Spatial-Temporal Characteristics And Influencing Of Land Use Carbon Emissions In The Yangtze River Economic Belt

With the intensification of global climate change and the implementation of China’s"double carbon"strategic goal,carbon emissions caused by human activities have received extensive attention from academia.Land is the spatial carrier of human activities.The change of land use directly reflects the change of human activities and has an important impact on carbon emissions.Revealing the coupling mechanism between land use and carbon emissions is of great theoretical significance for the implementation of the"double carbon"strategic goal and the mitigation of global climate change.The Yangtze River Economic Belt is a national key development strategy area and a green low-carbon economy leading demonstration zone.Taking the Yangtze River Economic Belt as the research area,exploring the relationship between land use and carbon emissions is of practical significance for revealing the green development mechanism in the region,and has reference value and decision-making reference significance for other regions.Based on land use,this paper constructs an evaluation model of land use carbon emissions,and evaluates the characteristics of land use carbon emissions in the Yangtze River Economic Belt.Based on the distribution characteristics,aggregation characteristics,center of gravity migration characteristics and efficiency characteristics,the spatial and temporal variation of land use carbon emissions was analyzed.The TAPIO decoupling model,LMDI factor decomposition model and IPAT model were used for quantitative analysis of carbon emission influencing factors and carbon emission reduction scenario prediction.The main conclusions are as follows.(1)The land use types of the Yangtze River Economic Belt are mainly forest land(47%)and cultivated land(30%).From 2000 to 2020,the area of construction land increased significantly,with a total increase of 33749 km~2.The area of cultivated land decreased significantly,a total of 27155 km~2.The expansion of construction land is mainly through the occupation of cultivated land and forest land,of which cultivated land accounts for 82.4%and forest land accounts for 14.3%.The transferred area of cultivated land mainly flows to construction land,and part of it flows to forest land and water area due to the implementation of the project of returning farmland to forest and lake.The spatial pattern of other land types changed little.(2)The net carbon emissions of land use in the Yangtze River Economic Belt increased from 1444.4 million tons in 2000 to 4145.13 million tons in 2020,an increase of nearly1.87 times.Construction land is the main carbon source,with an average annual contribution rate of more than 95%.Forest land is the main carbon sink,and the average annual contribution rate of carbon absorption reaches 96%.Affected by land use change,it shows a downward trend after reaching its peak in 2011,and the carbon absorption in 2020is 54.02 million tons.(3)From the perspective of city scale,the spatial difference of net carbon emission of urban land use in the Yangtze River Economic Belt is significant,showing the inherent distribution characteristics of’high in the east and low in the west’.From 2000 to 2020,the Moran’s I index continued to rise from 0.133 to 0.196,indicating that the net carbon emissions of land use had obvious spatial aggregation and tended to strengthen.From the perspective of local spatial clustering characteristics,Shanghai,Suzhou and Nantong belong to the"high-high"clustering type,indicating that the net carbon emissions of land use are high and have spillover effects.The"low-low"clustering types are concentrated in western underdeveloped cities such as Ganzi Tibetan Autonomous Prefecture and Dali Bai Autonomous Prefecture.The"high-low"clustering cities are mainly central cities such as Chongqing,Chengdu and Wuhan.Due to the tilt of regional resources,the net carbon emissions are much higher than those of neighboring cities.(4)The spatial gravity center migration characteristics of urban land use net carbon emissions in the Yangtze River Economic Belt are significant,showing obvious directional and phased laws.From the position of the barycenter coordinate,the center of gravity of net carbon emissions has always been biased towards the northeast,indicating that the contribution of net carbon emissions in the Yangtze River Delta cities has always maintained a high proportion.From the perspective of the migration path of the center of gravity,during the first stage(2000-2015),under the influence of the western development strategy,the proportion of net carbon emissions in cities in Southwest China continued to increase,and the center of gravity continued to migrate to the southwest,moving a total of53.4 km.During the second stage(2015-2020),under the background of"joint efforts to protect and not to develop",the growth rate of net carbon emissions in the southwest region has slowed down significantly,and the overall proportion has declined,resulting in a shift of the center of gravity to the northeast by 27.8 km.(5)From 2000 to 2020,the carbon emission intensity of land use in the Yangtze River Economic Belt showed a continuous downward trend.The average value decreased from35,500 tons/billion yuan in 2000 to 87,000 tons/billion yuan in 2020,and the gap between provinces and cities gradually narrowed.The per capita carbon emissions show a continuous upward trend,with the average value increasing from 2.59 tons/person to 6.84tons/person,and the differences between provinces and cities are gradually expanding.In terms of spatial distribution,cities with high land use carbon emission intensity are mainly concentrated in resource-based cities.For example,Liupanshui and Ma’anshan are highly dependent on energy and heavy industry,and their carbon emission intensity is far higher than the average level.Cities with higher per capita carbon emissions are concentrated in the Yangtze River Delta urban agglomeration.(6)Economic development level,construction land scale,energy consumption intensity,population density and energy utilization structure are the main influencing factors of land use carbon emissions in the Yangtze River Economic Belt.From 2000 to2020,the relationship between land use carbon emissions and economic growth has undergone a process of gradual transition from expansion and connection to weak decoupling,indicating that the economic development model of the Yangtze River Economic Belt is constantly moving towards green and low carbon.The decomposition results of LMDI influencing factors show that the level of economic development and the scale of construction land show positive effects,promote carbon emissions,and the cumulative carbon effects are 725.832 million tons and 237.873 million tons,respectively;energy consumption intensity,population density and energy utilization structure show negative effects,inhibiting carbon emissions,and the cumulative carbon effects are-5253.94 million tons,-171.408 million tons and-21.54 million tons,respectively.The scenario simulation results show that only under the optimistic scenario with significant carbon emission reduction,the total land use carbon emission,land use carbon emission intensity and per capita carbon emission reduction targets of the Yangtze River Economic Belt in 2030 can be fully achieved.