Global Climate Change

manding opportunities, realizing there will be successes and disappointments along the way. Take a deep breath and don’t be afraid to “ride the tiger.” n

Presented during S7: Floating Treatment Wetlands, 6/8/2021 8:35AM - 10:25AM ET

THE DUWAMISH RIVER FLOATING WETLANDS PROJECT: COMMUNITY SCIENCE AND PUBLIC OUTREACH

Andrews, Leann, Penn State Hampton, Adrienne Mocorro Powell, Ashley Engelke, Jen Bowles, Mason Rottle, Nancy The Duwamish River Floating Wetlands project deployed and monitored constructed floating wetlands (CFWs) during the 2019 and 2020 seasons of outmigrating juvenile salmon runs on the urban Duwamish River in Seattle, Washington. Embedded in the project was a highly integrated community science and public outreach program developed using best practices as described in Culturally Sustaining Pedagogies, Principles of Environmental Justice, and Jemez Principles for Democratic Organizing. The goals of the community science and outreach program were 1) to include and employ populations historically underrepresented in science, infusing equity and access at the forefront of the research, 2) to add local perspective and diverse viewpoints to the design and research approach, 3) to inform and educate the residents, workers and sustenance fishers in the Duwamish Valley neighborhoods on CFWs’ potential in the Duwamish River, 4) to inform and educate the general public on CFWs, building public support in the region which may have implications towards supportive policy changes in the future. Over two years, the design and research of the CFWs involved 44 community members, 50 students, 3 Doris Duke Conservation Scholars, and outreached to dozens of organizations inperson, and hundreds of individuals via a website and social media presence. Participants ranged from 12 to 75 years of age, with a high percentage of minority groups and Duwamish Valley residents. All participants in the project were compensated for their contribution, including community scientists, in cash and/or academic credits and youth community scientists were invited to participate in a complementary career exploration program. This session will outline the methods, approach, outcomes and lessons learned of the community science program. In particular, we will discuss how local community members were critical to completing the project in 2020 during the COVID-19 lockdowns, and how their perspective shaped the design, management, research and stewardship of the floating wetland systems. n

Presented during CS12: Restoration, Tuesday, June 8, 2021 1:15PM - 3:05PM ET HUMANS PREDATORS DRIVE RESTORATION OF SALT MARSH DIEBACK ON NANTUCKET, MA Karberg, Jennifer, Nantucket Conservation Foundation Extensive salt marsh dieback is driven by intense herbivory by the native purple marsh crab (Sesarma reticulata) and results in a complete loss of stabilizing low marsh vegetation, particularly smooth cordgrass (Spartina alterniflora). Salt marsh dieback dramatically reduces marsh resilience; leading to increases in soil erosion, sediment softening/subsidence and increased impacts of climate change and sea level rise. After over a decade of salt marsh dieback throughout mainland New England, marshes appear to be recovering although they have experienced significant erosion and subsidence. Purple marsh crab populations explode due to a lack of predators. On Nantucket Island, MA salt marsh dieback began about a decade later than other areas, meaning that loss of salt marsh elevation and area is not as extreme compared to mainland salt marshes. This gives us a unique opportunity to control the purple marsh crab and facilitate salt marsh revegetation before losing valuable soil sediments. In 2019, the Nantucket Conservation Foundation initiated a research project using humans as predators of the purple marsh crab with active trapping and removal during the field season. During both the 2019 and 2020 field seasons, significant numbers of purple marsh crabs were trapped and removed from two marshes in Polpis Harbor, Nantucket MA. Over this two-year project, NCF has observed significant recolonization of bare soil by smooth cordgrass and documented a reduction in crab grazing effort. In 2020, NCF out-planted plots of smooth cordgrass within the dieback areas and monitored a successful establishment of 50% survival. The success of this management effort as well as the documented low field work effort make the innovative use of humans as crab predators a successful response to salt marsh dieback. n

Presented during CS3: Wetland Chemistry, 6/3/2021 4:35PM - 6:25PM ET

DIURNAL VARIATION IN WETLAND METHANE FLUXES: GLOBAL PATTERNS

Bansal, Sheel, USGS Valach, Alex McNicol, Gavin

Methane emissions from wetlands is the largest source of uncertainty in the global methane budget. The high level of uncertainty is due, in part, to high temporal variability in methane flux rates over diurnal time scales. A better understanding of how methane flux rates change throughout diel cycles could help elucidate short-term, mechanistic drivers of flux, improve methane flux estimates from wetlands, and improve prediction of how future conditions could affect methane flux dynamics. However, developing generalized theories of diurnal variation in wetland methane fluxes is challenging due to the suite of interacting mechanisms and site-specific conditions that control diel patterns. We addressed this challenge using a unique methane flux dataset collection from >70 eddy covariance (EC) towers distributed around the world in diverse biomes and wetland classes. Diurnal patterns were highly variable among sites. The majority of sites had maximum flux (i.e., highest flux of the day) in the afternoon (~15:00), while about 20% had nighttime maxima. The timing of maximum and minimum flux was unrelated to wetland class, biome, or site conditions. In some cases, nighttime maxima may be attributable to artifacts associated with EC measurements, such as invalid flux measurements or changes in wind direction and associated EC footprint. The amplitude of daily flux (i.e., the difference between the highest and lowest flux of the day) varied by wetland class, mean annual temperature (MAT), dominant vegetation, and season. Tundra sites had the lowest amplitude, bogs and fens were intermediate, and swamps and marshes had the highest amplitude. Sites with higher MAT and aerenchymatous vegetation had greater amplitude, especially in the latter part of the growing season (i.e., autumn). Models indicated that gross primary productivity and latent heat of evaporation were near synchronously correlated to diurnal methane flux at many of the sites. n

Presented during CS4: Vegetation II, 6/3/2021 6:55PM - 8:45PM ET

SALT MARSH DOMINANT JUNCUS ROEMERIANUS MORPHOPHYSIOLOGY VARIES WITH TIDAL CREEK SPATIAL PATTERN AND MARSH SYSTEM IN THE BIG BEND REGION OF FLORIDA

