Characteristics And Ecosystem Health Evaluation Research Of The Yellow River Delta Wetland

The Yellow River delta wetland is the widest,youngest,and most complete wetland ecosystem in the warm temperate zone in our country,which played an important role in erosion controling,climate protecting and biodiversity conservation.Under the effect of climate change and human activities,the Yellow River delta wetland ecosystem are badly affected,problems rises frequently such as shoreline retreat,vegetation degradation and biological diversity decreasion,wetland ecosystem health facing serious challenges.In this context,based on multi-source remote sensing data of Yellow River delta,hydrologic meteorological data and field survey research results,this study systematically analyzes the characteristics of the Yellow River delta wetland and the ecosystem health status evaluation,aim at providing a scientific basis for the management and protection of the Yellow River delta wetland ecological system.The main contents and achievements of this reseach including the following aspects:(1)Multi-source remote sensing data were used to extract the water area,vegetation coverage and main landscape types of the Yellow River delta wetland from 2009 to 2017.The results show that ecological water replenishment has a direct and significant impact on the change of wetland water area,while the change of vegetation coverage show a delayed response to water replenishment,and a short term of water shortage has little impact on the growth of wetland vegetation.With the ecological water replenishment,the overall evolution direction of wetland landscape pattern can be described as follows:part of cultivated landscape changes to paddy field,beach landscape mainly changes to water area,and little changes to meadow landscape,the area of construction land within the region remains basically unchanged.(2)Changes of main ecological indices of Diaokou River wetland were analyzed with remote sensing and ecological survey data.The results showed that ecological water replenishment had a positive effect on the vegetation,water body,soil physical and chemical characteristics and habitat suitability.The water area of wetland increased significantly.Vegetation species were more abundant,the community height and vegetation coverage increased gradually.Due to the supplement of fresh water resources,the surface soil moisture content of wetland increased,and the soil salinity at different depths decreased at different degrees,while the organic matter content increased significantly.In addition,the formation of tidal flat and reed marsh made significantly increase of the waterfowl amounts in the wetland.(3)Based on the P-S-R framework,the ecosystem health evaluation index system of Diaokou River wetland was constructed and the corresponding index classification criteria were determined.On this basis,Fuzzy-AHP method was used to evaluate the ecosystem health of Diaokou River wetland in 2010,2015 and 2018.The evaluation results showed that the ecosystem health degree(CEI)of Diaokou River wetland in the three periods was 0.433,0.696 and 0.808,respectively.According to CEI classification criteria,the ecosystem health status of Diaokou River wetland in 2010,2015 and 2018 was in the state of "sub-morbidity","general" and "sub-health".Among the pressure indicators,the annual water volume of wetland has the greatest impact on ecosystem health.As state indicators,the vegetation coverage area is the most important and as to response indicators,the ecological restoration project has the greatest impact on ecosystem health.