Date of Award

Spring 1-1-2012

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Ecology & Evolutionary Biology

First Advisor

Carol A. Wessman

Second Advisor

Alex B. Guenther

Third Advisor

Russell K. Monson

Fourth Advisor

William D. Bowman

Fifth Advisor

Kenneth E. Foote

Abstract

The interactions between the atmosphere and the biosphere have been studied to a great extent in the last decades; it cannot be denied that these systems are altering each other’s processes. The production of terpenoid compounds by vegetation is an example of such interactions. Ecological and atmospheric scientists are interested in the production and emission of terpenoid compounds. However, they are studying them from substantially different points of view, driven largely by the scales at which they approach the process.

The aim of my dissertation was to study biogenic emissions and their effect on atmospheric chemistry using variables such as landscape structure, landscape configuration, and developmental stage; factors that have not been considered before from an atmospheric point of view. The main questions of my study were: (1) Does understory vegetation have an impact on regional emissions? (2) Does developmental stage affect terpenoid emissions? (3) Does the light environment in the forest affect the rate at which terpenoid compounds are emitted? To answer these questions, field studies were performed and terpenoid emissions were measured using branch enclosure measurements and GC-MS techniques.

The first question was assessed by using Pteridium aquilinum, one of the most abundant understory species. We determined that Pteridium was a terpenoid emitter, but its emissions did not influence the regional atmospheric chemistry. Nevertheless, this study is a first step to consider the herbaceous layer when studying monoterpene emissions. The second question studied the difference in emissions of Pinus ponderosa seedlings and mature trees, finding a significant difference in the magnitude of the emissions but not in their chemical composition; emissions of seedlings were greater. In this case, this study is one of the first on the developmental stage and monoterpene emissions in a woody species. The third question, addressing the differences of emissions of sun and shaded branches of Pinus ponderosa, found a significant difference between the branches’ emissions. The results of the different questions addressed in this work show that it is necessary to incorporate landscape component to have a better understanding of the production and effects of BVOC’s compounds in the atmosphere.

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