Suburban Philadelphia is a densely populated region with a history of urbanization and waterway channelization. Situated within the Delaware River watershed, 70% of the region’s stream segments are impaired, primarily due to excess sediment and nutrients. To improve water quality, the Upstream Suburban Philadelphia Cluster of the Delaware River Watershed Initiative (DRWI) established focus areas within the region for targeted implementation of stormwater control measures and community outreach about stormwater management. The focus areas consisted of upstream headwaters to four streams flowing into the Delaware River. The objective of this study was to determine sediment and nutrient concentrations in first flush overland flow (OLF) in three of the DRWI focus areas. Seven sites were selected for collection of OLF, stream, and rain samples. A total of 228 samples from 24 sample locations across 17 storms were collected from the Pennypack Creek, Jenkintown Creek, and Sandy Run watersheds. Samples were analyzed for nitrate (N), total dissolved phosphorous (TDP), total phosphorous (TP), suspended sediment concentration (SSC), and chloride (Cl), and results were compared to catchment metrics including area and land cover. OLF samples showed a wider variability of sediment, chloride, and nutrient concentrations than stream samples, and the stormwater quality varied between catchments with different land cover composition. Higher N correlated with increased road coverage and landscaping applications in vegetated areas. Lower TDP was linked to increased tree canopy, while higher TP was linked to smaller lot sizes. In the stream samples, higher SSC was linked to increased road coverage and smaller building sizes, and higher Cl was linked to nearby impervious surfaces. SSC was often reduced in the OLF samples after flowing downhill or through vegetated patches. Two bioretention basins were sampled at the inlet and outlet. Both basins experienced a decrease in SSC and N at the outlets, showed marginal to poor efficiency for TDP and TP removal, and provided an increase in Cl in outlet. A review of all collected data suggests that land cover and human activity in these watersheds are greater drivers of stormwater quality than rainfall and weather patterns. The data presented in this report has implications for stormwater control. First, this study provides an understanding of local heterogeneities in the distribution of nutrients, sediment, and chloride in stormwater runoff from seemingly similar watersheds in terms of land use. Second, the presented data can be used in projects and models at the headwater scale and the micro-catchment scale to improve planning and monitoring. / Geology

Land use/land cover (LULC) plays a vital role in the provision of ecosystem services. Changing natural vegetation to agricultural or urban uses affectss the socio-economic dynamics of the surrounding populations. Changing land use may also result in the impairment of ecosystem services. Rural and urban communities have different realities and perceptions on the importance of ecosystem services, which tend to vary by economic, generational, social, and cultural factors. This study assesses the subjective value of people in urban and rural communities on provisioning, regulating, and cultural ecosystem services. A quantitative and qualitative survey using interviews and spatial analysis with GIS is used to study ecosystem services. The survey evaluates the values, perceptions, and benefits of ecosystems in urban and rural regions. Environmental conservation plans that have been implemented on a national level and the traditional ecological activities that local communities play a crucial role in the governance of ecosystem services. There is a need to understand the effectiveness and awareness o actions resulting from governance regimes to be both applicable and useful in protecting ecosystem services in fragile and diverse ecosystems such as Ecuador.

Human alteration of the landscape for agricultural and urban land use has been linked to the degradation of streams and stream biota. Natural physical and climatic characteristics, or physiographic template, are important for determining natural land cover and constraining human land use, and are strongly related to stream habitat and stream biotic assemblages. Since the physiographic template differs among watersheds and is an important determinant of the processes being studied, it is important to account for these natural differences among watersheds so that the relationship between land cover and streams can be properly understood. The purpose of this thesis is to develop and assess the utility of a regional framework that classifies watersheds based on physical and climatic predictors of land cover. In Chapter 1, I identified physical and climatic predictors of land cover and classified watersheds into Land cover Distinguished Physiographic Regions (LDPRs) based on these predictors. I was able to identify and create classes based off eight climatic and landform characteristics that determined natural land cover and human land use patterns for both the Eastern and Western U.S. In Chapter 2, I utilized LDPRs to stratify a study region and investigated whether the relationships between land cover and stream fish assemblages varied between these regions. Five commonly used metrics covering trophic, reproductive and taxonomic groupings showed significant variation in their response to agricultural land use across LDPRs. The results suggest that the physiographic differences among LDPRs can result in different pathways by which land cover alterations impact stream fish communities. Unlike other commonly used regional frameworks, the rationale and methods used to develop LDPRs properly accounts for the causal relationship between physiography and land cover. Therefore, I recommend the use of LDPRs as a tool for stratifying watersheds based on physiography in future investigations so that the processes by which human land use results in stream degradation can be understood. / Master of Science

