U.S.-Mexico Collaborative Studies on Determinants of Distribution in Piper Species from a Tropical Rain Forest

该奖项将支持华盛顿卡内基学院的Christopher B.field教授和加州大学戴维斯分校的Robert W.Pearcy教授与墨西哥国家自治大学(UNAM)的Carlos Vasquez-Yanes教授合作进行研究。研究人员打算对生长在墨西哥韦拉克鲁斯“Los Tuxtlas”生物保护区的胡椒属植物的热带雨林植物生态学的两个重要但鲜为人知的方面进行实验。这些实验是对多个物种进行比较，利用原生于光照条件不同的栖息地的胡椒物种。其中一组实验侧重于植物幼苗期的生理生态，这一阶段的特点是死亡率高，但人们对此知之甚少。在不到几个月和不到10厘米高的植物上，他们打算研究生长速度的功能决定因素，包括生物量分配、矿物质营养、光合作用和组织构建成本。另一组实验研究波动光中的光合作用和蒸腾作用。众所周知，波动光利用效率的变化对几个物种的碳平衡具有重要影响。在一个系统中还没有研究过波动光的利用，在这个系统中，对生长的其他功能决定因素也像在胡椒属中那样被很好地理解。拟议的研究将继续发展胡椒属作为一个模式系统，以了解控制热带雨林植物分布的机制。由于两国主要调查人员之间长期的正式和非正式互动，合作的大部分基础设施已经建立。强调一个被广泛研究的模型系统应该会产生很高的回报，因为生态学中的许多问题只有通过整合关于有机体生物学的多个方面的信息才能得到回答。

This award will support Professor Christopher B. Field of Carnegie Institute of Washington and Professor Robert W. Pearcy of the University of California at Davis in a research collaboration with Professor Carlos Vasquez-Yanes of the Universidad Nacional Autonoma de Mexico (UNAM). The researchers intend to carry out experiments on 2 important but poorly understood aspects of the ecology of rainforest plants in the plant genus Piper, growing in the "Los Tuxtlas" biological preserve, in Veracruz, Mexico. The experiments are multi-species comparisons utilizing Piper species native to habitats of contrasting light availability. One group of experiments focuses on the physiological ecology of plants at the young seedling stage, a stage characterized by high mortality, but about which little is known. On plants less than a few months old and less than 10 cm tall, they intend to study the functional determinants of growth rate, including biomass allocation, mineral nutrition, photosynthesis, and tissue construction costs. The other group of experiments explores photosynthesis and transpiration in fluctuating light. Variation in the efficiency of utilizing fluctuating light is known to have important consequences for carbon balance for several species. The utilization of fluctuating light has not been studied in a system where other functional determinants of growth are as well understood as in the genus Piper. The proposed research will continue to develop the genus Piper as a model system for understanding the mechanisms controlling the distributions of tropical rainforest plants. Much of the infrastructure for the collaboration is already established, as a result of long-standing formal and informal interactions among the principal investigators in both countries. The emphasis on a widely studied model system should yield high returns because many questions in ecology can be answered only through the integration of information concerning multiple aspects of an organism's biology.