Recruitment Limitation, Resource-Based Niches, and the Maintenance of Tropical Tree Diversity

0075472科比这项建议提出了一套综合的野外实验和模型分析，以评估招募限制和基于资源的生态位对维持潮湿热带森林树种多样性的相对影响。这项提案的一个特别重点是土壤资源(水和矿物养分)，因为强有力的间接证据证明有必要审查它们在热带森林社区动态中的作用。拟议的方案涉及两套能够维持高度物种多样性的机制。首先，热带树种招募在多大程度上是有限的？物种在招募限制上有差异吗？第二，热带树种是否划分了资源可获得性的梯度？具体地说，土壤资源和光照对特定物种的幼苗存活和生长有什么影响？物种在低土壤资源下生存的能力与在高土壤资源下快速生长的能力之间是否存在权衡。物种在殖民潜力(繁殖力和分散度)与竞争能力(基于资源的生长和生存)之间是否存在权衡，这是维持多样性的基础？为了解决这些问题，将在哥斯达黎加的La Selva生物站进行实地和实验研究，建立苗木生产和传播以及苗木生长和存活的特定物种子模型。这项研究将有助于理解热带森林树种多样性高的机制。它将从苗木生产和传播的角度描述后代招募的特征，与种子诱捕器研究相比，这对分散在动物中的物种的偏见较小，并提供更强大的样本量来严格测试招募潜力。这项研究还测试了土壤资源和光照对特定物种幼苗存活和生长的影响。最后，这项研究将结合经验结果来评估招募限制与基于资源的生态位对维持热带树木多样性的相对重要性。

0075472KobeThis proposal presents an integrated set of field experiments and model analyses to evaluate the relative influences of recruitment limitation and resource-based niches on the maintenance of tree species diversity in wet tropical forests. A particular focus of this proposal is soil resources (water and mineral nutrients), because strong indirect evidence warrants an examination of their role in the dynamics of tropical forest communities. The proposed addresses two sets of mechanisms that could enable the maintenance of high species diversity. First, to what extent are tropical tree species recruitment limited? Do species differ in recruitment limitation? Second, do tropical tree species partition gradients of resource availability? Specifically, what is the influence of soil resource and light availability on species-specific seedling survivorship and growth? Is there a trade-off among species in the ability to survive under low soil resources versus rapid growth under high soil resources. Is there a trade-off among species in colonization potential (fecundity and dispersal) versus competitive ability (resource based growth and survivorship), which underlies the maintenance of diversity? To address these questions, species-specific sub-models of seedling production and dispersal, and seedling growth and survival will be developed from field and experimental studies at La Selva Biological Station in Costa Rica. This study will contribute to understanding the mechanisms that lead to high tree species diversity in tropical forests. It will characterize offspring recruitment in terms of seedling production and dispersion, which in comparison to seed trap studies, is less biased against animal dispersed species and provides more robust sample sizes to rigorously test recruitment potential. The study also tests the influence of soil resources and light availability on species-specific seedling survivorship and growth. Finally, the research will integrate empirical results to assess the relative importance of recruitment limitation versus resource-based niches to the maintenance of tropical tree diversity.