Development and Application of Landsat-Based Wetland Vegetation Cover and UnVegetated-Vegetated Marsh Ratio (UVVR) for the Conterminous United States

Ganju, Neil K.; Couvillion, Brady R.; Defne, Zafer; Ackerman, Katherine V.

doi:10.1007/s12237-022-01081-x

Cited by 17 publications

(7 citation statements)

References 30 publications

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“…A promising approach to include the effect of pond dynamics in the marsh carbon budget is to use spatially integrative metrics that can be estimated from remote sensing, such as the Unvegetated‐Vegetated marsh Ratio (UVVR) (Ganju et al., 2022). Detailed studies should investigate if the “missing” carbon due to the presence of ponds can be empirically correlated to the UVVR, and more specifically at what scale of spatial aggregation the UVVR needs to be calculated in order to best represent ponds as opposed to mudflats areas or channels.…”

Section: Discussionmentioning

confidence: 99%

Peat Decomposition and Erosion Contribute to Pond Deepening in a Temperate Salt Marsh

et al. 2023

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Salt marsh ponds expand and deepen over time, potentially reducing ecosystem carbon storage and resilience. The water filled volumes of ponds represent missing carbon due to prevented soil accumulation and removal by erosion and decomposition. Removal mechanisms have different implications as eroded carbon can be redistributed while decomposition results in loss. We constrained ponding effects on carbon dynamics in a New England marsh and determined whether expansion and deepening impact nearby soils by conducting geochemical characterizations of cores from three ponds and surrounding high marshes and models of wind-driven erosion. Radioisotope profiles demonstrate that ponds are not depositional environments and that contemporaneous marsh accretion represents prevented accumulation accounting for 32%-42% of the missing carbon. Erosion accounted for 0%-38% and was bracketed using radioisotope inventories and wind-driven resuspension models. Decomposition, calculated by difference, removes 22%-68%, and when normalized over pond lifespans, produces rates that agree with previous metabolism measurements. Pond surface soils contain new contributions from submerged primary producers and evidence of microbial alteration of underlying peat, as higher levels of detrital biomarkers and thermal stability indices, compared to the marsh. Below pond surface horizons, soil properties and organic matter composition were similar to the marsh, indicating that ponding effects are shallow. Soil bulk density, elemental content, and accretion rates were similar between marsh sites but different from ponds, suggesting that lateral effects are spatially confined. Consequently, ponds negatively impact ecosystem carbon storage but at current densities are not causing pervasive degradation of marshes in this system. Plain Language SummaryPonds are natural features of salt marshes but their expansion may be an indicator of ecosystem deterioration because they impede the marsh's ability to keep pace with sea-level rise and remove decades of buried soil carbon. The water filled holes created by ponds represent volumes of marsh soil carbon that are missing due to prevented accumulation or lost through erosion and decomposition. These loss pathways have different implications for coastal carbon cycling as eroded soils can be redeposited elsewhere while microbial decomposition represents permanent loss. We used geochemical and modeling approaches to assess how much of the carbon missing from ponds can be attributed to prevented soil accumulation, erosion, and decomposition as well as whether ponds reduce the integrity of the surrounding marsh. We estimate that these processes represent 32%-42%, 0%-38%, and 22%-68%, respectively, of soil carbon missing from three ponds in a New England salt marsh. The range of potential erosion losses reflect differences in fetch and wind-driven waves used in the models. Decomposition was calculated by subtracting the contributions of prevented accretion and erosion from the volume of missing carbon and, while t...

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Section: Discussionmentioning

confidence: 99%

Peat Decomposition and Erosion Contribute to Pond Deepening in a Temperate Salt Marsh

et al. 2023

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“…Despite the stress of increased inundation after the 1898 inlet switch, marshes along the North River channel have been resilient based on the US Geological Survey's widely applied metric for marsh health, the unvegetated to vegetated ratio (UVVR) (Ganju et al., 2022). Area weighted UVVR for the North River marshes averages 0.17, which falls in line with average UVVR for healthy marshes (Ganju et al., 2017).…”

