Collaborative Research: Natural Disturbance and Human Land-Use as Determinants of Tree Community Dynamics in a Subtropical Wet Forest

人为和自然干扰都可能在调节热带森林树种多样性方面发挥重要作用。开垦农业是热带地区最常见的人类干扰形式之一，而飓风对加勒比地区的森林构成最大的自然干扰威胁。为了调查人类和飓风干扰在热带森林中的相对重要性，调查人员将对16公顷的卢基洛森林动态地块(LFDP)中所有树木的直径、物种和位置进行普查。人口普查结果将与1990年、1995年和2000年进行的前几次人口普查进行比较。在1934年之前，LFDP的一部分被用于农业，飓风雨果(1989)和乔治(1998)都造成了相当大的破坏。四次人口普查的数据加在一起，将使我们能够对比经历了非常不同的飓风干扰模式的间隔期间的树木种群动态，以及具有不同农业土地使用历史的部分森林。我们将对普查数据进行新的分析，使用似然方法来研究森林内树木的空间配置和飓风干扰模式如何改变最常见树种的动态。未来的工作将使用森林模拟模型来整合我们的结果。我们的研究产生了更广泛的影响，包括作为热带森林科学中心的一部分，为全球热带林地网络做出贡献。这一网络一直是生态学家试图了解热带森林结构和功能的核心。我们的研究还将开发分析热带森林长期数据的新方法--这些方法可以在整个网络中得到更广泛的应用。该项目将为一大批热带生态学本科生，特别是少数民族学生提供研究经验。

Both human and natural disturbance may play an important role in regulating the diversity of tree species in tropical forests. Clearing for agriculture represents one of the most common forms of human disturbance in the tropics, while hurricanes pose the greatest threat of natural disturbance for forests of the Caribbean. To investigate the relative importance of human and hurricane disturbance in tropical forests the investigators will conduct a census of the diameter, species and location of all trees in the 16 hectare Luquillo Forest Dynamics Plot (LFDP). The census results will be compared with previous censuses taken in 1990, 1995 and 2000. A portion of the LFDP was used for agriculture prior to 1934, and Hurricanes Hugo (1989) and Georges (1998) both caused considerable damage. Together, data from the four censuses will allow us to contrast tree population dynamics during intervals that have experienced very different patterns of hurricane disturbance, and for parts of the forest with different agricultural land use histories. We will develop new analyses of the census data, using likelihood methods to examine how the spatial configuration of trees within the forest and patterns of disturbance by hurricanes change the dynamics of the most common tree species. Future work will integrate our results using a forest simulation model. The broader impacts of our research include contributing to the global network of tropical forest plots as part of the Center For Tropical Forest Science. This network has been central to the attempts of ecologists to understand the structure and function of tropical forests. Our research will also develop new methods for the analysis of long-term data in tropical forests - these methods can then be used more widely across the network. The project will provide research experience for a large number of undergraduate and particularly minority students in tropical ecology.