US-Republic of Congo (Brazzaville) Dissertation Enhancement: What Limits Recruitment of Tropical Trees? An Experimental Test of Seed and Establishment Limitation

Connie J. Clark女士将在佛罗里达大学的Douglas J. Levey教授和刚果共和国布拉柴维尔的Marien Ngouabi大学的Jean Marie Moutsabote教授的指导下在刚果共和国进行论文研究。她的研究将包括通过招募限制来确定热带树木的多样性，同时使用种子限制假说和建立限制假说。智力优势：热带森林占所有已知物种的近50%。然而，人们对维持或促进这种多样性的过程知之甚少。理论模型表明，限制新个体加入种群的过程是维持物种多样性的关键。通过控制更具竞争力的物种的种群数量，减缓竞争排斥，限制招募应该允许更多的物种共存。种子限制假说认为植物在一个地点招募的能力是由种子的可用性决定的。由此可见，在群落水平上，物种的丰度和分布是由“抽签”过程决定的——新物种是从碰巧到达一个地点的种子中随机抽取的。设立限制假说认为，招聘受到适当设立地点的限制。为了实验测试种子的相对重要性和种植限制，该项目在刚果共和国砍伐和未砍伐的森林中建立了30,1公顷的样地，绘制和鉴定了所有树木和树苗，测量了种子雨，并在所有样地的90个子样地对随机选择的6种树种进行了种子添加实验。正在收集有关种子捕食、幼苗出苗、幼苗生长和存活以及可能影响种子数量和建立限制的几种非生物和生物因素的数据。该项目已进入第三个年头，这笔奖金将用于支持返回刚果监测实验，并与大学合作者合作，最终确定幼苗、树苗和树木凭证标本的物种。更广泛的影响：通过与野生动物保护协会（WCS）和一家大型伐木公司刚果林业工业公司（CIB）的合作，该项目正在改善森林管理。WCS和CIB正在共同努力，改善努阿巴莱恩多基国家公园周围大型伐木特许权的林业和野生动物管理，希望到2009年实现森林管理委员会（FSC）对180万公顷连片森林的认证。该项目的另一个目标是提高刚果科学家和资源管理人员的技术能力。该项目还与皇家植物园（RBG）合作，为刚果学生提供实地植物学强化课程（迄今已培训13名学生）。在这项研究中收集的代金券标本将捐赠给RBG，用于制作刚果树木的实地指南，这将为刚果植物学家提供极好的资源。由于该项目是在埃博拉疫情的高风险地区开展的，因此该项目负责人接受了作为“第一响应者”的培训，并参加了WCS“现场兽医”计划，在发现多具灵长类动物尸体的地区监测和控制野生动物疾病暴发。为了确保特许权内的居民掌握必要的信息，以保护自己和家人，本项目的参与者是针对最容易接触该病毒的村民开展的埃博拉宣传运动的一部分。

Ms. Connie J. Clark will conduct dissertation research in the Republic of the Congo under the supervision of Professor Douglas J. Levey of the University of Florida, and Professor Jean Marie Moutsabote of the Université Marien Ngouabi of Brazzaville, Republic of the Congo. Her research will consist of determining tropical tree diversity through recruitment limitation, using both the seed limitation hypothesis and the establishment limitation hypothesis.Intellectual Merit: Tropical forests account for nearly 50% of all known species. Yet, very little is understood about the processes that maintain or promote such diversity. Theoretical models suggest that processes limiting recruitment of new individuals into populations are key to maintaining species diversity. By keeping population numbers of more competitive species in check and slowing competitive exclusion, recruitment limitation should allow greater numbers of species to co-exist. The seed limitation hypothesis posits that the ability of a plant to recruit at a site is determined by the availability of seeds. It follows that at the community level the abundance and distribution of a species is determined by a "lottery" process -- recruits are drawn at random from the seeds that happen to arrive at a site. The establishment limitation hypothesis posits that recruitment is limited by the availability of suitable microsites for establishment. To experimentally test the relative importance of seed and establishment limitation, this project has established 30, 1-ha plots in logged and unlogged forests in the Republic of Congo, mapped and identified all trees and saplings, measured seed rain, and conducted seed addition experiments for six randomly-selected tree species in 90 subplots in all plots. Data are being gathered on seed predation, seedling emergence, seedling growth and survival, and several abiotic and biotic factors that likely influence the magnitude of seed and establishment limitation. The project is entering its third year and this award will support return trips to Congo to monitor the experiment and work with University collaborators to finalize species identification of seedlings, saplings and tree voucher specimens. Broader Impacts: Improved forest stewardship is being achieved through the project's collaboration with the Wildlife Conservation Society (WCS) and a major logging company, Congolaise Industrielle des Bois (CIB). WCS and CIB are working together to improve forestry and wildlife management in large logging concessions surrounding Nouabale Ndoki National Park, hoping to achieve Forest Stewardship Council (FSC) certification of 1.8 million hectares of contiguous forest by 2009. Another goal of the project is to improve the technical capacity of Congolese scientists and resource managers. In collaboration with the Royal Botanical Gardens (RBG), the project also provides an intensive field botany course for Congolese students (13 students trained to date). Voucher specimens collected during this study are being donated to the RBG to produce a field guide to the trees of Congo, which will provide an excellent resource to Congolese botanists.Because this project is being conducted in a high risk area for Ebola outbreaks, the co-PI has been trained as a "first responder" and participates in the WCS "field vet" program to monitor and control wildlife disease outbreaks in areas where multiple carcasses of primates are found. To assure humans in the concessions are armed with the information necessary to protect themselves and their families, participants in this project are part of an Ebola awareness campaign directed toward villagers most at risk of exposure to the virus.