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关注，重新点燃了人们对生态学中一个经典问题的兴趣：稀有物种是如何持续存在的？如果没有分布在异质环境中的大量种群，传统上认为稀有物种容易因环境变化而灭绝。相比之下，许多共存模型表明，对于具有休眠状态的物种来说，环境波动可能是竞争群落持续存在的必要条件。不同的发芽和休眠允许物种利用时间变化来避免不利的环境和激烈的竞争。尽管群落生态学家接受环境波动可能通过这些“储存效应”机制有利于共存，但它们对理解稀有植物如何持续存在的意义才刚刚开始探索。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。该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利福尼亚海峡群岛高度变化的、外来草主导的栖息地中持续存在。岛上的年降雨量变化为10倍，有超过15种珍稀和濒危的一年生植物，为研究发芽生物学、环境变化和周围群落动态如何影响持久性提供了一个独特的机会。研究小组汇集了一位专门研究年度植物种群模型的理论生态学家，一位具有研究加州草本系统生物入侵经验的实地生态学家，以及一位在海峡群岛国家公园工作的保护实践者。该研究的智力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。考虑到气候变化预测的环境变化增加，以及外来物种的持续入侵，这一点尤为重要。更广泛的影响包括培养博士后、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，这个项目的结果将传达给公众和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.