The research involves first conducting a “case study” of ecological data and applying the results, together with the resilience concept, to the development of a greenspace conservation planning framework for urban regions. The first part of the research investigates the relationship between forest bird abundance and the surrounding landscape characteristics, especially, forest area and its spatial configuration in urban regions at multiple scales. The results are similar for simple and multiple regression analyses across three scales. The percentage of forest cover in a landscape is positively correlated with bird abundance with some thresholds. Overall, the percentage of forest cover in the landscape, contrast-weighted forest edge density, and the similarity of land cover types to forest cover are identified as important for the conservation of the target bird species. The study points to the importance of species-specific habitat requirements even for species with similar life history traits and of maintaining some forest edges and/or edge contrast. The second part of the research involves the development of a landscape planning meta-model and its conceptual application to greenspace conservation The research involves first conducting a “case study” of ecological data and applying the results, together with the resilience concept, to the development of a greenspace conservation planning framework for urban regions. The first part of the research investigates the relationship between forest bird abundance and the surrounding landscape characteristics, especially, forest area and its spatial configuration in urban regions at multiple scales. The results are similar for simple and multiple regression analyses across three scales. The percentage of forest cover in a landscape is positively correlated with bird abundance with some thresholds. Overall, the percentage of forest cover in the landscape, contrast-weighted forest edge density, and the similarity of land cover types to forest cover are identified as important for the conservation of the target bird species. The study points to the importance of species-specific habitat requirements even for species with similar life history traits and of maintaining some forest edges and/or edge contrast. The second part of the research involves the development of a landscape planning meta-model and its conceptual application to greenspace conservation.

Community and urban forestry is a multifaceted field ranging from tree planting to removal, hazard assessment, and public relations. However, the racial and gender diversity of the community forestry workforce is remarkably low. To gain a better understanding of this lack of diversity, I surveyed professionals in two major community/urban forestry organizations. Age, income, and years in the profession were considered, along with education level, to determine if there is some underlying reason for low representation of women and minorities in the community/urban forestry field. I found that while white males dominated all work sectors (especially private organizations), women were concentrated in public or non-profit organizations holding positions in offices, education, or other jobs with extensive public interaction. Minorities held similar positions to women or were in entry level jobs and general tree care rather than in more professionally advanced positions. Attitudes regarding most aspects of the profession varied little based on sex or minority status, with only minor differences on advancement potential and salary.

In March 2003, many communities in Mississippi fell under National Pollutant Discharge Elimination System (NPDES) regulations and were required to develop Stormwater Pollution Prevention Plans (SWPPPs). This study surveyed those in charge of SWPPPs in Mississippi’s regulated communities to determine the knowledge, efforts, and associated expenses, of complying with Stormwater Phase II regulations as well as what attempts regulated communities made to include urban forestry in their SWPPPs. While results indicated that all respondents were compliant with Stormwater Phase II regulations, regulated communities can improve efforts in several areas to best mitigate stormwater runoff pollution (e.g., public education and urban forestry). Findings will be useful when presented to current and, soon to be, regulated communities in an educational and outreach effort to increase their knowledge levels, reduce incurred costs, increase the effectiveness of their SWPPP, and enhance their ability to utilize urban and community forests as a stormwater mitigation tool.

No description available.

Automation of urban tree inventory using remote sensing is needed not only to reduce inventory costs but also to support carbon accounting for urban planners and policy-makers. However, urban areas are heterogeneous and complex, and a more sophisticated approach is needed for using remote-sensing technology like lidar for tree inventory in urban areas than is required for forested environments. Based on remote sensing and field data from a suburban residential area in the central United States, this dissertation presents a methodology for utilizing airborne small-footprint lidar data to inventory urban trees. This dissertation proposes approaches that have the potential to automate three main activities of urban tree inventory -- identifying the locations of trees, classifying the trees into taxonomic categories, and estimating biophysical parameters of individual trees -- using airborne lidar data. Mathematical morphological operations followed by a marker-controlled watershed segmentation were found to perform well (r = 0.82 to 0.92) to delineate individual tree crowns in urban areas, especially when the trees occur in relatively isolated conditions. Using various distribution metrics of lidar returns, random forests were used to classify individual trees into different taxonomic classes (broadleaves/conifers, genera, and species). A classification accuracy of 80.5% was obtained when separating trees only into broadleaf and conifer classes, 50.0% for genera, and 51.3% for species. Using spectral metrics from high-resolution satellite imagery in addition to lidar-derived predictors improved the classification accuracies by 10.4% (to 90.9%) for broadleaf and conifer, 8.4% (to 58.4%) for genera and 8.8% (to 60.1%) for species compared to using lidar metrics alone. Prediction models to estimate several biophysical parameters such as height, crown area, diameter at breast height, and biomass were developed using lidar point cloud distributional metrics from individual trees. A high level of accuracy was attained for estimating tree height (R²=0.89, RMSE=1.3m), diameter at breast height (R²=0.82, RMSE=9.1cm), crown diameter (R²=0.90, RMSE=0.7m) and biomass (R²=0.67, RMSE=1.2t). Our results indicate that, while using lidar data alone can achieve the automation of major urban forest inventory tasks to an acceptable level of accuracy, a synergistic use of lidar data with other spectral data such as hyperspectral or orthoimagery, which are usually available at least in the United States for most urban areas, can considerably improve the performance of the lidar-based method. / Ph. D.