Whitetop Mountain is Virginia's second highest peak and hosts two globally rare, insular ecosystems: a southern Appalachian grass bald and a red spruce-dominated forest. These areas provide important ecosystem services and habitat for rare and endangered species. They are highly prized for their cultural value and recreational areas that support nearby rural economies. This thesis investigated spatial patterns in both ecosystems on Whitetop. We documented a 24.73% decrease of in the extent of the southern Appalachian grass bald across 68 years through analysis of historical aerial photography. In the red spruce-dominated forest, we used a consumer grade unmanned aerial vehicle (UAV) to survey the health of all trees within a 46 ha sample plot. We assessed (dead, dying, healthy) over 9,000 individual trees based on visual patterns in the imagery and produced spatial products that will inform land managers about where resources are most needed. About 7.4% of the red spruce trees in our study area were classified as dead or dying. A model relating spruce mortality to biophysical landscape factors identified no single predictive factor related to mortality. The addition of optical information from the UAV imagery into the model proved utility for remotely-sensed data in identification of dead spruce within the forest canopy at Whitetop and possibly in other similarly structured forests. This research contributed to the limited body of knowledge surrounding the decline of both southern Appalachian grass balds and red spruce forests and provided technical insights for future mortality monitoring. / Master of Science / This thesis investigates land cover changes in two rare ecosystems on Whitetop Mountain, Virginia. The mountain has important biological significance and is a cultural landmark. The high-elevation summit hosts plant and animal species characteristic of northern climates, including a red spruce-dominated forest and a southern Appalachian grass bald. This work documented a 24.73% decrease in the size of the rare southern Appalachian grass bald ecosystem at Whitetop Mountain over 68 years and discussed potential drivers and proposed management for conservation. We also successfully used a camera-equipped unmanned aerial vehicle (drone) to produce high quality imagery for spruce mortality detection within the red spruce forest. Of over 9,000 standing spruce trees, 7.4% were categorized as either dead or dying. We built a predictive model to investigate the relationship between mortality and biophysical environmental factors, but did not identify a single causal factor. A second model that included the color band information from the drone camera revealed that different types of aerial imagery could play a valuable role in detection of tree mortality in forests of similar structure. Overall this research contributes to the body of knowledge surrounding the decline of both southern Appalachian grass bald and red spruce ecosystems and provides insights for management.

The terrestrial ecosystem is an integral component of the Earth System. Constant atmosphere-biosphere exchanges of energy and material affect both the physics and chemistry of the atmosphere. While the general roles of terrestrial ecosystems in regulating ozone and particulate matter air pollution have long been acknowledged, our understanding at both individual process and system level are far from perfect. Also, new process-level discoveries about terrestrial atmosphere-biosphere exchanges are not timely incorporated in numerical models routinely used to study and forecast air quality. These hinder our ability to understand how air quality respond to environmental changes and variabilities. Chapter 1 of this dissertation provides a brief overview on these topics. In Chapter 2 of this dissertation (Wong et al., 2019), we conduct global long-term simulations of ozone dry deposition velocity with four different types of dry deposition parameterizations. We find that none of the tested parameterizations universally stands out in terms of matching observed ozone deposition velocity over different land cover types. Combining this with sensitivity simulations from a global 3-D atmospheric chemistry model (GEOS-Chem), we find that the choice of dry deposition parameterizations can affect the mean, trend and variability of simulated surface O3 level. In Chapter 3 of this dissertation (Wong et al., 2022), we analyze long-term ozone flux observation from three field sites to examine the effects of extreme heat and dryness on ozone deposition. We find that non-stomatal ozone uptake tends to increase during hot days, which either partially offsets or dominates over the reduction in stomatal ozone uptake anticipated by ecophysiological theory. While the response of ozone deposition to dryness is more varied, changes in non-stomatal deposition are usually important. Current dry deposition parameterizations often fail to capture such changes in non-stomatal ozone uptake, resulting in considerable potential error in simulated surface ozone level during hot and dry days. In Chapter 4 of this dissertation (Wong and Geddes, 2021), we conduct global GEOS-Chem numerical experiments with anthropogenic emission inventories and land surface remote sensing products to compare the effects land cover versus land management changes on O3 and fine particulate matter air quality over 1992 – 2014. We find that land cover has stronger effects on O3, while land management has stronger effects on fine particulate matter pollution. We also find that land management has significantly altered regional and global nitrogen deposition, and therefore the risk of critical load exceedance. Chapter 5 of this dissertation includes the concluding remarks and suggestions for future work. In addition, I outline and present the preliminary result from a project examining the future of soil reactive nitrogen emissions and their impacts on air quality.

