巫山针叶林与阔叶林乔灌草结构特征及碳汇功能对比

Comparison of structural characteristics and carbon sink functions between trees,shrubs and herbs of coniferous and broadleaf forests in Wushan

【目的】针叶林与阔叶林构成了森林类型主体,研究二者的林分结构特征和碳汇功能差异对于森林质量精准提升和森林生态系统物种多样性保护具有重要意义。【方法】以巫山针叶林与阔叶林森林为研究对象,共142块乔木林样地(针叶林70块,阔叶林72块),调查分析样地内乔灌草的群落结构特征,计算植物物种多样性和地上碳储量,基于结构方程模型分析立地环境、群落结构和物种多样性对碳汇功能的响应关系。【结果】1)针叶林内共有乔木30种,隶属于28科30属,灌木16科20属20种,草本15科21属21种。阔叶林内共有乔木36种,隶属于30科36属,灌木16科21属21种,草本17科19属19种。乔木层中,针叶林和阔叶林的Patrick丰富度指数、Simpson优势度指数、Shannon-Wiener多样性指数和Pielou均匀度指数均存在显著性差异;2)群落结构对森林碳汇功能的总影响系数为2.466,平均影响系数为0.352,在群落结构特征的7个观测变量中,对森林固碳功能影响最大的因子是胸径(0.832);物种多样性对碳汇功能的总影响系数为0.859,平均影响系数为0.215,对固碳功能影响最大的物种多样性指数因子是优势度指数(0.32);立地环境对碳汇功能的总影响系数为2.253,平均影响系数为0.563,对森林固碳功能影响最大的立地因子是海拔(0.753)。对碳汇功能影响最大的因子是立地环境;3)在巫山,针叶林林分收获固定的碳是阔叶林的2.50倍,即针叶林的碳汇功能是阔叶林的2.50倍。【结论】本研究以巫山大量野外调查数据为基础,对南方针叶林、阔叶林的乔灌草植物组成特征、物种多样性与碳汇功能差异进行详细分析,并基于结构方程模型对立地环境、群落结构特征和物种多样性的量化因子对碳汇功能的影响系数进行分析,相关结果可为南方针叶林、阔叶林的碳汇功能研究提供理论支持,建议开展不同树种组成的针叶林、阔叶林林木生长长期监测,加强森林质量提升,助力国家“双碳”目标实现。

【Objective】Coniferous forests and broadleaf forests constitute the main body of forest types,and it is important to study the differences in stand structure characteristics and carbon sink functions between them for precise improvement of forest quality and conservation of species diversity in forest ecosystems.【Method】A total of 142 sample plots of coniferous and broad-leaved forests in Wushan(70 coniferous and 72 broad-leaved forests)were used to investigate and analyze the community structure characteristics of trees,shrubs,and grasses in the sample plots,calculate plant species diversity and above-ground carbon storage,and analyze the response of site environment,community structure and species diversity to carbon sink function based on structural equation modeling.【Result】1)There were 30 species of trees belonging to 30 genera of 28 families,20 species of shrubs belonging to 20 genera of 16 families and 21 species of herbs belonging to 21 genera of 15 families in coniferous forests.There were 36 species of trees belonging to 36 genera in 30 families,21 species in 21 genera in 16 families of shrubs,and 19 species in 19 genera in 17 families of herbs in broad-leaved forests.The Patrick richness index,Simpson dominance index,Shannon-Wiener diversity index and Pielou evenness index of coniferous and broad-leaved forests were significantly different in the tree layer;2)The total influence coefficient of community structure on forest carbon sink function was 2.466,with a mean influence coefficient of 0.352.Among the seven observed variables of community structure characteristics,the factor with the greatest influence on forest carbon sequestration function was diameter at breast height(0.832);the total influence coefficient of species diversity on carbon sink function was 0.859,with a mean influence coefficient of 0.215.The species with the greatest influence on carbon sequestration function.The dominance index(0.32)was the most influential factor on carbon sequestration;the total influence coefficient of site environment on carbon sink function was 2.253,with an average influence coefficient of 0.563,and the most influential site factor on carbon sequestration function was elevation(0.753).The factor with the greatest influence on carbon sink function was the stand environment;3)In Wushan,coniferous forest stands harvested 2.50 times more carbon fixed than broadleaf forests,which mean,the carbon sink function of coniferous forests was 2.50 times higher than that of broad-leaved forests.【Conclusion】Based on a large amount of field survey data in Wushan,this study provides a detailed analysis of the differences in plant composition characteristics,species diversity and carbon sink functions of coniferous and broadleaf forests in the south,and analyzes the influence coefficients of quantitative factors of stand environment,community structure characteristics and species diversity on carbon sink functions based on structural equation modeling.The relevant results provide theoretical support for the study of carbon sink functions of coniferous and broadleaf forests in the south,and suggest that long-term monitoring of the growth of coniferous and broadleaf forests with different tree species composition should be carried out to strengthen forest quality improvement and help the country achieve its dual carbon goals.