An urban tree canopy assessment (UTCA) is a new technology that can inform management decisions to optimize the economic, social and environmental benefits provided by urban forests. A UTCA uses remote sensing to create a comprehensive spatial snapshot of a locality's land cover, classified at a very fine scale (1 meter or less). Over the past decade, UTCAs have been conducted for numerous localities in the Chesapeake Bay watershed (CBW) as part of a strategy to enhance urban tree canopy (UTC) and reduce stormwater runoff that pollutes the Chesapeake Bay. Our research examined how local governments employ these UTCAs and identified barriers to and drivers of UTCA use for urban forest planning and management. We conducted a web-based survey of all localities in the CBW with populations over 2,500 for which a UTCA existed as of May 2013. We found that 33% of respondents reported being unaware that a UTCA existed for their locality. Even so, survey results showed that localities aware of their UTCA were using it to establish UTC goals, create and implement strategies to achieve those goals, and monitoring progress towards UTC goals. Survey localities were segmented based on how they reported using their UTCA to provide insight on possible outreach and technical assistance strategies that might improve future UTCA use. Overall, we found that larger localities with more developed urban forestry programs use their UTCA more frequently. However, we found several exceptions, suggesting that UTCAs could be an important catalyst for expanding municipal urban forestry programs. / Master of Science

Emerald ash borer (Agrilus planipennis Fairmaire) (EAB) is an invasive, wood-boring beetle (Coleoptera: Buprestidae) introduced unintentionally to the United States from East Asia that infests and eventually kills native ash trees (Fraxinus spp.). First detected near Detroit, Michigan in 2002, EAB had spread to fifteen U.S. states by 2011, killing an estimated 50 million ash trees along the way. EAB was first discovered in Virginia in 2003 and re-infested the state in 2008, raising concerns over impacts that the invasive pest might have on municipal urban forests and street trees. Despite these concerns, little is known about native ash abundance in Virginia's urban forests; as a result, potential EAB impacts have been difficult to project. In this study, street tree assessments were conducted in fourteen Virginia municipalities using i-Tree Streets®, which is a software program developed by the U.S. Forest Service that uses field inventory data to estimate street tree abundance and composition along with the quantity and monetary worth of functional benefits provided by these street trees. In addition to estimating potential losses of functional benefits provided by native ash street trees, information obtained from Virginia Dept. of Transportation was used to estimate the potential cost of removing these trees from the street side. The assessment indicated that there are about 4,600 native ash street trees in the fourteen studied localities and that native ash species comprise about 2% of municipal street tree populations on average. The highest relative abundance of native ash was found in Winchester City (5.8% of all street trees) whereas Richmond City had the greatest number of native ash street trees (estimated at 1,417). In terms of species importance (which accounts for both the relative abundance and relative size of trees in the population), only two localities (City of Roanoke and Town of Abingdon) had a native Fraxinus species among the top-five most important street tree species in the locality. In contrast, every municipality had at least one Acer species among the top-five, and eight of fourteen localities had at least one top-five Quercus species. Native ash street trees in the studied localities were estimated to provide functional benefits (energy conservation, stormwater mitigation, air pollution abatement, carbon sequestration, and aesthetic contributions) valued at over $535,000 annually, or roughly $38,000 per locality. In addition, carbon stored in these trees (about 17 million kilograms) was valued at nearly $277 thousand. The total estimated cost of removing lost ash trees was estimated at nearly $1.75 million, averaging about $124,000 for each municipality, and replacing the canopy cover and basal area provided by existing native ash street trees would exceed $17 million. In total, the studied localities would incur a gross financial impact of about $20.26 million due to losses of functional benefits and structural assets provided by native ash street trees. / Master of Science