Verhulst, Stephanie, University of Florida Reinhardt, Carrie Halophytes are specially adapted plants capable of tolerating high stress salt marshes environments where daily tidal flooding creates anoxic and highly saline soils. Sea-level rise and changing environmental conditions (e.g. drought, herbivory, sedimentation rates, and sudden vegetation die-off) have increased pressure on marsh vegetation adaptations resulting in marsh die-off. Modeling provides promising tools for predicting areas of potential die-off; however, salt marsh conditions are highly variable within and between marsh systems limiting broad landscape scale applicability. This project aims to identify potential linkages between vegetation stress indicators and drivers of marsh die-off (herbivore density, soil characteristics, and flooding) and their patterns within a marsh as another tool for predicting areas prone to marsh die-off. Twelve salt marshes spanning over 70 kms of Florida’s Gulf coast were selected based on similar dominant vegetation (Juncus roemerianus) and geomorphic characteristics. Vegetation and soil samples were collected in May-July 2019 at 3 distinct distances from the tidal creek mouth (coastal, mid-creek, and inland) and each distance had paired sampling locations at the creek bank and 40 meters into the marsh platform. Juncus roemerianus had significantly higher stress levels at the creek bank where soil salinity was higher and soil nutrients were lower indicated by 1) lower belowground biomass production and 2) higher proline concentrations, K+ ion levels, Na+ ion levels, and stem water content. Juncus closest to the coast had significantly higher belowground biomass and proline concentrations possibly confounding signs of stress. Other morphophysiological stress indicators (stomate density, aboveground biomass, and stem height) were elevated throughout the marsh system regardless of spatial location. Additionally, creek systems and proximity to large freshwater inputs played significant roles in the degree of stress exhibited by J. roemerianus. Marshes in the Big Bend region of Florida are at risk of die-off beginning at the margins, and this corresponds with increased salinity, suggesting that potential management strategies (e.g. thinsediment placement to increase marsh elevations, hydrological alterations to increase freshwater inputs, etc.) may reduce stress levels and increase marsh persistence. n

Presented during CS6: Climate Disruption, 6/3/2021 6:55PM - 8:45PM ET

ASSESSING THE ADAPTIVE CAPACITY OF LAURENTIAN GREAT LAKES WETLANDS TO CLIMATE CHANGE USING A COMPOSITE INDICATOR METHODOLOGY

Hrynyk, Morgan, Landscape Science and Technology Branch - Environment and Climate Change Canada Grabas,Greg Duffe, Jason Rivers, Patrick Quesnelle, Pauline Climate change is predicted to negatively impact the biodiversity, productivity and functionality of wetlands in the Laurentian Great Lakes Region. However, the ability for these wetlands to mitigate climate change remains poorly

understood and unquantified. Therefore, there is an immediate need to characterize the adaptive capacity of wetlands in order to inform the development and implementation of measures that promote climate change resilience. Adaptive capacity is defined here as the latent ability of a wetland to cope with climatic changes and maintain its current ecological regime. To operationalize this concept, Environment and Climate Change Canada (ECCC) has developed a composite indicator methodology that aggregates contemporary ecological variables hypothesized to affect the climatic response of wetlands into a simplified score. To determine adaptive capacity, ECCC selected 20 coastal wetlands with varying physical and biological characteristics along the Canadian shorelines of lakes Ontario, Erie, St. Clair, and Huron. Eight variables were measured at these sites through direct observation, remote sensing products, and geospatial analyses. Variables measured included; vegetation species richness, invasive Phragmites australis cover, wetland migration potential, protected areas, and surrounding land cover. Variables were then aggregated into four subindicator groupings (biological, landscape, protection, and migration potential) based on their influence on adaptive capacity. Composite indicator aggregation methodology accounted for variable correlation, and addressed independent and compensatory contributions to adaptive capacity using geometric and linear aggregation, respectively. Wetlands that received a high adaptive capacity score had three to four high-scoring sub-indicator groupings. These included wetlands along Lake Huron and Ontario with high biological and landscape conditions. However, it was common for at least one sub-indicator to receive a low score, suggesting that the adaptive capacity of high-scoring wetlands can be enhanced through management. Wetlands with a low adaptive capacity score had three or more sub-indicator groupings score poorly and were often clustered on the Huron-Erie Corridor and Lake Erie, where existing developmental pressure is high. The results of this analysis allow for a comparison of the 20 wetlands studied, and the scores of sub-indicator groups can be used to identify wetland resilience strategies. n

Presented during CS6: Climate Disruption, 6/3/2021 6:55PM - 8:45PM ET

SCALING-UP BEAVER POWERED RESTORATION IN THE UPPER COLUMBIA FOR CLIMATE RESILIENCE: A DECISION SUPPORT SYSTEMS APPROACH

Elliot-Perez, Crystal, Trout Unlimited Fesenmyer, Kurt In the aftermath of Washington’s mega-fires and in the context of climate change resilience in the Upper Columbia both for water availability and for fish species, Trout Unlimited realized the critical need to really scale-up beaverpowered restoration work to create impactful ecological benefits at a watershed level. We wanted to think beyond individual projects and look at a landscape perspective in terms of prioritizing sites for improving habitat for ESAlisted salmonids, increasing water storage capacity, and buffering fire effects. We needed a mechanism that could help us identify the sites that were both feasible and appropriate for beaver-powered restoration AND provide maximum ecosystem benefit in the context of local landscape conditions and limiting factors. In partnership with the U.S. Forest Service (USFS), University of Washington (UW), Washington Department of Fish and Wildlife (WDFW), U.S. Fish and Wildlife Service (USFWS), the Confederated Tribes of the Colville Reservation (CTCR), and the Drinking Water Providers Partnership (DWPP), we set about building a Decision Support System (DSS) tool that would do just that. TU’s Upper Columbia Beaver-Powered Restoration DSS tool helps practitioners and agency staff identify beaver-powered restoration opportunities across the Upper Columbia, including beaver dam analog (BDA) installation, beaver relocation, and low-tech wood placement, such as post-assisted log structures (PALS). This tool enables us to target specific locations that provide the maximum combined benefits for ESA-listed salmonids, post-fire recovery areas, and water storage for climate resilience. In a nutshell, we now have a powerful landscape-level analysis that serves as a first-order filter for identifying the most impactful areas for beaver-powered restoration work in a critical basin for salmon and agriculture that is on the front lines of mega fires and climate change – a place where beaverpowered restoration is needed most. n

