Microstegium vimineum is a non-native invasive plant species classified as an annual, shade-tolerant C4 grass. There is limited research regarding variables affecting the spread of M. vimineum. Two studies were conducted to investigate the spread of M. vimineum. A field study was undertaken in 2009 to determine how M. vimineum spreads in relation to litter disturbance. In 2010, a greenhouse study was conducted to determine the impact light has on M. vimineum aboveground biomass, height growth, and photosynthetic efficiency. The field study consisted of three treatments, Undisturbed (Control), Stirring, and Removal of leaf litter, employed along the boundary of existing M. vimineum populations in ½-meter by 2-meter plots. Distance of spread from the existing population and percent cover were documented for one growing season. Plants were counted at the end of the study. Neither stirring nor removal of leaf litter had a significant impact on spread rate, percent cover, or the number of plants in a given treatment suggesting pre-growing season leaf litter disturbance does not influence M. vimineum spread, percent cover, or number of plants. The greenhouse study consisted of growing M. vimineum under four light treatments: 100, 70, 45, and 20 percent of full light. Heights were measured weekly while minimum, maximum, and variable fluorescence emission, non-photochemical and photochemical quenching, and maximum quantum yield of Photosystem II photochemistry (QYmax) were measured every 10 days. Aboveground biomass accumulation was calculated at the end of the study. Results indicate that M. viminuem aboveground biomass accumulation is highest in 70 percent to 100 percent light while photosynthetic efficiency is highest between 45 percent and 70 percent light. This research indicates that M. vimineum does not spread appreciably at low light levels (closed canopies) in areas with litter disturbances that do not change the light regime. M. vimineum has greater aboveground biomass and photosynthetic efficiencies at higher levels of light. Thus, forest disturbances that result in more light reaching the ground may influence the spread of M. vimineum by creating a more favorable environment.

Microstegium vimineum is a non-native invasive plant species classified as an annual, shade-tolerant C4 grass. There is limited research regarding variables affecting the spread of M. vimineum. Two studies were conducted to investigate the spread of M. vimineum. A field study was undertaken in 2009 to determine how M. vimineum spreads in relation to litter disturbance. In 2010, a greenhouse study was conducted to determine the impact light has on M. vimineum aboveground biomass, height growth, and photosynthetic efficiency.The field study consisted of three treatments, Undisturbed (Control), Stirring, and Removal of leaf litter, employed along the boundary of existing M. vimineum populations in ½-meter by 2-meter plots. Distance of spread from the existing population and percent cover were documented for one growing season. Plants were counted at the end of the study. Neither stirring nor removal of leaf litter had a significant impact on spread rate, percent cover, or the number of plants in a given treatment suggesting pre-growing season leaf litter disturbance does not influence M. vimineum spread, percent cover, or number of plants.The greenhouse study consisted of growing M. vimineum under four light treatments: 100, 70, 45, and 20 percent of full light. Heights were measured weekly while minimum, maximum, and variable fluorescence emission, non-photochemical and photochemical quenching, and maximum quantum yield of Photosystem II photochemistry (QYmax) were measured every 10 days. Aboveground biomass accumulation was calculated at the end of the study. Results indicate that M. viminuem aboveground biomass accumulation is highest in 70 percent to 100 percent light while photosynthetic efficiency is highest between 45 percent and 70 percent light. This research indicates that M. vimineum does not spread appreciably at low light levels (closed canopies) in areas with litter disturbances that do not change the light regime. M. vimineum has greater aboveground biomass and photosynthetic efficiencies at higher levels of light. Thus, forest disturbances that result in more light reaching the ground may influence the spread of M. vimineum by creating a more favorable environment.

