基于土地利用变化的县域碳收支空间格局预测

Prediction of Spatial Patterns of County-scale Carbon Budget based on Land Use Change

【目的】土地利用/覆被变化是引起全球碳排放的主要原因之一,通过预测土地利用变化评估未来县域尺度碳排放空间格局对于制定区域减排政策具有重要意义。【方法】基于2005—2020年重庆市渝北区土地利用数据及CLUE-S模型预测2025—2030年该区土地利用变化及碳收支时空动态。【结果】2005—2030年渝北区耕地面积将持续减少4.57×10^4 hm^2,林地面积呈现“增加-减少”反复波动的趋势,面积净增长2293.8 hm^2;水域及未利用地面积略有增加;建设用地扩张最明显,面积增长3.32×10^4 hm^2,整体扩张强度为0.92%。人类活动影响指数(HAI)呈先降低后增长的趋势,其值在2020年最低(0.49),并在2030年最高(0.54)。渝北区耕地的碳汇功能和建设用地能源消费分别是该区碳吸收和碳排放的主要来源。渝北区碳吸收随耕地面积减少而逐渐降低,2005—2030年碳吸收由2.17×10^5 t逐渐降低为1.43×10^5 t,而碳排放却由2.07×10^5 t逐渐增加到1.02×10^6 t,导致渝北区净碳排放量由-1.01×10^4 t增长为8.79×10^5 t。渝北区地均碳吸收值在海拔较高的山地及该区北部平行岭谷的丘陵地带较高;地均碳排放值在西南部平坦丘陵地带较高,并随建设用地的扩张向北沿平行岭谷蔓延。【结论】基于CLUE-S模型对土地利用变化的预测从而获得未来县域碳收支空间格局的方法是可行的。现有产业结构下合理调整土地利用结构是保证县域低碳发展的重要途径。

[Objective]Land use/cover change constitutes one of the major sources of global carbon emission.It is of profound significance to formulate regional emission reduction policies by predicting land use changes to assess the future county-scale carbon emission spatial pattern.[Method]Based on the CLUE-S model and land use change data of Yubei District,Chongqing municipality from 2005 to 2020,this study predicted both the spatiotemporal dynamics of land use change and the carbon budget of Yubei District from 2025 to 2030.[Result]The results showed that the area of farm land in Yubei District would continue to decrease by 4.57×10^4 ha from 2005 to 2030,and the area of forest land would display a trend of repeated increase and then decrease,with a net increase of 2293.8 ha.The area of waters and unused land would both increase slightly.Construction land would mostly expand with the area increasing by 3.32×10^4 ha,and its overall expansion intensity would be 0.92%.The human activity impact index(HAI)showed a trend of decreasing at first and then increasing.Its value is the lowest in 2020(0.49)and would be the largest in 2030(0.54).The carbon sink function of farm land and the energy consumed on construction land are both main components of carbon sequestration and carbon emissions in Yubei District,respectively.Carbon sequestration in Yubei District would decline gradually with the decrease of cultivated land area.From 2005 to 2030,the carbon sequestration would decrease gradually from 2.17×10^5 t to 1.43×105 t;while the carbon emission would increase from 2.07×10^5 t to 1.02×10^6 t.They would force the net carbon emission of Yubei District to increase from-1.01×10^4 t to 8.79×10^5 t.The average carbon sequestration values of Yubei District are higher in the mountainous areas with higher altitude and the hilly areas of the parallel ridge valleys in the northern part.The average carbon emission value is higher in the flat hilly area in the southwest region,and it spreads northward along the parallel ridge valleys with the expansion of construction land.[Conclusion]Based on the prediction of land use change based on the CLUE-S model,it is feasible to obtain the spatial pattern of future county-scale carbon budget.Reasonably adjusting the land use structure under the existing industrial structure is a key way to ensure the low-carbon development of the county-scale region.