This dissertation comprises three interrelated studies exploring the effects of hurricanes on forestlands and the optimization of salvage logging practices. The first study examines land cover changes and salvage logging patterns following Hurricane Michael. It utilizes predictive models to identify key drivers of these changes, exploring the relative influence of storm intensity, forest vulnerability, and economic/operational factors. The second study builds upon these findings, focusing on the agent attribution for land cover change observations leveraging advanced remote sensing tools and relevant spatial data. By distinguishing between wind damage and salvage logging activities, it advances the understanding of post-hurricane land cover dynamics. The third study introduces a novel timber supply model that utilizes robust stochastic optimization to optimize salvage operations under uncertainty. It integrates various data sources to optimize site selection, transportation logistics, and resource allocation under uncertain timber stocks, aiming to enhance salvage operations' efficiency and economic returns. Collectively, these studies provide valuable insights for improved hurricane disturbance management.

Characterizing streamflow trends is important for water resources management. Streamflow conditions, and trends thereof, are critical drivers of all aspects of stream geomorphology, sediment and nutrient transport, and ecological processes. Using the non-parametric modified Mann-Kendall test, we analyzed streamflow trends from 1996 to 2022 for the Southern Appalachian (SA) region of the U.S. The forested uplands of the SA receive high amounts of rain and act as a "water tower" for the surrounding lowland area, both of which have experienced higher than average population growth and urban development. For the total of 127 USGS gages with continuous streamflow measurements, we also evaluated precipitation and land change rates and patterns within the upstream contributing areas. Statistical methods (i.e., generalized linear models) were then used to assess any linkages between land cover change (LCC) and streamflow trends. Our results show that 42 drainage areas are experiencing increasing trends in their precipitation, and 1 is experiencing a negative trend. A total of 71 drainage areas are experiencing increasing trends in either their annual streamflow minimums, maximums, medians, or variability, with some experiencing changes in multiple. From our models, it is suggested that agricultural expansion is associated with increasing minimum streamflow trends, but increasing precipitation is also positively linked. With this information, water managers would be aware of which areas are experiencing changes in streamflow amounts from LCC or precipitation and could then apply this in planning and predictions. / Master of Science / Water availability is important for resources management. Streamflow is a measure of available surface water and is an important component in the hydrological cycle. Using the non-parametric modified Mann-Kendall test, we analyzed streamflow trends from 1996 to 2022 for the Southern Appalachian (SA) region of the U.S. The forested uplands of the SA receive high amounts of rain and act as a "water tower" for the surrounding lowland area, both of which have experienced higher than average population growth and city expansion. For the total of 127 USGS gages with continuous streamflow measurements, we also evaluated precipitation and land cover change rates within the area upstream of the gage (or drainage/contributing area). Statistical methods (i.e., generalized linear models) were then used to assess any linkages between land cover change (LCC) and streamflow trends. Our results show that 42 drainage areas are experiencing increasing trends in their precipitation, and 1 is experiencing a negative trend. A total of 71 drainage areas are experiencing increasing trends in either their annual streamflow minimums, maximums, medians, or variability, with some experiencing changes in multiple. From our models, it is suggested that agricultural expansion is associated with increasing minimum streamflow trends, but increasing precipitation is also positively linked. With this information, water managers would be aware of which areas are experiencing changes in streamflow amounts from LCC or precipitation and could then apply this in planning and predictions.

