scholarly journals Modeling Salt Marsh Vegetation Height Using Unoccupied Aircraft Systems and Structure from Motion

2020 ◽  
Vol 12 (14) ◽  
pp. 2333
Author(s):  
Alexandra E. DiGiacomo ◽  
Clara N. Bird ◽  
Virginia G. Pan ◽  
Kelly Dobroski ◽  
Claire Atkins-Davis ◽  
...  
Keyword(s):  
Salt Marsh ◽  
Structure From Motion ◽  
Salt Marshes ◽  
Dimensional Space ◽  
Coastal Development ◽  
Above Ground Biomass ◽  
Vegetation Height ◽  
Aircraft Systems ◽  
Ground Biomass ◽  
Short Period

Salt marshes provide important services to coastal ecosystems in the southeastern United States. In many locations, salt marsh habitats are threatened by coastal development and erosion, necessitating large-scale monitoring. Assessing vegetation height across the extent of a marsh can provide a comprehensive analysis of its health, as vegetation height is associated with Above Ground Biomass (AGB) and can be used to track degradation or growth over time. Traditional methods to do this, however, rely on manual measurements of stem heights that can cause harm to the marsh ecosystem. Moreover, manual measurements are limited in scale and are often time and labor intensive. Unoccupied Aircraft Systems (UAS) can provide an alternative to manual measurements and generate continuous results across a large spatial extent in a short period of time. In this study, a multirotor UAS equipped with optical Red Green Blue (RGB) and multispectral sensors was used to survey five salt marshes in Beaufort, North Carolina. Structure-from-Motion (SfM) photogrammetry of the resultant imagery allowed for continuous modeling of the entire marsh ecosystem in a three-dimensional space. From these models, vegetation height was extracted and compared to ground-based manual measurements. Vegetation heights generated from UAS data consistently under-predicted true vegetation height proportionally and a transformation was developed to predict true vegetation height. Vegetation height may be used as a proxy for Above Ground Biomass (AGB) and contribute to blue carbon estimates, which describe the carbon sequestered in marine ecosystems. Employing this transformation, our results indicate that UAS and SfM are capable of producing accurate assessments of salt marsh health via consistent and accurate vegetation height measurements.

Data from: Modeling salt marsh vegetation height using Unoccupied Aircraft Systems and Structure from Motion

2020 ◽  
Author(s):  
Clara N. Bird ◽  
Justin T. Ridge ◽  
David W. Johnston ◽  
Kelly Dobroski ◽  
Alexandra E. DiGiacomo ◽  
...  
Keyword(s):  
Salt Marsh ◽  
Structure From Motion ◽  
Salt Marsh Vegetation ◽  
Marsh Vegetation ◽  
Vegetation Height ◽  
Aircraft Systems

scholarly journals Above-ground biomass and species richness in a Mediterranean salt marsh

1993 ◽  
Vol 4 (3) ◽  
pp. 417-424 ◽  
Author(s):  
L.V. García ◽  
T. Maranón ◽  
A. Moreno ◽  
L. Clemente
Keyword(s):  
Species Richness ◽  
Salt Marsh ◽  
Above Ground Biomass ◽  
Ground Biomass

scholarly journals Retrieval of Salt Marsh Above-Ground Biomass from High-Spatial Resolution Hyperspectral Imagery Using PROSAIL

2019 ◽  
Vol 11 (11) ◽  
pp. 1385 ◽  
Author(s):  
Rehman S. Eon ◽  
Sarah Goldsmith ◽  
Charles M. Bachmann ◽  
Anna Christina Tyler ◽  
Christopher S. Lapszynski ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Salt Marsh ◽  
Imaging System ◽  
Hyperspectral Imagery ◽  
Spatial Scales ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Above Ground Biomass ◽  
Ground Truth Data ◽  
Ground Biomass

Salt marsh vegetation density varies considerably on short spatial scales, complicating attempts to evaluate plant characteristics using airborne remote sensing approaches. In this study, we used a mast-mounted hyperspectral imaging system to obtain cm-scale imagery of a salt marsh chronosequence on Hog Island, VA, where the morphology and biomass of the dominant plant species, Spartina alterniflora, varies widely. The high-resolution hyperspectral imagery allowed the detailed delineation of variations in above-ground biomass, which we retrieved from the imagery using the PROSAIL radiative transfer model. The retrieved biomass estimates correlated well with contemporaneously collected in situ biomass ground truth data ( R 2 = 0.73 ). In this study, we also rescaled our hyperspectral imagery and retrieved PROSAIL salt marsh biomass to determine the applicability of the method across spatial scales. Histograms of retrieved biomass changed considerably in characteristic marsh regions as the spatial scale of the imagery was progressively degraded. This rescaling revealed a loss of spatial detail and a shift in the mean retrieved biomass. This shift is indicative of the loss of accuracy that may occur when scaling up through a simple averaging approach that does not account for the detail found in the landscape at the natural scale of variation of the salt marsh system. This illustrated the importance of developing methodologies to appropriately scale results from very fine scale resolution up to the more coarse-scale resolutions commonly obtained in airborne and satellite remote sensing.

