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，就像随后的早期生命阶段--种子萌发和幼苗存活和生长一样。 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供果实发育，或者当条件有利于幼苗生长和存活时，种子被分散。因此，热带森林的繁殖和再生容易受到气候变化的影响。这个项目，延长了五年，使用长期数据来了解热带植物繁殖的时间和成功率如何每年变化，因为开花，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。该研究在三个热带森林研究地点（厄瓜多尔、波多黎各和巴拿马）进行，以将当地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，并支持扩大这项工作长期范围的项目。热带森林是全球重要的，因为它们的生物多样性和碳储存的巨大贡献，因此更好地了解影响热带植物繁殖的环境条件将加强我们预测热带森林生存和这些森林带来的好处的能力。这项研究跨越了不同的森林多样性，季节性，干扰和气候来测试假设：（1）诱导开花的环境线索;（2）多年或数十年自然气候循环对热带森林生殖的影响;（3）具有不同功能性状的物种幼苗对气候变化的反应;以及（4）情景生殖如何构成成年种群，有效地缩小了早期繁殖研究与幼树和成年树种群动态之间的人口差距。在我们的三个站点使用的标准化方法包括每周或每两周记录特定物种的花，果，种子雨在永久性陷阱和年度普查的所有木本幼苗在地块附近的陷阱。研究在大型（16-50公顷）森林动态绘图区进行，所有直径1厘米的树木都被确定并定期测量。在多个温带和热带森林中也采用了类似的方法，这有利于跨站点的比较，扩大了我们的结果的普遍性。该项目由人口和社区生态计划以及刺激竞争研究的既定计划（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知识价值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.