Environmental Variation, Dormancy, and Rare Plant Persistence in Invaded Habitats

对受威胁和濒危物种持续存在的日益担忧，重新点燃了人们对生态学中的一个经典问题的兴趣：稀有物种如何持续存在？如果没有大量种群分布在不同的环境中，稀有物种传统上被认为容易因环境变化而灭绝。相比之下，许多共存模型表明，对于休眠物种来说，环境波动可能是竞争群落中持续生存的关键。可变的萌发和休眠使物种能够利用时间变化来避开不利的环境和激烈的竞争。尽管群落生态学家承认，环境波动可能有利于通过这些“储存效应”机制共存，但它们对理解稀有植物如何持久存在的影响才刚刚开始探索。更好地了解休眠、周围群落动态和环境变化如何影响持久性，对于成功管理受威胁种群至关重要。这项提案概述了一项研究，旨在研究稀有的一年生植物如何在加州海峡群岛高度可变的、以外来植物为主的栖息地中生存。由于年降雨量变化十倍，以及超过15种稀有和濒危的一年生植物，这个岛屿系统提供了一个独特的机会来研究萌发生物学、环境变化和周围群落动态如何影响持久性。研究小组汇集了一名专门研究年度植物种群模型的理论生态学家，一名具有研究加州草本植物系统生物入侵经验的野外生态学家，以及一名在海峡群岛国家公园工作的保护实践者。这项拟议研究的学术价值在于，它将阐明休眠、环境变化和周围群落动态如何影响稀有一年生植物的持久性。考虑到随着气候变化而预测的环境变化的增加，以及外来物种的持续入侵，这一点尤其重要。更广泛的影响包括培训博士后、研究生和本科生在模型和实验的界面上工作，以及生成成功管理海峡群岛稀有一年生植物所需的数据。通过与国家公园管理局和自然保护协会的合作，这一项目的结果将传达给公众和那些直接负责管理独特岛屿植物群的人。

Growing concerns over the persistence of threatened and endangered species have rekindled interest in one of the classic problems in ecology: how do rare species persist? Without large populations distributed across heterogeneous environments, rare species are traditionally regarded as susceptible to extinction from environmental variability. By contrast, numerous coexistence models suggest that for species with dormancy, environmental fluctuations may beessential for persistence in competitive communities. Variable germination and dormancy allow species to exploit temporal variation to avoid both unfavorable environments and intense competition. Despite acceptance among community ecologists that environmental fluctuations may favor coexistence via these "storage effect" mechanisms, their implications for understanding how rare plants persist are only beginning to be explored. Better understanding how dormancy, surrounding community dynamics, and environmental variation influence persistence is essential to successfully managing threatened populations. This proposal outlines research to examine how rare annual plants persist in the highly variable, exotic grass dominated habitats of the California Channel Islands. With tenfold annual variation in rainfall, and over 15 rare and endangered annual plants, the island system provides a unique opportunity to examine how germination biology, environmental variation, and surrounding community dynamics influence persistence. The research team brings together a theoretical ecologist specializing in annual plant population models, a field ecologist with experience studying biological invasions in California herbaceous systems, and a conservation practitioner working in the Channel Islands National Park. The intellectual merit of the proposed research is that it will clarify how dormancy, environmental variation and surrounding community dynamics influence the persistence of rare annual plants. This is particularly important considering the increased environmental variation forecasted with climate change, and the continuing invasion of exotic species. The broader implications include the training of postdoctoral, graduate, and undergraduate students to work at the interface of models and experiments, and the generation of data necessary for successfully managing the rare annual plants of the Channel Islands. Through collaborations with the National Park Service and Nature Conservancy, the results of this project will be communicated to the general public and those directly responsible for managing the unique island flora.