负密度制约和生境过滤对古田山幼苗功能多样性年际变化的影响

Effects of negative density dependence and habitat filtering on the functional diversity of seedlings in the subtropical forest of Gutianshan

生物多样性的维持机制一直是群落生态学研究的核心内容。目前利用负密度制约和生境过滤分别解释群落多样性空间分布格局的研究较多,但结合这两种机制来解释功能多样性格局年际变化的研究还很少。本文以古田山亚热带常绿阔叶林24 ha动态监测样地的木本植物幼苗为研究对象,利用2006年和2007年的幼苗动态监测数据,比较了幼苗功能α和β多样性随时间推移而变化的趋势。结果表明:2006–2007年间,随着时间的变化,幼苗群落内与木质密度、比叶面积、叶片氮含量、叶片磷含量4种功能性状相关的功能α多样性显著增加,与气孔密度相关的α多样性变化不显著;幼苗群落间基于5种功能性状的β多样性均呈显著增加趋势。综合分析表明,负密度制约能够促进古田山木本植物幼苗群落内的功能α多样性,而生境过滤只能在一定程度上解释群落的功能β多样性。该结论还需要更长期的调查数据来验证。

How forest communities maintain their biodiversity has been challenged ecologists during the last few decades. Negative density-dependence and habitat filtering have been proposed as key players in community assembly. However, few studies have explored how negative density dependence and habitat filtering impact seedling dynamics over time. To test the relative roles of these two mechanisms in community assembly, we analyzed the temporal trends of functional α and β diversity in seedling communities in the 24 ha Gutianshan forest dynamics plot during 2006–2007. We found that functional α diversity within communities significantly increased over time except for functional α diversity associated with stomatal density. Functional β diversity significantly increased with time for five traits（such as wood density, specific leaf area, leaf nitrogen content, leaf phosphorus content and stomatal density） between communities. Our results suggest that negative density dependence can promote functional α diversity at local scales, while habitat filtering can partly explain functional β diversity.