LTREB: The Population and Community Dynamics of Desert Winter Annuals

本研究将调查索诺兰沙漠一年生植物的动态，以确定这些植物如何适应不可预测的环境。沙漠一年生植物已被用于研究高度变化环境下的群落动态，但种子萌发和传播的动态，被认为是持续和共存的主要决定因素，尚不清楚。这项研究将继续并扩展亚利桑那大学沙漠实验室（前身为1903年成立并持续运作的卡内基沙漠研究实验室）关于沙漠冬季一年生植物种群和群落动态的12年数据集。由于长期休眠种子的生产被认为是沙漠一年生植物在不利条件下持续存在的一个重要特征，他们将确定种子库每年发芽的种子比例，并为野外的自然和实验种子库构建枯竭曲线。此外，还将进行田间试验，测量种子的传播距离。田间和实验室发芽实验将描述种子休眠机制。最后，将构建物种对天气变化的响应，并将其用于休眠和扩散以及方差介导的物种共存进化的计算机模拟。了解沙漠一年生植物的动态将提高我们对沙漠生态系统的认识，因为一年生植物是沙漠动物赖以生存的初级生产力的一个主要和高度可变的组成部分。世界各地的沙漠正在经历地理边界的变化。由于一年生植物对天气变化反应迅速，对沙漠一年生植物的长期监测也应该提供对全球变暖和气候变化的生物影响的独特评估。

This research will investigate the dynamics of Sonoran Desert annual plants in order to determine how these plants adapt to unpredictable environments. Desert annuals have been used to study community dynamics in highly variable environments yet the dynamics of seed germination and dispersal, considered primary determinants of persistence and coexistence are not well known. This research will continue and extend a 12 year data set on the population and community dynamics of desert winter annual plants at the Desert Laboratory of the University of Arizona (formerly the Carnegie Desert Research Laboratory founded and in continuous operation since 1903). Since the production of long-lived dormant seeds is considered to be an important feature permitting desert annuals to persist though unfavorable conditions they will determine the fraction of seeds the seed bank germinating each year and construct depletion curves for both natural and experimental seed banks in the field. Also, field experiments will be conducted to measure seed dispersal distances. Field and laboratory germina tion experiments will describe seed dormancy mechanisms. Finally, species responses to weather variation will be constructed and used in computer simulations of the evolution of dormancy and dispersal and variance-mediated species coexistence. Understanding the dynamics of desert annuals will improve our knowledge of desert ecosystems, since annuals represent a major and highly variable component of primary productivity on which the desert animals depend. Deserts worldwide are undergoing shifts in geographic boundaries. Since annual plants respond quickly to weather shifts, the long-term monitoring of desert annuals should also provide a unique assessment of the biotic impacts of global warming and climate change.