Collaborative Research: LTREB Renewal: RUI: Cyclic vs. anthropogenic causes of long-term variation in the regeneration of tropical forests with contrasting latitude and diversity

成功的植物繁殖--开花和结果--对环境条件很敏感，种子萌发和幼苗存活和生长后的早期生命阶段也是如此。植物通常利用环境的变化作为繁殖的线索，例如，确保有足够的能量和水分来发育果实，或者确保种子在有利于幼苗生长和存活的条件下散播。因此，热带森林的繁殖和再生很容易受到气候变化的影响。该项目续期五年，使用长期数据来了解热带植物繁殖的时机和成功程度如何随着开花、结果和幼苗存活的线索和条件因年内季节性、多年气候周期(如厄尔尼诺)和/或气候变化的影响而变化。这项研究在三个热带雨林研究地点(厄瓜多尔、波多黎各和巴拿马)进行，以将当地地点条件的影响与长期区域气候模式分开。参与这项研究的本科生和早期职业实习生每年都会接受培训，并为扩大这项工作长期范围的项目提供支持。热带森林因其高度的生物多样性和对碳储存的巨大贡献而在全球具有重要意义，因此更好地了解影响热带植物繁殖的环境条件将增强我们预测热带森林生存和这些森林所带来的好处的能力。这项研究跨越不同的森林，以检验以下假设：(1)诱导开花的环境线索；(2)多年或数十年的自然气候周期对热带森林繁殖的影响；(3)具有不同功能特征的物种的幼苗对气候变化的响应；以及(4)间歇性繁殖如何构建成树种群，有效地缩小了早期繁殖研究与幼树和成树种群动态之间的人口统计差距。在我们的三个地点使用的标准化方法包括每周或每两周记录永久陷阱中特定物种的花卉、水果和种子雨，以及在陷阱附近的地块中每年对所有木本植物幼苗进行普查。研究在大型(16-50公顷)绘制的森林动态地块内进行，在那里所有直径1厘米的树木都被识别并定期测量。在多个温带和热带森林中也采用了类似的方法，这有助于跨地点比较，从而扩大了我们结果的概括性。该项目由人口与社区生态计划和已建立的激励竞争性研究计划(EPSCoR)共同资助。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Successful plant reproduction – flowering and fruiting – is sensitive to environmental conditions, as are the early life stages that follow – seed germination and seedling survival and growth. Plants often use variation in their environment as a cue to reproduce, ensuring, for example, there is adequate energy and moisture for fruit development or that their seeds are dispersed when conditions are favorable for the growth and survival of young seedlings. The reproduction and regeneration of tropical forests are therefore vulnerable to a changing climate. This project, renewed for five more years, uses long-term data to understand how the timing and success of reproduction in tropical plants varies year-to-year as the cues and conditions for flowering, fruiting, and seedling survival vary due to within-year seasonality, multi-year climate cycles such as El Niño, and/or the effects of climate change. The research takes place at three tropical forest study sites (Ecuador, Puerto Rico, and Panama) to separate the effects of local site conditions from long-term regional climate patterns. Undergraduates and early career interns participating in this research receive training each year and support for projects that expand on the long-term scope of this work. Tropical forests are globally important because of their high biodiversity and large contributions to carbon storage, and thus a better understanding of the environmental conditions that affect tropical plant reproduction will strengthen our ability to predict the survival of tropical forests and the benefits these forests confer.This research spans forests differing in diversity, seasonality, disturbance, and climate to test hypotheses concerning: (1) environmental cues that induce flowering; (2) effects of multiyear or multidecadal natural climate cycles on reproduction in tropical forests; (3) survival and growth of seedlings from species with different functional traits in response to climatic variation; and (4) how episodic reproduction structures adult populations, effectively closing the demographic gap between studies of early reproduction and the dynamics of sapling and adult tree populations. Standardized methodology used at our three sites includes weekly or biweekly recording of species-specific flower, fruit, and seed rain in permanent traps and annual censuses of all woody seedlings in plots adjacent to the traps. The research take place within large (16-50 ha) mapped forest dynamics plots where all trees 1 cm in diameter are identified and regularly measured. Similar methodology is also employed in multiple temperate and tropical forests, which facilitates cross-site comparisons that broaden the generalizability of our results. This project is jointly funded by the Population and Community Ecology program, and the Established Program to Stimulate Competitive Research (EPSCoR).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.