Date of Completion

12-13-2013

Embargo Period

12-12-2014

Major Advisor

Dr. Robin L. Chazdon

Associate Advisor

Dr. John A. Silander, Jr.

Associate Advisor

Dr. Cynthia S. Jones

Field of Study

Ecology and Evolutionary Biology

Degree

Doctor of Philosophy

Open Access

Open Access

Abstract

Over half of the Neotropical forests have been damaged by human activity, often converted to pasture or agriculture. Under the right conditions, second-growth forests can naturally regenerate once these lands are abandoned, providing a means of recuperating biodiversity and ecosystem services. However, the mechanisms of community assembly during the process of natural regeneration are not fully understood. Here I assess the relative influences of environmental filtering and stochasticity in the regeneration of pre-montane moist forest and lowland wet forests in Costa Rica. I quantify the ecological characteristics of trees and palms with leaf and stem functional traits, which are species-specific morphological and physiological attributes. I explore changes in species composition and functional trait composition over successional time, both across four pre-montane old-fields in the first 11 years of natural regeneration, and among two old-growth and six second-growth stands ranging in age from 10–40 years after abandonment of pasture in the lowland wet tropical forest region. I also compare patterns of taxonomic and functional beta diversity over time within each set of forest stands (pre-montane and lowland wet) to assess if functional characteristics of the communities are converging at a different rate from the species composition. Finally, I use an experimental approach to test the ability of species with different functional traits to survive and grow under three habitat treatments (pasture, second-growth forest, and old-growth forest) representing restoration scenarios.

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