Abstract:

It is important to quantify the carbon supply (sequestration) and demand (emission) of land use to reveal the impacts of human activities on terrestrial ecosystems and formulate carbon emission reduction policies. Therefore, this study first quantified carbon emissions and carbon sequestration by integrated approaches, including carbon emission coefficient, carbon emission coefficient, and InVEST model, and further calculated the carbon supply demand ratio to analyze the spatial matching states of carbon emission-carbon sequestration. Second, the Geoda spatial autocorrelation analysis model was used to analyze the spatial agglomeration characteristics of carbon emissions, carbon sequestration, and the carbon supply-demand ratio. Finally, we analyzed how the main driving factors affected carbon emissions and sequestration in administrative units in different counties (districts). The results showed that 1) the areas with high carbon emissions in Sichuan Province were concentrated in counties (districts) of the Chengdu Plain and hilly zones of the Sichuan Basin, which were characterized by a developed agricultural and industrial economy. The high value of carbon sequestration was concentrated in counties (districts) of the Western Sichuan Plateau, where the dominant land-use types were woodland and grassland. 2) The values of the carbon supply demand ratio range from −0.951 to 0.818. More than 75% of the counties (districts) had ecological deficits, which showed the spatial characteristics of “surplus in the west and deficit in the east”. Southwest mountains regions and plateau areas have abundant vegetation resources and an ecological surplus. In contrast, the eastern Chengdu Plain areas have serious ecological deficits because of their widespread coverage by cropland, urban construction land, and a developed industrial economy. 3) From a spatial perspective, the agricultural indicator was a crucial factor affecting carbon emissions and carbon sequestration had the strongest correlation with vegetation cover conditions. From the results of the local correlation perspective, the impact of the primary industry’s GDP on carbon emissions decreased from the southwest to northeast of the study site. NPP had a significantly positive impact on carbon sequestration in the western and southeastern regions of China.

Key words: carbon emission-sequestration estimation, carbon supply-demand ratio, land use types, Correlated relationship analysis, Sichuan Province

摘要：

量化土地利用碳供需对揭示人类活动对陆地生态系统的影响机制、制定碳减排政策具有重要意义。首先采用碳排放系数法-能源系数法-InVEST模型对碳排放和碳储存分别进行定量评估，分析碳供需空间分布特征；其次采用Geoda空间自相关分析模型，分析碳排放、碳储量和碳供需比的空间集聚特征；最后基于斯皮尔曼秩相关系数法、地理加权模型分析影响碳排放、碳储量的空间分异的驱动因素。结果如下，1）四川省高碳排放中心主要集中分布于农、工业经济较发达的成都平原和四川盆地丘陵区（双流区、龙泉驿区、安岳县）；碳储量空间上呈“西高东低”，高值聚集分布于林草面积广阔的川西高原，空间溢出效应明显。2）碳供需比位于−0.951－0.818之间，全省超过75%的区（县）处于生态赤字状态。空间上呈现“西部盈余东部赤字”的特点，西部高山高原区和盆周山区地广人稀，植被资源丰富，有较高的盈余。东部成都平原区农田、城市建成地面积占比高，工业、经济发达，有严重的赤字。3）从研究全域来看，农业相关指标对碳排放的解释力度最大；碳储存与植被覆盖相关指标相关性最强。从空间局部分析结果来看，第一产业生产总值对碳排放的影响程度由西南到东北下降；此外，净初级生产力对川西、川东南部分区（县）的碳储量的正向影响更显著。

关键词: 碳排放-碳储存估算, 碳供需比, 土地利用类型, 相关性分析, 四川省