Understanding the response of variability in tree reproduction (masting) to climatic and environmental change

背景：许多树种表现出一种被称为“肥大年”的繁殖策略，其特征是在繁殖投资丰盈的年份（“肥大年”）和低投资的年份之间转换。值得注意的是，这种变异在树木种群内部和种群之间是同步的。各种机制可以解释树木如何能够a)每年改变它们的种子产量，b)在个体之间同步这种变化。这些机制大多直接或间接地依赖于气候作为捕集的关键调节器，这意味着捕集可能对气候变化作出反应。然而，人类对气候变化的反应仍然高度不确定。这一点很重要，因为森林再生受到种子生产、传播和捕食的强烈调节，影响物种组成、从干扰中恢复以及为应对气候变化而迁移。这些过程都受到控制的影响。例如，我们最近的研究表明，当气候变暖导致的种子产量增加与繁殖“中断”有关时，繁殖投资增加的好处主要体现在种子捕食者身上，而不是植物身上。这个例子表明，包括在不断变化的环境中，植被形态的变化如何对森林生态系统的功能和动态具有根本重要性。目标：本项目将建立桅杆对近期气候变化的响应，并预测由于持续的环境变化而导致的桅杆未来的变化。一个关键的目标将是确定不同物种的不同生理机制是否会导致对环境变化的不同反应。

Background: Many tree species show a reproductive strategy known as masting, which is characterised by switching between years of bumper investment in reproduction ("mast years"), and years of low investment. Remarkably, this variation is synchronised within and across tree populations. Various mechanisms may explain how trees are able to a) vary their seed production year-to-year, and b) synchronise this variation between individuals. Most of these mechanisms rely either directly or indirectly on climate as the key regulator of masting, implying that masting may respond to changes in climate. However the response of masting to climate change remains highly uncertain. This is important because forest regeneration it strongly regulated by seed production, dispersal and predation, influencing species composition, recovery from disturbance and migration in response to climate change. These processes are all influenced by masting. For example, we have recently shown that when warming-driven increase in seed production is associated with a "breakdown" in masting, the benefits of increased investment in reproduction accrue largely in seed predators, rather than the plants. This example demonstrates how changes to masting patterns are of fundamental importance to the functioning and dynamics of forest ecosystems, including in a changing environment.Objectives: This project will establish the response of masting to recent changes in climate, and predict future changes in masting resulting from ongoing environmental change. A key objective will be establish whether the different physiological mechanisms that underpin masting in different species result in contrasting responses to environmental change.