LTREB: Woody Seedling Dynamics in a Wet Tropical Forest: Mechanisms of Species Co-existence

生态学中的一个主要挑战是了解是什么决定了自然群落中植物物种的数量和相对丰富度。这一挑战在潮湿的热带森林中尤其令人望而生畏，因为它是世界上所有生态系统中物种多样性最高的地方。植物生命周期的苗期对病原体以及光、养分和水的可用性特别敏感。在这个关键阶段发生的事情在森林物种组成上留下了深刻的印记，从林下到树冠。树木的寿命可能比人类长得多，森林的动态表现在更长的时间尺度上；因此，有必要进行长期数据收集，以捕捉短期研究可能遗漏的重要事件(例如，某些物种的种子生产可能每12年发生一次)。这项提议将延长哥斯达黎加五个林场苗木调查的~8年记录，目标是开发森林更新的关键方面(苗木生产、扩散、生长和死亡)的森林模型，以应对光线、土壤肥力和天敌。更好地了解控制树种相对丰度的因素将有助于预测森林对人类影响的反应，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，外来树种经常被用于重新造林，因为当地树种的更新要求不是很清楚，这项研究将有助于弥补这一知识鸿沟。作为该项目的一部分，K-6年级的学生将在密歇根州种植植物，以了解在所有陆地生态系统(从农田到潮湿的热带森林)中运行的生态过程。研究结果、数据和在线鉴定工具将通过一个项目网站与公众和其他科学家共享。

A major challenge in ecology is to understand what determines the number and relative abundance of plant species in natural communities. This challenge is especially daunting in wet tropical forests, which harbor the highest species diversity of any ecosystem in the world. The seedling phase of a plant's life cycle is especially sensitive to pathogens and to the availability of light, nutrients, and water. What happens during this critical stage impresses a signature on forest species composition, from the understory to the canopy. Trees can live for much longer than humans and the dynamics of forests play out over even longer time scales; therefore, long-term data collection is necessary 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 an ~8 year record of seedling surveys in five forest stands in Costa Rica, with the goal of developing forest models of critical aspects of forest regeneration (seedling production, dispersion, growth and mortality) in response to light, soil fertility, and natural enemies. A better understanding of the factors that govern the relative abundance of tree species will aid in predicting 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 often are used for reforestation because the regeneration requirements of native species are not well known, a knowledge gap that this research will help remedy. As part of this project, K-6 students will be growing plants in Michigan to learn about ecological processes that operate in all terrestrial ecosystems (from agricultural fields to wet tropical forest). Research results, data, and on-line identification tools will be shared with the public and other scientists through a project website.