上海四种常见树种单株固碳能力差异及其影响因子

城市树木的固碳能力是决定城市绿地碳汇大小的重要因素。为探究上海常见树种单株固碳能力的差异及影响因子,使用174个城市森林固定样地的长期观测数据,估算了香樟、水杉、银杏和雪松四个树种的单株固碳能力(即年固碳量),采用多元线性回归模型分析了各树种单株固碳能力与个体大小、植株密度和城市环境因子(温度、降水量和夜间灯光强度)的关系。结果表明:(1)香樟、水杉、银杏和雪松的单株固碳能力分别介于4.01-51.58 kg/a、1.04-13.47 kg/a、0.62-18.56 kg/a和1.48-8.47 kg/a之间,在各径组中香樟的固碳能力均显著高于其他树种。(2)个体大小是决定单株固碳能力的最主要因子,个体越大(胸径0-50 cm范围内)单株固碳能力越大;植株密度越大,香樟和水杉的单株固碳能力越小,银杏的单株固碳能力越大。(3)城市环境因子中,温度对树木单株固碳能力有显著负向影响,而降水量和夜间灯光强度对树木单株固碳能力的影响因树种而异。其中香樟和水杉分别与降水量呈显著负相关和正相关关系,但均与夜间灯光强度呈显著正相关关系。在上海未来城市森林建设和管理中,应根据不同树种单株固碳能力的差异及其对不同环境因子的敏感性,适地适树绿化造林,提升城市森林的固碳效益。

Individual carbon sequestration capacity of four common tree species and their impact factors in Shanghai

The carbon sequestration capacity of trees plays a crucial role in determining the carbon sink potential in urban green spaces. To investigate the variations in carbon sequestration capacity among tree species and their impact factors, we selected four common tree species (Cinnamomum camphora, Metasequoia glyptostroboides, Ginkgo biloba, and Cedrus deodara) in Shanghai. The individual carbon sequestration capacity of the four tree species (i.e., annual carbon sequestration) was evaluated based on long-term observation data from 174 monitoring plots in Shanghai. We examined the influence of plant size, plant density, and environmental factors (i.e., temperature, precipitation, and artificial light intensity at night) on the individual carbon sequestration capacity of each tree species using the multiple linear regression model. The results showed that: (1) The individual carbon sequestration capacity of C. camphora, M. glyptostroboides, G. biloba, and C. deodara was 4.01-51.58 kg/a, 1.04-13.47 kg/a, 0.62-18.56 kg/a, and 1.48-8.47 kg/a, respectively. The individual carbon sequestration capacity of C. camphora was significantly higher than other tree species in all groups of the diameter at breast height (DBH). (2) The plant size was the major determinant of individual carbon sequestration capacity, and the individual carbon sequestration capacity increased with the growth of plant size (within the range of 0-50 cm DBH). The individual carbon sequestration capacity of C. camphora and M. glyptostroboides decreased with the increase in plant density, while that of G. biloba positively related with plant density. (3) The temperature had a significantly negative impact on individual carbon sequestration capacity, while the impacts of precipitation and artificial light intensity at night varied among tree species. The precipitation showed a negative correlation with individual carbon sequestration capacity of C. camphora, whereas the precipitation displayed a positive correlation with that of M. glyptostroboides. The artificial light intensity at night demonstrated the positive correlation with the individual carbon sequestration capacity for C. camphora and M. glyptostroboides. Overall, we suggest that the selection of tree species should take into account both their individual carbon sequestration capacity and their sensitivity to environmental factors for future construction and management of urban forests in Shanghai.