Our overall objective is to understand what controls the vulnerability of coastal marshes to risks associated with global change drivers and rising sea levels. Fundamental questions pertaining to coastal wetland vulnerability still need to be addressed. What factors explain spatial and geographic variation in tidal wetland vulnerability? How do short term climatic events (storms) influence the longer term response of coastal marshes to sea level rise? What biological processes mediate marsh elevation responses to sedimentation? What processes control wetland transgression into adjacent uplands?Our goal is to provide a process-based framework that enables the development of a spatial model that simulates the dynamics of marsh transgression.
The Challenge: Accelerations in sea-level rise and changing environmental stressors have important implications for the integrity of coastal wetlands and for efforts to restore and protect the ecosystem services they provide. Their persistence and adaptation to these stressors depends on the net effects of changes in physical processes and biotic responses. Future planning by decision makers will require scientifically sound forecasts of potential impacts, knowledge of sea-level rise thresholds, and indications of the potential effectiveness of various adaptation strategies.
The Science: The response of coastal wetland elevation, stability, and ecosystem function to multiple interacting factors is varied and complex. Because it is difficult to predict the response of these ecosystems to the effects of environmental and human stressors, it is critical that we understand the susceptibility of the Nation’s coastal wetlands to projected changes in relative sea level as well as the biological and physical processes driving coastal wetland surface elevation change. In this project, we attempt to explore these issues through the following research questions:
- What are the linkages and feedback effects that control habitat stability of coastal wetlands, specifically how do wetlands maintain surface elevations relative to sea level?
- How do external forcing functions, such as sea-level rise, elevated CO2, and nutrients, interact with these internal processes to affect ecosystem stability?
- Can we develop a predictive capacity to forecast future responses of coastal wetlands to changes in external forcing functions?
The Future: The work conducted in this research program is designed to both test hypotheses and predict the response of coastal wetlands to environmental stressors. To accomplish both of these objectives, data collected from the field research component of this study will be used to develop a modeling framework that incorporates both multivariate hypothesis testing and forecast modeling. This modeling effort will enable us to forecast ecosystem responses to a wide variety of scenarios and provide critical feedback to managers, which will enable them to modify strategies for the sustainable management of coastal wetlands.
Below are publications associated with this project.
Spatio-temporal development of vegetation die-off in a submerging coastal marsh
Balanced sediment fluxes in southern California’s Mediterranean-climate zone salt marshes
Effects of climate change on tidal marshes along a latitudinal gradient in California
Potential effects of sea-level rise on plant productivity: Species-specific responses in northeast Pacific tidal marshes
Overestimation of marsh vulnerability to sea level rise
Greenhouse gas fluxes from salt marshes exposed to chronic nutrient enrichment
The vulnerability of Indo-Pacific mangrove forests to sea-level rise
Sediment transport-based metrics of wetland stability
Response of plant productivity to experimental flooding in a stable and a submerging marsh
Use of structured decision making to identify monitoring variables and management priorities for salt marsh ecosystems
Temperature sensitivity of organic-matter decay in tidal marshes
The impact of sea-level rise on organic matter decay rates in Chesapeake Bay brackish tidal marshes
- Overview
Our overall objective is to understand what controls the vulnerability of coastal marshes to risks associated with global change drivers and rising sea levels. Fundamental questions pertaining to coastal wetland vulnerability still need to be addressed. What factors explain spatial and geographic variation in tidal wetland vulnerability? How do short term climatic events (storms) influence the longer term response of coastal marshes to sea level rise? What biological processes mediate marsh elevation responses to sedimentation? What processes control wetland transgression into adjacent uplands?Our goal is to provide a process-based framework that enables the development of a spatial model that simulates the dynamics of marsh transgression.