Presented during S12: Landward migration of tidal wetlands I, 6/10/2021 3:35PM - 5:25PM ET

ELEVATION AS A CONTROL ON SALT-MARSH UPLAND ECOTONES ON THE MISSISSIPPI COAST

Anderson, Carlton, University of Southern Mississippi, Gulf Coast Geospatial Center Anderson, Carlton Waldron, Margaret Salt marshes are unique shallow-gradient landscapes that are highly susceptible to the combined effects of altered sediment supply, sea level rise, and other environmental factors. Changes in elevation on the order of centimeters to decimeters can alter the spatial arrangement and composition of plant species. As a result, vertical zones of plant communities exist within narrow ranges of elevation marked by sharp changes in vegetation composition and

diversity. The ecotone zone, situated between the lowerintermediate marsh and upland plant communities, consists of specialized plant species adapted to tolerate certain extreme edaphic conditions. The spatial locations of ecotones in estuaries are highly dynamic and respond via migration as certain edaphic conditions change , such as soil salinity. Thus, marsh ecotones could potentially be used to quantify and predict marsh transgression. The goal of this study was to use field surveys to examine and quantify the precise elevation of plant community and ecotone transitions in marshes on the Mississippi coast. High precision survey grade integrated GNSS and traditional style surveying methods were used to measure elevation along parallel line transects extending from the intermediate marsh through the marsh-upland ecotone. Elevation and vegetation were documented at ~1 m intervals at 12 different study sites among 5 coastal preserves. The lower and upper elevation thresholds for ecotones sampled occurred in narrow elevation ranges across all combined sites (lower = 0.427 m, upper = 0.526 m) and among the individual coastal preserve sites: Hancock County, Wolf River, Biloxi River, Pascagoula River, and Grand Bay. The elevation thresholds determined by this study may facilitate precise spatial modeling of marsh transgression as coastal plant communities along the Mississippi Sound respond to sea level rise, subsidence, changes to sediment flux, and coastal squeeze. n

Presented during S12: Landward migration of tidal wetlands I

HISTORICAL LAND COVER CHANGES AT RIVERINE VS. MARINE DOMINATED COASTAL ESTUARIES IN SOUTHEASTERN MISSISSIPPI – FOREST-MARSH DYNAMICS

Jen, Devin, University of Southern Mississippi Carter, Gregory Battaglia, Loretta Waldron, Margaret Biber, Patrick Wu, Wei Coastal marshes, which provide a number of ecosystem services including flood control, nutrient regulation, carbon sequestration, and wildlife habitat, have been experiencing extensive loss due to sea level rise (SLR) in addition to other natural and anthropogenic factors. One way in which coastal marshes can respond to SLR is through landward migration when suitable habitat is available to mitigate overall loss. The objective of this research is to assess whether the landward migration of coastal marshes was occurring in southeastern Mississippi over two ~30-year intervals since 1955. More specifically, we aim to identify land cover types with the greatest change over time and those that contributed to the replacement of upland forests and marshes in a marine dominated estuary (Grand Bay National Estuary Research Reserve – GBNERR) and a riverine dominated estuary (Pascagoula delta). Additionally, we will compare the landcover change at GBNERR (19551988 and 1988-2015) to that of the Pascagoula delta over similar timeframes (1955-1996 and 1996-2015). We applied the Land Change Modeler in TerrSet 2020 to evaluate land cover change based on the National Wetland Inventory (1955 and 1988) and WorldView-2 based classification (2015) for GBNERR. For the Pascagoula delta, image data was obtained from the U.S. Geological Survey (1955), the National Aerial Photography Program (1996), and the National Agricultural Imagery Program (2014). We found that (1) forest experienced the greatest net change followed by agricultural land and coastal marsh from 1955-1988 while coastal marsh experienced the largest net change, followed by non-vegetated type and forest from 1988-2015 at the GBNERR, while in the Pascagoula delta, coastal marsh experienced the greatest net change in both timeframes followed by woodland from 1955-1996 and water from 1996-2014; (2) forest-marsh dynamics were dominated by forests replacing marshes and the replacement rate declined while the rate of marshes replacing forests increased in the second 30-year time window; and (3) upland forests were replaced by marshes mainly between mean tidal level and mean high tide. This research improves our understanding of how wetlands in Mississippi may respond to SLR, and will contribute to more informed ecosystem management. n

Presented during S12: Landward migration of tidal wetlands I

SHIFTING ALLOCATIONS BETWEEN BIOMASS AND SOIL CARBON POOLS DRIVE NET LOSS OF CARBON IN RETREATING COASTAL FORESTS

Smith, Alexander, Virginia Institute of Marine Science, College of William and Mary Kirwan, Matthew Sea level rise is leading to the migration of coastal ecosystems and the replacement of terrestrial forests with tidal wetlands. Wetland soils are well known to accumulate carbon at faster rates than terrestrial soils, implying that sea level rise may lead to enhanced carbon accumulation. Here, we quantify biomass and soil carbon stocks across four rapidly migrating forest-to-marsh ecotones in the Chesapeake Bay (USA), a hotspot for sea level rise and coastal forest retreat. We find that despite increases in the amount of carbon stored in marsh soils, herbaceous vegetation, and shrubs across the forest-marsh ecotone, sea-level driven marsh migration results in an approximately 50% reduction

of stored carbon. Because carbon stored in tree biomass of the upland forests greatly exceeds carbon stored in adjacent marsh soils, tree mortality greatly reduces total carbon stocks. Continued marsh soil carbon accumulation in the newly formed, young marsh may eventually offset forest carbon loss, but we estimate that the time to replacement is similar to estimates of marsh survival (i.e. centuries), suggesting that forest carbon may never be replaced. These findings reveal a new carbon source in coastal carbon budgets, driven by migrating ecosystems and shifting allocations between carbon stored in soils and biomass. n