In recent decades land use and land cover change (LULCC) has occurred throughout the Intermountain West. The Crown of the Continent Ecosystem (CCE) extends along the Rocky Mountains adjacent to the Canada-U.S. International border. In the U.S. portion of the CCE, located in northwestern Montana, development has increased since the 1990s, largely because of urban to rural migration. The CCE has become an amenity-based destination, which in turn is likely to threaten its terrestrial and aquatic ecological diversity (Quinn and Broberg 2007). Specifically, development pressures on private lands surrounding federally protected lands, are intensifying and thus threatening core habitat of native species and connectivity of forested areas. By characterizing the spatial and temporal patterns of LULCC, we can better understand landscape-scale changes influenced by human-environment interactions. Using National Land Cover Database (NLCD) products, I identified areas that have experienced land cover change for three time periods: 1992-2001, 2001-2006, and 2006-2011. Additionally, I used case studies to further investigate LULCC in the study area. The findings suggest that the highest rates of development in proximity to Glacier National Park were dependent on existing urban land cover, meaning existing roadway infrastructure and established urban areas saw the greatest urban development. Additionally, communities adjacent to Glacier National Park were hotspots for urban development. Based on the results, areas in proximity to federally protected lands are likely to experience continued urban intensification over the next few decades. / Master of Science

Invasive plant species threaten native plant communities and inhibit efforts to restore disturbed landscapes. Surface coal mines in the Appalachian Mountains are some of the most disturbed landscapes in North America. Moreover, there is not a comprehensive understanding of the land cover characteristics of post- mined lands in Appalachia. Better information on mined lands' vegetative cover and ecosystem recovery status is necessary for implementation of effective environmental management practices. The invasive autumn olive (Elaeagnus umbellata) is abundant on former coal surface mines, often outcompeting native trees due to its faster growth rate. The frequent revisit time and spatial and spectral resolution of Landsat satellites make Landsat imagery well suited for mapping and characterizing land cover and forest recovery on former coal surface mines. I performed a multitemporal classification using a random forest analysis to map autumn olive on former and current surface coal mines in southwest Virginia. Imagery from the Operational Land Imager on Landsat 8 were used as input data for the study. Calibration and validation data for use in model development were obtained using high-resolution aerial imagery. Results indicate that autumn olive cover is sufficiently dense to enable detection using Landsat imagery on approximately 12.6% of the current and former surface coal mines located in the study area that have been mined since the early 1980s. The classified map produced here had a user's and producer's accuracy of 85.3% and 78.6% respectively for the autumn olive coverage class. Overall accuracy in reference to an independent validation dataset was 96.8%. These results indicate that autumn olive growing on reclaimed coal mines in Virginia and elsewhere in the Appalachian coalfields can be mapped using Landsat imagery. Additionally, autumn olive occurrence is a significant landscape feature on former surface coal mines in the Virginia coalfields. / Master of Science

Forested mountain watersheds provide essential resources and services (e.g., water supply) to downstream ecosystems and human communities. Fast-growing mountainside residential development not only modifies the terrestrial system but also aquatic systems by changing the nutrient input from the terrestrial to aquatic. However, the impacts of mountainside residential development on stream ecosystems are complex because interactions between in- stream process and hillslope soils control in-stream nutrient dynamics, and it is difficult to experimentally study these interactions at broad spatial scales. In my dissertation research, I first developed models for leaf decomposition in a forested headwater stream by synthesizing several important ecological concepts, including ecological stoichiometry, microbial nutrient mining, and microbe-substrate interaction. I then extended the single stream model to a stream network model and further linked the stream network model with a terrestrial model that simulates nutrient processes and hydrology in hillslope soils. With this complete modeling framework, I conducted a global sensitivity analysis to evaluate the importance of terrestrial nutrient input versus in-stream processes in modifying nitrogen export. I also conducted a simulation to investigate the impacts of housing density, buffer zone protection, and stream travel distance from the residential development to the catchment outlet on nitrogen export at the local and regional scale. The model for leaf decomposition performed better for predicting detritus decay and nutrient patterns when microbial groups were divided into immobilizers and miners and when leaf quality was included as a variable. The importance of terrestrial nutrient input versus in-stream nutrient processes greatly depended on the level of terrestrial nutrient input. When terrestrial nitrate input was low, nitrogen export was more sensitive to in-stream net microbial nitrogen flux (mineralization - immobilization) than nitrate input. However, when terrestrial nitrate input was high, nitrate input was more important than in-stream net nitrogen flux. Greater impacts, i.e., higher nitrogen export at the local scale or greater change in nitrogen export at the regional scale, were associated with higher residential density, a lack of buffer zone protection, and shorter stream travel distance from the residential development to the catchment outlet. Although subject to model assumptions and further validation through field experiments, this research provides a general modeling framework for in-stream processes and aquatic-terrestrial linkages and expands an understanding of interactions between terrestrial and in-stream nitrogen dynamics and the impacts of mountainside development on stream ecosystems, identifies directions for further research, and provides insights for land and river management in mountainous areas. / Ph. D.