The Challenge: Accelerations in sea-level rise and changing environmental stressors have important implications for the integrity of coastal wetlands and for efforts to restore and protect the ecosystem services they provide. Their persistence and adaptation to these stressors depends on the net effects of changes in physical processes and biotic responses. Future planning by decision makers will require scientifically sound forecasts of potential impacts, knowledge of sea-level rise thresholds, and indications of the potential effectiveness of various adaptation strategies.
The Science: The response of coastal wetland elevation, stability, and ecosystem function to multiple interacting factors is varied and complex. Because it is difficult to predict the response of these ecosystems to the effects of environmental and human stressors, it is critical that we understand the susceptibility of the Nation’s coastal wetlands to projected changes in relative sea level as well as the biological and physical processes driving coastal wetland surface elevation change. In this project, we attempt to explore these issues through the following research questions:
- What are the linkages and feedback effects that control habitat stability of coastal wetlands, specifically how do wetlands maintain surface elevations relative to sea level?
- How do external forcing functions, such as sea-level rise, elevated CO2, and nutrients, interact with these internal processes to affect ecosystem stability?
- Can we develop a predictive capacity to forecast future responses of coastal wetlands to changes in external forcing functions?
The Future: The work conducted in this research program is designed to both test hypotheses and predict the response of coastal wetlands to environmental stressors. To accomplish both of these objectives, data collected from the field research component of this study will be used to develop a modeling framework that incorporates both multivariate hypothesis testing and forecast modeling. This modeling effort will enable us to forecast ecosystem responses to a wide variety of scenarios and provide critical feedback to managers, which will enable them to modify strategies for the sustainable management of coastal wetlands.
- Publications
Below are publications associated with this project.
Filter Total Items: 13Spatio-temporal development of vegetation die-off in a submerging coastal marsh
In several places around the world, coastal marsh vegetation is converting to open water through the formation of pools. This is concerning, as vegetation die-off is expected to reduce the marshes' capacity to adapt to sea level rise by vegetation-induced sediment accretion. Quantitative analyses of the spatial and temporal development of marsh vegetation die-off are scarce, although these are neeAuthorsLennert Schepers, Matthew Kirwan, Glenn R. Guntenspergen, Stijn TemmermanBalanced sediment fluxes in southern California’s Mediterranean-climate zone salt marshes
Salt marsh elevation and geomorphic stability depends on mineral sedimentation. Many Mediterranean-climate salt marshes along southern California, USA coast import sediment during El Niño storm events, but sediment fluxes and mechanisms during dry weather are potentially important for marsh stability. We calculated tidal creek sediment fluxes within a highly modified, sediment-starved, 1.5-km2 salAuthorsJordan A. Rosencranz, Neil K. Ganju, Richard F. Ambrose, Sandra M. Brosnahan, Patrick J. Dickhudt, Glenn R. Guntenspergen, Glen M. MacDonald, John Y. Takekawa, Karen M. ThorneEffects of climate change on tidal marshes along a latitudinal gradient in California
Public SummaryThe coastal region of California supports a wealth of ecosystem services including habitat provision for wildlife and fisheries. Tidal marshes, mudflats, and shallow bays within coastal estuaries link marine, freshwater and terrestrial habitats, and provide economic and recreational benefits to local communities. Climate change effects such as sea-level rise (SLR) are altering theseAuthorsKaren M. Thorne, Glen M. MacDonald, Rich F. Ambrose, Kevin J. Buffington, Chase M. Freeman, Christopher N. Janousek, Lauren N. Brown, James R. Holmquist, Glenn R. Guntenspergen, Katherine W. Powelson, Patrick L. Barnard, John Y. TakekawaPotential effects of sea-level rise on plant productivity: Species-specific responses in northeast Pacific tidal marshes
