| The Lan-Xi urban agglomeration with Lanzhou and Xining as the center is one of the Yellow River Basin urban agglomerations planned by The State Council.It is an important urban agglomeration supporting land and ecological security and maintaining the prosperity and stability of northwest China.In March 2018,The State Council approved the Development Plan of Lanzhou-Xining Urban Agglomeration,officially elevating the construction of Lan-Xi urban agglomeration as a national strategy.In February 2022,Gansu and Qinghai provinces jointly issued the Implementation Plan of the 14 th Five-Year Plan for the Development of Lan-Xi urban agglomeration,which proposed that by 2025,the coordinated development pattern of Lan-Xi urban agglomeration will take shape,the living environment and ecological environment quality will be significantly improved,and the vitality of economic development and population agglomeration capacity will be significantly enhanced.Therefore,in order to cultivate and develop the Lan-Xi urban agglomeration,it is necessary to coordinate the land development and ecological protection.In this paper,we selected the land use data from the four phases of1990,2000,2010 and 2020,The land use transfer matrix is used to study the land use change in the past 30 years;The driving factors of land use change were analyzed by Logistic regression method;Drawing on the previous research results of urban agglomeration and combining with the current situation and development policy of Lan-Xi urban agglomeration,Set two development scenarios,"natural development" and "ecological protection",The CA-Markov model was used to predict,simulate and analyze the land use pattern in the two scenarios in 2030;Calculate the ecosystem service value change of Lan-Xi urban agglomeration over the years,And estimated the value of ecological services under the two development scenarios in 2030,Explore the optimal land use development scenario conducive to the future development of Lan-Xi urban agglomeration,It provides a certain reference for its social economy and ecological health and safety development.the results show that:(1)Land use change in Lan-Xi urban agglomeration.From 1990 to 2020,the proportion of all kinds of land area in Lan-Xi urban agglomeration is: grassland>cultivated land> forest land> unused land> water area> construction land.The area of cultivated land and unused land continues to decrease,among which the decrease of unused land reached 16.82%;the area of forest land,grassland,water area and construction land has increased,including the main converted land,with the maximum increase of 52.00%.The occupation of cultivated land and grassland and vigorously developing unused land is serious.There is a large area of mutual conversion of woodland and grassland.Due to the influence of the policy of "returning farmland to forest and grassland",the conversion of cultivated land to ecological land such as forest and grassland is accelerated.The unused land,as the main type of land,is the main reason for the increase of grassland and water area.(2)Driving force of land use change in Lan-Xi urban agglomeration.Based on the actual situation of the land use change in the Lan-Xi urban agglomeration,This paper selects the six drivers of elevation,slope,population density,distance from rivers,railway and highway,The Logistic regression method was used to analyze the role relationship between the distribution and drivers of different land types,The results show that the natural elements are the background of the spatial pattern of land use,Therefore,the elevation and slope factor play a significant influence in the distribution of different classes;The positive effects of social and economic development and population growth are closely linked,Population growth will drive humans to change the type of land use through social activities,However,the spatial distribution of unused land,water area and grassland in this study showed an inverse relationship with population density,The distribution of construction land is directly proportional to the population density.The distance from rivers,railways and highways plays a strong role in guiding the expansion and transformation of construction land and unused land.(3)Simulation of the future development scenario of Lan-Xi urban agglomeration.First,the CA-Markov model was constructed,combining the driving factors and conversion rules to simulate the land distribution pattern of Lan-Xi urban agglomeration in 2020.The simulation results were compared with the accuracy of the actual data,which showed that the Kappa coefficient reached0.950.This method predicted the land use pattern of the study area under the scenario of "natural development" and "ecological protection" respectively in 2030.The results show that in 2030,under the natural development scenario of cultivated land,the cultivated land area decreased by 6.1%,the area of forest land decreased by 8.7%,while the construction land expanded sharply,with an increase of 85.6%,mainly concentrated in the expansion of the two core cities of Lanzhou and Xining.In addition,the growth momentum of construction land in Baiyin city and Linxia City is also very fierce.However,under the ecological protection scenario,the cultivated land area in 2030 almost did not decline,and the construction land only increased by 3.4%.It can be seen that the contradiction between the sharp decrease of cultivated land and the rapid growth of construction land was greatly alleviated,and the reduction of the degree of unused land was reduced,and the disorderly expansion of urbanization in Lan-Xi urban agglomeration was suppressed.(4)Change of ecosystem service value in Lan-Xi urban agglomeration.From1990 to 2020,the total value of ecosystem services in Lan-Xi urban agglomeration showed a significant increase first and then decreased slightly.The reason for the decline in ecosystem service value in 2020 is the decrease of ecological land use due to the acceleration of urbanization in Lan-Xi urban agglomeration,which reduces the value of ecological service to a certain extent.Natural development in2030 scenario of ecosystem service value is 165.488 billion yuan,from 2020,because the mode of urban agglomeration construction land and ecological land contradictions,cultivated land is occupied speed,unused to construction land conversion,ecological service value reduced,overall is not conducive to national and regional food security and ecological construction.In 2030,the ecological service value of the area will reach the highest level of 167.811 billions yuan.In this situation,Lan-Xi urban agglomeration protects cultivated land and water area,reduces the expansion of ecological land to construction land,increases the protection of ecological control area,and can prevent the disorderly spread of cities under the premise of respecting the urban natural ecosystem and reasonable environmental carrying capacity,so as to improve the value of ecological service,and have greater potential of ecological development.Thus it can be seen that the ecological protection scenario is more suitable as the guiding direction of land optimization allocation in Lan-Xi urban agglomeration in the future. |
PDF Full Text Request