scholarly journals Changes in plant communities of low‐salinity tidal marshes in response to sea‐level rise

Ecosphere ◽  
2021 ◽  
Vol 12 (7) ◽  
Author(s):  
Abbey Humphreys ◽  
Adrianna L. Gorsky ◽  
Donna M. Bilkovic ◽  
Randolph M. Chambers

2021 ◽  
Author(s):  
Olivier Gourgue ◽  
Jim van Belzen ◽  
Christian Schwarz ◽  
Wouter Vandenbruwaene ◽  
Joris Vanlede ◽  
...  

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.



2014 ◽  
Vol 11 (4) ◽  
pp. 6019-6037 ◽  
Author(s):  
M. L. Kirwan ◽  
G. R. Guntenspergen ◽  
J. A. Langley

Abstract. Approximately half of marine carbon sequestration takes place in coastal wetlands, including tidal marshes, where ecosystems accumulate organic matter to build soil elevation and survive sea level rise. The long-term viability of marshes, and their carbon pools, depends in part on how the balance between productivity and decay responds to climate change. Here, we report the sensitivity of soil organic matter decay in tidal marshes to seasonal and latitudinal variations in temperature measured over a 3 year period. We find a moderate increase in decay rate at warmer temperatures (3–6% °C−1, Q10 = 1.3–1.5). Despite the profound differences between microbial metabolism in wetlands and uplands, our results indicate a strong conservation of temperature sensitivity. Moreover, simple comparisons with organic matter production suggest that elevated atmospheric CO2 and warmer temperatures will accelerate carbon accumulation in marsh soils, and enhance their ability to survive sea level rise.



2014 ◽  
Vol 148 (1) ◽  
pp. 5-18
Author(s):  
Antoine Meirland ◽  
Emilie Gallet-Moron ◽  
Hervé Rybarczyk ◽  
Frédéric Dubois ◽  
Olivier Chabrerie


2021 ◽  
Vol 4 (1) ◽  
pp. 168-192
Author(s):  
Judith S. Weis ◽  
Elizabeth Burke Watson ◽  
Beth Ravit ◽  
Charles Harman ◽  
Metthea Yepsen

Salt marshes are key coastal ecosystems that provide habitats for wildlife, including invertebrates, fishes, and birds. They provide ecosystem services such as protection from storm surges and waves, attenuation of flooding, sequestration of pollutants (e.g., blue carbon), and nutrient removal. They are currently under great threat from sea level rise (SLR). We collected information about trends in the horizontal extent (acreage) of New Jersey salt marshes and recent elevation changes compared with the current local rate of SLR in New Jersey, which is between 5 and 6 mm year−1. We found pervasive, although variable, rates of marsh loss that resulted from both anthropogenic disturbance as well as edge erosion and interior ponding expected from SLR. Elevation trends suggest that the current rates of SLR exceed most marsh elevation gains, although some Phragmites-dominated marshes keep pace with SLR. Four potential remedies to address current coastal trends of marsh loss were described in the context of New Jersey’s regulatory and management environment: protection of marsh inland migration pathways, altered management of Phragmites, thin layer sediment placement, and living shoreline installations. Proactive steps are necessary if coastal wetland ecosystems are to be maintained over the next few decades.



2014 ◽  
Vol 11 (17) ◽  
pp. 4801-4808 ◽  
Author(s):  
M. L. Kirwan ◽  
G. R. Guntenspergen ◽  
J. A. Langley

Abstract. Approximately half of marine carbon sequestration takes place in coastal wetlands, including tidal marshes, where organic matter contributes to soil elevation and ecosystem persistence in the face of sea-level rise. The long-term viability of marshes and their carbon pools depends, in part, on how the balance between productivity and decay responds to climate change. Here, we report the sensitivity of labile soil organic-matter decay in tidal marshes to seasonal and latitudinal variations in temperature measured over a 3-year period. We find a moderate increase in decay rate at warmer temperatures (3–6% per °C, Q10 = 1.3–1.5). Despite the profound differences between microbial metabolism in wetlands and uplands, our results indicate a strong conservation of temperature sensitivity. Moreover, simple comparisons with organic-matter production suggest that elevated atmospheric CO2 and warmer temperatures will accelerate carbon accumulation in marsh soils, and potentially enhance their ability to survive sea-level rise.