Coastal wetland plants are adapted to varying degrees of inundation. However, functional relationships between inundation and productivity are poorly characterized for most species. Determining species-specific tolerances to inundation is necessary to evaluate sea-level rise (SLR) effects on future marsh plant community composition, quantify organic matter inputs to marsh accretion, and inform preAuthorsChristopher Janousek, Kevin J. Buffington, Karen M. Thorne, Glenn R. Guntenspergen, John Y. Takekawa, Bruce D. DuggerOverestimation of marsh vulnerability to sea level rise
Coastal marshes are considered to be among the most valuable and vulnerable ecosystems on Earth, where the imminent loss of ecosystem services is a feared consequence of sea level rise. However, we show with a meta-analysis that global measurements of marsh elevation change indicate that marshes are generally building at rates similar to or exceeding historical sea level rise, and that process-basAuthorsMatthew L. Kirwan, Stijn Temmerman, Emily E. Skeehan, Glenn R. Guntenspergen, Sergio FagherazziGreenhouse gas fluxes from salt marshes exposed to chronic nutrient enrichment
We assessed the impact of nutrient additions on greenhouse gas fluxes using dark static chambers in a microtidal and a macrotidal marsh along the coast of New Brunswick, Canada approximately monthly over a year. Both were experimentally fertilized for six years with varying levels of N and P. For unfertilized, N and NPK treatments, average yearly CO2 emissions (which represent only respiration) atAuthorsGail L. Chmura, Lisa Kellman, Lee van Ardenne, Glenn R. GuntenspergenThe vulnerability of Indo-Pacific mangrove forests to sea-level rise
Sea-level rise can threaten the long-term sustainability of coastal communities and valuable ecosystems such as coral reefs, salt marshes and mangroves. Mangrove forests have the capacity to keep pace with sea-level rise and to avoid inundation through vertical accretion of sediments, which allows them to maintain wetland soil elevations suitable for plant growth. The Indo-Pacific region holds mosAuthorsCatherine E. Lovelock, Donald R. Cahoon, Daniel A. Friess, Glenn R. Guntenspergen, Ken W. Krauss, Ruth Reef, Kerrylee Rogers, Megan L. Saunders, Frida Sidik, Andrew Swales, Neil Saintilan, Le Xuan Thuyen, Tran TrietSediment transport-based metrics of wetland stability
Despite the importance of sediment availability on wetland stability, vulnerability assessments seldom consider spatiotemporal variability of sediment transport. Models predict that the maximum rate of sea level rise a marsh can survive is proportional to suspended sediment concentration (SSC) and accretion. In contrast, we find that SSC and accretion are higher in an unstable marsh than in an adjAuthorsNeil K. Ganju, Matthew L. Kirwan, Patrick J. Dickhudt, Glenn R. Guntenspergen, Donald R. Cahoon, Kevin D. KroegerResponse of plant productivity to experimental flooding in a stable and a submerging marsh
Recent models of tidal marsh evolution rely largely on the premise that plants are most productive at an optimal flooding regime that occurs when soil elevations are somewhere between mean sea level and mean high tide. Here, we use 4 years of manipulative “marsh organ” flooding experiments to test the generality of this conceptual framework and to examine how the optimal flooding frequency may chaAuthorsMatthew L. Kirwan, Glenn R. GuntenspergenUse of structured decision making to identify monitoring variables and management priorities for salt marsh ecosystems
Most salt marshes in the USA have been degraded by human activities, and coastal managers are faced with complex choices among possible actions to restore or enhance ecosystem integrity. We applied structured decision making (SDM) to guide selection of monitoring variables and management priorities for salt marshes within the National Wildlife Refuge System in the northeastern USA. In general, SDMAuthorsHilary A. Neckles, James E. Lyons, Glenn R. Guntenspergen, W. Gregory Shriver, Susan C. AdamowiczTemperature sensitivity of organic-matter decay in tidal marshes
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 sensitivitAuthorsMatthew L. Kirwan, Glenn R. Guntenspergen, J.A. LangleyThe impact of sea-level rise on organic matter decay rates in Chesapeake Bay brackish tidal marshes
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 flAuthorsM.L. Kirwanm, J.A. Langley, Gleen R. Guntenspergen, J.P. Megonigal - Partners