Collaborative Research: Does variation in development explain variation in phenological responses to temperature?

北方森林（覆盖美国和加拿大29%的栖息地）正在经历早春，夏季温暖和秋季延长。虽然许多植物对温暖的春天的反应是提前开花，但相当多的物种没有反应，有些甚至表现出延迟开花。这种模式与基于对温度的生理反应的预测不一致。然而，对于生长在北方森林中的植物来说，以花蕾绽放结束的过程实际上在开花前一年或更久就开始了，这一发育过程被称为“预形成”。这项研究将检验一个假设，即温度上升对预形成期延长的影响可以解释开花推迟的原因。温度上升对预形成的影响可能会限制植物适应环境变化的程度。这一发现可以极大地提高我们预测高纬度地区群落开花时间的能力，也可以让我们深入了解温带树木和灌木（其中大部分是开花植物）对温度升高的反应。该项目还将涉及公民科学家，他们将获得阿拉斯加各地的物候、温度和雪深数据。本项目将评估温度升高对花原基发育的三个潜在影响：1)提高温度可诱导花的早期定芽和休眠；2)诱导更快的发育和/或延迟芽的形成，使一些芽在它们开始的那一年的秋天成熟；3)延缓花的起始。研究了8种林下寒带灌木；由于它们是木质的，它们可能与不同植物群落的主要乔木和灌木具有相同的预形成特征。在一到两个生长季节里，开放式舱室将被用来提高温度，随后的三年将进行开发。温度将与花开放的潜在发育决定因素有关：起始时间、发育速度和生长停止。通过控制和分析积雪融化时间、生长起始日期和温度对代表性物种花发育的整个多年轨迹的影响，研究人员将确定“非典型”物候反应的机制。

The boreal forest (a habitat that covers 29% of the US and Canada) is undergoing earlier springs, warmer summers, and extended falls. While many plants respond to warmer springs by flowering earlier, a significant number of species do not respond, and some even show delayed flowering. Such patterns are inconsistent with predictions based on well-understood physiological responses to temperature. For plants that grow in boreal forest, however, the process that ends in the bursting of flower buds actually begins a year or more before flowers open, a developmental process known as "preformation". This research will test the hypothesis that the effects of rising temperatures on the extended period of preformation explain delayed flowering. The effects of rising temperatures on preformation may limit the extent to which plants can adapt to environmental variability. The discovery of a strong role for development could dramatically improve our ability to predict the timing of flowering in high-latitude communities and may also provide insights into how temperate trees and shrubs, the majority of which preform flowers, will respond to increasing temperatures. This project will also involve citizen scientists, who will obtain phenology, temperature and snow depth data from across Alaska.This project will evaluate three potential effects of warm temperatures on the development of flower primordia: increasing temperatures could 1) induce early bud set and dormancy; 2) induce more rapid development and / or a delay in bud set so that some buds mature in the fall of the year in which they were initiated; and 3) delay flower initiation. Eight species of understory boreal shrubs will be studied; their small stature makes them amenable to experimental temperature manipulation, and because they are woody they likely share features of preformation with the dominant trees and shrubs of diverse plant communities. Open-topped chambers will be used to raise temperatures for one or two growing seasons, and development will be followed over the course of three years. Temperature will be related to potential developmental determinants of flower opening: timing of initiation, rate of development, and cessation of growth. By manipulating and analyzing the effects of time of snow melt, date of growth initiation and temperature across the entire multi-year trajectory of flower development for representative species, the researchers will identify the mechanisms that underlie "non-typical" phenological responses.