Biomass and above-ground productivity of salt-marsh plants in south-eastern Australia

1994 ◽  
Vol 45 (8) ◽  
pp. 1521 ◽  
Author(s):  
PJ Clarke ◽  
CA Jacoby
Keyword(s):  
Salt Marsh ◽  
Perennial Grass ◽  
Temporal Trends ◽  
Dry Weight ◽  
Spatial And Temporal Variation ◽  
Organic Carbon Content ◽  
Above Ground Biomass ◽  
Ground Biomass ◽  
Sporobolus Virginicus ◽  
Eastern Australia

The above-ground biomass of three dominant salt-marsh vascular plants (Juncus kraussii, Sarcocornia quinquejlora and Sporobolus virginicus) was measured to assess both spatial and temporal variation and to provide baseline data. Additionally, the culm dynamics of the rush J. kraussii were measured so that aboveground productivity could be estimated. No distinct seasonal patterns were detected in above-ground biomass in J. kraussii. Averaged over all sites and times, the above-ground biomass of J. kraussii was 1116 g dry weight m-2. Culms are replaced annually, hence standing crop approximated annual above-ground productivity. Much of the dead aboveground biomass appears to accumulate in the upper marsh, as evidenced by the elevated nutrient and organic carbon content of the soil there relative to the sediment in the mangrove zone. Above-ground biomass of the decumbent perennial grass Sporobolus virginicus and the procumbent perennial chenopod Sarcocornia quinqueflora showed no consistent spatial or temporal trends. The above-ground standing crops of these species were about one-third that of J. kraussii.

scholarly journals Biophysical properties of salt marsh canopies — Quantifying plant stem flexibility and above ground biomass

2015 ◽  
Vol 100 ◽  
pp. 48-57 ◽  
Author(s):  
F. Rupprecht ◽  
I. Möller ◽  
B. Evans ◽  
T. Spencer ◽  
K. Jensen
Keyword(s):  
Salt Marsh ◽  
Above Ground Biomass ◽  
Biophysical Properties ◽  
Ground Biomass ◽  
Plant Stem

Erodibility of vertically exposed salt marsh sediments

2020 ◽  
Author(s):  
Olivia Shears ◽  
Iris Möller ◽  
Tom Spencer ◽  
Katherine Royse ◽  
Ben Evans
Keyword(s):  
Salt Marsh ◽  
Structure From Motion ◽  
Salt Marshes ◽  
Tidal Flat ◽  
Three Dimensional ◽  
The United States ◽  
Small Scale ◽  
External Forcing ◽  
Marsh Sediments

<p>Salt marshes are valuable habitats, providing natural coastal protection. However, change in the extent of salt marsh habitats is occurring globally; regional hotspots include widespread losses in Northwest Europe. These lateral losses are occurring despite relative stability in the vertical dimension (i.e. surface elevation and its relation to rising sea levels). Whilst there are an increasing number of studies reporting and quantifying salt marsh losses, the understanding of what controls lateral marsh dynamics remains weak.</p><p>Numerical models and large-scale experimentation (e.g. in wave flumes) have, to a degree, improved understanding of the mechanisms by which salt marshes can change in the lateral dimension. However, empirical field evidence exploring the role of specific marsh properties and exposure characteristics is lacking. What biophysical factors (i.e. vegetation and sediment characteristics) control internal marsh substrate stability, and how do these factors influence the vulnerability of lateral marsh margins to external forcing?</p><p>The three-dimensional biophysical response of salt marsh substrates to external forcing representative of tidal flat conditions has been investigated. Intertidal sediment sections were extracted from two contrasting UK salt marsh sites: clay-silt rich Tillingham Marsh, Essex, Southeast England, and sand-dominated Warton Marsh, Morecambe Bay, Northwest England. Vertical sections of sediment were exposed to in-situ external forcing conditions on the fronting tidal flat at Tillingham Marsh. Structure-from-motion digital photogrammetry was used to quantify volumetric and structural changes on the vertical faces of the exposed sedimentary cores at approximately 14-day intervals. Three-dimensional structure-from-motion models were analysed alongside empirical water level measurements and meteorological data. Greater loss of material, typically around root structures, characterised the upper section of the sediment core from Warton Marsh. The Tillingham Marsh sediments were more resistant to erosion, including within the upper section. This indicates possible variability in the mechanical role of rooting structures (as also found in previous work (e.g. Feagin et al. 2009; Ford et al. 2016)), under a different marsh sedimentology.</p><p>Small-scale marsh stability is thus strongly influenced by physical sedimentology, biological root structures, hydrodynamic sequencing, and the interactions between these factors. A combination of inundation history, bulk sediment strength and belowground vegetation structure is likely to influence salt marsh lateral stability, at least at the cm to m scale. Understanding under which conditions (e.g. location, wave regime) these factors become more or less important, and how these small scale controls scale up to larger scales is crucial towards modelling and predicting future salt marsh change.</p><p>References:</p><ul><li>Feagin, R. A., Lozada-Bernard, S. M., Ravens, T. M., Möller, I., Yeager, K. M., & Baird, A. H. (2009). Does vegetation prevent wave erosion of salt marsh edges? Proceedings of the National Academy of Sciences of the United States of America, 106(25), 10109–10113. https://doi.org/10.1073/pnas.0901297106</li> <li>Ford, H., Garbutt, A., Ladd, C., Malarkey, J., & Skov, M. W. (2016). Soil stabilization linked to plant diversity and environmental context in coastal wetlands. Journal of Vegetation Science, 27(2), 259–268. https://doi.org/10.1111/jvs.12367</li> </ul>

