滇东南峰丛洼地磷素“源-汇”格局演变及其与湖泊富营养化的耦合机制

Karst Peak Cluster depression area is widespread in China, in which both of the environment pollution and ecological damage are very serious as the extensive human activity, fragile eco-environment and intensively frequent interaction between the surface and ground water. Phosphorus which is the limitation factor of lake and river eutrophication has drawn a lot of attention from scientist both from domestic and overseas, and there are several reports about its transport processes in all kinds of places including forests, farmlands, wetlands, lakes, rivers and so on. However, the transport of phosphorus in the karst Peak Cluster Depression area is becoming a hot spot, and the existing research mainly focus on either the micro-scale as the phosphorus transport between surface and ground water or the macro-scale as the phosphorus transport in a catchment. The relation between the micro- and macro-scale of phosphorus transport in Peak Cluster Depression area, which concerns the relation between the evolution of phosphorus “Source and Sink” pattern and lake eutrophication and is seldom considered, is very important and deserves much more attention. Thus in this proposal, we would choose the eco-transport process of phosphorus in each type of landscape in Puzhehei Peak Cluster Depression area of southeast of Yunnan Province as the research object, and focus on the relationship between dynamic landscape pattern and eutrophication of catchment water. We intend to solve the following two scientific problems: (1) To ascertain the response of phosphorus in the water body to the spatial and its dynamic change of catchment landscape type; (2) To quantitatively describe the relationship between distribution of landscape spatial pattern and ecological process. In order to fulfill our target, we would firstly build the comparison model of landscape spatial loading which cross the spatial scale by analyzing the effects of different landscape type and by using the Lorenz Curve Theory, and describe the relationship between the distribution pattern of landscape space and ecological process by based on the “Source and Sink” landscape theory. Secondly, we would describe the relationship between the landscape and ecological process from the indicators of “distance”, “relative height” and “slope” according to the distribution characteristics of “Source and Sink” landscape unit in the space and its relationship with phosphorus contamination. Finally, we would clarify the contribution of different landscape to the phosphorus contamination and propose the optimum landscape ecosystem in the catchment. The research results could not only provide the theoretical basis for the protection and sustainable development of water environment in the Peak Cluster Depression area, but also provide the example and reference for the control of Lake Eutrophication in other karst area.

磷素在喀斯特峰丛洼地的迁移过程成为研究热点，其“源汇”格局演变与湖泊富营养化的关系值得关注，本研究以滇东南普者黑峰丛洼地磷素在各景观类型中输移的生态过程为对象，开展景观动态格局与流域水体富营养化关系的研究，拟解决如下两个科学问题：（1）水体中磷素对流域景观类型空间格局及动态变化的响应；（2）定量刻画景观空间分布格局与生态过程间的关系。研究以“源汇”景观理论为基础，通过分析不同景观类型的地位和作用，利用洛伦兹曲线理论，提出跨越空间尺度的景观空间负荷对比模型，并刻画景观空间分布格局与生态过程的关系。根据“源汇”景观单元在空间上的分布特征及其与磷污染的关系，从“距离”、“相对高度”和“坡度”刻画景观与生态过程的关系，最终通过研究不同景观对磷素的贡献，优化配置得出流域内的良性景观生态系统。研究结果可为峰丛洼地区域水环境保护和可持续发展提供理论依据，亦可为其他喀斯特湖泊富营养化控制提供借鉴和参考。

磷素在喀斯特峰丛洼地的迁移过程成为研究热点，其“源汇”格局演变与湖泊富营养化的关系值得关注，本研究以滇东南普者黑峰丛洼地磷素在各景观类型中输移的生态过程为对象，开展景观动态格局与流域水体富营养化关系的研究，结果表明：（1）耕地和林地是普者黑流域主要景观组成类型，分别占流域总面积的50.87%和33.94%，园地、裸地和荒草地所占比例均低于2%。各子流域占比前3的景观类型组合中，耕地＞林地＞居民地组合最多。（2）普者黑岩溶湿地流域内河流、湿地及湖库水体碳氮磷浓度时空分布存在差异性，在丰水期，W-TN、NH4+-N及W-TP质量浓度最高，枯水期最低，平水期居中，而PO43--P及TOC质量浓度则呈现枯、丰、平三个时期逐渐递增的状态；且氮磷表现为河流>湿地>湖库；碳表现为湖库>湿地>河流。（3）普者黑岩溶湿地流域内河流、湿地及湖库水体在丰水期处于中度营养化状态，枯水期和平水期的湿地和湖库处于贫营养状态；且EI呈现河流>湿地>湖库，范围为42.05-23.10。在不同时期，湿地及湖库水体属磷限制状态，CN/CP的波动较大；河流属氮限制状态，CN/CP的波动较小，不会有发生水华的风险。（4）景观组成、格局对水质的影响：耕地在枯水期与TN呈正相关，丰水期时与PO43--P正相关；不同时期水质与水域均为负相关关系。总体上，枯水期和丰水期的水质受景观组成的影响要大于平水期；斑块密度（PD）、多样性指数（SHDI）与水质指标响应关系密切。IJI与水质指标间相互关系不明显，不适合做为该流域景观格局的特征指数。（5）景观空间负荷对比指数与水质之间的关联性：LWLI与3个水期TP、PO43--P和NH4+-N均为显著正相关。与DO表现出负相关，但仅丰水期达到显著水平。LWLI与TOC无相关关系。回归分析发现，丰水期TP与LWLI之间的回归系数最大，R2为0.856。（6）在普者黑流域水污染治理过程中，除了对各景观组成进行合理的规划外，“控源增汇”也是一个必不可少的科学手段。降低“源”景观的相对重要性指数，并提高流域内公众参与水环境保护的意识和行动，可改善流域水质状况和延缓湿地退化，促进流域可持续发展。