Restored saltmarshes lack the topographic diversity found in natural habitat

Lawrence, Peter J.; Smith, Graham; Sullivan, Martin J. P.; Mossman, Hannah L.

doi:10.1016/j.ecoleng.2018.02.007

Cited by 58 publications

(68 citation statements)

References 62 publications

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“…Another important implication of this work relates to marsh restoration. Recent studies have shown that restored marshes generally lack the topographic diversity of their natural counterparts (Brooks et al, ) and, more relevant to this study, have significantly lower creek densities than natural marshes (Lawrence et al, ). In addition, restored systems have higher sedimentation rates than natural systems (Garbutt et al, ; Mazik et al, ): a characteristic of flood dominant conditions (Aubrey, ; Christiansen et al, ; Stevenson et al, ; Leonard et al, ; Van de Kreeke & Robaczewska, ; Van Maren & Winterwerp, ).…”

Section: Discussionmentioning

confidence: 87%

“…The creek networks corresponding to the reference were identified and ordered according to Strahler (1952) by the following approach. Creek lines were generated from the reference using the hydrology tools in ArcGIS 10.3 software (sensu Tarboton et al, 1991), which is a widely accepted, well known method that has been successfully applied to salt marsh landscapes (e.g., Lawrence et al, 2018;Vandenbruwaene et al, 2012Vandenbruwaene et al, , 2013. Additionally, a minimum creek depth of 0.10 m was specified to limit the extent of first-order creeks.…”

Section: Characterization Of Creek Network and Model Scenariosmentioning

confidence: 99%

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Intertidal Creeks and Overmarsh Circulation in a Small Salt Marsh Basin

2019

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The role of intertidal creek networks in overmarsh circulation is not well constrained. In this study, we systematically remove intertidal creeks from a high‐resolution salt marsh digital elevation model and conduct new flow simulations with each iteration. Overall, removal of first‐ and second‐order creeks reduced drainage density by 65%, and this had a negligible effect on overmarsh circulation and tracer distribution. However, upon removal of third‐ and fourth‐order creeks, drainage density was reduced by 80% of the original value, and changes in peak velocity magnitude across various spatial and temporal scales reveal a system‐wide switch from ebb to flood dominance. This response coincides with the interruption of topographically connected creeks that facilitate the direct exchange of water and tracer between the marsh interior and the larger subtidal system. Further, this reduction in hydraulic connectivity gives rise to less expansive tracer dispersal and a systematic decline in tracer residence time. Together, these results reveal that for the Groves Creek marsh, lower‐order intertidal creeks have a minor role in overmarsh circulation, while higher‐order creeks increase the potential for short circuiting of flow; they greatly influence overall flood and ebb dominance, and net tracer dispersal and associated retention time. Results reported here provide new insight on, for example, salt marsh restoration and the requisite digital elevation model bathymetry for robust simulations of overmarsh circulation.

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Section: Discussionmentioning

confidence: 87%

Section: Characterization Of Creek Network and Model Scenariosmentioning

confidence: 99%

Intertidal Creeks and Overmarsh Circulation in a Small Salt Marsh Basin

2019

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“…, Lawrence et al. ). As wetlands contribute ~6% of the global land surface and ~12% of the global carbon pool (Erwin ), their biodiversity declines create important, yet still poorly understood, risks for their long‐term functioning and response to stressors such as sea level rise and coastal flooding.…”

Section: Introductionmentioning

confidence: 99%

“…Recent studies have reported significant associations between field‐measured plant diversity and spectral vegetation indices (SVIs) from moderate to coarse (30 m+) satellite imagery (Gibbs , Lawrence et al. ) and, in some cases, variation of SVIs in space (Castillo‐Riffart et al. , Madonsela et al.…”

Section: Introductionmentioning

confidence: 99%

“…These risks are particularly evident in wetlands, which are among the most stressed ecosystems due to their worldwide loss and fragmentation (Davidson 2014, Dixon et al 2016, and yet also among the richest biodiversity hotspots crucial for resident and migratory species (Gibbs 2011, Kingsford et al 2016. Recent evidence suggests that losses of wetland biodiversity may not be easily replenished via restoration (Aronson and Galatowitsch 2008, Moreno-Mateos et al 2012, Meli et al 2014, Lawrence et al 2018. As wetlands con-tribute~6% of the global land surface and~12% of the global carbon pool (Erwin 2009), their biodiversity declines create important, yet still poorly understood, risks for their long-term functioning and response to stressors such as sea level rise and coastal flooding.…”

