| Land use change affects atmospheric carbon content and global climate change,and is an important reference for countries and regions to master carbon emission dynamics and seek low-carbon development paths.As a key upstream urban agglomeration in the national strategy of ecological protection and high-quality development in the Yellow River Basin,Lanxi Urban Agglomeration plays an important role in supporting homeland security and ecological security.We should seek low-carbon development mode of land use in Lanxi Urban Agglomeration and explore low-carbon development path with characteristics of Northwest inland region.It is of great practical significance to ensure the overall ecological security of Lanxi urban agglomeration,promote the high-quality development of the Yellow River Basin,and realize China’s "double carbon" goal and sustainable land use.This paper takes the land use carbon emissions of Lanxi Urban Agglomeration and its city-prefecture region as the research object.Based on the remote sensing images in2000,2010 and 2020,the carbon emission estimation method is used to calculate the carbon emissions of each land use type in the study area,to clarify the carbon source,carbon sink and the carbon emission effect of land class transfer,and to analyze the temporal and spatial variation characteristics of land use carbon emissions.To master the risks and pressures of land use carbon emissions,this paper predicts the land use carbon emissions of Lanci urban agglomeration in 2030 and 2060,the target period of carbon peaking and carbon neutral,with the help of Markov model,and tries to provide reasonable suggestions for the low-carbon development of Lanci urban agglomeration.The main conclusions are as follows:(1)From 2000 to 2020,the land use type and structure change of Lanxi urban Agglomeration showed that the cultivated land and grassland decreased,while the forest land,water area,construction land and unused land increased.(1)Among the land types with decreased area,the decreasing area was grassland > cultivated land,and the decreasing area was the grassland in Hainan Tibetan Autonomous Prefecture and the cultivated land in Lanzhou City.Among the land types with increasing area,the growth area is in the order of construction land > water area > forest land > unused land,among which,the "double circle" of Lanxi urban agglomeration--Lanzhou-Baiyin metropolitan area and Xining-Haidong metropolitan area are the main growth space of construction land,the growth rate of water area and unused land area in Hainan Tibetan Autonomous Prefecture is the largest,and the growth rate of forest area in Haidong City is the largest.(2)The comprehensive dynamic attitude of land use in Lanxi urban agglomeration was 0.22%.The dynamic attitude of land use in urban agglomeration was mainly construction land adjustment,and the single dynamic attitude of land use was construction land > forest land > water area > unused land > grassland > cultivated land.The adjustment of construction land in some node cities has exceeded the central city.(3)Cultivated land and grassland are the two largest types of land use transfer area,and the other types of land use transfer area and transfer area are relatively small.(4)There are some problems in urban agglomeration such as fast expansion of construction land,slow improvement of woodland and grassland conditions and unreasonable land use layout.(2)Net carbon emissions generated by land use in Lanxi urban Agglomeration during the study period are closely related to urban first degree,carbon emissions in central cities are significantly higher than those in surrounding cities,and the spatial distribution of carbon sources tends to be "high in the east and low in the west".(1)In the category of carbon sources,carbon emissions from cultivated land decreased slightly,and carbon emissions from construction land doubled steadily every ten years.The central cities of urban agglomerations were the main sources of carbon emissions from land use,and carbon sources from cities and states increased significantly,showing a spatial pattern of "high in the east and low in the west".(2)Among the carbon sinks,grassland carbon uptake decreased,forest land,water area and unused land carbon uptake increased to different degrees,forest land and water area environment and carbon sink effect significantly improved;The carbon sinks of cities and states have obvious regional differences and staggered distribution,showing an irregular "high in the east and low in the west" feature.The carbon source/carbon sink ratio basically increased steadily,gradually forming a spatial pattern of "high in the east and low in the west".(3)In the spatial and temporal distribution of carbon emissions from different land types,the carbon emissions from cultivated land were "high in the east and low in the west" and relatively stable.The spatial difference of forest land carbon uptake was significant,and the central city state > eastern city state > western city state.The carbon uptake of grassland tends to be concentrated and contiguous in space.The spatial and temporal variation of carbon uptake in water area from relatively uniform distribution tended to be "high in the east and low in the west".The carbon emission of construction land is obviously "high in the east and low in the west" and continues to deepen.The carbon uptake of unused land is very low and irregularly distributed.(4)The carbon emission conduction effect of land class transfer is net carbon emission effect,and carbon source class plays a leading role.The carbon transfer and carbon transfer from cultivated land and construction land are much higher than other land types.(5)Land use carbon emissions in urban agglomerations have such problems as large risk pressure,weak carbon absorption capacity and unbalanced carbon emission pattern.(3)The continuous increase of carbon emissions from construction land makes the carbon emission risk and pressure index of Lanci urban Agglomeration continue to rise,maintaining the spatial pattern of "high in the east and low in the west",and the regional differences are constantly narrowing.The Markov chain prediction results show that in2030 and 2060,among the carbon sources,the adjustment of cultivated land will be most obvious in the core cities of Lanzhou and Xining,and the carbon emissions of cultivated land will decrease slightly,while the carbon emissions of construction land will continue to increase substantially,and the contribution of cities and states will be obvious.The carbon sequestration capacity of Linxia Hui Autonomous Prefecture,Xining City,Haidong City and Hainan Tibetan Autonomous Prefecture was enhanced,the carbon sequestration capacity of grassland decreased slightly,and the carbon sequestration of unused land changed little.Aiming at the problems of land use and carbon emission in urban agglomerations,the following low-carbon development paths are proposed: low-carbon land use paths are planned according to different urban positioning,such as central city,node city and peripheral town;Optimize the structure of land use,low-carbon development and construction land;Restore land carbon sink ecology and develop carbon sink land resources. |
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