Click on the title of a talk to view the abstract.
9:00am-9:45am // Clark Hall // Mural Room
9:45am-10:00am // Clark Hall // Mural Room
Session 1. Land and Atmosphere Systems
10:00-11:15am // Clark Hall // Room 133
10:00-10:15 am Nitrogen and Carbon Dynamics throughout Secondary Succession following Agricultural Abandonment in North-Central Virginia. Alexandra Parisien and Howard Epstein
Long-standing theoretical models predict carbon (C) cycle dynamics during succession following agricultural disturbance. Less understood, however, are the interactive dynamics of the nitrogen (N) and C cycles throughout secondary succession, and how plant-available N may or may not limit vegetation transitions and net primary productivity over time. Two chronosequences at the Blandy Experimental Farm in Boyce, north-central Virginia were examined to elucidate N and C cycle dynamics over a temporal successional gradient. Each chronosequence consists of one early, one mid, and one late secondary successional field (~15 years, ~30 years, and ~100 years post agricultural abandonment, respectively). Five 10×10 m plots were established in each of the six fields. Total soil N and C data were collected to 30 cm depth, and net N mineralization and nitrification were measured twice per growing season using an in-situ anion-cation exchange resin bag technique. Live foliar and litter C and N were also examined in each plot, and soil CO2 efflux was measured biweekly. While soil N varied insignificantly across successional stages, soil C was significantly higher in late succession than early succession in the 0-10 cm fraction. Soil C:N peaked in mid succession in the 0-10 cm fraction. Net N mineralization and nitrification both trend upward from early to late succession. Live foliar N increased through successional stage, but litter N sharply decreased in late succession, indicating an increase in N use efficiency. Soil CO2 efflux decreased significantly through successional stages, correlating with a decrease in soil temperature from early to late succession. Previous studies at this location have demonstrated increasing net primary production and therefore net ecosystem production with time since abandonment, suggesting a lack of N limitation. A thorough understanding of N and C cycling dynamics during secondary succession is especially important in the southeastern United States, where a significant amount of previously cultivated land has been abandoned over the past century due to advances in farming efficiency and the move westward to more fertile soils. Much of the southeastern U.S. is now undergoing secondary succession, and quality data on the dynamics of N and C cycling during this procession can help guide future land management decisions and model predictions.
10:15-10:30 am Regicide: Conopid fly parasitoids are also killing bumblebee queens. Amber Slatosky
Bumblebees are among pollinators found to have declining populations worldwide. To better understand these declines, examination of their interactions with natural enemies is required. Most studies of interactions between parasitoid conopid flies and their bumblebee hosts focus on risks for non-reproductive members of bumblebee colonies because it is assumed queens hibernate too quickly after maturity to experience substantial risk. This work examines parasitism rates for all three castes (worker, male, queen) of a species that experiences risk of infestation during reproductive dispersal. This work examines whether queens are less likely to be infested than males or workers, exposure will be positively correlated with parasitism for all castes, and that queens will be more likely to exhibit a melanization response in the presence of a conopid fly larva. Reported here: the highest rate of queen parasitism on record, that evidence of melanization on conopid larvae is rare and even among all three castes, and that exposure is most important to understanding risk of infestation. These findings suggest queen bumblebees’ parasitoid fly mortality rates may be higher than previously thought for certain species, and that resistance appears to be low.
10:30-10:45 am Insights on vegetation functioning using remotely-sensed measures of solar-induced fluorescence and reflectance spectroscopy. Andrew Jablonski, Xi Yang, and Manuel Lerdau
The purpose of this talk is to outline the current state of using remote-sensing methods to monitor vegetation functioning – namely carbon and water fluxes. I will identify current outstanding questions and methodological gaps, and demonstrate how my research provides a framework for addressing such questions.
