Study On Lake Ecoregion Technique And Application In China

Lake ecoregion is based on objective knowledge of the formation process, the structure and function characteristics, distribution law and the relevant factors of lake ecological system, to reveal the cause, the manifestation and the evolution trend of eutrophication reflected the lakes regional differences. It can really, objectively and comprehensively reflect the regional variation rule of lake eutrophication, and provides a base to scientifically formulate lake nutrient criteria, eutrophication control standards and lake management. Due to lake regional differentiation significantly, the difference of the inherent level of nutrients and eutrophication effect, a single standard used for lake management at present, lacks of national lake ecoregion reflecting the regional differences of the nutrient effect. The nutrient criteria and standards cannot be determined regionally, hence the regional control of national lake eutrophication cannot be implemented.This paper conducted the study of the lake ecoregional technology, the lake I-level ecoregion and its application, Yungui Plateau lake ecoregion II-level partition and its application, and discussed the ecoregional nutrient criterion threshold and ecoregional control of lake eutrophication. The main results were as follows:1. A spatial overlay analysis of geomorphic types and climate zones (zonal and meridional) was used to classify the national I-level nutrient ecoregions via a top-down approach with the indices for geomorphic types and water heat conditions as the dominant factors. Based on the quantitative partition model combined statistical analysis method (principal component analysis, clustering analysis and discriminant analysis) and spatial analysis methods (geographic information system analysis, spatial autocorrelation method and spatial fusion technology), many methods were organically integrated to build II-level partition technology via a down-top approach. The quantitative partition simulation can conduct partition study scientifically and reasonably, minimize the impact of human factors, and have the better adaptability and feasibility.2. Ⅰ-level ecoregion mainly considered the natural geographical characteristics of lake ecosystem, i.e., its characteristics of geography and climate, geomorphic types and water heat conditions as the dominant factor. Ⅰ-level ecoregion indexes selected were geomorphic types, rainfall, and temperature. Ⅱ-level partition indexes mainly reflected the influence of the natural factors on lake ecological environment and eutrophication. Based on the regional differences, the indexes were selected through cluster analysis, discriminant analysis, and principal component analysis. By the index optimization case study of typical lake ecoregion (Yungui Plateau Lake Ecoregion), the comprehensive indicators of nutrient, climate, land use, soil texture were selected as the optimize indexes of Ⅱ-level partition, and their principal component score as anew parameter values.3. National lakes have been divided into eight Ⅰ-level ecoregions based on a spatial overlay analysis that considered the boundaries of water resources (Ⅱ-level divisions), and provincial administration. In addition, the values of Chl a/TP and Chl a/TN in various ecoregions were used to verify the rationality and scientificity of the partition. The differentiation of nutrient effect was analyzed to reflect the regional diversity of lake nutrient effect. The stressor-response model was applied to determine the nutrient criteria of the seven lake ecoregions. Combining with the characteristics, the pollution status, and river basin economic development model of the different lake ecoregions, the control strategy of lake eutrophication in I-level ecoregion was formulated in our country.4. Yungui Plateau Lake Ecoregion was chosen as the research object of the II-level partition, the integrated methods of modern statistical analysis methods (principal component analysis, cluster analysis, and discriminant analysis) and geographical spatial analysis (spatial autocorrelation and spatial integration, etc.) were applied to complete preliminary the II-level partition of Yungui Plateau Lake Ecoregion. The lake eutrophication comprehensive control measures of the II-level partition were proposed by integrating the characteristic and the pollution status of lakes.