Assessment Of Wetland Biodiversity In The Yunnan Province

Wetland is a special ecosystem formed under the interaction of land and water.It plays an important role in regulating the climate and hydrology,degrading environmental pollution,protecting biodiversity,maintaining bio-geochemical cycle and regional ecological balance.Plateau wetland is a special type of wetland developed in the China's Qinghai-Tibet Plateau and the Yunnan-Guizhou Plateau,and its ecological construction and restoration as well as biodiversity protection and management are highly related to the ecological health of the entire Yangtze River Valley downstream and the sustainable development of the social economy.Therefore,the protection of the plateau wetland is the primary task in constructing the southwest ecological security barrier.In view of the inadequacy of past wetland biodiversity assessment research and the uncertainty of decision-making benefits,this study aims to propose a comprehensive wetland biodiversity assessment scheme which combines the PSR(Press-Status-Response)assessment framework and the Bayesian Network.Based on the subjective suggestions of experts in the field of ecology,this evaluation method uses objective wetland environment and biodiversity data to make a systematic evaluation of the wetland biodiversity status in 72 wetlands and natural reserves of the Yunnan Province.Meanwhile,according to the results of nodes sensitivity analysis,scenario simulation and decision benefit analysis of Bayesian Network in the Netica software,this research provides theoretical basis for wetland species conservation management measures made by wetland conservation decision makers in the Yunnan Province.The main results and conclusions of this study are as follows:(1)In the past 15 years,climate change and human activities had a great impact on the land use / cover and ecological environment of typical plateau lake basins.Due to the rapidly increase of the population in the Napahai Basin,the wetland resources in the middle reaches were occupied by construction land.Under the combined influence of climate warming and drainage projects in this region,the overall wetland environment in the lower reaches of the river basin tends to be dry,and the vegetation communities in marshes are gradually replaced by mesophytes.Currently,the main ecological problems in the Napahai basin are agricultural non-point source pollution,point source pollution,overgrazing and non-standard tourism,which pose a serious threat to the water quality and soil quality as well as the ecological functions of wetlands in the basin.(2)For the 72 basins of wetlands and natural conservation in the Yunnan Province,8.3% basins have the better wetland biodiversity condition;29.2% basins have the good level of wetland biodiversity status;33.3% basins wetland biodiversity condition reach the medium level;the basins which wetland biodiversity condition are bad and worse level accounted for 26.4% and 6.9%,respectively.The spatial analysis results of the wetland biodiversity evaluation are as follows: For most basins in the northeastern region of the Yunnan Province,wetland biodiversity status stay at the medium level,their wetland biodiversity index are within the range of 0.413 to 0.509;basins wetland biodiversity condition in the southern region are the best,their wetland biodiversity index are higher than0.509.The index of the Huanglian Mountain Nature Reserve is the highest of the whole basins at here,its wetland biodiversity index reaches 0.747;wetland biodiversity status show as good or medium level for most basins in the northwest of the Yunnan Province,their wetland biodiversity indexes range from 0.509 to 0.607,but wetland biodiversity index of the Erhai lake basin and its surrounding basins in this region are lower;wetland biodiversity condition of basins in the central region of the Yunnan Province are not optimistic,the wetland biodiversity indexes are lower than 0.413.Basin of the Luliang wetland has the lowest wetland biodiversity index condition of the whole study areas,its wetland biodiversity index is only 0.189.(3)The analysis results of the Bayesian Network model show that the pressure index,status index and response index nodes are the three nodes which have a strong influence on the wetland biodiversity index node,followed by nodes of land use,natural environmental conditions and watershed soil conservation ecological services value.The analysis results of the Bayesian network decision-making and benefit shows that the theoretical optimal scenario for the biodiversity status of the Yunnan wetland is when the pressure index,status index and corresponding index nodes in the Bayesian Network are set to level 4,level 4 and level 5,respectively.Meanwhile,the probability value of wetland biodiversity index which status are higher than level 2 in the model training set is 75% under this scenario mode,and the expected value of the utility node in the Bayesian network decision system is 75,which is less than the initial value of 77.818.(4)The wetland biodiversity conservation in the Yunnan Province should give priority to the central region where human activities have greatly disturbed the wetland environment;For the small lake basins with good wetland biodiversity status in the southern and western of the Yunnan,decision makers should maintain the current wetland environment condition to prevent the loss of wetland species caused by the deterioration of ecological environment.(5)For the lake basins such as Erhai,Lashihai and Jianhu in the northwestern region where wetland biodiversity under the dual influence of the extreme climate and human activities,managers should establish a balanced relationship between socioeconomic development and wetland development and utilization.Wetland protection also requires regular environmental surveys and special surveys.Environmental surveys include the rational use of wetland water resources and water pollution monitoring.Special surveys need to fill in unrecorded wetland species in the database.To improve the conditions of lakes and wetlands in Yunnan,pollution source control and cultivation of native aquatic plants can be considered,and the degraded wetlands on the lakeside can be repaired without changing the structure and function of the original wetland ecosystem to achieve species protection.