Section: Discussionmentioning

confidence: 99%

Salt Marsh Response to Inlet Switch‐Induced Increases in Tidal Inundation

et al. 2022

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Salt marshes aggrade in quasi-equilibrium with sea level rise (SLR) via the accumulation of organic matter and mineral sediment, thereby maintaining marsh platform elevation within the tidal frame (e.g., Allen, 2000;Cahoon et al., 2019). External perturbations, such as an acceleration of relative SLR, can be compensated for by increased sediment delivery to the marsh platform. Increased inundation depth tends to augment sediment delivery as the associated longer flood duration increases time to trap suspended sediment (Day et al., 1999;Reed, 1990;Temmerman et al., 2003). In some cases, increased suspended sediment concentrations associated with land clearance has allowed marshes to recover from rapid SLR (Peck et al., 2020;Watson, 2004). In addition to increased mineral sediment delivery, there is some evidence that bioproductivity of low marsh grasses may increase with moderate increases in inundation, with subsequent vegetation drowning at higher levels of inundation (Morris et al., 2002;Voss et al., 2013). However, many studies have found declining biomass with increased

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“…For specific wetland complexes/units, the unvegetated to vegetated ratio (UVVR) has been found to be correlated with sediment budgets and sea-level rise (Ganju et al, 2017). UVVR has been mapped with high-resolution aerial imagery and Landsat satellite imagery (Ganju et al, 2022). Approaches like DECODE and UVVR can be used to provide robust condition-based information to land managers that can highlight trajectories of land cover types within coastal wetlands.…”

Section: Wetland Mapping Advancements For Observing Anticipated Changesmentioning

confidence: 99%

“…These types of transitions may also be of interest when observing estuarine vegetated wetland change. Recent research has pointed to the importance of the unvegetated to vegetated ratio for gauging coastal wetland vulnerability (Defne et al, 2020; Ganju et al, 2022), and other indicators (Wasson et al, 2019). Building on this research, the analysis of land cover transitions for estuarine vegetated wetlands can be helpful to identify loss of vegetated area (i.e., conversion to open water or tidal flats) and the transition between land cover types that are upslope and/or adjacent to estuarine vegetated wetlands (i.e., palustrine wetlands or upland land cover types).…”

Section: Introductionmentioning

confidence: 99%

Observing coastal wetland transitions using national land cover products

Enwright,

Osland,

Thorne

et al. 2023

Progress in Physical Geography: Earth and Environment

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Over the coming century, climate change and sea-level rise are predicted to cause widespread change to coastal wetlands. Estuarine vegetated wetlands can adapt to sea-level rise through both vertical development (i.e., biophysical feedbacks and sedimentation) and upslope/horizontal migration. Quantifying changes to estuarine vegetated wetlands over time can help to inform current and future decisions regarding land management and resource stewardship. In this study, we show how coastal land cover maps readily available in the US can be used to assess and understand estuarine vegetated wetland changes. This assessment involves two steps: (1) identifying the net gain/loss of estuarine vegetated wetlands and (2) determining which land cover types contribute to the net gain/loss. From this information, we developed estuarine vegetated wetland change scenarios that evaluate whether estuarine vegetated wetland gain kept up with loss and whether the contribution was from: (1) estuarine vegetated wetland migration or tidal restoration; (2) land building (i.e., development); or (3) both. We assessed changes from 1996 to 2016 for: (1) the conterminous US; (2) each major US coastline; and (3) focal estuaries with the most change per coast. We found that the change scenario (1, 2, or 3) varied across coastlines. Moving forward, national coastal land cover programs can be informed by utilizing methodologies that leverage contemporary information for delineating the estuarine zone from upslope/adjacent wetlands. We highlight approaches that could be used to address this challenge and provide complementary information related to wetland condition changes.

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Development and Application of Landsat-Based Wetland Vegetation Cover and UnVegetated-Vegetated Marsh Ratio (UVVR) for the Conterminous United States

Cited by 17 publications

References 30 publications

Peat Decomposition and Erosion Contribute to Pond Deepening in a Temperate Salt Marsh

Peat Decomposition and Erosion Contribute to Pond Deepening in a Temperate Salt Marsh

Salt Marsh Response to Inlet Switch‐Induced Increases in Tidal Inundation

Observing coastal wetland transitions using national land cover products

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