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道格拉斯J. Levey教授和刚果共和国布拉柴维尔马里安Ngouabi大学Jean玛丽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补充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。通过控制更具竞争力的物种的种群数量和减缓竞争排斥，招募限制应该允许更多的物种共存。种子限制假说假定植物在一个地点的补充能力取决于种子的可用性。因此，在群落一级，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成员。建立限制假说假定，招聘是有限的，由合适的微型网站的建立。为了通过实验检验种子的相对重要性和建立限制，该项目在刚果共和国的已采伐和未采伐森林中建立了30.1公顷的地块，绘制了所有树木和树苗的地图并进行了识别，测量了种子雨，并在所有地块的90个子地块中为随机选择的6个树种进行了种子添加实验。正在收集关于种子捕食、出苗、幼苗生长和存活以及可能影响种子数量和定居限制的若干非生物和生物因素的数据。该项目已进入第三个年头，该奖项将支持返回刚果监测实验，并与大学合作者合作，以完成幼苗，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和一家主要伐木公司刚果木材工业公司的合作，正在改善森林管理。WCS和CIB正在共同努力，改善努瓦巴莱恩多基国家公园周围大型伐木特许区的林业和野生动物管理，希望到2009年实现森林管理理事会（FSC）对180万公顷毗连森林的认证。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合作，为刚果学生（迄今已培训了13名学生）提供野外植物学强化课程。在这项研究中收集的树木标本将捐赠给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进行的，共同主要研究者已被培训为“第一反应者”，并参加了WCS的“实地审查”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爆发的计划。为了确保特许经营区的人类掌握保护自己和家人所需的信息，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意识运动的一部分。

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.