Presented during S12: Landward migration of tidal wetlands II, 6/10/2021 5:55PM - 7:45PM ET

COASTAL ECOSYSTEM VULNERABILITY AND SEA LEVEL RISE IN SOUTH FLORIDA: A MANGROVE TRANSITION PROJECTION

Sklar, Fred, SFWMD Coroinado-Molina, Carlos Carlson, Christine We used static, elevation and land cover data to estimate sea level rise impacts (SLR) to urban, developed lands and coastal wetland systems in Everglades National Park and the East and West coastal regions in South Florida. Maps and data tables estimating potential state change to open water were compiled through overlay analysis of elevation, land cover, and SLR masks with future land cover projected using a land cover transition threshold model. Analysis was based on a 2- to 5-km-wide longitudinal band along the SW and SE coasts of Florida where sea-level rise has no surface impediments to inundation and will likely cause coastline transgression and wetland migration. Analysis used three different projections; 0.27 m (0.9 ft), 0.76 m (2.5 ft) and 1.13 m (3.7 ft) greater than current sea level by 2070 estimated by NOAA and IPCC. Under a 0.27 m SLR projection 51% of the coastal land cover may be impacted. Under 0.76 m and 1.13 m projected SLR, coastal land cover areas were impacted by 56.5% and 59.1%, respectively. Migration of coastal wetlands from their current location into more inland areas in response to increased water depths and as a function of empirically derived marsh and mangrove accretion rates were also evaluated. With a SLR of 0.76 m by 2070, without accretion, 1160 sq km of wetland became open estuarine water. However, with accretion values of 0.211 m (4.1 mm yr-1) and 0.55 m (11 mm yr-1) by 2070, there was a transition of wetland cover to open estuarine water of only 349 sq km and 41 sq km, respectively. Under a low SLR of 0.27 m by 2070 scenario with accretion, the coastal mangroves were able to migrate inland while maintaining the current coastline. It was only under the more extreme scenario of 1.13 m SLR by 2070 that accretion was not able to compensate for inundation and there was a loss of wetland coastline everywhere. n

Presented during S12: Landward migration of tidal wetlands II

ZONATION IN COASTAL COMMUNITIES: MALADAPTATION TO CLIMATE CHANGE OR HIDDEN CLIMATE-PROOFING?

Battaglia, Loretta, Southern Illinois University Delfeld, Bradley Murphy, Gwendolyn Cherry, Julia Weisenhorn, Pamela Coastal communities exhibit pronounced zonation in composition across the marine-terrestrial transition. With rising seas and intensified storm surges, species that are ecologically “locked” in rigid zones may be at a disadvantage if they are slow to move to more suitable inland habitat. In contrast, species that span several zones, as adults and/or propagules in the soil, should be quicker to respond to chronic and acute saline intrusions. We hypothesized that the latter pattern is more common than previously thought because organisms may be inconspicuous outside of their dominant zone. The objective of this study was to determine the degree of zone rigidity for bacteria, mycorrhizae, vascular plants, and fiddler crabs, a dominant consumer in Gulf Coast ecosystems. We sampled these four groups in plots established along transects that were arrayed perpendicular to the coast. Bacteria and mycorrhizae were sampled using soil cores and identified to operational taxonomic units using molecular techniques. Plants were identified to species and their cover estimated in 1m2 quadrats. Fiddler crabs were sampled from replicate 4m2 enclosures established in each zone. Based on a cadre of multivariate analyses, we found significant overlap between zones for all organism types. Despite exhibiting dominance in a particular zone, all groups had relatively low zone fidelity and spanned more zones than expected, particularly when the “hidden flora and fauna” were accounted for in the datasets. Even relatively large adult fiddler crabs were found in unexpected areas. These flamboyant consumers were often obscured in the taller vegetation in upslope fresh marsh, a zone that had been overlooked in the literature as fiddler crab habitat. We conclude that these coastal zones are less rigid than they appear at first glance. Results bode well for species at the sea-land interface in that they appear to have a “jump start” on rising tides. n

Presented during S3: Coastal Wetland Science in a Changing World: Driving Innovation in Coastal Research I, 6/1/2021 8:35-10:25AM ET

MORTALITY MECHANISMS FOR WOODY PLANTS UNDER CHANGING SEAWATER EXPOSURE

McDowell, Nate, Pacific Northwest National Laboratory There are increasing observations of widespread loss of woody plants from coastal ecosystems due to changes in sea level and storm surges. While research on salinity effects on plants per se are well studied, there is a striking paucity of research on the causes of plant loss from seawater exposure. Here are review the evidence for mechanisms of woody plant mortality under seawater exposure, with a focus on two case studies: one from the Pacific Northwest and another from the Chesapeake Bay. Mortality mechanisms occur both below and above ground, with ion toxicity causing reductions in root survival and photosynthetic biochemistry, and low soil oxygen conditions exacerbating these impacts. Elevated seawater exposure appears to cause mortality through carbon starvation , with dramatic declines in non-structural carbohydrates as trees progress to death, with relatively minor hydrauilc failure occuring simultaneously. Dramatic photosynthetic declines at the whole-plant scale are driven by crown foliage loss and by ion toxicity driven reductions in photosynethic biochemistry. Growth is a strong predictor of the likelihood of mortality, with low growth strongly predicting mortality from seawater exposure. Prediction of vegetation change at coastal shoreline boundaries is enabled by models that now simulate carbon starvation, with development and validation of such models for coastal systems an urgent priority. n

Presented during S3: Coastal Wetland Science in a Changing World: Driving Innovation in Coastal Research II, 6/1/2021 10:55AM- 12:45PM ET

