Quantitative Assessment Of The Ecological Health Of Wetlands In Honghe Supported By RS And GIS Techniques

Wetlands, which provide comprehensive ecological and productive services in terms of flood mitigation, pollution prevention and climate control, is an important ecosystem which has a unique structure and function in the world. With the worldwide ecosystem degradation problems of natural wetland have become more and more serious nowadays, restoration, protection, assessment and sustainable utilization of wetland has become the focus in the international community today. China has widespread territory and complicated habitat environment. There are different types of natural wetlands which spread widely from the tropics to the cold temperate zone. However, the wetland system has turned into one of the most seriously threatened ecosystem around the world, due to the exacerbation of overexploitation of wetland resources. It is also results in serious damage of material circulation and energy flow of wetland system. As a consequence, a thorough and scientific assessment of the wetland ecological health not only can supply a guarantee to health of wetlands ecosystem, but also can maintain wetland biodiversities and develop wetland management.Sanjiang Plain locates in Heilongjiang province of China. It is one of the biggest inland plains, and is also one of the most serious degradation wetland areas in China. Honghe National Nature Reserve, which locates in Northeast Sanjiang Plain, is a representative and typical miniature swamp wetland. Due to fierce agricultural exploitation, the wetland landscape of Honghe National Nature Reserve and three farms surrounding it have changed a lot since 1950s, changing from the "Great Northern Wilderness" to the "Great Northern Granary". Research on wetland ecological health and evaluate its status from local scale, will bring us a more thorough and concrete expression to existing wetland health, and give more benefit measures for evaluation and comparison between adjacent wetlands. Studying on wetland ecological health and its temporal dynamic patterns is significant to understanding wetland and the evolution of Sanjiang Plain wetlands, It is also important to the study of natural wetlands with long term disturbance.In this paper, Honghe region in the northeast of Sanjiang Plain was selected as the study area, which is a typical inland wetland and consists of Honghe National Natural Reserve, Honghe farm, Qianfeng farm and Yaluhe farm. Based on the theory of wetlands, landscape ecology and the spatial information technologies, (including Geographic Information System, Remote sensing and Global Information System), with the application of Analytic Hierarchy Process (AHP) method and the model of Pressure-State-Response (PSR), we extracted the assessment elements including hydrologic factors, geomorphic factors, vegetation factors, landscape types, landscape patterns, human disturbance and dynamic change information. In addition, a healthy assessment database of wetland ecological was established from temporal and spatial respects. The difference of spatial characteristic of healthy condition in wetland ecological and the temporal dynamic process were also researched in this paper.The research results show that:â‘ There is a significant difference existed in wetland ecological health condition in Honghe region. The health condition in Honghe National Nature Reserve is best, and the value of integrated indices of assessing wetland ecosystems from high to low is as follows:Yaluhe farm, Qianfeng farm, Honghe farm.â‘¡Among the functional zones in Honghe National Nature Reserve, the ecological health condition of the core zone is the best while the experimental zone is the worst.â‘¢From 1975 to 2006, average value of the integrated indices for assessing wetland ecosystems decreased 0.307. Among which, from 1975 to 1989, average value of the integrated indices decreased 0.148.and the area of decline mean value of the index accounts for nearly 2/5 of the total study area. From 1989 to 2006, average value of the integrated indices decreased 0.159, and the area of decline average value of the index accounts for almost 3/4 of the total study area.â‘£The wetland ecological health pressure index increased one time or more in 1975-1989 and 1989-2006.Because the pressure of wetland in Honghe regions has been on the increase in these 30 years, the ecological health condition of wetland declined obviously. Damage to wetland ecology by human disturbance became more serious during the periods. So the response of wetland ecosystem to human disturbance became more and more obvious.