10:45-11:00 am Atmospheric Drivers of the California Current System Daniel F. Schmidt, Dillon H. Amaya, Kevin M. Grise, and Arthur J. Miller
Upwelling in the California Current system is crucial to bringing nutrient-rich water to the photic zone and supporting the associated ecosystem. This upwelling is a result of the wind-driven ocean circulation and is therefore susceptible to changes in the atmospheric circulation. We use both climate models and observational data to explore the response of the California Current to shifts in the Hadley cell and the North Pacific subtropical high–including both shifts due to short-term variability and longer-term shifts in a climate change scenario. We find that the subtropical high has a much stronger influence than the Hadley cell on upwelling in this area, and that uncertainties in the future of the California Current and its ecosystem can be traced in part to uncertainties in the future evolution of the subtropical high.
11:00-11:15 am Observing Air Pollution Inequality Using High Spatial Resolution Nitrogen Dioxide Remote Sensing Measurements in Houston, Texas Mary Angelique Demetillo, Kimberly Fields, Aracely Navarro, Katherine Knowles, Jeffrey Geddes, Caroline Nowlan, Scott Janz, Laura Judd, Jassim Al-Saadi, Kang Sun, Brian McDonald, Glenn Diskin, Sally Pusede
Houston, Texas is a major U.S. urban and industrial area, where poor air quality is unevenly distributed, with a disproportionate share in low-income, non-white, and Hispanic neighborhoods. We have traditionally lacked city-wide observations with which to fully describe intra-urban pollutant heterogeneities for reactive gases like nitrogen dioxide (NO2). Here, we analyze novel high-spatial-resolution (250 m x 500 m) NO2 vertical columns measured by the NASA GCAS airborne spectrometer, collected over Houston as part of the September-2013 NASA DISCOVER-AQ mission, and quantify differences in population-weighted NO2 distribution with census tract demographics. We find 37 % higher NO2 in low-income and non-white/Hispanic (LIN) census tracts compared to high-income white (HIW) tracts, and report NO2 disparities separately by race-ethnicity (11–32%) and poverty status (15–28%). We observe substantial temporal variability in LIN-HIW NO2 differences (and other metrics), driven by the greater prevalence of large NOx ( NO + NO2) emission sources in LIN neighborhoods. We use the GCAS dataset to evaluate measurements from the recently-launched satellite-based TROPOMI (3.5 km x 7 km), averaged to 0.01∘ x 0.01∘ using physics-based oversampling, and demonstrate TROPOMI resolves similar relative, but not absolute, differences in census-tract-scale NO2. We utilize the high-resolution FIVE and NEI NOx emission inventories, plus one year of TROPOMI weekday-weekend variability, to attribute tract-level NO2 disparities to industrial sources and heavy-duty diesel vehicles. We evaluate GCAS and TROPOMI observations against in-situ column and surface measurements. We discuss future opportunities for satellite remote sensing to constrain census-tract-level NO2 disparities.
11:15-11:30 am Assessing the Geographical Distribution and Reduction Potential of the Nitrogen Footprint of a Community: A Case Study in Charlottesville, VA Julia Stanganelli
Nitrogen is imperative to life on earth, but excess reactive nitrogen can have harmful effects on marine and terrestrial environments, the atmosphere, and human health. Anthropogenic creation of reactive N (Nr; all N species but N2) and consequent inputs to the environment are associated largely with agricultural production and fossil fuel combustion. A Nitrogen Footprint is a tool created to track the impact of an individual, institution, or community’s impact on excess Nr released to the environment. This study aims to use the community nitrogen footprint tool to ask: 1) what is the geospatial variability of the N footprint in Charlottesville City, and 2) how does it relate to socio-economic patterns such as average household income and racial make-up of a population segment, as well as distance from the University of Virginia? Additionally, 3) where in Charlottesville City are the greatest opportunities for reduction in the N footprint, and 4) how might certain changes in consumer choices offer strategies for reduction? Previous studies have shown that more socioeconomically advantaged populations contribute more to global climate change and environmental pollution. The results of this study may support this theory in terms of unequal impact on Nr additions to the environment.
