Research On Ecological Restoration Optimization Of Alpine Wetland In Zoige Plateau Based On Multi-objective Genetic Algorithm

The Zoige Plateau which has greatest peat marshland in the world on the eastern margin of the Qinghai-Tibet Plateau,is the significant ecological function zones and the sensitive zones of climate change and ecological environment.As an important water conservation and replenishment area in the upper reaches of the Yellow River,the alpine wetland on the Zoige Plateau has played an important role in stabilizing the ecological balance of the Yellow River Basin.Over the years,with the global warming and the enhancement of human activities,the alpine wetland in Zoige Plateau is facing environmental problems such as area reduction,animal and plant habitat deterioration,and ecosystem structure and function degradation.Under the increasingly severe situation of the ecological environment of the alpine wetland,the state and local governments have established a number of alpine wetland nature reserves and carried out a series of alpine wetland protection and ecological restoration work.The ecological protection,restoration and reconstruction of the alpine wetland are becoming more and more important.This paper takes Zoige alpine wetland as the research object.On the basis of determining the landscape pattern and area change of Zoige Plateau in historical period,the landscape pattern change of Alpine Wetland in Zoige Plateau was analyzed based on landscape evolution function.Aiming at the natural ecological environment and human disturbance conditions of the alpine wetland on the Zoige Plateau,construct the evaluation model of the restoration suitability of the alpine wetland ecosystem in the Zoige Plateau from the three aspects of natural environment,social environment and management policies,and quantitatively evaluate its restoration suitability level.At the township level,it is proposed to give priority to repairing the pattern.Finally,based on the principles of sustainable social and economic development and ecological protection,a multi-objective optimization model for ecological restoration on the Zoige Plateau is constructed,and the NSGA-II algorithm is used to explore the maximization of economic benefits,maximization of ecological benefits,maximization of space compactness,and suitability for restoration.On the premise of meeting the sustainable development of economy,the optimal spatial optimization scheme suitable for wetland ecological restoration in Zoige Plateau was sought.The main conclusions are as follows:(1)The landscape types of Zoige Plateau can be divided into three types:natural wetland,constructed wetland and non-wetland.The changes in the area of alpine wetlands on the Zoige Plateau from 1980 to 2018 showed that the area of wetlands in the region showed a fluctuating growth trend,with a growth rate of 3.08 km~2/a.The main type of wetland transfer was the mutual transformation between wetland and grassland.Based on the wetland landscape evolution function,the Zoige Plateau Wetland is divided into four types:restoration type,fluctuation type,stable type and degradation type.The degradation type wetland area is 1225 km~2,accounting for 28.34%of the total wetland area,which is in urgent need of wetland restoration.(2)Based on the three aspects of natural environment,social environment and management policies,the Zoige Plateau’s alpine wetland ecosystem restoration suitability evaluation model was constructed,and determined the index weights by using the double-layer priority chart method.At the element level,climate(0.222)、hydrology(0.194)and Soil(0.167)has a greater impact on the suitability of wetland restoration.On the whole,the remediation suitability level of the alpine wetland on the Zoige Plateau is between 1.31-4.78,and the area at the appropriate level is 1533.72 km~2,accounting for 7.72%of the total area of the region.Baozuo,Dazhasi,Xiaman Sheep Farm,Nenwa,Heihe Ranch,Axi,Xiaman,Maixi,Manrima of Zoige and Maqu Counties have high levels of suitability for restoration and should be prioritized for restoration.(3)Based on the principles of sustainable social and economic development and ecological protection,four goals for multi-objective optimization of wetland ecological restoration on the Zoige Plateau(maximum economic benefit,maximal ecological benefit,maximization of space compactness,maximization of restoration suitability)and their Constraint conditions,build a multi-objective optimization model of wetland ecological restoration on the Zoige Plateau.With the help of the NSGA-II algorithm,five optimization schemes are obtained:no preference(that is,optimal equal weight),superior economic benefit,superior ecological benefit,superior space compactness,and superior restoration suitability.No preference is the optimal optimization scheme with equal weight.No preference strategy improves economic efficiency by 41.45%,ecological efficiency by 9.18%,and wetland restoration suitability by 1.65%.Mainly,woodland,grassland and unused land were allocated as wetlands,and the wetland area is increasing by 991 km~2,and 316 km~2 of woodland has been configured as grassland,and 349 km~2 of grassland has been configured as woodland.In addition,215km~2 of unused land is configured as woodland,grassland,cropland and construction land.