EXPERIMENTAL, MODELING, AND OBSERVATIONAL APPROACHES TO ASSESSING SEA-LEVEL RISE IMPACTS TO TIDAL WETLANDS ALONG THE PACIFIC COAST

Janousek, Christopher, Oregon State University Borde, Amy Drucker, Brandon Dugger, Bruce Cornu, Craig Diefenderfer, Heida Thorne,Karen Buffington, Kevin Bridgham, Scott Climate change is likely to alter estuarine ecosystems through sea-level rise (SLR) and changes to other ecosystem drivers. Predicting SLR impacts to tidal wetlands in estuaries requires an understanding of how key wetland processes change along gradients of increasing inundation and salinity. We provide an overview of two NOAA-funded SLR projects on the west coast of the US designed to characterize and model the effects of SLR on tidal wetland structure and function. In the San Francisco Bay-Delta Estuary, we conducted manipulative field and greenhouse experiments to develop relationships between wetland plant productivity and inundation and salinity, and used additional site-specific data to inform a mechanistic model of SLR on wetland persistence and carbon sequestration. Our data show that dominant plant species in the estuary have different responses to inundation, but that sediment availability and SLR scenario were principal drivers of wetland persistence in the model. In two large PNW estuaries, we are measuring fluxes of greenhouse gas emissions (GHG) such as methane, and quantifying hydrologic variables across a land use gradient (natural, restored, and disturbed wetlands). Together with estimates of sequestration rates, those data will allow us to develop statistical models of environmental drivers of GHG fluxes, evaluate the impacts of land use on carbon dynamics, and ultimately better understand how wetland restoration may increase blue carbon sequestration and enhance estuarine resilience to SLR. We highlight the value of integrating observational studies, manipulative experiments, and modeling to project SLR impacts to coastal estuaries and their functions. Complementary approaches can provide data across a range of spatiotemporal scales to assess SLR impacts and ensure that modeling efforts are grounded in sound mechanistic understanding of wetland processes derived from empirical data. n

Presented during S3: Coastal Wetland Science in a Changing World: Driving Innovation in Coastal Research II

MODELLING THE COASTAL WETLANDS RESPONSE TO CLIMATE CHANGE IN THE GREAT LAKES

Theriault, Dominic, Hydrodynamic and Ecohydraulic Section, Environment Climate Change Canada Maranda, Antoine Sévigny, Caroline Morin, Jean Bachand, Marianne Roy, Mathieu Gosselin, Rémi Hogue-Hugron, Sandrine The coastal wetlands of the Great Lakes are of major importance, as they provide critical ecological and societal services such as water filtration, nutrient assimilation and habitats for a large number of species. Coastal wetland

classes (e.g. emergent vegetation, meadow marsh, ect.) are generally structured along a topographical gradient, as they bear a decreasing level of tolerance to prolonged submersion with increasing elevation relative to average lake level. Coastal wetlands might be particularly vulnerable to climate change, given that changes in net basin supply might affect seasonal and long-term trends in water level. In this study, to evaluate wetland sensitivity to climate change, we developed the Coastal Wetland Response Model to predict the spatiotemporal succession of wetland classes under hydroclimatic scenarios. Based on the Canadian Regional Climate Model, lake water levels, along with water and energy budgets were simulated for the periods 1980-2009 and to 2070-2099, under both RCP 4.5 and RCP 8.5 emission scenarios. At each of 20 coastal wetland study sites in the Canadian shore of the Great Lakes, airborne terrestrial LIDAR surveys provided a detailed characterization of ground elevation. At each site, a total of 300 species-level vegetation quadrats and 450 precise elevation points were collected along transects in the summers of 2018 and 2019. Statistical models based on multispectral imagery and ground truth elevations developed to attenuate LIDAR errors associated with signal penetration in dense vegetation allowed reducing errors by 51.5%, when compared with classic ground classification algorithms. Hydrodynamic models and wave models for each lake were calibrated and used to simulate seiche and wind set-up and produce numerous physical variables (e.g. water depth, frequency of submersion/exondation, etc) at each grid point, for each quarter month of the projected water level time series. Wetland classes were derived from species-level vegetation quadrats using principal components and cluster analyses. We then used a random forest, a machine learning approach to predict the probability of occurrence of each wetland class. A succession algorithm was developed to predict the changes in wetland classes based on changes on environmental thresholds. This way, wetland maps were produced for each year of the time series and compared to wetland delineations based on historical aerial photos interpretation for validation. By predicting wetland migration and changes in extent and composition, the Coastal Wetland Response Model provided a basis to evaluate wetland vulnerability to climate change and to develop adaptive measures to enhance wetland resilience in the Great Lakes. n

Presented during S4: Novel approaches to quantifying synergistic interactions between climate and land-use change on prairie-pothole wetlands I, 6/1/2021 8:35-10:25AM ET

USING PROCESS-BASED MODELING TO QUANTIFY RELATIVE IMPACTS OF CLIMATE SHIFTS AND CONSOLIDATION DRAINAGE ON PRAIRIE-POTHOLE WETLANDS

McKenna, Owen, USGS Northern Prairie Wildlife Research Center Mushet, David Kucia,Samuel Prairie-pothole wetlands provide critical habitat necesPrairie-pothole wetlands provide critical habitat necessary for supporting North American migratory waterfowl populations. However, climate and land-use change threaten the sustainability of these wetland ecosystems. Very few experiments and analyses have been designed to investigate the relative impacts of climate and land-use change drivers as well as the antagonistic or synergistic interactions among these drivers on ecosystem processes. Prairie-pothole wetland water budgets are highly dependent on atmospheric inputs and especially surface runoff, which makes them especially susceptible to changes in climate and land use. Here, we present the history of prairie-pothole climate and land-use change research and address the following research questions: 1) What are the relative effects of climate and land-use change on the sustainability of prairie-pothole wetlands? and 2) Do the effects of climate and land-use change interact differently under different climatic conditions? To address these research questions, we modeled 25 wetland basins (1949–2018) and measured the response of the lowest wetland in the watershed to wetland drainage and climate variability. We found that during an extreme wet period (1993–2000) wetland drainage decreased the time at which the lowest wetland reached its spill point by 4 years, resulting in 10 times the amount of water spilling out of the watershed towards local stream networks. By quantifying the relative effects of both climate and landuse drivers on wetland ecosystems our findings can help managers cope with uncertainties about flooding risks and provide insight into how to manage wetlands to restore functionality. n