scholarly journals MODELING WAVE ATTENUATION DUE TO SALTMARSH VEGETATION USING A MODIFIED SWAN MODEL

2018 ◽  
pp. 73
Author(s):  
Elizabeth Christie ◽  
Iris Möller ◽  
Tom Spencer ◽  
Marissa Yates
Keyword(s):  
Salt Marsh ◽  
Drag Coefficient ◽  
Salt Marshes ◽  
Wave Attenuation ◽  
Vegetation Type ◽  
Coastal Protection ◽  
Wave Dissipation ◽  
Vegetation Height ◽  
Wave Conditions ◽  
Spatially Varying

Vegetated shorelines have been increasingly recognized for their contribution to natural coastal protection due to their ability to dissipate wave energy. Within the UK, salt marshes are beginning to be included in flood defence schemes. Predicting wave dissipation over vegetation requires accurate representation of salt marsh canopies and the feedback relationship between vegetation and wave conditions. We present a modification to the SWAN vegetation model, which includes a variable drag coefficient and a spatially varying vegetation height. Its application is demonstrated by modelling wave propagation over UK salt marshes. The third generation wave model, SWAN includes a vegetation module for calculation of wave attenuation over vegetation. Wave dissipation is determined based on the vegetation properties and a drag coefficient. This drag coefficient, C_D, is used to calibrate the model, and a fixed value is used per model run. Empirically the drag coefficient has been found to vary with ambient wave conditions. Typically the drag coefficients are defined empirically as a function of either the stem Reynolds number, Rev, or the Keulegan-Carpenter number, KC. The parameter values have been shown to vary with vegetation type. In this paper, we modify the SWAN vegetation module to include a temporally varying CD. This allows the drag coefficient to vary with ambient wave parameters, which gives an improved prediction under time varying wave conditions (e.g. passage of a storm) and includes the change in wave conditions as they travel through the vegetation. We also incorporate spatially varying vegetation height into the model to further improve the representation of the complexity of vegetated shorelines. Using the new formulation we find improved prediction of wave dissipation over both idealized laboratory and field salt marsh vegetation.

scholarly journals High Spatial Resolution Remote Sensing for Salt Marsh Mapping and Change Analysis at Fire Island National Seashore

2019 ◽  
Vol 11 (9) ◽  
pp. 1107 ◽  
Author(s):  
Anthony Campbell ◽  
Yeqiao Wang
Keyword(s):  
Salt Marsh ◽  
Spatial Resolution ◽  
Salt Marshes ◽  
High Spatial Resolution ◽  
Hurricane Sandy ◽  
Coastal Development ◽  
Change Analysis ◽  
Marsh Edge ◽  
Fire Island ◽  
National Seashore

Salt marshes are changing due to natural and anthropogenic stressors such as sea level rise, nutrient enrichment, herbivory, storm surge, and coastal development. This study analyzes salt marsh change at Fire Island National Seashore (FIIS), a nationally protected area, using object-based image analysis (OBIA) to classify a combination of data from Worldview-2 and Worldview-3 satellites, topobathymetric Light Detection and Ranging (LiDAR), and National Agricultural Imagery Program (NAIP) aerial imageries acquired from 1994 to 2017. The salt marsh classification was trained and tested with vegetation plot data. In October 2012, Hurricane Sandy caused extensive overwash and breached a section of the island. This study quantified the continuing effects of the breach on the surrounding salt marsh. The tidal inundation at the time of image acquisition was analyzed using a topobathymetric LiDAR-derived Digital Elevation Model (DEM) to create a bathtub model at the target tidal stage. The study revealed geospatial distribution and rates of change within the salt marsh interior and the salt marsh edge. The Worldview-2/Worldview-3 imagery classification was able to classify the salt marsh environments accurately and achieved an overall accuracy of 92.75%. Following the breach caused by Hurricane Sandy, bayside salt marsh edge was found to be eroding more rapidly (F1, 1597 = 206.06, p < 0.001). However, the interior panne/pool expansion rates were not affected by the breach. The salt marsh pannes and pools were more likely to revegetate if they had a hydrological connection to a mosquito ditch (χ2 = 28.049, p < 0.001). The study confirmed that the NAIP data were adequate for determining rates of salt marsh change with high accuracy. The cost and revisit time of NAIP imagery creates an ideal open data source for high spatial resolution monitoring and change analysis of salt marsh environments.

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