Temporal And Spatial Variation Of Land Use Carbon Emissions And Decoupling Effect In Northwest Sichuan Basin

With the rapid development of national economy and the acceleration of industrialization and urbanization,a large amount of CO₂ generated by human activities is an important reason for the gradual aggravation of the greenhouse effect,making carbon emission become the focus of attention and research from all walks of life.Energy consumption,industrial and agricultural production,living and industrial structure layout in the process of human production and life all occur on land,and carbon emissions caused by land use change account for about 1/3 of the global total.Therefore,the study on the change of land use and its carbon emission has important reference value for the rational planning of land use,and also has important significance for improving the quality of social and economic development and promoting sustainable development.In this paper,the northwestern sichuan basin of deyang and mianyang two level city as research area,using 2000～2020,a total of 5multi-source remote sensing data of land use,combined with the quantitative analysis of land use change model to 20 years regional land use change characteristics,including land use change of time and space,dynamic,degree of land use and transfer of land use;Combined with the interpreted land use data and fossil energy consumption data,the carbon emission accounting model was used to calculate the change of carbon emissions,and the spatial autocorrelation model and hot spot analysis model were used to analyze the change characteristics of spatial agglomeration.Kaya identity and logarithmic mean Dith index decomposition model were used to explore the influencing factors of regional land use carbon emissions.Finally,Tapio decoupling elasticity model is used to study the relationship between carbon emission change and economic development.The main conclusions are as follows:（1）The main types of land use were cultivated land,forest land and grassland,of which the cultivated land accounted for about half of the total area,showing a rapid decreasing trend,while the area of forest land and grassland decreased slowly.The area of land used for construction increased rapidly,more than doubling;Small increase of water area;The area of unused land increased by nearly 10 times.The most obvious spatial change of land use is that the urban construction land keeps expanding to the surrounding cultivated land and the cultivated land keeps shrinking,while the spatial pattern of other land use types does not change much.（2）The dynamic change range of land use was large,and the dynamic attitude of regional land use was 1.81%during the 20 years.The land types with positive dynamic attitude include unused land,construction land and water area,of which unused land is the largest,followed by construction land,and water area is the smallest.The dynamic attitudes of cultivated land,forest land and grassland were all less than 0.The degree of land use has been in the middle and above level,and the trend is more obvious,the degree of intensification of land use is deepening,and the land has been in the state of development.（3）The spatial transfer of land use was characterized by the transfer of cultivated land,forest land and grassland,and the transfer of cultivated land to construction land.The transfer of cultivated land,forest land and grassland was mainly distributed in the mountainous area of northwest China and the hilly area of basin.The transfer of cultivated land to construction land is concentrated in the Chengdu plain area in the southwest of the study,where the urban distribution is very dense and the urban expansion is mainly occupied by cultivated land.The land use transfer area was the most severe from 2005 to 2010,the land use transfer area was relatively small from2015 to 2020 and 2010 to 2015,and the land use transfer area was the least from 2000to 2005.（4）Carbon sources increased rapidly from 2000 to 2010,and gradually decreased from 2010 to 2020.The contribution of fossil energy consumption in construction land to carbon sources was the largest.From 2000 to 2020,carbon sequestration remained stable with a small decrease,and forest land contributed the most to carbon sequestration.The net carbon emissions increased rapidly from 2000 to 2010,and gradually decreased from 2010 to 2020.The carbon sink effect was far from enough to offset the carbon source effect.The Z values of carbon source,carbon sink and net carbon emissions were all above the critical value of 1.96,and the P values were all 0.The spatial agglomeration of carbon source,carbon sink and net carbon emissions was significant,and the spatial agglomeration gradually increased.The carbon source towns and villages in the high value area are concentrated in the built-up area of Chengdu plain,while the carbon source in the low value area is mainly concentrated in the hilly area of the eastern basin.The carbon sink towns in the high value region are concentrated in the mountainous region of northwest China,while the carbon sink towns in the low value region are distributed in the Plain and hilly region of Chengdu.The towns and villages with high net carbon emissions are mainly located in the densely populated areas of Chengdu plain,while the towns and villages with low net carbon emissions are located in the mountainous areas in northwest China and the hilly areas in the basin.（5）Economic development factor and urban expansion factor are driving the growth of land use carbon emission,and economic development factor is the main driving factor of carbon emission change,and the driving effect of both factors is strengthened first and then weakened.On the whole,energy use efficiency and land use efficiency inhibited the growth of land use carbon emissions,and energy use efficiency played a major role in inhibiting the growth of land use carbon emissions.The inhibitory effects of energy use efficiency and land use efficiency increased first and then decreased.The overall relationship between land use carbon emissions and economic development is weak decoupling,and the decoupling states in the four periods are expansion connection,weak decoupling,strong decoupling and strong decoupling respectively.The decoupling state gradually improves,and the sustainable development prospect is good.In the elastic decomposition of decoupling,energy use efficiency plays the most important role in promoting the benign development of decoupling,followed by land use efficiency.On the contrary,the level of economic development has the strongest inhibitory effect on the benign development of decoupling state,followed by the scale of urban expansion.