Lunch: 11:30 am – 12:45pm
Odum Room, Clark Hall
Session 2. Aquatic Systems
12:45-1:45pm // Clark Hall // Room 133
12:45-1:00 pm Quantifying and mapping intertidal oyster reefs utilizing LiDAR-based remote sensing Sara Hogan, Matthew Reidenbach
The eastern oyster, Crassostrea virginica, is primarily found within intertidal regions on the Eastern Shore of Virginia, USA, although their abundance and distributions are not well known. Here we determine if Light Detecting and Ranging (LiDAR) derived data can be used to classify land cover and identify intertidal oyster reefs. We use the locations of existing reefs to determine the physical characteristics of oyster habitat, through the use of existing elevation, fetch, and water residence time data for the region. We found that oyster patches mapped using LiDAR-based elevation data overlapped greater than 90% with oyster patches mapped in-situ using GPS ground-truth data. Trained with elevation, intensity, and surface slope, and curvature data derived from LiDAR, the land cover classification identified oyster cover with an accuracy of 81 %. Ground-truth patches were small, with the 50th percentile for area and perimeter being 11.6 m2 and 14.5 m. Reefs were also found to exist in a narrow range of elevation (-0.81 to -0.18 m relative NAVD88) and average vertical relief of 0.15 – 0.87 m relative to their surrounding land. Analysis of land cover with similar physical characteristics also suggests there is still ample viable intertidal area for future oyster population restoration. We conclude that LiDAR data, coupled with physical attributes of existing reefs, can help understand oyster distributions and be used to target and prioritize locations for future restoration.
1:00-1:15 pm Getting the timing right: Ice sheet retreat and margin stabilization due to land emergence Marion McKenzie, Lauren Simkins
The Cordilleran Ice Sheet (CIS), arguably the least understood of all former ice sheets and yet the most similar to the modern Greenland Ice Sheet (GrIS), provides an opportunity to enhance our current understanding of interactions between ice sheet retreat behavior and the solid earth on which ice sheets rest. Specifically, I ask: what was the influence of solid Earth rebound, due to ice unloading, on the retreat of the southernmost CIS, and can we use CIS retreat to better understand ice sheet behavior across emergent marine to terrestrial landscapes, a potentially important consideration for contemporary margins of the GrIS? This project aims to answer these questions by mapping and characterizing glacial landforms and lakes in the Puget Lowland using LiDAR data and collecting a series of lake sediment cores and uplifted outcrop sediments during a field expedition to the Puget Lowland, Washington in May 2020. This process-based study using the paleo-record of ice sheet retreat on an emergent bed will help constrain the sensitivity of ice sheets to earth uplift, which is critical for testing coupled solid Earth – ice sheet models used to project future sea level scenarios.
1:15-1:30 pm Lobster Search in Turbulent Odor Plumes. Brenden Michaelis
Animals often use their sense of smell to locate food, identify mates and predators, and find suitable living habitats. Odor molecules are often dispersed from their source by turbulent wind or water currents. In both terrestrial and aquatic environments, the instantaneous temporal and spatial distribution of odors is complex, and odor plumes are often composed of filaments of chemicals at high concentrations that are adjacent to fluid with little or no odor. Navigation in turbulent chemical plumes has typically been considered a spatial information problem where individuals aim to path towards higher concentration. Concentration information alone is too irregular in turbulent plumes, particularly in water, to explain search speed and accuracy of many animals that undergo search. Recent discoveries of bursting olfactory neurons in the spiny lobster, Panulirus argus, suggest a mechanism for accurately sampling the temporal structure of chemical signals. We believe that considering the temporal element of chemical cues, such as intermittency encoding, is necessary to provide plume information on time scales relevant for informing efficient search behavior. Lobster pathing was analyzed in small scale flume experiments, using planar induced fluorescence, to measure the intermittent temporal signal encountered by searching lobsters as they navigate in a turbulent odor plume towards a source of food. Reactions to the intermittent signal are compared by analyzing changes in search speed and trajectory in response to frequency and intensity of the encountered stimulus.