2017 ◽  
Vol 114 (34) ◽  
pp. 9134-9139 ◽  
Author(s):  
Christopher R. Field ◽  
Ashley A. Dayer ◽  
Chris S. Elphick

The human aspects of conservation are often overlooked but will be critical for identifying strategies for biological conservation in the face of climate change. We surveyed the behavioral intentions of coastal landowners with respect to various conservation strategies aimed at facilitating ecosystem migration for tidal marshes. We found that several popular strategies, including conservation easements and increasing awareness of ecosystem services, may not interest enough landowners to allow marsh migration at the spatial scales needed to mitigate losses from sea-level rise. We identified less common conservation strategies that have more support but that are unproven in practice and may be more expensive. Our results show that failure to incorporate human dimensions into ecosystem modeling and conservation planning could lead to the use of ineffective strategies and an overly optimistic view of the potential for ecosystem migration into human dominated areas.



Botany ◽  
2015 ◽  
Vol 93 (10) ◽  
pp. 671-683 ◽  
Author(s):  
Elizabeth Burke Watson ◽  
Holly M. Andrews ◽  
Amy Fischer ◽  
Morgan Cencer ◽  
Laura Coiro ◽  
...  

For tidal marshes of the US Northeast, the late twentieth century decline of Spartina patens (Aiton) Muhl. has been attributed to increased flooding associated with accelerated sea level rise and nitrogen over-enrichment from cultural eutrophication. The objective of this study was to examine the impacts of inundation and nutrient availability on growth, photosynthesis, and interactions of S. patens and Distichlis spicata (L.) Greene, which co-occur and are common marsh species. Plants were grown in a factorial greenhouse experiment, where flow-through seawater was used to simulate semidiurnal tides. Field surveys were additionally conducted to relate plant distributions to environmental conditions. For S. patens grown in monoculture, nutrient additions did not enhance growth for the high inundation treatment. In addition, the combination of high nutrient availability and high inundation adversely affected S. patens tiller density, photosynthetic efficiency, and leaf CO2 uptake. For D. spicata, nutrient additions enhanced growth for both inundation treatments with respect to aboveground biomass and tiller density. For species pairings, S. patens expanded relative to D. spicata under low inundation, low nutrient availability conditions, but declined relative to D. spicata under daily inundation in combination with nutrient amendments. These findings were additionally supported by field data, which indicated that D. spicata was more common than S. patens where nutrient availability was high. These results suggest that S. patens persistence is favored by low nutrient inputs and well-drained conditions, and supports the interpretation that this species is vulnerable to loss where high nutrient loads coincide with accelerated sea level rise.



2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Claudia Zoccarato ◽  
Cristina Da Lio

AbstractThe resilience of marsh ecosystems to expected sea-level rise is determined by a complex interplay of organic and inorganic sedimentation dynamics. Marshes have formed over past centuries to millennia and consist of extremely reactive bodies with sediments that can experience high compaction. Here we provide a quantification of the degree to which the past history of a salt marsh can affect its long-term evolution. A dataset of elevation dynamics was established in the Venice Lagoon (Italy) and interpreted using a physics-based model of deposition and large consolidation of newly deposited material. We found that the fate of low-lying tidal landscapes over the next century of accelerating sea-level rise will be highly dependent on compaction of soft, recently deposited soils. Our results imply that a sedimentation rate twice the present rate will be needed to counterbalance the expected sea-level rise.



2012 ◽  
Vol 9 (10) ◽  
pp. 14689-14708 ◽  
Author(s):  
M. L. Kirwan ◽  
J. A. Langley ◽  
G. R. Guntenspergen ◽  
J. P. Megonigal

Abstract. The balance between organic matter production and decay determines how fast coastal wetlands accumulate soil organic matter. Despite the importance of soil organic matter accumulation rates in influencing marsh elevation and resistance to sea-level rise, relatively little is known about how decomposition rates will respond to sea-level rise. Here, we estimate the sensitivity of decomposition to flooding by measuring rates of decay in 87 bags filled with milled sedge peat, including soil organic matter, roots and rhizomes. Experiments were located in field-based mesocosms along 3 mesohaline tributaries of the Chesapeake Bay. Mesocosm elevations were manipulated to influence the duration of tidal inundation. Although we found no significant influence of inundation on decay rate when bags from all study sites were analyzed together, decay rates at two of the sites increased with greater flooding. These findings suggest that flooding may enhance organic matter decay rates even in water-logged soils, but that the overall influence of flooding is minor. Our experiments suggest that sea-level rise will not accelerate rates of peat accumulation by slowing the rate of soil organic matter decay. Consequently, marshes will require enhanced organic matter productivity or mineral sediment deposition to survive accelerating sea-level rise.



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