Presented during S4: Novel approaches to quantifying synergistic interactions between climate and land-use change on prairie-pothole wetlands I

USING WETLANDSCAPE TO SIMULATE RECENT CLIMATE TRENDS IN THE PRAIRIE POTHOLE REGION

Werner, Brett, Centre College Millett, Bruce Johnson, Carter Tracy, John Voldseth, Richard WETLANDSCAPE (WLS) has been developed over 30 years of peer-reviewed scholarship to investigate the role of climate change and agricultural land use (both land cover and agricultural drainage) in prairie wetlands, specifically

those in the Prairie Pothole Region of North America. This presentation will demonstrate the power of WLS as a research tool, and the insights into landscape-scale wetland dynamics for the purposes of wetland management and restoration. The system dynamics model currently runs in Stella Architect (ISEE, 2020) and incorporates both surface water and groundwater dynamics using climate data and a simulated set of basins from Orchid Meadows in eastern South Dakota. In this presentation, we will offer an overview of WLS and its development (Johnson & Poiani, 2016), along with the calibration and validation process. Then we will present novel results of model experiments simulating recent climate (2006-2019) in the Prairie Pothole Region, comparing these results to the sensitivity tests of 21st Century climate change projections for the region (Johnson et al., 2010) and in reference to earlier multidecadal comparisons (Werner et al., 2013). We will also offer insights from recent work on agricultural drainage and prairie pothole wetlands, following up on Werner et al. (2016). We conclude with a few notes into the insights offered by the WLS model results into the suite of wetland conservation and restoration options available. n

Presented during S4: Novel approaches to quantifying synergistic interactions between climate and land-use change on prairie-pothole wetlands III, 6/1/2021 1:15PM - 3:05PM ET

AUTOMATIC MAPPING OF WETLAND INUNDATION DYNAMICS IN THE PRAIRIE POTHOLE REGION USING GOOGLE EARTH ENGINE

Wu, Qiusheng, University of Tennessee, Knoxville The Prairie Pothole Region of North America is characterized by millions of depressional wetlands, which provide critical habitats for globally significant populations of migratory waterfowl and other wildlife species. Due to their relatively small size and shallow depth, these wetlands are highly sensitive to climate variability and anthropogenic changes, exhibiting inter- and intra-annual inundation dynamics. Moderate-resolution satellite imagery (e.g., Landsat, Sentinel) alone cannot be used to effectively delineate these small depressional wetlands. By integrating multi-temporal (2009-2018) NAIP aerial imagery and ancillary geospatial datasets, a fully automated approach was developed to delineate wetland inundation extent at watershed scales using Google Earth Engine. Machine learning algorithms were used to classify aerial imagery with additional spectral indices to extract potential wetland inundation areas, which were further refined using ancillary geospatial datasets. The wetland delineation results were then compared to the U.S. Fish and Wildlife Service National Wetlands Inventory (NWI) geospatial dataset and existing global-scale surface water products to evaluate the performance of the proposed method. The results showed that the proposed method can not only delineate the most up-to-date wetland inundation status, but also demonstrate wetland hydrological dynamics, such as wetland coalescence through fill-spill hydrological processes. The proposed automated algorithm provides a practical, reproducible, and scalable framework, which can be easily adapted to delineate wetland inundation dynamics at broad geographic scales. n

Presented during S8: Tropical wetlands and opportunities for climate change adaptation and mitigation – Scientific advancements and innovative tools I, 6/8/2021 8:35AM - 10:25AM ET

BIOTIC AND ABIOTIC DRIVERS THAT IMPACT THE ABILITY OF PACIFIC HIGH ISLAND MANGROVE FORESTS TO KEEP UP WITH SEA LEVEL RISE

MacKenzie, Richard Eperiam, Eugene Grow, Jessica Val Klump, J. Thorne, Karen Krauss, Ken Buffington, Kevin Apwong, Maybeleen Marquez, Roseo Greenstone Alefaio, Tamara Micronesian mangroves represent some of the most intact and productive mangroves in the world and provide food, fiber, and fuel for indigenous peoples across the Micronesian region. These forests are also important role for climate change mitigation and adaptation as they can remove and bury massive amounts of atmospheric CO2 as well as maintain coastline elevations relative to sea level. Both of these services are largely influenced by belowground processes, such as accretion, sedimentation, and C burial. We used the Pacific high island of Pohnpei as a model system to examine how different biotic and abiotic drivers influence these belowground processes. Forty-eight sediment cores were collected from riverine, interior, and fringe zones of eight mangroves around the island. Accretion, sedimentation, and carbon burial rates were determined using 210Pb, bulk density, and organic carbon content. Accretion rates varied from 0.13 to 1.7 cm/yr, organic matter accumulation from 0.027 to 0.29 gOM/cm2/yr, mineral accumulation from 0.01 to 0.44 gMIN/cm2/yr, and C burial rates from 121.2 ± 53.9 to 195.4 ± 89.2 gC/m2/yr1. Rates will be compared against biotic (e.g., aboveground biomass, litter fall, stem density, basal area) and abiotic (percent deforestation, rainfall, salinity, watershed area, watershed slope,

hydrologic zone, distance from ocean) factors measured from within the same plots to identify factors influencing the ability of these high island mangroves to maintain their elevation relative to sea level. Results can then be used to develop management plans or inform vulnerability assessments for mangroves in Pohnpei as well as across the western Pacific. n

Presented during S8: Tropical wetlands and opportunities for climate change adaptation and mitigation – Scientific advancements and innovative tools II, 6/8/2021 10:55AM - 12:45PM ET

