How important is "colored" stochasticity for plant population dynamics?

生态学家需要预测人类引起的变化对动植物种群的影响。这些预测通常是使用人口模型做出的，该模型将人口动态率（出生率、增长率和死亡率）结合起来，以估计人口规模如何随着环境变化而变化。生命率的变化通常被建模为“白噪音”，这意味着某一年的比率与最近的过去或最近的将来的比率无关。然而，有充分的理由相信变异可能是“红色”的，这意味着好年份往往会跟着好年份（由于环境条件的趋势或生理条件的延续），并且有证据表明一些物种经历了“蓝色”噪音，这意味着坏年份往往会跟着好年份（例如，如果繁殖耗尽了储存的资源）。在少数情况下，研究人员在植物和动物种群中寻找“有色”噪音，这些影响大大改变了对种群动态的预测。该项目将开发估算“有色”随机性的方法，并评估这种变化对种群动态的重要性。本研究将比较代表不同极端的三种多年生野花的种群动态：1)干旱环境的多年生野花，繁殖成本高，典型的“蓝色噪音”；2)一种生活在蜿蜒河流边的野花，它会经历环境的方向性变化，典型的“红色噪音”；3)兰花在其全球分布的北部边缘附近。在后一种物种中，噪音的颜色是未知的，但可能对生命史进化和对气候变化的反应很重要。作为该项目的一部分，研究人员还将评估数百项针对不同植物物种的短期（3-10年）研究（迄今已发表300多项）是否以及如何用于推断环境变化对植物的长期影响。其他更广泛的影响包括开发用于分析短时间序列的统计方法，教育学生数学生物学和生态预测，以及通过与芬兰奥兰卡（芬兰/俄罗斯边境北极圈附近）的植物学家和澳大利亚布里斯班的统计生态学家的合作，提高国际意识。

Ecologists need to predict the impacts of human-caused change on plant and animal populations. These predictions are often made using demographic models, which combine vital rates (birth, growth, and death rates) into estimates of how population size changes in response to changes in the environment. Variation in vital rates is usually modeled as "white noise", meaning that rates in one year are not correlated with rates in the recent past or recent future. However, there are good reasons to believe that variation may be "red", meaning good years tend to follow good years (due to trends in environmental conditions or carry-over through physiological condition), and there is evidence that some species experience "blue" noise, meaning bad years tend to follow good years (for example, if reproduction depletes stored resources). In the few cases where researchers have looked for "colored" noise in plant and animal populations, these effects have substantially changed predictions about population dynamics. This project will develop methods for estimating "colored" stochasticity and also evaluate how important this variation is for population dynamics. The research will compare population dynamics of three species of perennial wildflowers, representing different extremes: 1) a perennial wildflower of arid environments, which experiences high costs of reproduction, typical of "blue noise"; 2) a wildflower that lives along meandering rivers, which experiences directional changes in the environment, typical of "red noise"; and 3) an orchid near the northern edge of its global distribution. In this this latter species the color of noise is unknown, but likely important for life-history evolution and responses to climate change. As part of this project, the researcher will also evaluate if and how hundreds of short-term (3-10 year) studies of different plant species (more than 300 have been published to date) can be used to infer long-term effects of environmental change for plants in general. Additional broader impacts include developing statistical methods for analysis of short time series, educating students in mathematical biology and ecological forecasting, and promoting international awareness through collaboration with botanists in Oulanka, Finland (near the intersection of the Arctic Circle with the Finland/Russia border) and with statistical ecologists in Brisbane, Australia.