Section: Introductionmentioning

confidence: 99%

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The potential of satellite greenness to predict plant diversity among wetland types, ecoregions, and disturbance levels

Taddeo

Dronova

Harris

2019

Ecological Applications

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The unprecedented global biodiversity loss has massive implications for the capacity of ecosystems to maintain functions critical to human well‐being, urgently calling for rapid, scalable, and reproducible strategies for biodiversity monitoring, particularly in threatened ecosystems with difficult field access such as wetlands. Remote sensing indicators of spectral variability and greenness may predict the diversity of plant communities based on their optical diversity; however, most evidence is based on narrowband spectral data or terrestrial ecosystems. We investigate how spectral greenness and heterogeneity from publicly available broadband multi‐spectral Landsat satellite imagery explain variation in vegetation diversity across different wetland types, ecoregions, and disturbance levels using 1,138 sites surveyed by U.S. EPA's National Wetland Condition Assessment. We found positive correlations of plant species richness and diversity with indicators of annual maximum spectral greenness and its spatial heterogeneity, explaining up to 43% variation within the global sample, 48% within wetland types or ecoregions, and up to 61% with abiotic covariates. The combined effect of spectral greenness and heterogeneity was stronger than the best‐performing model using climatic, topographic, and edaphic factors alone. When compared among major U.S. watersheds and individual states, the fit of diversity‐greenness models increased when more wetland types were included within the corresponding region's boundaries, up to 61% at the watershed and 77% at the state level, respectively, for diversity models and up to 73% and 80%, respectively, for richness models. Model outliers were characterized by a significantly greater diversity of nonnative species (P < 0.0001), suggesting that changes in model performance and greenness distributions could be used as indicators of shifts in plant community composition, particularly in tidal wetlands making the majority of outliers with significantly lower than predicted diversity. This study represents a first‐time national‐scale effort to use publicly available remote sensing, climatic, and topographic data to predict plant diversity in wetlands, which tend to be understudied compared to terrestrial ecosystems despite being among the most stressed ecosystems on Earth. Our study suggests that multi‐temporal broadband satellite imagery could provide a low‐cost assessment of regional and national wetland biodiversity for prioritization of conservation efforts and early detection of biodiversity loss.

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Restoration of biogeomorphic systems by creating windows of opportunity to support natural establishment processes

Fivash

Temmink

D’Angelo

et al. 2021

Ecological Applications

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In degraded landscapes, recolonization by pioneer vegetation is often halted by the presence of persistent environmental stress. When natural expansion does occur, it is commonly due to the momentary alleviation of a key environmental variable previously limiting new growth. Thus, studying the circumstances in which expansion occurs can inspire new restoration techniques, wherein vegetation establishment is provoked by emulating natural events through artificial means. Using the salt-marsh pioneer zone on tidal flats as a biogeomorphic model system, we explore how locally raised sediment bed forms, which are the result of natural (bio)geomorphic processes, enhance seedling establishment in an observational study. We then conduct a manipulative experiment designed to emulate these facilitative conditions in order to enable establishment on an uncolonized tidal flat. Here, we attempt to generate raised growth-promoting sediment bed forms using porous artificial structures. Flume experiments demonstrate how these structures produce a sheltered hydrodynamic environment in which suspended sediment and seeds preferentially settle. The application of these structures in the field led to the formation of stable, raised sediment platforms and the spontaneous recruitment of salt-marsh pioneers in the following growing season. These recruits were composed primarily of the annual pioneering Salicornia genus, with densities of up to 140 individuals/m 2 within the structures, a 60-fold increase over ambient densities. Lower abundances of five other perennial species were found within structures that did not appear elsewhere in the pioneer zone. Furthermore, recruits grew to be on average three times greater in mass inside of the structures than in the neighboring ambient environment. The success of this restoration design may be attributed to the combination of three factors: (1) enhanced seed retention, (2) suppressed mortality, and (3) accelerated growth rates on the elevated surfaces generated by the artificial structures. We argue that restoration approaches similar to the one shown here, wherein the conditions for natural establishment are actively mimicked to promote vegetation development, may serve as promising tools in many biogeomorphic ecosystems, ranging from coastal to arid ecosystems.

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Restored saltmarshes lack the topographic diversity found in natural habitat

Cited by 58 publications

References 62 publications

Intertidal Creeks and Overmarsh Circulation in a Small Salt Marsh Basin

Intertidal Creeks and Overmarsh Circulation in a Small Salt Marsh Basin

The potential of satellite greenness to predict plant diversity among wetland types, ecoregions, and disturbance levels

Restoration of biogeomorphic systems by creating windows of opportunity to support natural establishment processes

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