1:30-1:45 pm The effects of thermal stress and sulfide toxicity on seagrass resilience in a Virginia Coastal Bay. Amelie Berger, Peter Berg, Karen McGlathery
Seagrass meadows are valued for the ecosystem services they provide, including blue carbon sequestration and storage. In response to recent worldwide seagrass declines, conservation efforts have emerged to protect, monitor, and restore seagrass habitats. Understanding the resilience of seagrass meadows is key to the successful restoration of ecosystem services. A recent eelgrass (Zostera marina) die-off event in one of the coastal bays of the Virginia Coast Reserve Long Term Ecological Research (VCR-LTER) site provides an unprecedented opportunity to study the recovery and resilience of seagrass habitats. This seagrass meadow is part of a landscape-scale restoration project at the VCR LTER that started in 2001. The meadow expanded and thrived until summer 2015, when field observations indicated a dramatic decline in seagrass shoot density. This study uses high-resolution in situ water temperature data to investigate the potential effects of thermal stress on seagrass resilience at the VCR-LTER. Sulfur isotope analyses of seagrass tissue were also used to determine whether another stressor – sulfide toxicity – contributed to the die-off event in 2015. Preliminary data suggest seagrass mortality was brought on by the synergistic effects of thermal stress and sulfide toxicity. Spatiotemporal differences in water temperature may also explain the heterogeneity of seagrass density observed throughout the meadow during the recovery period from 2016-2018. The VCR LTER site is a model for temperate systems globally, and is an ideal natural laboratory to study the potential impact of warming oceans on seagrass resilience.
Session 3. POSTER SESSION
2:00-3:30pm // Clark Hall // Mural Room
Predictive Modeling of Coastal Water Quality using Landsat-8. Sarah Lang, Dr. Max C.N. Castorani, Dr. Scott C. Doney
The water quality of coastal ecosystems is highly variable on a spatiotemporal scale due to various natural processes and anthropogenic causes. Coupling remotely sensed satellite measurements with in situ measurements could provide a more complete understanding of water quality changes and drivers in coastal ecosystems. In this study, in situ Secchi depth data from the Virginia Coast Reserve (VCR) Long-Term Ecological Research was used to validate Landsat-8 derived Secchi depths in the VCR. It was found that the Landsat-8 overpredicted Secchi disk depths relative to in situ measurements. A predictive statistical model was created to predict in situ Secchi depths from L8 Secchi depths. 56 satellite images were used to fill temporal gaps in the in situ data, generating a more complete time series documenting water clarity changes in this water body. Additionally, seasonality was analyzed using in situ and satellite data, showing that water quality in the summer is most likely driven by phytoplankton increase, as a dip in Secchi depth corresponds to a peak in chlorophyll-a concentration.
Patterns and Drivers of Spatial Synchrony of Lyme Disease in the Northeastern United States. Asad Ali, Jonathan Walter, Allison Gardner, Herman Shugart
Incidence of Lyme disease, a tick-borne illness widespread across the US, has been increasing in endemic regions in the US, as well as in regions with no previous history of the illness, leading to significant public health impacts. This study examines space-time patterns of Lyme disease incidence and the influence of climate and weather on Lyme disease. Specifically, we will address the following questions: 1) Does Lyme disease incidence exhibit spatial synchrony, and if so, what geographic patterns does Lyme disease synchrony exhibit? 2) Do climate oscillations and weather drive Lyme disease synchrony? 3) Do the effects of climate and weather on Lyme disease incidence differ between the northern and southern parts of its range? We examine synchrony patterns of Lyme disease incidence among 398 counties and assess the coherence between disease incidence and weather variables and climate oscillations to determine whether these factors drive synchrony in Lyme disease. This study can provide a valuable perspective on the population dynamics of Lyme disease which can then be translated into the realm of public health in the effort to limit disease incidence.
