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决定自然群落中植物物种数量和相对丰度的机制。这一挑战在潮湿的热带森林中尤为严重，因为热带森林是全球物种多样性最高的生态系统。所有的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。幼苗是一个至关重要的阶段，它给森林的物种组成留下了深刻的印记，从林下到树冠。植物，特别是树木的寿命比人类长得多，森林的动态变化在更长的时间尺度上发挥作用，因此需要长期数据来捕捉短期研究可能错过的重要事件（例如，某些物种可能每12年产生一次种子）。该提案将延长哥斯达黎加5个森林林分约7年的幼苗调查记录，目标是根据不同物种的幼苗如何在光照、土壤肥力和天敌的影响下生长和存活，建立森林模型。更好地了解控制树种相对丰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，已知需要再生的外来树种经常被用于重新造林，因为潜在有用的本地树种并不为人所知，这项研究将有助于弥补这一知识差距。研究结果和数据将通过项目网站与公众和其他科学家共享。

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.