生物和非生物因子对宝天曼落叶阔叶林植被碳库分布格局的影响

Forest biomass carbon (C) storage and distribution pattern are becoming one of research hotspots in ecology under global climatic change. Understanding the effects of environmental factors on the spatial pattern of biomass C storage is essential to understand the relationship between global climate change and forest C sink. Although biotic and abiotic heterogeneity play important roles in shaping the distribution of forest C storages, few studies considered their influence process, resulting that the underlying mechanisms have not been revealed. The present study will be carried out based on census data of the 25-ha Baotianman Forest Dynamics Plot (BFDP). The indices of biotic and abiotic factors in BFDP will be obtained by incorporating both mechanical and random sampling methods. The Structural Equation Models (SEM) will be used to quantify the roles of biotic and abiotic factors for above- and below- ground biomass C storage distributions, by combining new environmental factors (i.e. light and soil) with the existing data of topography, species, community, phylogeny, diameters at breast height (DBH), heights and allometric equations for tree species of BFDP together. Other advanced statistic methods such as Canonical Correspondence analysis (CCA), Multivariate Regression Tree (MRT), Torus-translation, variance decomposition, Principal Coordinates of Neighbor Matrices (PCNM) and Generalized Least Squares (GLS) model, will also be used to analyze the processes and influences of different factors on biomass C storage. We will also explore the extent to which complementary and selection effect mechanisms can explain the combined biotic and abiotic effects on biomass C storage distribution of the BFDP. Finally, we will try to elucidate the underlying mechanisms of biomass C storage distribution patterns in BFDP. This project could provide valuable theoretical insights for forest C sink increment and ecological management.

全球气候变化背景下，森林植被碳库及其分布格局成为生态学研究热点之一，明确现阶段环境因子对森林植被碳库分布格局的影响，是理解全球气候变化与森林植被碳汇关系的重要前提。森林植被碳库分布格局受到生物因子和非生物因子异质性的影响，但相关研究较少涉及影响过程，导致其影响机制仍未被阐明。本项目拟基于25-ha宝天曼森林监测样地平台，采用机械布点与随机布点相结合的方法布设测定和取样点，获取环境因子数据。结合已有的地形、物种、群落、谱系和异速生长方程等数据，通过结构方程模型(SEM)量化不同生境中生物和非生物因子对地上和地下植被碳库分布格局的影响和相互作用的强度；采用多元统计分析方法揭示各因子对植被碳库分布格局造成的影响，验证补偿效应和选择效应对物种多样性和植被碳库关系的适用性，明确植被碳库分布格局的形成机制。本项目研究结果将为森林碳增汇和生态系统管理提供重要理论依据。

森林植被碳库及其分布格局是当前全球变化背景下生态学研究的热点。森林植被碳库分布格局受到生物因子和非生物因子异质性的影响，阐明其影响机制是理解全球气候变化与森林植被碳汇关系的重要前提。本项目按照计划书开展工作，基于25-ha宝天曼森林监测样地平台，采用机械布点与随机布点相结合的方法布设测定和取样点，获取环境因子数据。结合地形、物种、群落、谱系和异速生长方程等数据，通过结构方程模型(SEM)量化生物和非生物因子对植被碳库分布格局的影响，揭示碳库格局形成机制。结果表明宝天曼落叶阔叶林凋落物含水率、土壤含水率、SOM和LAI的空间分布格局具有强烈异质性，并有沿样地东北-西南向梯度变化的趋势；基于MRT法将宝天曼25-ha 落叶阔叶林样地(宝天曼样地)划分为5种生境类型：普通山谷(Hab1)、西北向山谷(Hab2)、缓坡(Hab3)、高海拔陡坡(Hab4)和低海拔陡坡(Hab5)；5种生境类型的总植被碳库分别为77.34, 82.47, 86.24, 84.98和85.16 t/ha，根冠比分别为0.270, 0.259, 0.293, 0.262和0.271；不同物种对各生境植被碳库的贡献率存在较大差异，表现出强烈的生境依赖性，且地下植被碳库的分配格局也能准确地体现植被总碳库的环境依赖性；植被碳库主要由大树的多度决定，而与小树的多度关系不大；各生境地上、地下和总生物量一定程度上表现出系统发育信号(K)，根冠比的系统发育信号明显弱于生物量。地下植被碳库的生境依赖性更容易受到系统发育历史的影响，系统发育亲缘关系较近物种的共存一定程度上可以促进某些生境植被碳库的增加；SEM结果表明非生物因子通过物种和群落间接决定植被碳库分布格局，系统发育的作用被弱化，互补效应和选择效应两种机制在植被碳库格局形成过程中同时起作用。本项目研究结果为森林碳增汇和生态系统管理提供重要理论依据。在该项目的支持下，目前发表论文4篇（SCI论文1篇），出版译著1部。拟投SCI论文1篇。项目执行期间，培养研究生2名，本科生4名，获批横向科研课题两项。