Nitrate Removal in Eastern Shore Streambeds Emma Cronin
The Eastern Shore’s low relief streams flow through fertilized agricultural areas on their way to Virginia’s nutrient sensitive coastal lagoons, so nitrate addition and removal processes in the gaining streams have profound downstream impacts. To examine controls on nitrate removal in groundwater discharging to streams on Virginia’s Eastern Shore, organic matter, dissolved oxygen, NO3- profiles were examined in four different streams. A flow-through experiment was also conducted on cores taken from these streambeds to monitor loss of nitrate along flow paths. Preliminary findings suggest that these streambeds are poised for denitrification and can remove most groundwater-nitrate before the water enters the stream.
Spatial patterns of fishes and invertebrates across a restored seagrass landscape. Elizabeth Daly*, Selina Cheng*, Kinsey N. Tedford, Michael R. Cornish, Sean Hardison, and Max C. N. Castorani
Complex biogenic habitats such as seagrass meadows, kelp forests, coral reefs, and salt marshes are a hallmark of coastal seascapes, where they strongly structure faunal biodiversity. Although such habitats are heterogenous at a variety of spatial scales and exist within the broader environmental context, disentangling the influence of these factors on consumer communities remain a persistent challenge in coastal ecology. We investigated spatial patterns of consumer communities across a 6.8 km2 restored eelgrass (Zostera marina) seascape situated within the coastal lagoon system of the Virginia Coast Reserve Long-Term Ecological Research site. Specifically, explored how spatial variation within and among seagrass patches influenced the abundance of fishes and benthic invertebrates. We repeatedly surveyed fishes using beach seines and baited underwater videography; blue crabs (Callinectes sapidus) using baited traps; and slow-moving or sessile invertebrates using benthic cores and snorkel surveys. Results indicate that Atlantic silversides (Menidia menidia) and silver perch (Bairdiella chrysoura) were more abundant in the meadow interior than edges. Male blue crabs were primarily found in the interior of meadows, while female blue crabs, hermit crabs, mud crabs, were concentrated along edges. Females bearing mature eggs were most abundant near oceanic inlets. Infaunal clams were more abundant at the interiors of seagrass patches, while other benthic invertebrates did not show strong spatial patterns across the seascape. Together, these results suggest that large-scale seagrass restoration has likely increased faunal abundance and diversity, but that landscape-scale characteristics mediate these positive effects.
UVA’s Institutional Nitrogen Footprint: Meeting the 30% Reduction Goal by 2030. Alicia Zheng, Michael Nicklas, Elizabeth Dukes, Rachel McGill, Andrew Pettit, James Galloway
The goal of this project is to track the university’s nitrogen (N) footprint over time to determine reductions needed to reach the university-wide reduction goal of 30% by 2030, from the 2010 baseline. The 2010, 2014, and 2016 nitrogen footprints were calculated and analyzed for reduction progress, with 11% (2014) and 17% (2016) reductions from the baseline (2010). However, Business As Usual (BAU) projections show that reductions will only be 2% in 2025 due to growth in UVA population and square footage. This requires projection and scenario analysis to identify initiatives that can be implemented to reduce nitrogen emissions and reach the reduction goal. Our project has worked with stakeholders from the Office for Sustainability, Facilities Management, UVA Dining, Darden School of Business, and UVA Health System Dining to identify and analyze scenario opportunities relating to food, energy, and wastewater to reach 25% reductions by 2025, which was the original nitrogen footprint reduction goal set by the UVA Board of Visitors. By researching these opportunities, documenting them in a Nitrogen Action Plan, and continued collaboration with stakeholders, our team aims to determine feasible strategies to ensure the nitrogen goal is met for both 2025 and 2030.
