Abstract:

Rapid development of urbanization and increase of human activity have led to great changes in land use as well as a series of ecological environment and climate problems. As carbon peaking and carbon neutrality strategies are taken in China, new and higher requirements for the quantitative structure and spatial distribution of future land use were raised. Under the carbon neutrality strategy, predicting future land use changes and carbon emission characteristics by simulating land use structure and spatial optimization based on multi-objective scenarios is of great significance for the land dimension of carbon neutrality. Combined with future climate, historical and policy scenarios of SSPs, this paper simulated land use changes in Chengdu-Chongqing economic circle during 2010-2030 based on PLUS model, including quantity and spatial structure characteristics. Based on four objective function constraints of economic benefit, carbon emission, carbon storage, and ecosystem service value, it conducted spatial optimization on land use structures of Chengdu-Chongqing economic circle in 2030 under different scenarios, and deeply analyzed carbon emission characteristics of land use changes in 2030. As shown by the results, (1) from 2010 to 2020, there was the decreased area of cultivated land and grassland, but increased area of construction land, forest land, water area and unused land in Chengdu-Chongqing economic circle. (2) The predicted land use changes in the Chengdu-Chongqing economic circle in 2030 based on five future scenarios were different. Besides, the overall change pattern in the SSP126 and SSP245 scenarios was similar to that in the historical scenario, but the forest expansion was faster in the SSP126 scenario. Under the SSP585 scenario, the construction land and forest land rapidly expanded to the cultivated land. Apart from that, the policy scenario took into account the development of construction land and ecological land, so the cultivated land decreased the most, but the cultivated land area remained above the red line of cultivated land. (3) The land use carbon emission of the Chengdu-Chongqing economic circle in 2030 predicted by the five scenarios was all lower than that of 2020, with the carbon emission under the SSP126 scenario being the lowest and that under the policy scenario being the biggest. The research results verify that the realization of carbon peaking and carbon neutrality goals of the Chengdu-Chongqing economic circle is dependent on the clean transformation of energy structure, the low-carbon adjustment of the industrial structure, the consolidation and improvement of the ecological carbon sink of plants, etc. In the mid-and-long term, the future land resources planning of Chengdu-Chongqing economic circle should be inclined to follow SSP245 scenarios or fall somewhere between SSP245 and SSP126 scenarios, in order to better bridge the carbon neutrality strategies.

Key words: SSPs scenarios, land use, carbon emissions, spatial optimization, PLUS model, Chengdu-Chongqing Economic Circle

摘要：

快速城市化及人类活动增强，使得土地利用剧变并带来了一系列生态环境及气候问题。中国碳达峰、碳中和战略的提出，对未来土地利用的数量结构及空间分布提出了新的更高要求。碳中和战略下，通过多目标情景模拟土地利用结构和空间优化，预测未来土地利用变化及其碳排放特征，对土地维度碳中和具有重要意义。结合SSPs未来气候情景、历史情景和政策情景，基于PLUS模型模拟了2010-2030年成渝经济圈土地利用变化，包括数量和空间结构特征。并进一步基于经济效益、碳排放量、碳储量、生态系统服务价值四目标函数约束，对2030年不同情景下成渝经济圈土地利用结构进行了空间优化。深入分析了2030年的土地利用变化碳排放特征。结果表明，（1）2010-2020年，成渝经济圈主要表现为耕地、草地面积减少，建设用地、林地、水域和未利用地面积增加。（2）基于5种未来情景预测的成渝经济圈2030年土地利用变化各不相同。SSP126情景、SSP245与历史情景下，整体变化模式类似，但SSP126情景下林地扩张更快；SSP585情景下，建设用地、林地迅速向耕地扩张；政策情景兼顾建设用地与生态用地的发展，耕地减少最多，但耕地面积仍然高于耕地红线。（3）5种情景预测的2030年成渝经济圈土地利用碳排放量均低于2020年，且SSP126情景碳排放最低，最大为政策情景，研究结果证实了，成渝经济圈双碳目标的实现依赖于能源结构清洁化转型、产业结构低碳化调整、巩固提升植被生态碳汇等途径，从中长期来看，成渝经济圈的未来国土资源规划应趋向SSP245情景或介于SSP245与SSP126情景之间，以更好衔接碳中和战略。

关键词: SSPs情景, 土地利用, 碳排放, 空间优化, PLUS模型, 成渝经济圈