Urban tree canopy cover is important because it mitigates negative impacts of urbanization such as urban heat and stormwater. Land development leads to canopy loss through tree removal, but some localities have regulations in place that require trees to be retained or replanted during development. The goal of these regulations is to preserve tree cover. Since 2009, Fairfax County, Virginia has had an ordinance that requires parcels to reach a certain amount of canopy 10 years post-development. However, it was unknown if the requirements of this ordinance were being met. To investigate this issue, we determined which developed parcels met their required canopy using remotely-sensed tree canopy cover data from 2021. We then conducted an additional analysis on a sample of developed parcels using their site plans to compare the canopy proposed by developers to the measured canopy from the geospatial data. These results were then compared to potential predictors of ordinance compliance to determine if there were certain attributes of a parcel that may drive ordinance compliance. Of all 482 parcels in Fairfax County that were developed from 2009 to 2011, 79.46% met their canopy requirements by 2021. For the sample of 151 developed parcels, 70% reached the proposed amount of canopy by 2021. The results suggest that Fairfax County's ordinance is promoting preservation of tree canopy cover in developed areas as intended. Zoning type, amount of canopy required, parcel size, impervious cover, and pre-existing canopy were all found to have a significant relationship with ordinance compliance. These findings could improve the understanding of the efficacy of tree ordinances in other localities. / Master of Science / Trees in cities provide residents with many benefits including absorbing stormwater, reducing pollutants entering waterways from runoff, filtering air pollutants, and lessening soil erosion. However, the removal of trees during construction reduces the number of trees, which reduces the benefits trees provide. One way municipalities are combating this issue is through creating policies that protect canopy in areas undergoing development. Fairfax County, Virginia has a policy that requires developers to ensure the land they develop has a certain amount of tree canopy 10 years after construction. This policy has been in effect in Fairfax County since 2009, but until now the county did not know if developed areas were meeting the required amount of tree canopy 10 years after construction. We used measurements of tree canopy cover as well as information from the construction plans of developed areas to determine where tree canopy requirements were being met and where they were not. Of all 482 parcels in Fairfax County that were developed from 2009 to 2011, 79.46% met their canopy requirements by 2021. We also investigated if certain attributes of a developed area may impact if that area will reach its required canopy in 10 years. Zoning type, amount of canopy required, parcel size, impervious cover, and pre-existing canopy were all identified as factors that may impact policy compliance. These findings could help other localities protect tree canopy cover using land development policies.

Urban forested natural areas (UFNAs) are the remnants of larger forested ecosystems that have become surrounded by urban land development. Due to their proximity to dense population centers, UFNAs provide levels of ecosystem services disproportionate with their small size. However, stressors on UFNAs, such as fragmentation, invasive species, urban heat islands, soil compaction, altered seed predator populations, and disrupted disturbance regimes, can alter species composition and forest structure such that the continued flow of these ecosystem services is unlikely. Further, management of these systems is confounded by their size and location. While most urban forests are managed using individual tree techniques (arboriculture), UFNAs have too many trees for this approach to be tenable. Likewise, traditional forest management techniques (silviculture) may not be possible due to the relatively small size of UFNAs and their proximity to urban population centers where silvicultural strategies may not be politically acceptable. This dissertation helps inform UFNA management strategies by documenting how species composition and forest structure have changed over time as a result of a mostly laissez-faire management strategy in a UFNA of Memphis, Tennessee. Evidence of the negative impacts of this approach on native tree species can be used by managers to build public support for management interventions. This work also examines potential recruitment barriers for the native overstory species northern red oak (Quercus rubra L). and tulip poplar (Liriodendron tulipifera L.) which provide much of the large tree character in this UFNA. These results can guide specific management strategies to promote these important species. Finally, this research elucidates the potential threat to native plant biodiversity in this UFNA posed by a popular non-native ornamental tree species, cherry laurel (Prunus caroliniana Aiton). The results can aid in the development of appropriate policies regarding this specific tree and similar species in other UFNAs. Combined these studies provide a glimpse into the complicated dynamics and management of this UFNA. Given the widespread nature of the species examined and the methods used, this research may also provide useful insights into UFNA management in the surrounding regions.

published_or_final_version / Geography and Geology / Doctoral / Doctor of Philosophy