<p><h1>This study discusses energy and water balance in an 80-year-old deciduous Carolinian forest in the Great Lakes region in southern Ontario, Canada. The eddy covariance technique and associated meteorological and soil variables were used to make a year-round measurements of energy and water vapour fluxes from January-December,2012. This site is part of the Turkey Point Flux Station and global Fluxnet. The linear relationship between daily turbulent (sensible heat (H), latent heat (LE)) and radiative fluxes (net radiation (Rn),soil heat (G) and canopy heat storage ( S)) has a the slope of 0.75 (intercept of -15.8 Wm^-2, and a correlation coefficient, r² of 0.93) indicating a 25% deficiency in energy balance closure. The mean value of canopy albedo was 0.16 during the growing season. Maximum daily evapotranspiration (E) rate was 3.8 mm day^-1 in June, when growing is at its peak in the region. Total annual E was 400 mm, which accounted for 42% of the total annual precipitation of 950 mm. The water storage in upper soil column (1.0 m depth) was approximately 100 mm, indicating that about 450 mm of water was lost from the forest as runoff. Apart from radiation, vapour pressure deficit (D) was the dominant control on E. Maximum value of bulk surface conductance (Gs) was about 18.5 mm s^-1. Gs linearly decreased in response to increase in D. The minimum Gs values were recorded when D was maximum, i.e. 3 to 3.5 kPa. Gs also showed high sensitivity to the volumetric soil water content (ϴ), during dry periods, for example the drought event in 2012. In the growing season, the typical value of Priestley-Taylor α ranged between 0.8 to 1.2 with a maximum of 1.8, indicating a wet deciduous forest. However, the LE/Rn relationship showed a linear increase with increasing D with a low (0.26) slope, indicating a conservative response of forest E to atmospheric demand. This study provides insight into energy partitioning, the water balance and their controls in this Carolinian deciduous forest. A better understanding of evapotranspiration processes and their controls in these forests would help to better quantify water availability at local and regional scales and to evaluate the impacts of future climate change on water resources in the region.</h1></p> / Master of Science (MSc)

The Forest Inventory and Analysis (FIA), the United States’ forest census, measured sixty-six Mexican spotted owl nest stands in order gain insight into the structure and composition of the nest habitat of this threatened species. I used these data, along with the greater FIA database and the Forest Vegetation Simulator to explore questions surrounding the management of Mexican spotted owl habitat, specifically how to balance the objective of sustaining and enhancing nest habitat in face of increasing forest fire size and severity in the Southwest. My research consisted of three studies. The first study quantified the structure and composition of the Mexican spotted owl nest stands and scrutinized current evaluation criteria of nest habitat. The second study estimated how much of the Southwestern landscape is at risk to high-severity crown fire and how much of the landscape is suitable Mexican spotted owl nest habitat. The third study modeled forest dynamics and silvicultural intervention in potential Mexican spotted owl nest stands. The purpose of this research is to assist in management of Southwestern forests in order to decrease fire size and severity while sustaining and enhancing current and future Mexican spotted owl nest habitat.

The Oak Ridge Reservation established under The Atomic Energy Commission was the site for uranium enrichment and the construction of the atomic bomb during the early 1950’s and 60’s. Unfortunately, large quantities of “heavy metals” such as mercury, uranium, technetium, plutonium and fission products that were produced were dumped into unlined landfills, settling ponds and surface streams. One such creek affected was East Fork Poplar Creek, whose head water begins at the Y-12 Facilities located on the Oak Ridge Reservation, and was once used as an industrial drainage ditch for runoff, which included mercury and other heavy metals. The release of mercury, in particular, into East Fork Poplar Creek was probably lethal to established seed banks, vegetation, and soil microbial and fungal communities. The soil microbial communities play an important role in ecological processes, and the fungal communities are important, in particular, due to the mutualistic associations shared with more than 85% of plant species. This study evaluating the long term effects of mercury on plant and fungal presence and abundance indicated that soil mercury concentration was not significantly correlated with these factors. In order to better understand the effects of mercury compounds on plant and fungal interaction, a greenhouse study was conducted. Survival of seedlings in mercury-contaminated media was more dependent on mercury compound applied than on the presence of fungal inoculates tested. The ability of four tree species to germinate in different mercury compounds was also investigated. The germination of seedlings in mercury solution was dependent on tree species, mercury compound and concentration. The detection of mercury in environmental samples was based on conventional methods such as cold vapor atomic absorption spectroscopy (CVAAS), and inductively coupled plasma emission mass spectrometer (ICP-MS). Analysis of mercury and other metals by non-destructive techniques such as infrared spectroscopy, specifically near-infrared (NIR) and mid-infrared (MIR) spectroscopy was investigated. Quantitative analysis of plant foliar tissue exposed to mercury was investigated by NIR, and mercury- contaminated soil was investigated by MIR. Due to mercury’s volatility, the ability to differentiate NIR spectra of control versus treated seedlings could not be confirmed through statistical analysis, however MIR spectra obtained from mercury-contaminated soil was used to develop significant calibration models for mercury and several other metals correlated to mercury.

