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

康妮·克拉克女士将在佛罗里达大学的道格拉斯·J·利维教授和刚果共和国布拉柴维尔马里恩·恩古阿比大学的让·玛丽·穆特萨博特教授的指导下，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。智慧的优点：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，限制新个体进入种群的过程是维持物种多样性的关键。通过控制更具竞争性的物种的种群数量和减缓竞争排斥，补充限制应该允许更多的物种共存。种子限制假说认为，植物在某一地点招募的能力取决于种子的可获得性。因此，在群落层面上，物种的丰度和分布是由“抽签”过程决定的--从碰巧到达某个地点的种子中随机抽取新兵。建立限制假说假定招募受限于可用于建立的合适的微站点。为了从实验上检验种子和建立限制的相对重要性，该项目在刚果共和国的伐木和未砍伐森林中建立了30个1公顷的样地，绘制和识别了所有树木和树苗，测量了种子雨，并在所有样地的90个子样地中随机选择了6个树种进行了种子添加试验。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个非生物和生物因素的数据。该项目进入第三个年头，该奖项将支持返回刚果监测实验，并与大学合作者合作，最终完成苗木、树苗和树木凭证标本的物种鉴定。更广泛的影响：通过该项目与野生动物保护协会(WCS)和一家大型伐木公司--刚果工业公司(CIB)的合作，正在改善森林管理。WCS和CIB正在共同努力，改善Nouabale Ndoki国家公园周围大型采伐特许权的林业和野生动物管理，希望到2009年实现180万公顷连续森林的森林管理委员会(FSC)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(迄今已培训了13名学生)提供了强化实地植物学课程。在这项研究中收集的凭证标本将被捐赠给RBG，以制作刚果树木的野外指南，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爆发的高风险地区进行的，联合PI已被培训为“第一反应人员”，并参与了WCS的“现场兽医”计划，以监测和控制在发现多具灵长类动物身体的地区爆发的野生动物疾病。为了确保特许区的人们获得保护自己和家人的必要信息，该项目的参与者是针对最有可能接触病毒的村民的埃博拉宣传活动的一部分。

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.