Ecosystem service delivery in restoration projects: the effect of ecological succession on the benefits of tidal marsh restoration

Duque-Núñez

et al. 2019

Sci Rep

Coastal vegetated ecosystems are major organic carbon (OC) and total nitrogen (TN) sinks, but the mechanisms that regulate their spatial variability need to be better understood. Here we assessed how superficial sedimentary OC and TN within intertidal vegetated assemblages (saltmarsh and seagrass) vary along a flow gradient, which is a major driver of sediment grain size, and thus of organic matter (OM) content. A significant relationship between flow current velocity and OC and TN stocks in the seagrass was found, but not in the saltmarsh. OC and TN stocks of the saltmarsh were larger than the seagrass, even though that habitat experiences shorter hydroperiods. Mixing models revealed that OM sources also varied along the flow gradient within the seagrass, but not in the saltmarsh, showing increasing contributions of microphytobenthos (17–32%) and decreasing contributions of POM (45–35%). As well, OM sources varied vertically as microphytobenthos contribution was highest at the higher intertidal saltmarsh (48%), but not POM (39%). Macroalgae, seagrass and saltmarsh showed low contributions. Local trade-offs between flow current velocities, hydroperiod and structural complexity of vegetation must be considered, at both horizontal and vertical (elevation) spatial dimensions, for better estimates of blue carbon and nitrogen in coastal ecosystems.

Section: Introductionmentioning

confidence: 99%

Superficial sedimentary stocks and sources of carbon and nitrogen in coastal vegetated assemblages along a flow gradient

Duque-Núñez

et al. 2019

Sci Rep

“…The LSMA method we propose enables an improved long‐term assessment of salt marsh evolution, and it can give rise to a new methodology for detecting vegetation patchiness that could reflect the biotic processes that shape the landscape. The method represents a significant step forward in respect to using classical NDVI for vegetation detection (Kearney & Fagherazzi, ), and this step is necessary when considering the complexity of ecological processes, such as vegetation succession, particularly in highly dynamic ecosystems such as estuaries (Boerema et al, ; Bouma et al, ). By comparing the patterns in different vegetation types, our methodology provides a tool that can be used to gain information about the interaction of various successional stages of vegetation with geomorphology; this tool can also be used to describe the tidal channel networks as a distinct topographic signature of life (Dietrich & Perron, ).…”

Section: Discussionmentioning

confidence: 99%

Indications of Dynamic Effects on Scaling Relationships Between Channel Sinuosity and Vegetation Patch Size Across a Salt Marsh Platform

et al. 2018

Salt marshes are important coastal areas that consist of a vegetated intertidal marsh platform and a drainage network of tidal channels. How salt marshes and their drainage networks develop is not fully understood, but it has been shown that the biogeomorphic interactions and feedbacks between vegetation development and channel formation play an important role. We examined the relationships among tidal channel sinuosity, marsh roughness, vegetation type (pioneer, Elymus athericus or Phragmites australis), and patch size at different spatial scales using a high‐resolution vegetation map (derived from aerial photography) and lower‐resolution satellite imagery processed with linear spectral mixture analysis. The patch‐size distribution in all vegetation types corresponded to a power law, suggesting the presence of self‐organizational processes. While small vegetation patches are more dominant in pioneer vegetation, they were present in all vegetation types. The largest patch size is restricted to E. athericus. We observed an inverse logarithmic relationship between channel sinuosity and vegetation patch size in all vegetation types. The fact that this relationship is observed in both pioneer and later successional stages suggests that after the establishment of a drainage network in the dynamic pioneer stages of salt marsh development, the later stages of salt marsh succession largely inherit the meandering pattern of the early successional stages. Our study confirms recent evidence that no significant changes in the specific features of tidal channel networks (e.g., channel width, drainage density, and efficiency) take place during the later stages of salt marsh development.

“…The surrounding region has a long embankment history, starting from the Middle Ages, including large scale intentional dike breaching for military operations in the late 16 th century, and followed by subsequent stepwise reembankment projects until the early 20 th century (Jongepier et al, 2015). In the coming years, the dikes of Hedwige Polder on the Dutch side (2.95 km 2 ) and Prosper Polder on the Belgian side (1.70 km 2 ) will be breached to re-introduce tides and restore natural intertidal habitats (Boerema et al, 2016). This managed realignment project is part of the Sigma Plan, which aims at improving flood protection in the tidal part of the Scheldt basin in Belgium (Smolders et al, 2015), while at the same time restoring natural estuarine habitat (Cox et al, 2006;Maris et al, 2007).…”

Section: Study Site: Managed Realignment Of Hedwige-prosper Poldermentioning

confidence: 99%

Biogeomorphic modeling to assess resilience of tidal marsh restoration to sea level rise and sediment supply

Gourgue

Belzen

Schwarz

et al. 2021

Preprint

Self Cite

Abstract. There is an increasing demand for creation and restoration of tidal marshes around the world, as they provide highly valued ecosystem services. Yet, tidal marshes are strongly vulnerable to factors such as sea level rise and declining sediment supply. How fast the restored ecosystem develops, how resilient it is to sea level rise, and how this can be steered by restoration design, are key questions that are typically challenging to assess. In this paper, we apply a biogeomorphic model to a planned tidal marsh restoration by dike breaching. Our modeling approach integrates tidal hydrodynamics, sediment transport and vegetation dynamics, accounting for relevant fine-scale flow-vegetation interactions (less than 1 m2) and their impact on vegetation and landform development at the landscape scale (several km2) and on the long term (several decades). Our model performance is positively evaluated against observations of vegetation and geomorphic development in adjacent tidal marshes. Model scenarios demonstrate that the restored tidal marsh can keep pace with realistic rates of sea level rise and that its resilience is more sensitive to the availability of suspended sediments than to the rate of sea level rise. We further demonstrate that restoration design options can steer marsh resilience, as it affects the rates and spatial patterns of biogeomorphic development. By varying the width of two dike breaches, which serve as tidal inlets to the restored marsh, we show that a larger difference in the width of the two inlets leads to more diversity in restored habitats. This study showcases that biogeomorphic modeling can support management choices in restoration design to optimize tidal marsh development towards sustainable restoration goals.