.01)。研究结果可以为长江流域生态系统水质净化服务的提升提供多途径的管理信息:流域景观尺度上,增加森林面积比例、控制农田与城镇面积比例,并减少景观破碎度而增加平均斑块形状复杂性;斑块类型水平上,可增加灌丛/湿地斑块形状复杂性,减小农田边缘密度和城镇斑块密度;森林主导景观的子流域应降低景观破碎度,以农田主导景观的子流域则应该增加斑块类型丰富度和团聚程度。研究也可为其他流域水质净化服务管理提供参考。

Relationships between landscape pattern and ecosystem water purification service in the Yangtze River Basin

Landscape patterns can affect pollutant discharge into rivers by influencing ecological processes, and further affect water purification service of ecosystems in the watershed. It is of great significance for landscape planning, ecosystem protection, and ecosystem services promotion to explore the relationships between landscape patterns and ecosystem water purification service. The landscape pattern characteristics were analyzed and ecosystem water purification service was assessed by using InVEST (Integrated Valuation of Ecosystem Services and Tradeoffs) model in 45 sub-basins of the Yangtze River Basin. Then the relationships between landscape patterns and ecosystem water purification service were identified. For the landscape composition, the proportions of farmland and urban areas were logarithmically correlated with ecosystem water purification service (P < 0.01), whereas the proportion of forest area was positively correlated with it (P < 0.01). For the landscape configuration, water purification service was negatively correlated with patch density and landscape fragmentation, and positively correlated with the average patch area and shape (P < 0.01). For the patch-type, average patch area of forest/shrub and the average patch shape of shrub and wetland were positively correlated with ecosystem water purification service, while the average patch area and edge density of farmland and urban patch density were negatively correlated with water purification service (P < 0.01). Only landscape fragmentation and the ecosystem water purification service was negatively correlated in the forest-dominated sub-basin (P < 0.01). In the farmland-dominated sub-basin, ecosystem water purification services were positively correlated with landscape aggregation and Shannon diversity indexes (P < 0.01). The above results can provide management information for the promotion of ecosystem services in the Yangtze River basin. At the landscape scale of the basin, increasing the area proportion of forest, controlling the farmland and urban area proportions, reducing the landscape fragmentation, and increasing the complexity of the average patch shape would be helpful for the improvement of ecosystem water purification service. At the patch-type level, increasing the area of the shrub patch and the shape complexity of the shrub and wetland patches, and reducing the edge density of urban and the patch density of farmland would also contribute to the promotion of ecosystem water purification service. In the forest-dominated sub-basins, landscape fragmentation should be prevented, while the diversity and aggregation of different types of patches should be increased in the farmland-dominated sub-basins. The information can also provide important for the management of ecosystem water purification service in other basins.