Individual function and community processes in desert annuals

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。该项目将研究索诺兰沙漠冬季一年生植物的生理，以深入了解它们的种群和群落动态，以及物种在高多样性下共存的机制。一年生植物是干旱地区的主要组成部分，那里的降水既少又多变。植物以一种有助于物种共存的方式对这种可变性作出不同的反应。物种以不同的方式权衡最大生长速率以获得有效的水利用，从而产生不同的种群动态。研究表明，该群落中有效利用水分的物种具有较低的光合作用温度。本提案的目标是确定温度最优和水利用效率的变化如何导致种群动态的差异。将结合自然观测、野外和实验室实验以及种群动态模型来确定物种是否专门在每日、风暴锋或季节周期的不同时段进行光合作用。野外实验将控制降水脉冲大小和季节时间，并测量物种的差异反应。这些数据将用于预测物种对温度和降水变化的特定反应。这项工作将为理解生理差异如何导致重要的群落特性：物种共存和多样性提供一个独特的框架。一个更机械的群落生态学和更以生态学为基础的生理学将增加我们对自然系统如何适应不断变化的环境的理解。这项研究将把研究和教育结合起来，培养未来的生态科学家。本科生、研究生和博士后将获得实践科学训练。一名研究生将开发一个教育亭，成千上万的亚利桑那大学生物圈2号的游客将与之互动。将鼓励妇女和未被充分代表的种族和文化群体以各种方式参与这项研究，包括与校园内的少数族裔接触项目合作。从这项工作中获得的理解将应用于应对气候变化的沙漠系统资源管理。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).This project will investigate the physiology of Sonoran Desert winter annual plants in order to provide insights into their population and community dynamics and the mechanisms that allow species to coexist at high diversity. Annual plants are a major component of arid land, where precipitation is both low and highly variable. Plants respond differently to this variability in a manner that contributes to species coexistence. Species trade off maximal growth rate for efficient water use in different ways, resulting in distinct population dynamics. It has been shown that the species of this community that efficiently use water have lower temperature optima for photosynthesis. The goal for this proposal is to determine how variation in temperature optima and water use efficiency results in differences in population dynamics. A combination of natural observations, field and lab experiments and models of population dynamics will be used to determine if species are specializing to photosynthesize during different parts of the daily, storm front or seasonal cycle. Field experiments will manipulate precipitation pulse sizes and seasonal timing and the differential responses of species will be measured. The data will be used to forecast species-specific responses to changes in temperature and precipitation. This work will provide a unique framework for understanding how differences in physiology lead to important community properties: species coexistence and diversity. A more mechanistic community ecology and more ecologically grounded physiology will increase our understanding of how natural systems adapt to changing environments. This research will combine research and education in ways that train the ecological scientist of tomorrow. Undergraduate, graduate and postdoctoral students will gain hands-on scientific training. A graduate student will develop an educational kiosk that the hundreds of thousands of visitors to the University of Arizona's Biosphere 2 will interact with. Women and underrepresented ethnic and cultural groups will be encouraged to participate in this research in various ways including working with minority access programs on campus. The understanding gained from this work will have applications for resource management of desert systems in response to a changing climate.