The Landuse Spatial Pattern Of Simulation Of Minqin Oasis Based On The CLUE-S Model

Regional land use is a complex process.Establishing model of land use change is an important method to understand the causes,processes and future trends of the land use change.As the only oasis between Chinese two deserts,the ecological environment of Minqin Oasis is very fragile.Recently,unreasonable land use patterns have made a serious threat to the ecological security and sustainable development in Minqin Oasis.Therefore,Minqin Oasis is selected as the study area,and the CLUE-S model is used to simulate the land use change.Based on the land use data of 1986,2000,2006 and 2014,this paper analyses the dynamic evolution of the land use in Minqin Oasis over the past decades,and simulates the spatial patterns of land use in Minqin Oasis from 2015 to 2030.The results show that:(1)From quantity aspects,from 1986 to 2014,the areas of cultivated land,residential land and grassland are increased,while the areas of forest land and unused land are decreased.At the same time,there was no significant difference in plaque shape index between all kinds of land use types.It is indicated that various land use have no change greatly in plaque shape index.However,due to human activities,the aggregation degree of cultivated land and residential land are increased,comparing with other land use types.(2)In the non-spatial analysis module of CLUE-S model,based on entropy weight theory,the gray combination model is used to forecast the demand of future land.The prediction error is 1.17%,which is smaller than the error of the gray prediction model(1.187%)and the DGM discrete gray model(1.86%).From the verification results,the posterior differences between ratio C and the minimum error frequency P of the entropy weight combination model are 0.1051 and 1 respectively.The results show that the entropy combination model can be used to measure and analysis the demand of land use.(3)In this study,Logistic regression analysis is used to explore various land use and driving factors at 100m,200m,250m,300m,400m and 500m scales.It is found that,when the scale is 250m,the ROC value of various land use reaches the largest.So,250m is the most suitable spatial scale to explain the spatial distribution of various land use,using the binary regression analysis.(4)In the 250m optimal scale,the land demand is estimated using the entropy combination model from 2015 to 2030.Firstly,the CLUE-S model is used to simulate the spatial pattern of land use in 2006 and 2014.Then,these results are compared with the actual land use data.The results show that the kappa coefficients are 86.25%and 56%,respectively,and the ROC values of various land use are all more than 0.5.It proves that the CLUE-S model is more suitable for simulating the land use spatial pattern in Minqin Oasis,and the accuracy is high.(5)This paper sets up three different scenarios:to maintain the current land used trend,to maintain the same cultivated land areas,to convert farmland into forest and grassland project.Under the three scenarios,the land use spatial pattern of Minqin Oasis is simulated from 2015 to 2030.The ecological environment is gradually recovered under thes three scenarios.According to the current land use trend and the situation of converting farmland into forest and grassland project,the degree of ecological environment recovered is larger.The ecological environment recovery is not obvious in the case of keeping the cultivated land constant.