Lakes Wetlands Ecosystem Health Assessment

Ecosystem health and stability are important for ecosystem to maintain healthy state and promote virtuous circles, which is necessary to human survival and development. However, in recent years, under the pressures of natural and human activities, lake wetlands are facing up a series of environmental problems, which has threatened human health and the development of society and economy. The study of ecosystem health is useful for wetland ecological management and development, for health keeping of ecological system, and for promoting realizing ecological, social and economic coordination and concordance.Ecosystem health is a new multi-discipline developed since1970s. It includes earth science, environmental science, ecology, economics and social science. Ecosystem health first appeared in America, Japan, Europe, and under the sustainable development demands, developed increasingly with the most attractive focus. So far, researches in ecosystem health are conducted in a verity of systems, including agriculture, forest ecological system, urban ecological system, and other types of ecosystem. In recent years, more attention has been paid by Chinese researchers to ecosystem health. Most of researches on lake ecosystem health focus on definition, index selection, ranking methods, and so on, but quantitative evaluation is still lacking. However, arguments are still exist in this field and therefore it is necessary to keep on the studies of related issues, such as definition, index system, evaluation methods and comprehensive interpretation of results on lake ecosystem healthBased on normal method of ecosystem health following Costanza and the real situation of lake wetlands in Jianghan flood plain, our study constructed the index system, including the aspects of structure, status, economy, society and ecological values. The system was thus a relatively integrated system indicating of the current situation of lakes in this region, in which the repeated and non-accessible information were excluded. By combining qualitative and quantitative analysis method, the system was divided in five evaluation standard levels, i.e. very good, good, normal, bad, and very bad. We used hierarchy analysis and fuzzy mathematics to evaluate the weight of index and to model the assessment of ecosystem health, respectively. The complete index system was finally formed and the typical lake ecosystem health in Jianghan flood plain was assessed.Investigation results showed that water quality in these lakes is decreasing because the content of nitrogen and phosphorus exceeds normal standards. Compared with the situations in1950s, the lakes areas are greatly decreased and morphological characteristics are changed seriously. Water levels are decreased and the ability of the water exchange with Yangtze River is inhibited due to dam segregation. Additionally, inappropriately economic development makes the status of lake ecosystem health more serious, with natural resources damaged, spatial heterogeneity reduced and the inhabits destructed. The diversity is damaged by reducing coverage and distribution area of aquatic plants. A large number of aquatic organisms are reduced and even extinct.Results of ecosystem health assess showed that the ecosystem health of these lakes was varied and Lake Liangzi had the highest score of70.95%, a good ecosystem health state. Lake Futou had the minimum score of55.98%, regarding as a normal level. Both Lakes Wang and Zhangduare in normal status, with scores of64.51%and57.60%, respectively. The results are consistent with environment characteristics, showing that the reliability of this method. In view of ecosystem health of these lakes, the protection and recovery on lake wetland need to be strengthened which can promote the sustainable development of society.