ADVANCEMENTS INTO CLIMATE REGULATION OF PEATLAND GREENHOUSE GASES FLUXES: AN EXPERIENCE IN A TROPICAL PEATLAND, IQUITOS, PERU

Fachin, Lizardo, Instituto de Investigaciones de la AmazonÃa Peruana - IIAP del Castillo Torres, Dennis Lilleskov, Erik Cadillo-Quiroz, Hinsby Rengifo, Jhon Kolka, Randy Chimner, Rodney Griffis, Tim Roman, Tyler While much work has been done to understand the ecosystem processes of boreal peatlands, tropical peatlands are lagging in their representation in global peatland research projects, despite the knowledge that they represent one of the largest natural terrestrial carbon (C) pools. The Peruvian Amazon basin contains approximately 75,000 square kilometers of lowland peatlands, which are known to contain large amounts of C, specifically, the Loreto region of Peru which is home to a large portion of these peatlands and provides an excellent region to further our scientific knowledge of these ecosystems. In recent years the Intensive Carbon Monitoring Site – Quistococha (SMIC-Q) has been home to several novel research projects, and provides an excellent location for future work due to the accessible location near the city of Iquitos, Peru as well as the expertise from the local Research Institute of the Peruvian Amazon (IIAP). The SMIC-Q is representative of the tropical “aguaje” palm (Mauritia flexuosa) peatlands which are prevalent throughout the region. Initial research in the area included mapping these palm peatlands as well as assessing C stocks in above and belowground biomass. In 2017 an Eddy Covariance flux tower was installed in the forest and has provided some initial results indicating the system is a sink of approximately 460 g CO2-C m-2 y-1 and a source of approximately 22 g CH4-C m-2 y-1 (Griffis et al., 2020). Further, these observations indicate a decline in the CO2 uptake rate during the dry season. Ongoing work associated with the tower aim to better understand the sub-ecosystem processes that contribute to the overall fluxes measured by the tower. While these palm peatlands are important globally for their C pools, they are also important locally as a source of palm fruit. The most common method for harvesting the palm involves cutting down the tree, which has led to increased forest degradation in some portions of the region. Representatives from IIAP are working with local groups to teach more sustainable harvesting practices, as well as educating locals on the importance of these natural ecosystems. Overall, this area provides an excellent location for furthering our understanding of greenhouse gas fluxes in tropical peatlands. n

Presented during S8: Tropical wetlands and opportunities for climate change adaptation and mitigation – Scientific advancements and innovative tools II

CRITERIA AND INDICATOR APPROACHES TOWARDS BETTER MONITORING AND MANAGEMENT OF TROPICAL PEATLANDS

Bhomia, Rupesh, CIFOR Murdiyarso, Daniel Peatland restoration needs to be underpinned by monitoring efforts that allow for adaptive approaches to peatland restoration. Peatland restoration monitoring can inform the design, strategy, selection of site and management approaches, and improve restoration efforts through adjustments. Tested monitoring protocols that are simple, easy to measure over time can be very helpful. Scientifically robust, reliable, and practical set of criteria and indicators (C & I) can help to assess progress and outcomes of restoration efforts. An attempt to identify a set of C & I for peatland restoration monitoring in Indonesia was made. The C and I approach focussed on several bio-physical, social, economic and governance criteria underpinned by quantifiable indicators. Bio-physical indicators for ecology, hydrology, and fire were identified, while indicators for social networks, equality, trust and justice were described for social aspects. Economic indicators included aspects of incentives and livelihood options across peatland landscapes. With regards to governance indicators exploring appropriate policies at local, provincial and national level for successful implementation were determined to be important. In this presentation some of these identified C and I will be discussed, along with some strategies for verification and testing of there C and I on the ground. n

Presented during S8: Tropical wetlands and opportunities for climate change adaptation and mitigation – Scientific advancements and innovative tools II

PROCESS-BASED MODELLING OF PEAT GREENHOUSE GAS EMISSIONS IN INDONESIAN PEATLANDS

Swails, Erin, Center for International Forestry Research (CIFOR) Deng, Jia Hergoualc’h, Kristell Frokling, Steve Efforts aimed at mitigating greenhouse gas (GHG) emissions from land use and land-use change rely on quantification of baseline emissions reference levels and monitoring of actual emissions. Therefore, accurate and precise estimates of peat GHG fluxes are critical for mitigating anthropogenic GHG emissions from tropical peatlands. However, existing measurements of tropical peat GHG fluxes are sparse compared to measurements in temperate and boreal peatlands. Furthermore, due to the high spatial and temporal variability of peat GHG fluxes, quantification using extrapolation of point-based field measurements is inherently uncertain. Process-based models rely on relationships between GHG fluxes and controlling factors to extrapolate measurements collected at specific locations at specific points in time to larger regions over extended time periods. We investigated the potential for refining estimates of tropical peat GHG emissions using process-based modelling. The process-based DeNitrification – DeComposition (DNDC) model was used to generate GHG emissions for key land-use categories and management practices in tropical peatlands. We used field data from undrained peat swamp forests and drained oil palm plantations on peat from Central Kalimantan, Indonesia, to calibrate and validate the DNDC model for use in tropical peatlands. Our goals were (1) to compare modelled emission factors with emission factors developed from point-based flux measurements to determine whether process-based modeling can reduce uncertainty in tropical peat GHG emissions estimates, and (2) to use process-based modeling to investigate relationships between peat GHG fluxes and proxy variables. Preliminary model runs indicate that DNDC can successfully simulate ecological drivers (climate, soil, vegetation, and management practices) and peat GHG fluxes (CO2, CH4, and N2O) in undrained tropical peat swamp forests and drained oil palm plantations on peat. Additional results will be provided in the presentation. n

Presented during S8: Tropical wetlands and opportunities for climate change adaptation and mitigation – Scientific advancements and innovative tools II

