Construction And Evaluation Of The Ecosystem Health System Of Huixian Karst Wetland

In recent years,the dual effects of climate change and human activities have led to many ecological problems,such as the deterioration of the ecological environment,the serious rocky desertification,and the degradation of ecological functions.The karst area has complex terrain and landform,the ecosystem is fragile,the rocky desertification situation is severe,and the ecological problem of karst wetland is becoming more and more intense.How to reduce the restriction of many factors on the healthy development of karst wetland ecosystem has become a hot spot and a difficult problem in the current ecosystem research.This thesis selects the typical karst wetland in southern China — Huixian karst wetland as the research object,uses the comprehensive evaluation index method and the fuzzy comprehensive evaluation method to evaluate the health of the Huixian karst wetland ecosystem,and the comparison and analysis of the evaluation results are carried out to verify the scientificity of the evaluation index system constructed.The main research contents and results are as follows:(1)By interpreting the remote sensing images of the study area,five key characteristic parameters required for health evaluation of landscape diversity index,landscape evenness index,plaque densities,wetland vegetation coverage and ecological elasticity in 1988,2003 and 2018 were quantitatively analyzed.Analysis of changes in the area of land-type landscapes and five characteristic parameters showed that the overall wetland landscape was gradually fragmented from 1988 to 2018.(2)Based on the regional characteristics of karst areas,17 evaluation indicators were selected to construct the health evaluation index system of Huixian karst wetland ecosystem from the three aspects of pressure(P),state(S),and response(R),the index system highlights the characteristics of karst wetlands including groundwater quality,degree of rocky desertification,karst groundwater level variation,and the development morphology of underground karst pipelines.The analytic hierarchy process was used to determine the parameter weights in the index system,and the key factors affecting the health status of Huixian wetland ecosystem were identified.The index classification standards suitable for karst wetlands were divided,and the health status of the wetland ecosystem was divided into five levels from very healthy to ill.The comprehensive evaluation index method and fuzzy comprehensive evaluation index method were used to calculate the scores of each single index,criterion layer and target layer,and the ecosystem health evaluation model of karst wetland was constructed,and the ecosystem health status of Huixian karst wetland was evaluated by this model.(3)By analyzing the health evaluation results of the comprehensive evaluation index method and the fuzzy comprehensive evaluation method,it is more reasonable to select the comprehensive evaluation index method.The evaluation results are as follows:1)The comprehensive score of Huixian wetland ecosystem health evaluation is 3.67,and the evaluation level is sub-health;the health scores of stress,state and response system are 3.23,4.36 and 2.23,respectively,and the evaluation level is sub-health,unhealthy and healthy.Among them,in the pressure indicators,population density has the greatest impact on the health of the wetland ecosystem;in the state indicators,the rocky desertification degree has the greatest impact;and in the response indicators,the wetland protection management level is the most important.2)Based on the evaluation results of this thesis,aiming at the reduction of water area,serious wetland water pollution and aggravation of rocky desertification faced by wetlands,suggestions on the healthy and sustainable development of wetlands were put forward from three aspects:wetland water area protection,wetland water quality improvement and rocky desertification restoration.The research results can provide technical support for the health evaluation of Huixian karst wetlands and even southern karst wetlands,and provide decision-making references for maintaining the healthy development of Huixian wetlands.