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Access Type
Open Access
Document Type
thesis
Degree Program
Plant & Soil Sciences
Degree Type
Master of Science (M.S.)
Year Degree Awarded
2010
Month Degree Awarded
September
Keywords
urban forest, street trees, photochemical oxidant cycle, pollution
Abstract
Nitrogen dioxide (NO2) levels were measured inside and adjacent to canopies of urban trees in Springfield, MA, over two growing seasons. Nitrogen dioxide levels were consistently and significantly higher inside tree canopies compared to levels outside. During the second growing season, ozone (O3), temperature, and relative humidity (RH) were also measured using samplers co-located with the NO2 samplers. Ozone levels were significantly lower inside the canopy whereas temperatures were higher inside the canopy, and RH was not different between inner and outer canopy locations. The results corroborate theoretical models predicting elevated NO2 and depressed O3 levels inside tree canopies based on photochemistry, but put into question the mechanisms involved in generating these levels.
In a separate study, the use of a common urban street tree (Acer rubrum) as a tool for measuring NO2 uptake under field conditions was evaluated using a model previously applied only to potted herbaceous plants and coniferous trees. Using potted saplings of A. rubrum located at locations with high or low NO2 levels in Springfield, MA, and Amherst, MA, we measured 15N stable isotope signatures (δ15N) and total N (%N) of leaves throughout the growing season. There was no significant difference in leaf δ15N or %N change between sites over the course of the season. Changes in δ15N were likely the result of input from N sources in the nutrient solution. Changes in %N followed a natural seasonal decline reported elsewhere in the literature. The study highlights the difficulties in applying this particular model to deciduous trees and suggests work needed to overcome these challenges.
DOI
https://doi.org/10.7275/1400419
First Advisor
William J. Manning
Included in
Ecology and Evolutionary Biology Commons, Environmental Chemistry Commons, Environmental Sciences Commons, Forest Sciences Commons, Plant Sciences Commons