SOIL GREENHOUSE GAS EMISSION FACTORS FOR TROPICAL PEATLANDS

Hergoualc’h, Kristell, Center for International Forestry Research Swails, Eric Tropical peatlands are large carbon (C) deposits which store most of their C belowground. When disturbed either by vegetation changes, drainage or both, the soil organic matter which accumulated over thousands of years mineralizes very quickly releasing large amounts of greenhouse gas (GHG) into the atmosphere. Current knowledge on the magnitude of these transfers remains extremely limited, disbalanced geographically, and inaccurate in some instances. For example, tropical organic soil emission factors of the 2013 Wetland Supplement to the 2006 IPCC guidelines were exclusively based on data collected in Southeast Asian ombrotrophic (i.e. nutrient-poor) peatlands and may not reflect accurately emission rates from peatlands in other tropical regions with e.g. minerotrophic (i.e. nutrient-rich) peat and/or different land uses and management/drainage practices. We reviewed the scientific literature on tropical peatlands published since the IPCC Wetland Supplement was finalized which related to fluxes of soil GHG, above and belowground litter, and dissolved organic C in different land uses as well as fire-induced losses of soil organic matter, and CO2 and CH4 emissions. We applied methods and criteria from the Wetland supplement to select studies, assess their quality, and compute GHG soil emission factors. Out of 45 peer-reviewed soil CO2, CH4, N2O flux studies selected, 25 were discarded for not meeting quality criteria of measurement frequency (minimum frequency of every two months), experimental length (> 9 months), omission of micro-spatial heterogeneity in sampling design or inappropriate measurement methods. Among studies selected, only 21% monitored soil fluxes of N2O which is a potent GHG. Finally, studies conducted outside of Southeast Asia were all from Latin America including lowland and highland peatlands of Colombia, Panama, and Peru. GHG fluxes from tropical African peatlands remain unstudied. While more results will be provided during the presentation, conclusions from current search points towards critical research gaps and a profound need for improving scientific research methods in tropical peatlands. n

Presented during S8: Tropical wetlands and opportunities for climate change adaptation and mitigation – Scientific advancements and innovative tools III, 6/8/2021 1:15PM - 3:05PM ET

COMPARING THREATS, CHALLENGES AND OPPORTUNITIES IN SOUTH AMERICAN TROPICAL MOUNTAIN PEATLANDS AND LOWLAND PEATLANDS

Lilleskov, Erik Maria Planas, Ana Wayson, Craig del Castillo Torres, Dennis Suárez, Esteban Carlos Benavides, Juan Hergoualc’h, Kristell Chavez, Laura Kolka, Randy Chimner, Rodney Peatlands are ecologically, economically, and culturally important in both the Andes and Amazon basin of tropical South America. Yet the nature, and human uses, of these peatlands differ greatly. Here we provide a synthetic contrast of these systems based on our work and that of others. Andean peatlands are largely herbaceous fens dominated by cushion plants or graminoids. Existing in a zone where grazing is common, they are often intensively used in grazing and cropping agroecosystems, with the intensity of that use appearing to increase with seasonality of precipitation. Grazing can have a strong impact on greenhouse gas emissions rates, especially leading to increases in methane emissions, whereas drainage for agriculture can drive increases in CO2 emissions. In contrast, lowland Amazonian peatlands in the western Amazon, best studied in the Peruvian Amazon, are dominated by peat swamp forests with comparatively lower human impacts. These forests include two major ecotypes—palm swamps and pole forests. Although deforestation rates are quite low in these ecosystems, the former can be degraded by destructive native palm (Mauritia flexuosa) fruit harvest, which can affect greenhouse gas fluxes. Nevertheless, the absence of extensive drainage, deforestation, and intensive agriculture in the peat swamp forests of Amazonia provide for potential long-term maintenance of intact peatlands. However, the lack of explicit legal protection of peatlands increases the potential for degradation as roads, oil and gas operations, and intensive agroforestry such as oil palm expand their footprint in the region. Protections for peatlands are evolving, and vary among countries. For example, Peru is developing a national definition of peat and is working on a national wetlands inventory and national peatland maps, first steps in developing protections and sustainable management practices for these ecologically unique and diverse ecosystems. Taking a regional view will help parse out the ecological, social, and political dimensions affecting sustainable peatland management planning. n

Presented during S8: Tropical wetlands and opportunities for climate change adaptation and mitigation – Scientific advancements and innovative tools III

MOUNTAIN PEATLANDS IN THE NORTHERN ANDES AND THEIR RELEVANCE IN THE NATIONAL GHG INVENTORIES

Carlos Benavides, Juan, Pontificia Universidad Javeriana Lilleskov, Erik Velasquez, Esther Chimner, Rodney Worldwide peatlands store nearly one third of the soil carbon, storing nearly as much carbon as the atmosphere. Peatlands in the tropical alpine ecosystems in the Andes (paramos) are frequent and have large concentrations of carbon (up to 2000 MgC ha-1) and are important stocks that are not usually included in the national carbon inventories of South American countries. Peatland degradation has been an important source of carbon dioxide and other greenhouse gases to the atmosphere worldwide but little is known about the climatic impacts of peatland degradation on tropical high elevations. Carbon balance of mountain peatlands is related to elevation, dominant vegetation and human disturbances. Methane emissions from peatlands have a clear relationship with the dominant vegetation and hydrological disturbances. Our estimates indicate that one third of the peatlands in the tropical alpine areas (paramo) are degraded. Recent conservation programs require that paramo lands used in the past for agriculture and cattle grazing should migrate into uses that are compatible with lower environmental impacts and climate mitigation mechanism. Here, we present the estimated potential gains on climate change mitigation by the peatlands of the Colombian Andes under different conservation and restoration strategies. We compared the potential GHG emissions from peatlands after different restoration and protection scenarios until 2050. Our results indicate that passive restoration has limited gains on soil carbon and almost no effect on reduction of methane emissions, while the intermediate restoration intensity provides a strong management of methane and important gains in soil carbon within a 15-year time window. Restoration of Andean peatlands can supply nearly 25% of the national determined contributions under the Paris agreement. However, the societal and economic impacts of the different conservation and restoration strategies on