Dendrochronological techniques are currently limited to the identification of visible fire scars. However, through the development of new dendrochemical techniques, the potential exists to provide insight into a broader array of pyric ecosystems. In addition, the ability to identify historic climate-growth responses provides a better understanding of the conditions under which historic fire regimes occurred. This study provides the groundwork for the identification of a dendrochemical nutrient fire signature in xylem and identifies the climate-radial growth responses of loblolly pine (Pinus taeda L.) on five sites in the Piedmont of South Carolina. Changes in N, P, K, Ca, Mg, Zn, Cu, Mn, Fe, S, and Na concentrations in xylem as a result of a single fire were examined. The influences of monthly mean temperature, monthly total precipitation, Palmer Drought Severity Index (PDSI), Palmer Hydrological Drought Index (PHDI), and selected ocean-atmospheric oscillations such as El Nino-Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), Pacific Decadal Oscillation (PDO), and Southern Oscillation Index (SOI) on radial growth using univariate and multivariate techniques were also assessed. Soil and duff analyses indicated sites were similar, but nutrient poor. Xylem mobile and immobile nutrient concentration analyses differed significantly through time for N, P, K, Ca, Mg, Zn, Cu, Mn, and S. No interactions were significant, thus identification of a nutrient fire signature was unsuccessful. The lack of significant interactions is attributed to the methodology used to collect the xylem nutrient samples; however, immobile nutrients indicate the most potential for future research. Climate-tree growth analyses indicate climate plays a role in the growth of mature loblolly pine in the South Carolina Piedmont. Temperature, precipitation, PDSI, positive phase NAO, and positive phase PDO are the primary drivers of loblolly pine radial growth. Temporal consistency results suggest drought sensitivity increases with tree age. Unlike the climate variables, the relationships between ocean-atmospheric oscillations and radial growth appear to be more cyclical in nature and only influence growth in positive phases.

The urban forest is a structure that is fluid in both species composition and how it is integrated in our cities and suburban areas. Much like the fluidity in its structure, the urban forest provides ecosystem services and disservices in many forms. These services and disservices can often come in the form of temperature regulation, lower crime rates, and even higher property values. The latter, which is associated with the economic value of trees, is a part of the hedonic pricing literature which suggests that there is a disparity in the value associated with trees to house prices. With the City of Tampa conducting its own hedonic pricing study, along with the presence of robust urban forest data, 2,000 residents of the city who had recently purchased or rented their home were mailed a questionnaire gauging how trees influenced their decision to live at their current residence and how they perceived the urban forest. Out of the 2,000 properties, 400 of the surveys were received resulting in a 20% return rate. Five hypotheses were tested to determine how people’s perceptions affected the value they place on trees. It was hypothesized that home owners were more likely than renters to report tree disservices due to high maintenance costs, and potential damage. Additionally, it was hypothesized that homeowners would likely report more negative opinions of trees compared to renters. The analysis showed that tree drawbacks related to cost/maintenance and damage were reported by 43% and 45% of homeowners respectively. Likewise, 32% of renters reported cost/maintenance and 37% reported damage as their top drawbacks of trees. Although homeowners more frequently reported cost/maintenance and damage as drawbacks of trees, there was no significant statistical difference in opinion on trees at the .05 level. It was hypothesized that because neighborhood trees have less drawbacks such as property damage, residents would favor neighborhood trees more than trees on their property. Cross tabulating Likert statements with canopy cover did not reveal a preference for neighborhood trees above trees found directly on resident property. It was hypothesized that respondents living in homes with lower assessed values would express more negative opinions of trees such as cost and maintenance being reported as drawbacks. Cross tabulating sales price with the negative Likert statements concerning trees revealed that homes with higher assessed value reported more negative opinions of trees. It was hypothesized that different ethnic groups such as African Americans, Hispanic/Latinos, and White/Caucasians as well as residents of different affluence would report similar opinions and tree cover percentages with people from similar demographics. Despite the current literature suggesting differences in opinions, preferences, and canopy cover for different races/ethnicities, the analysis did not reveal a link between race/ethnicity and the availability of tree canopy or landscape preference. Finally, it was hypothesized that there would be a high correlation between residents’ purchases and/or rental decisions and the extent of canopy cover from trees originating on their property and/or in their neighborhood. For respondents who strongly agreed/agreed that trees influenced their rental/purchase decision there was a marginally higher canopy cover in the area surrounding their property than directly on their property. Additionally, there appeared to be no relationship with the level of agreement that trees influenced residents’ decision to rent/purchase and the amount of tree canopy on their property and in their neighborhood. The conclusions of the study are that the opinions of trees in Tampa, FL are primarily positive among those in the sample population. In order to gain less biased results it is suggested that a door to door method be utilized in the future. It is also suggested that residents’ opinions are sampled after a severe storm to assess how hazardous conditions affect the overall opinions surrounding trees.

