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Title:Trait-based approaches to understanding the response of forest understory herbs to environmental variation
Author(s):Candeias, Matthew B
Director of Research:Fraterrigo, Jennifer
Doctoral Committee Chair(s):Dalling, Jim
Doctoral Committee Member(s):Leakey, Andrew; O'Dwyer, James
Department / Program:Natural Res & Env Sci
Discipline:Natural Res & Env Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:Ph.D.
Genre:Dissertation
Subject(s):functional traits
community assembly
environmental filters
phenotypic plasticity
environmental gradients
understory herbs
plant demography
fitness
vital rates
integral projection model
temperate deciduous forest
Abstract:Ecosystems are complex and subject to changes in resource availability over a range of temporal and spatial scales. Understanding relationships between abiotic conditions and plant fitness components (i.e., survival, growth, and performance) can provide valuable insights into how populations and communities will respond to future environmental change. Trait-based approaches can thus offer valuable insights into how populations and communities will respond to environmental change by providing a mechanistic link between plant traits and the environment. This dissertation explores the trait-mediated effects of environmental change on understory herb presence, abundance, and performance across individual, population, and community scales. Specifically, I utilized plant traits in observational, experimental, and population modeling approaches to reveal patterns in understory herb community assembly across environmental resource gradients, understand the impacts of trait phenotypic plasticity on plant growth and survival, and to forecast population-level performance of natural and introduced populations of an endangered understory herb endemic to the southern Blue Ridge Mountains. At the community level, I found evidence of two levels of environmental filtering influencing understory herb community assembly in the southern Appalachian Mountains. Specifically, trait coordination is more important for explaining species abundance than species presence-absence along the environmental resource gradient, with abundant species possessing more favorable combinations of traits for maximizing fitness in a given environment. At the species level, all traits responded plastically to the resource availability gradient, but life history strategy influenced the direction of phenotypic responses. I found no link between trait plasticity and transplant survival; however, plasticity in height, leaf area, and leaf area ratio were strongly related to the growth of surviving transplants. Finally, at the individual level, I found that individual size and soil moisture availability had a positive effect on plant performance such that large plants were more likely to survive, grow, flower, and reproduce vegetatively as soil moisture increased. These results demonstrate how easy to measure, individual traits in concert with abiotic variables can be used to predict population dynamics for species of conservation concern. Overall, this dissertation affirms that plant trait approaches can provide valuable insights into understanding how resource conditions shape plant presence, abundance, and performance across scales.
Issue Date:2021-06-07
Type:Thesis
URI:http://hdl.handle.net/2142/113120
Rights Information:Copyright 2021 Matthew Candeias
Date Available in IDEALS:2022-01-12
Date Deposited:2021-08


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