Study of Nitrogen Efficiency in a Hydroponics System versus Conventional Farming. Neha Awasthi, Selina Cheng, James Galloway, Aaron Mills
Nitrogen is necessary for the growth of plants. However, in conventional farming, a large amount of nitrogen is wasted through excess fertilizer, leading to harmful environmental impacts such as eutrophication. The goal of this study was to compare the nitrogen use of a hydroponics system to that of conventional farming. We used a hydroponics system set up by Babylon Microfarms, containing three shelves of basil that were monitored throughout the semester. We calculated the virtual nitrogen factor (VNF) by considering the amount of nitrogen used in solution, the amount of nitrogen produced by the lights, and the amount of nitrogen in the final harvested leaves. The healthiest tray of basil plants achieved a VNF of 4.79 – for every gram of consumable basil, 4.79 grams of nitrogen were lost to the environment. However, in a past study, it was found that lettuce grown in hydroponics systems can have a smaller VNF of 2.9, compared to a VNF of 5.1 from conventional farming. During the experiment, the basil exhibited varying levels of die-off that may have contributed to its high VNF. The results suggest that if the basil plants were completely healthy, we may have obtained a still-lower VNF.
Incorporating simulation of solar-induced chlorophyll fluorescence into the Community Land Model version 5 Rong Li
Solar-induced chlorophyll fluorescence (SIF) is the electromagnetic radiation emitted by chlorophyll as a byproduct of photosynthesis and has recently emerged as a proxy of gross primary production. Recent satellite observations of SIF provide a new proxy for assessing and constraining the simulation of photosynthesis in global land surface models (e.g., the Community Land Model). These applications require accurate simulation of SIF within the models. But there are limited attempts to incorporate SIF simulation into land surface models, and they do not account for canopy scattering and/or viewing geometry, which may have a large impact on simulated SIF that reaches remote sensor. Here we provide SIF simulation within the Community Land Model version 5 with canopy scattering and viewing geometry properly taken into account. The simulation is validated with canopy level model and satellite observations.
Expansion of nitrogen footprint tracking at UVA Samuel Mogen, Elizabeth Dukes, James Galloway
Release of excess reactive nitrogen into the environment has detrimental effects on human and ecosystem health. The Nitrogen Footprint Tool (NFT) was developed in 2009 by Allison Leach as part of her undergraduate thesis. The NFT provided a look at the reactive nitrogen emissions associated with University practices. In 2013, the Board of Visitors set a 25% reduction goal of N by 2025 from a 2010 baseline. Work has focused on reducing the tracked streams of N emissions. In addition to what is currently tracked (i.e., N from food and energy use), there are many N sources that have yet to be measured. This study focused on expanding tracking of reactive N to business travel and paper purchasing. Business travel included all airfare purchased by UVA (e.g. basketball team, conference travel) and tracked using a centralized software. These values show that in 2019, UVA released 2.97 MT Nitrogen and 38,1006 MTCDE. Business travel is now annually tracked. A novel tool was also developed to measure the N released by paper products using resources from the Environmental Paper Calculator. The tool was applied to Clark Hall and with two main paper types: copy and tissue paper. In 2016, 88.5 kg N were released as a result of paper purchasing in Clark Hall, which is 16% of the estimated 2016 nitrogen footprint for the building. Paper tracking will soon be expanded to Newcomb Hall. Expansion of N tracking offers a path to further understand and minimize institutional emissions at all levels.
