基于植物功能性状及谱系关系研究南亚热带森林群落稀有种的维持机制

Niche differentiation has been proposed as an explanation for rarity in species assemblages based on niche theory but been challenged by neutral theory. To test this hypothesis requires quantifying and comparing the species dissimilarities between groups of rare and common species. Species dissimilarity can potentially be estimated by using functional distinctiveness and evolutionary distinctiveness, which are defined by species functional traits and phylogenetic relatedness, respectively. In this present proposal, we predict that if niche differentiation does explain the co-occurrence of rare and common species, the functional/evolutionary distinctiveness of rare species should be significantly different from that of common species. We aim to test this hypothesis by using the data of a 20 ha permanent subtropical forest plot (Dinghu Mountain) in Guangdong Province. First, by measuring the functional traits (morphological, physiological and phonological) of each species, we can determine the key traits that affect the relative abundance of species in the forest. Second, we will measure the species dissimilarity of each species by functional/evolutionary distinctiveness. Finally, we will develop two novel methods that integrate species rank-abundance distribution with species dissimilarity and trend analysis to compare the species dissimilarities between the groups of rare and common species. The major objective of this project is to reveal the role of species dissimilarity in the maintenance of rare species and provide a scientific basis for the conservation of rare species in subtropical forests.

经典生态位理论认为物种差异是群落物种相对多度格局维持的重要机制，而群落中性理论则认为随机性过程决定群落中物种的相对多度。因此，物种差异是否在稀有种的形成与维持方面具有重要作用是经典生态位理论和中性理论的主要分歧。检验这个假说的关键在于量化和比较稀有种与常见种的物种差异，而物种差异可由功能性状以及谱系独特性来表征。因此，本项目拟以南亚热带鼎湖山20公顷永久常绿阔叶林大样地为研究对象，通过测量物种的功能性状（包括形态学、生理生态及物候性状）及其谱系关系，找出影响物种相对多度的关键性状，计算每个物种在群落中的功能性状/谱系独特性。结合物种多度分布与物种功能性状/谱系关系，本项目提出了两种比较稀有种与常见种之间的物种差异的方法，以期揭示物种差异对南亚热带常绿阔叶林稀有种的维持机制，为深入研究森林群落物种共存和生物多样性保育提供科学依据。

稀有种的形成和维持机制，是群落生态学的核心问题之一，也是生物多样性保育及持续利用中必不可少的理论基础和科学依据。生物多样性的维持本质上是延缓稀有种的灭绝。本项目通过南亚热带森林中稀有种与常见种的功能独特性、谱系独特性和植物间正相互作用的相对重要性，探讨生态位差异和种间相互作用在稀有种形成和维持中的作用。我们以广东省鼎湖山国家级自然保护区的南亚热带常绿阔叶林为主要研究对象，结合了野外群落学调查和理论分析相结合的方式，揭示了南亚热带森林中稀有种相对于常见种对功能多样性和谱系多样性具有更大的贡献，而常见种则在植物间相互作用中获益更多。研究结果强调了生态位分化和植物间正相互作用对稀有种形成和维持的作用。本项目的研究结果不仅完善了现有的物种共存和生物多样性维持理论，还为南亚森林生物多样性保育和恢复提供了重要的理论基础。

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