From plant traits to plant communities

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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.