Data rescue for six decades of river migration observations in the US Yuan Li and Ajay Limaye
River migration and channel morphology are central concerns in geology and civil engineering, as they influence sediment transport, landscape evolution, and the stability of engineered structures. A number of numerical models with different degrees of physical realism have been developed to predict sediment transport and river migration over a wide range of timescales. However, data availability currently limits opportunities for model testing and comparison. The National Cooperative Highway Research Program (NCHRP) produced a dataset of meander migration measurements in 2004 that could, in principle, be used for these purposes. The original dataset included observations for 1,503 meander bends on 89 rivers in the U.S. over six decades. However, the dataset has been largely unused due its uncommon file formats and incomplete documentation. In this study, we filled these usability gaps in the NCHRP dataset by reconstructing missing information on spatial referencing, observation time, and the nature of mapped river segments; and by converting the data to a GIS-ready format. After this processing, 81% of the original dataset was determined to be useable for analysis. In ongoing work, we are applying the dataset to calculate time series of river centerline position in preparation for testing meandering models and exploring the mechanics of meander evolution.
On the temperature dependence of ozone surface loss. Laura Barry, Madeline Miles, Ester Rekhelman, Xi Yang, Todd Scanlon, Elizabeth Tatham, Gabriel Isaacman-VanWertz, Sally Pusede
Tropospheric ozone (O3) is an air pollutant that is harmful to humans and plants. It is well known that O3 concentrations positively correlate with air temperature. Past research has described the temperature dependence of O3 production; however, the relationship between O3 loss and temperature is not well established. Here, we use six months of eddy-covariance O3 flux measurements collected in Central Virginia to explore the dependence of canopy-scale O3 loss on temperature. We discuss the influence of O3 loss on the temperature dependence of O3 concentrations.
UVA-SWO Partnership for Rangeland Ecology Research and Education. Sophie Wong, Magnolia Matthews, Megan Eisenfelder, Howard Epstein
The UVA-SWO Partnership for Rangeland Ecology Research and Education is a unique project that combines environmental sciences research, educational exchange, and community health on the Lake Traverse Reservation of the Sisseton-Wahpeton Oyate (SWO) tribe in northeastern South Dakota. Founded in the spring of 2017, this project investigates the effects of bison versus cattle grazing on native tallgrass prairie plant populations, productivity, and soil health. In the coming summer, the team will continue to investigate whether bison grazing is better for the health of the tallgrass prairie on Native American Reservations in environmental, cultural and health terms. Three fields, a bison pasture, a cattle pasture, and a control wildlife refuge, are being analyzed for species composition, biomass type and C/N ratios, and soil C/N and moisture. Since most Dakotah medicinal plants are forbs, we are looking for an increase in the abundance of these plants. Preliminary data has already shown an increase in native prairie grasses such as big bluestem, little bluestem, and blue grama grass, as well as a return of Eastern prairie coneflower, a traditional medicinal whose populations were reduced due to overexploitation. These results will have broad cultural and economic implications for the tribe.
Solar-induced chlorophyll fluorescence: a novel approach to quantify photosynthesis in wetland ecosystems Hannah Mast, Sally Pusede, Xi Yang
Forecasting the global carbon budget requires accurate estimates of vegetation-atmosphere exchanges of carbon dioxide (CO2). Despite a small geographic extent, salt marshes serve as a large carbon sink and sequester carbon dioxide from the atmosphere through highly efficient photosynthesis. Quantifying gross primary production (GPP) in an intertidal marsh is complicated by tidal cycles as the traditional eddy covariance (EC) method cannot measure photosynthesis of plants both above and below water levels. Solar-induced chlorophyll fluorescence (SIF) has been observed to directly correlate with photosynthesis and thus may provide new insight into GPP in wetlands that cannot be attained with EC. I will develop a SIF-based method to estimate GPP in intertidal ecosystems by coupling SIF and EC measurements at a salt marsh on Virginia’s Eastern Shore. I will first determine the correlation of SIF and EC-derived GPP during low tide periods, then extrapolate the correlation to estimate a SIF-derived GPP at high tides when EC may not yield reliable results. I will also develop a complementary LED reference system to validate SIF retrieval. This method will allow me to more accurately estimate the amount of carbon entering a salt marsh and provide a vital framework to the coastal carbon scientific community.