Pattern of Tropical Forest Succession Subsequent to Hurricane Damage

1988年，飓风琼严重破坏了尼加拉瓜东海岸大片热带雨林。这项提议旨在继续进行一项为期12年的研究，研究飓风过后受损地区的森林演替情况。自飓风以来，森林发生了重大变化，目前正进入一个关键的变薄（死亡）阶段。在这个节骨眼上，它是必不可少的，以确定是否个别树木死亡随机相对于他们的物种身份。这个问题是相关的热带雨林物种多样性的维护最近的理论，并代表了一个潜在的重要贡献，了解种间树木的竞争是如何与冠层生长在这样的森林。这是一个重要方面的中性理论，死亡事件在间伐冠层随机发生在行业内的树种。理论的一部分假设，第一，招聘和增长到间伐冠层是随机的，第二，随后的死亡率从间伐冠层也是随机的（相对于物种身份）。根据一些分析，即使偏离这一关键假设很小，也可能产生严重后果。将通过每年监测9个永久地块中的所有树木和大树苗来收集数据。智力上的优点。本研究将有助于澄清基于演替状态的生态物种集团的定义。“生态位”模型是中性模型的替代，它表明，随着稀疏化的进行，一些物种将更有可能在稀疏化过程开始时死亡，而另一些物种将在稀疏化过程结束时死亡。最近的理论强调可能的殖民竞争权衡，其中物种被放置在一个连续体之间的穷人竞争者/好殖民者和好竞争者/穷人殖民者。大多数中立理论的支持者会认为，中立性适用于树种行业协会（先驱者，原始森林物种和中间物种），而不是在这些行业协会中，因为只有少数行业协会，某种形式的中立性可能是主导力量。或者，生态位理论的支持者会认为，对先驱者和非先驱者的模糊划分只是一个初步的粗略划分，更精细的划分不仅是可能的，而且可以解释物种共存的大部分原因。虽然理论已经发展到处理这些演替生态位的更完整的划分，到目前为止，这些想法所依据的数据并不完全令人满意。大约有100名圭亚那人、4名哥斯达黎加人和30名北美人（主要来自密歇根大学、胡德学院和圭尔夫大学）的研究生和本科生参加了该项目的数据收集工作。除了项目的直接实地工作外，还鼓励所有学生开发与一般主题相关的个人项目。在实地活动之前，参与的学生将获得为期一周的生物多样性，森林自然历史，基本生态理论和实地研究方法的强化课堂和实验室课程，由PI，co-PI和参与合作者（包括密歇根州的研究生）通过波多黎各加勒比海岸自治区大学（URACCAN）教授。部分由于这一研究项目及其教学价值，URACCAN建立了自然资源，环境和可持续发展研究所（IRENMADES），该研究所现在赞助这些年度实地课程，其中包括继续进行这项研究的两个地点。1996年，该小组因该国自然资源方面的最佳研究项目而获得哥伦比亚Sempervirens奖。已经用当地语言制作了各种实地指南和附有插图的通俗小册子，用于环境教育。

Hurricane Joan severely damaged an extensive area of tropical rain forest on the easternseaboard of Nicaragua in 1988. This proposal seeks to continue a twelve-year study on post hurricane forest succession in the damaged area. Since the hurricane the forest has undergone significant changes and is now entering a critical as thinning (mortality) stage. At this juncture it is essential to determine whether individual trees die at random with respect to their species identity. This question is relevant to recent theories of the maintenance of species diversity in tropical rain forests and represents a potentially important contribution to the understanding of how interspecific tree competition is related to canopy growth in such a forest. It is a crucial aspect of Neutrality Theory that mortality events in the thinning canopy happen randomly within guilds of tree species. Part of the theory supposes first, that recruitment and growth into the thinning canopy is at random and second, that subsequent mortality from the thinning canopy is also random (with respect to species identity). According to some analyses, even small deviations from this critical assumption may have dramatic consequences. Data will be collected by yearly monitoring of all trees and large saplings in nine permanent plots. Intellectual merit. This research project will help to clarify the definitions of ecological species guilds based on successional status. "Niche-based" models, alternative to the neutrality models, suggest that as thinning proceeds, some species will be more likely to die at the beginning of the thinning process and others will do so at the end of that process. Recent theory emphasizes the probable colonization-competition tradeoff, in which species are placed on a continuum between poor competitors/good colonizers and good competitors/poor colonizers. Most proponents of neutrality theory would argue that it is within tree species guilds (pioneers, primary forest species and intermediates), not among such guilds, that neutrality applies, and since there are only a few guilds, some form of neutrality is likely to be a dominant force. Alternatively, proponents of niche-based theory would argue that the faint division into pioneers and non-pioneers is only an initial rough cut and that finer divisions are not only possible, but also explain much of species coexistence. While theory has been developed to treat a more complete division of these successional niches, thus far the data on which these ideas are based are not quite fully satisfying.Broader impacts. Approximately 100 Nicaraguan, four Costa Rican, and 30 North American (mainly from the University of Michigan, Hood College, and University of Guelph) graduate and undergraduate students have participated in data gathering for this project. In addition to the direct field work on the project, all students are encouraged to develop their own individual projects related to the general subject matter. Prior to field campaigns, participating students are provided with an intensive one-week classroom and lab course in biodiversity, forest natural history, basic ecological theory, and field research methods, taught by PI, co-PI and participating collaborators (including graduate students at Michigan) through the University of the Autonomous Regions of the Nicaraguan Caribbean Coast (URACCAN). Partly as a result of this research project and its teaching value, URACCAN developed their Institute of Natural Resources, Environment and Sustainable Development (IRENMADES)which now sponsors these yearly field course, and which includes the two sites at which this research continues. In 1996 the group received the Nicaraguan Sempervirens Award for the best research project on natural resources in the country. Various field guides and illustrated popular pamphlets have been produced in local languages for use in environmental education.