宁德三都澳群岛马尾松人工林群落谱系结构及其驱动因素研究(附录)

Phylogenetic structure and its driving factors of Pinus massoniana plantation communities in the Sandu'ao Islands of Ningde

关键词:  海岛, 马尾松人工林, 层片, 谱系结构, 环境因子, 空间效应

Key words:  island, Pinus massoniana plantation, synusia, phylogenetic structure, environmental factors, spatial effect

摘要:

为探讨海岛特殊生境下马尾松(Pinus massoniana)人工林不同层片群落谱系结构的构建机制,以宁德三都澳海岛马尾松林为研究对象,基于群落调查数据,分别计算乔木层、灌木层和草本层的净谱系亲缘关系指数(NRI)和净最近种间亲缘关系指数(NTI)以表征其谱系结构。综合运用空间自相关分析、回归分析、空间滞后模型(SLM)及结构方程模型(SEM),解析气候、土壤和光照等环境因子对不同层片谱系结构的影响路径与空间效应。结果表明:(1)不同层片群落谱系结构存在显著分异:乔木层主要表现为谱系发散,表明生境过滤作用较弱,竞争排斥主导其构建过程; 灌木层趋于谱系聚集,体现出较强的环境过滤作用; 草本层则呈弱发散格局,构建机制相对复杂。(2)土壤酸碱度是调控群落谱系结构的主导环境因子; 碱解氮不仅直接正向影响乔木层与草本层的谱系指数,而且还作为中介变量介导土壤酸碱度对二者的间接效应; 郁闭度对乔木层谱系结构具有显著调控作用,表明光照条件对乔木层谱系构建至关重要。(3)草本层NTI在环境距离加权矩阵下存在显著的空间滞后效应,即其谱系结构受到邻近样方群落组成的显著影响; 郁闭度、土壤酸碱度和风速是该空间效应的核心驱动因子,三者综合正向效应最为显著,揭示生境异质性与风力干扰在草本层群落谱系结构构建中的协同作用。该研究揭示了海岛马尾松林不同层片谱系结构的差异化驱动机制,明确了环境过滤与空间效应对岛上植物群落构建的相对贡献,可为海岛植被修复与马尾松林生态系统保护提供科学依据。

Abstract:

To explore the assembly mechanisms of phylogenetic structures across different synusiae in Pinus massoniana plantations under the unique island habitat, this study focused on P. massoniana forests in the Sandu'ao Gulf Islands of Ningde, Fujian Province, China. Based on community survey data, we calculated net phylogenetic relatedness index(NRI)and net the nearest taxon index(NTI)for the arbor, shrub, and herb layers to characterize their phylogenetic structures. Spatial autocorrelation analysis, regression analysis, spatial lag model(SLM), and structural equation model(SEM)were comprehensively employed to parse the influence pathways and spatial effects of climatic, edaphic, and light factors on the phylogenetic structure of each synusia. The results were as follows:(1)Significant differences in phylogenetic structure were observed among synusiae: the arbor layer was predominantly characterized by phylogenetic overdispersion, indicating weak habitat filtering and suggesting that competitive exclusion dominates its construction process; the shrub layer tended towards phylogenetic clustering, reflecting a strong effect of environmental filtering; the herb layer exhibited weak overdispersion, implying more complex construction mechanisms.(2)Soil pH was identified as the dominant environmental factor regulating community phylogenetic structure; available nitrogen not only had a direct positive effect on the phylogenetic indices of the arbor and herb layers but also served as a mediating variable for the indirect effect of soil pH; canopy density exerted a significant regulatory effect on the phylogenetic structure of the arbor layer, highlighting the critical role of light conditions in its construction.(3)The NTI of the herb layer displayed a significant spatial lag effect under the environmental distance-weighted matrix, meaning its phylogenetic structure was significantly influenced by the community composition of neighboring plots; canopy density, soil pH, and wind speed were the core driving factors of this spatial effect, exhibiting the most significant comprehensive positive effect, and this finding revealed the synergistic roles of habitat heterogeneity and wind disturbance in shaping the community phylogenetic construction of the herb layer. This study reveals the differentiated driving mechanisms of phylogenetic structure across different synusiae of island P. massoniana plantations, and clarifies the relative contributions of environmental filtering and spatial effects on island plant community construction. The results provide a scientific basis for vegetation restoration and ecosystem protection of P. massoniana plantations in island areas.