From plant traits to plant communities

该提案涉及研究(i)不同植物性状在物种间比较时如何相互关联，（ii）不同植物性状值如何决定它们在给定环境中生存、生长和繁殖的能力，（iii）不同环境如何选择不同性状值，以及（iv）这一过程如何决定植物物种组装成生态群落。不同的植物种类和类型是不同栖息地的典型特征。植物生态学的一个重要但尚未实现的目标是预测在不同的地点和环境（群落“集合”）中，哪些物种将占主导地位，哪些将处于从属地位，哪些将不存在。我已经开发了一个数学模型来预测这种现象，并理解它是如何在不同的环境中作为特征选择的结果而出现的。该统计模型（CATS）将植物功能性状、环境变量和区域物种库联系起来，以产生相对丰度的定量预测。在接下来的5年里，我的团队将利用魁北克南部落叶林的林下植物群落来改进CATS，这些植物群落在农业“海洋”中以岛屿的形式存在，在大小、隔离程度和年龄方面都有所不同。在这个系统中，群落聚集的三种主要力量（分散限制、基于性状的选择和人口统计学随机性）应该特别强。我们还将检验一个假设，该假设旨在解释叶片性状之间众所周知且非常普遍的共变模式，即“全球叶片经济谱”的因果起源。这一假说将这种模式解释为维管植物叶片构造的“设计约束”的结果。最后，我和我的学生将改进和测试一种新的方法来量化一个重要的环境选择因素（土壤肥力），这是植物生态学中最基本的环境选择因素。

This proposal concerns research into (i) how different plant traits are related to each other when comparing between species, (ii) how different values of plant traits  determine how well they can survive, grow and reproduce in a given environment, (iii) how different environments will select for different trait values and (iv) how this process determines the assembly of plant species into ecological communities.  Different plant species, and different types of plants, are typical of different habitats. An important, and unattained, goal of plant ecology is to predict which species will be dominant, which will be subordinate, and which will be absent, in different sites and environments (community "assembly").  I have developed a mathematical model designed to predict this phenomenon and to understand how it arises as a consequence of trait selection in different environments.  This statistical model ("CATS") links plant functional traits, environmental variables, and regional species pools to produce quantitative predictions of relative abundance.  In the next 5 years my team will refine CATS using the understory plant communities of deciduous woods in southern Quebec, which exist as islands in an agricultural "sea" and that differ in terms of size, isolation and age.  In this system the three main forces of community assembly (dispersal limitation, trait-based selection, and demographic stochasticity) should be especially strong.  We will also test an hypothesis which purports to explain the causal origin of a well-known and very general pattern of covariation between leaf traits, the "worldwide leaf economic spectrum".  This hypothesis explains this pattern as a consequence of "design constraints" on how leaves of vascular plants are constructed.  Finally, my students and I will refine and test a new method of quantifying one important environmental selection agent (soil fertility) which is a fundamental environmental selection agent in plant ecology.