| The expansion of urban construction land is the most obvious feature of urbanization in space,and its expansion and change result is one of the key indicators to measure the level of urbanization.With the progress of urbanization,the contradiction between urban construction land,resources,environment and economic development has become increasingly prominent.Different land use methods have a direct and important impact on urban economic growth and regional sustainable development.Therefore,the expansion of urban construction land has gradually become one of the core contents of land use change research.In order to strictly limit the uncontrolled expansion of cities and solve the problem of "spreading the pie" in China,in 2014,it was clearly proposed at the National Land Conference that the boundary of urban growth should be delineated and the city's smart growth should be promoted.At the same time,China has promised to the world that carbon dioxide emissions per unit of GDP in 2030 will be 60% to 65% lower than in 2005,in order to alleviate the contradiction between regional economic growth and ecological and environmental pressures.This series of policy measures has pointed out the direction and ideas for the next stage of urban development in China.Wuhan Urban Agglomeration,as a pilot area for the reform of China's "two-type society",is in a critical period of urbanization and transformation.The population,economic level,culture and material exchanges are becoming more frequent,and the expansion of urban construction land is further intensified.In this context,the article takes the Wuhan Urban Agglomeration as the research object,based on the theory of low-carbon economy,urban development and sustainable development,quantitatively analyzes the historical evolution of urban construction land and the characteristics of land use carbon emissions in the Urban Agglomeration.The development potential of urban construction land in Wuhan Urban Agglomeration,designing three development scenarios,using the SLEUTH model to simulate the future expansion of urban construction land in the Urban Agglomeration,and further exploring the carbon emission response characteristics of urban construction land expansion under different scenarios as a future city in the Urban Agglomeration.The development path provides some reference.The main conclusions are as follows:(1)From 2000 to 2015,the area of urban construction land in Wuhan Urban Agglomeration continued to increase,carbon emissions continued to rise,urban development destroyed a large amount of arable land and ecological land,and the form of the ecological environment became more and more severe;in addition,Wuhan Urban Agglomeration 2000-2015 The net carbon emissions of land use increased by 121%,121%,and 60% every five years during the year;during the same period,China 's urbanization rate increased from 36.22% in 2000 to 56.1% in 2015,an increase of 19.88%.Carbon emissions show a decoupling trend,indicating that the Wuhan Urban Agglomeration gradually shows high-quality,high-level and high environmental protection characteristics in the process of urbanization;(2)An analysis of the expansion characteristics of construction land in Wuhan Urban Agglomeration reveals that 2010-2015 is the fastest expansion year in Wuhan Urban Agglomeration,with an average annual expansion rate of 11.22%,which is higher than that in 2000-2005 and 2005-2010,respectively 7.11% and 8.21% out of the total;based on the calculation results of the relative change rate of land use type,it is found that the spatial change rate of construction land relative change rate in Wuhan Urban Agglomeration is obvious,and the hot spots of construction land expansion in different periods are manifested in different cities.On the whole,from 2000 to 2015,the hotspot areas for construction land expansion in Wuhan 's Urban Agglomeration were mainly concentrated in the three cities of Xiaogan,Xianning,and Ezhou.As a central city,Wuhan 's construction land expansion has changed less than the surrounding cities in the past 15 years.Shows the characteristics of low hot spots,the reason is related to the large base area of construction land;(3)From 2000 to 2015,the urban construction land area of Wuhan Urban Agglomeration and the carbon emissions of urban construction land showed a synchronous increase trend,but the carbon emission per unit construction land area increased first and then decreased,indicating that the carbon emissions of construction land in Wuhan Urban Agglomeration There is a trend of mitigation over time;in addition,from the evolution trend of carbon emissions of newly added construction land area,it can be seen that the Urban Agglomeration has undertaken more high-carbon emission industries from 2005 to 2010.Correlation analysis of urban construction land area and urban construction land carbon emissions in Wuhan Urban Agglomeration,Person value is 0.901,passed the significance test of 0.01 level(two sides),the two showed a high correlation;(4)From the perspective of expansion area,the construction land area of Wuhan Urban Agglomeration under the three scenarios has greatly increased from 2015 to 2030.Existing development scenarios focus on the natural and historical expansion trend of the city,with fewer restrictions and the largest expansion area It reaches 1804.36 square kilometers;the low-carbon scenario focuses on the protection of the ecological environment during urban development,and is subject to many restrictive factors.The minimum expansion area is 1039.02 square kilometers.Among them,the increase in urban construction land area varies greatly among cities,but the increase in construction land area decreases with the development of the city's emphasis on the ecological environment,showing the overall convergence characteristics with the Wuhan Urban Agglomeration.Among the three scenarios of low-carbon development,existing trends,and reasonable development and construction,the existing trend development scenarios have random new growth patches in the peripheral areas of the city,and the number is more than the low-carbon development scenarios and reasonable development and construction scenarios.The total number of new patches in the carbon development scenario is lower than the current trend development scenario and the reasonable development and construction scenario,indicating that the lowcarbon development scenario occupies less agricultural land during the urban development process.Has greater practical significance.(5)In the three scenarios,cultivated land,forest land,and water land are the main sources of future urban construction land expansion in the Wuhan Urban Agglomeration,and the food security and ecological security situations are more severe.Among them,the city with the largest demand for construction land in Wuhan Urban Agglomeration is Wuhan.The area of cultivated land occupied in low-carbon,reasonable and existing trend scenarios is 319.67 square kilometers,348.15 square kilometers,and 403.96 square kilometers,respectively;the demand for construction land The smallest city is Tianmen City,which occupied 17.57 square kilometers,23.67 square kilometers,and 30.43 square kilometers in the low-carbon,reasonable,and current trend development scenarios.As a prohibited development zone in the low-carbon scenario,forest land is restricted to urban development,reducing the amount of ecological land converted to construction land,and has a good fit with the development concept of the Wuhan Urban Agglomeration to promote a "two-type society".(6)Carbon emissions show significant differences in different urban development concepts.The carbon emission response coefficient values for low-carbon,reasonable,and existing development scenarios are: 1.29,0.84,and 0.73,respectively.The results show that low-carbon scenarios are strictly restricting ecological land use.Under the transition background,it shows high sensitivity characteristics,while the land use of reasonable scenarios and existing development scenarios is less responsive to carbon emissions.In addition,the carbon emission response results based on the land use transfer matrix show that the land use types with strong carbon sink capacity for urban construction land expansion and expansion have higher carbon emission response coefficient values and higher sensitivity,and vice versa. |
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