LTREB: Long-Term Woody Seedling Dynamics in a Wet Tropical Forest: Mechanisms of Species Co-Existence

生态学的一个主要挑战是了解自然群落中植物物种数量和相对丰度的决定机制。这一挑战在潮湿的热带森林中尤为严峻，因为那里拥有全球任何生态系统中最高的物种多样性。所有植物最终都是从幼苗开始生命的，这一阶段对病原体以及光、营养和水的可用性特别敏感。幼苗是一个关键阶段，它在森林的物种组成上留下了印记，从林下到树冠。植物，特别是树木，可以比人类活得更长，森林的动态在更长的时间尺度上发挥作用，需要长期数据来捕捉短期研究会错过的重要事件（例如，有些物种每12年产生一次种子）。该提案将延长哥斯达黎加5个林分的幼苗调查的7年记录，其目标是根据不同物种的幼苗如何生长和存活以响应光照、土壤肥力和天敌来开发森林模型。 更好地了解决定树种相对丰富度的因素不仅是一项学术工作，而且对于预测森林对人类影响的反应至关重要，包括大气中氮，硫和其他化学污染物的沉积。此外，在热带地区，已知再生要求的外来树种通常用于重新造林，因为潜在有用的本地物种并不为人所知，这项研究将有助于弥补知识差距。研究结果和数据将通过项目网站与公众和其他科学家分享。

A major challenge in ecology is to understand the mechanisms that determine the number and relative abundance of plant species in natural communities. This challenge is particularly extreme in wet tropical forests, which harbor the highest species diversity of any ecosystem globally. All plants ultimately start life as a seedling, a phase that is especially sensitive to pathogens and to the availability of light, nutrients, and water. Seedlings are a critical stage, one that impresses a signature on the species composition of forests, from the understory to the canopy. Plants, and especially trees, can live for much longer than humans and the dynamics of forests play out over even longer times scales, necessitating long-term data to capture important events that would be missed by short-term studies (e.g., seed production may occur every 12 years for some species). This proposal will extend a ~7 year record of seedling surveys in five forest stands in Costa Rica, with the goal of developing forest models based upon how seedlings of different species grow and survive in response to light, soil fertility, and natural enemies. A better understanding of the factors that govern the relative abundance of tree species is not merely an academic exercise but is critical to predict forest responses to human influences, including the deposition of nitrogen, sulfur, and other chemical pollutants from the atmosphere. Furthermore, in tropical areas, exotic tree species of known regeneration requirements often are used for reforestation because potentially-useful native species are not well known, a knowledge gap that this research will help remedy. Research results and data will be shared with the public and other scientists through a project website.