A large amount of the world’s biodiversity is located in a disproportionately small amount of area, namely the tropics. Many of these areas are experiencing rapid landscape changes, mainly in the form of deforestation for agricultural practices. Current conservation efforts are focused on agricultural areas and their ability to provide habitat. The conservation value of a novel land-sparing agroforestry system, known as Integrated Open Canopy (IOC), was recently demonstrated on the study site when applied to coffee. IOC coffee supports forest species that are uncommon or absent in shade grown coffee. I generated best management practices for IOC farms relative to the conservation of forest-dependent birds by examining what features support the highest richness of species. The goal was to help develop guidelines for the implementation of IOC grown coffee. The Golden-winged warbler (Vermivora chrysoptera) is a Neartic-Neotropical migrant of high conservation priority which has been documented using a range of nonbreeding habitat types, including IOC coffee farms. However, as is the case with many migrant species, little is known about whether survival differs among habitats. Though generally forest dependent, previous work found Golden-winged warblers select for habitat features other than categorical forest types, such as canopy height and microhabitat features. In an attempt to identify quality nonbreeding habitat, I estimated Golden-winged survival rates specific to an array of habitat features.

Trees provide countless environmental, economic, and societal benefits to the urban environment, and may become increasingly important to maintaining environmental quality and human well-being in the face of increasing urbanization and climate change. However, trees in these urban areas are rapidly diminishing across the United States. Much of this loss can be prevented with proper planning and management, focused on selecting tree species that are both well-suited to the area’s growing conditions and able to survive the many stress factors in an urban setting. Choosing which tree species to plant in Massachusetts is especially challenging considering the lack of resources specific to the state’s growing conditions and the urban environment. I conduct a literature review to answer two research questions: (1) What ecological considerations should be made before tree selection, and (2) Which species should be planted in the urban environments of Massachusetts. My results yielded a comprehensive guide, in book form, detailing the five ecological considerations I recommend to make before selection, and profiles of 75 tree species recommended to plant in these areas. This book may act as a resource for tree wardens and homeowners to help choose the best species for their specific planting site, prompt other states to create or update their own state-specific selection guide, and encourage tree nurseries to grow and distribute favorable species, ultimately providing their communities with the benefits that trees provide.

As urban greening efforts continue, it is important to assess whether decisions to intensify street tree planting are meeting intended goals of improving urban canopy cover and increasing ecosystem services. Benefits of the urban forest take many forms, from ecological and economic to social and cultural, and are frequently cited in support of street tree planting. However, it is unknown to what extent factors such as species or nursery production method affect the ability of trees to successfully establish and provide ecosystem services in the urban environment. Using a system of oak trees planted along roads in South Amherst, Massachusetts during spring 2014, growth in caliper at six inches, diameter at breast height, and total tree height from fall 2014 to fall 2018 were modeled to determine whether species and/or nursery production method influenced street tree establishment and growth. Economic benefits were examined using a novel approach, whereby the breakeven point of costs and returns in ecosystem services was identified. Results indicated that both species and nursery production method influenced the success of these trees, which provided a return on investment by year 2018, in terms of both growth and benefits provided. This information is relevant to tree wardens and others tasked with street tree planning and maintenance, who must work within the confines of limited budgets in an environment that poses many challenges for trees.