Mast-Seeding in Perennial Plants: A Test of the Pollen Coupling Hypothesis

在许多植物种群中，种子产量随时间波动很大。这些波动，通常被称为桅杆播种，直接影响许多植物和动物物种。尽管如此，对桅杆播种的直接原因的经验检验实际上是不存在的。Crone和Sala将在两种植物中测试桅杆播种的近似机制：黄芪（一种蜜蜂授粉的野花）和白皮松（一种风传粉的树木）。对于每个物种，Crone和Sala将测试花粉可用性是否限制种子生产，以及种子生产对储存资源的影响。这些实验测试了“花粉耦合”的假设，这是一个最近提出的，但未经验证的关于桅杆播种如何发生的假设。Crone和Sala还将评估花粉耦合模型的预测，使用白皮松的大尺度地理同步模式和全植株的果位和花粉有效性操作。桅杆播种植物的果实或种子产量的波动是调节具有重要经济意义的野生动物和害虫物种的关键因素。白皮松例证了了解桅杆播种对管理的重要性。在黄石国家公园，白皮果作物歉收引发了人类与灰熊的冲突；为了处理这些冲突和相关的公共关系，管理者需要预测非最佳年份。在冰川国家公园，白皮松已经被一种引入的病原体白松水疱锈病摧毁。预测树冠年将有助于管理人员定位和收集抗性树木的种子，并设计恢复策略，保持树冠播种的关键要素。除了直接应用研究成果外，该项目还将为本科生和研究生提供教育机会，并与正在进行的为城市和美洲原住民本科生提供研究机会的项目相结合。

Seed output fluctuates dramatically over time in many plant populations. These fluctuations, often called mast seeding, directly affect numerous plant and animal species. Nonetheless, empirical tests of the proximate causes of mast seeding are virtually nonexistent. Crone and Sala will test proximate mechanisms of mast seeding in two plant species: Astragalus scaphoides (bitterroot milkvetch), a bee-pollinated wildflower, and Pinus albicaulis (whitebark pine), a wind-pollinated tree. For each species, Crone and Sala will test whether pollen availability limits seed production, and the effect of seed production on stored resources. These experiments test the assumptions of "pollen coupling" a recently proposed, but untested, hypothesis for how mast-seeding occurs. Crone and Sala will also evaluate predictions of pollen coupling models, using wide-scale geographic patterns of synchrony in whitebark pine and whole-plant manipulations of fruit set and pollen availability in bitterroot milkvetch. Fluctuations in the fruit or seed output of mast-seeding plants are a key factor regulating economically important wildlife and pest species. Whitebark pine exemplifies the importance of understanding mast seeding for management. In Yellowstone National Park, whitebark cone crop failures cause human-grizzly conflicts; managers need to predict non-mast years in order to deal with these conflicts and associated public relations. In Glacier National Park, whitebark pine has been decimated by an introduced pathogen, white pine blister rust. Predicting mast years will help managers locate and collect seeds of resistant trees, and design restoration strategies that maintain key elements of mast-seeding. In addition to direct application of research results, this project will provide educational opportunities for undergraduate and graduate students, and integrate with ongoing programs that provide research opportunities for inner-city and Native American undergraduate students.