Coastal (marine) wetlands are recognized as one of the world's most efficient sinks for organic carbon (“blue carbon”), and credits for their restoration and conservation can be obtained from carbon ...markets. We reviewed 50 studies to compare the climate mitigation potential of the invasive cordgrass Spartina alterniflora to that of native vegetation in marshes along the coast of China. The importance of S alterniflora marshes as a carbon sink varied geographically; however, at all sites soils associated with S alterniflora emitted substantially more methane than soils populated with native plants. Because the species was deliberately introduced, the carbon stored in S alterniflora marshes could qualify for inclusion within China's national inventory of greenhouse‐gas emissions. However, in locations where it significantly increases carbon stocks, its dominance results in the loss of other ecosystem services. Therefore, if included in a national inventory, S alterniflora marshes could conflict with China's action plan for meeting UN Sustainable Development Goals.
Tidal salt marshes provide a range of ecosystem services. The most recently recognized is their provision of highly effective sinks for atmospheric carbon dioxide, a characteristic they share with ...mangroves swamps which largely replace salt marshes in the intertidal zones of tropical regions. Efforts are emerging to use salt marsh preservation or restoration in carbon offset programs, similar to the REDD initiative for tropical forests, but a number of issues first must be addressed to determine if a site meets the requirements of these programs. As intertidal systems, both salt marshes and mangrove swamps are threatened by increasing rates of sea level rise, and it will be essential to determine their sustainability, thus meeting the requirement of permanence of the carbon sink. In many areas the vegetation responsible for marsh soil accretion may not survive increased flooding periods, resulting in submergence of the marsh in its present location or inability to restore a marsh at its previous elevation. However, the marsh and its carbon sink, may survive if allowed to migrate inland. Thus assessment of permanence requires a determination if inland migration will be hindered by barriers such as high slopes or development, i.e., if the ecosystem is in a coastal squeeze. Presently, the only technology that can provide elevation models at the required vertical accuracy is Lidar, which also is extremely valuable for assessing vulnerability of coastal communities to flooding. Yet, Lidar data is not available for all coastlines, even those in the developed world. To effectively plan for the future of our coastlines requires Lidar coverage on all sensitive coastlines and its free availability for impact assessments.
► Carbon crediting systems require sinks be sustainable for ∼100 yr. ► Increasing sea levels threaten tidal marsh sustainability and Blue Carbon sinks. ► Assessment of marsh sustainability requires high resolution elevation data. ► Lidar technology uniquely provides this data, but we need to fund its acquisition.
Recent research has highlighted the valuable role that coastal and marine ecosystems play in sequestering carbon dioxide (CO
2
). The carbon (C) sequestered in vegetated coastal ecosystems, ...specifically mangrove forests, seagrass beds, and salt marshes, has been termed "blue carbon". Although their global area is one to two orders of magnitude smaller than that of terrestrial forests, the contribution of vegetated coastal habitats per unit area to long-term C sequestration is much greater, in part because of their efficiency in trapping suspended matter and associated organic C during tidal inundation. Despite the value of mangrove forests, seagrass beds, and salt marshes in sequestering C, and the other goods and services they provide, these systems are being lost at critical rates and action is urgently needed to prevent further degradation and loss. Recognition of the C sequestration value of vegetated coastal ecosystems provides a strong argument for their protection and restoration; however, it is necessary to improve scientific understanding of the underlying mechanisms that control C sequestration in these ecosystems. Here, we identify key areas of uncertainty and specific actions needed to address them.
The white-footed mouse (Peromyscus leucopus) is an important reservoir host for Borrelia burgdorferi, the pathogen responsible for Lyme disease, and its distribution is expanding northward. We used ...an Ecological Niche Factor Analysis to identify the climatic factors associated with the distribution shift of the white-footed mouse over the last 30 years at the northern edge of its range, and modeled its current and potential future (2050) distributions using the platform BIOMOD. A mild and shorter winter is favouring the northern expansion of the white-footed mouse in Québec. With more favorable winter conditions projected by 2050, the distribution range of the white-footed mouse is expected to expand further northward by 3° latitude. We also show that today in southern Québec, the occurrence of B. burgdorferi is associated with high probability of presence of the white-footed mouse. Changes in the distribution of the white-footed mouse will likely alter the geographical range of B. burgdorferi and impact the public health in northern regions that have yet to be exposed to Lyme disease.
Salt marshes are highly effective carbon (C) sinks and have higher rates of soil C burial (per square meter) than terrestrial ecosystems. Marsh reclamation and anthropogenic impacts, however, have ...resulted in extensive losses of salt marshes. Restoration of marshes drained and "reclaimed" for agriculture (referred to in Canada as dykelands) and degraded marshes can generate C credits, but only if C burial is reliably quantified. To date, studies reporting on C burial rates have been limited primarily to restored marshes which are more than 10 years old. Here we report on a study which assessed C burial six years after the return of tidal flooding to a section of dykeland in Aulac, New Brunswick on Canada's Bay of Fundy. The C burial rate in the restored marsh averaged 1 329 g C m-2 yr-1, more than five times the rate reported for a nearby mature marsh. Carbon density in the recovering marsh was relatively consistent with depth and although salt marsh cordgrass (Spartina alterniflora) became established in 2012, the bulk of the C in the new marsh deposit is assumed to be allochthonous. Financial constraints are a barrier to marsh restoration projects and C markets could provide a considerable source of funding for restoration work in the future. For marsh restoration projects to be recognized in C crediting systems, however, it must also be demonstrated that the allochthonous C would not otherwise have been sequestered; the potential for this is discussed.
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) at the microtidal marsh (13, 19, and 28 mmoles CO2 m(-2) hr(-1), respectively) were higher than at the macrotidal marsh (12, 15, and 19 mmoles m(-2) hr(-1), respectively, with a flux under the additional high N/low P treatment of 21 mmoles m(-2) hr(-1)). Response of CH4 to fertilization was more variable. At the macrotidal marsh average yearly fluxes were 1.29, 1.26, and 0.77 μmol CH4 m(-2) hr(-1) with control, N, and NPK treatments, respectively and 1.21 μmol m(-2) hr(-1) under high N/low P treatment. At the microtidal marsh CH4 fluxes were 0.23, 0.16, and -0.24 μmol CH4 m(-2) hr(-1) in control, N, and NPK and treatments, respectively. Fertilization changed soils from sinks to sources of N2O. Average yearly N2O fluxes at the macrotidal marsh were -0.07, 0.08, and 1.70, μmol N2O m(-2) hr(-1) in control, N, NPK and treatments, respectively and 0.35 μmol m(-2) hr(-1) under high N/low P treatment. For the control, N, and NPK treatments at the microtidal marsh N2O fluxes were -0.05, 0.30, and 0.52 μmol N2O m(-2) hr(-1), respectively. Our results indicate that N2O fluxes are likely to vary with the source of pollutant nutrients but emissions will be lower if N is not accompanied by an adequate supply of P (e.g., atmospheric deposition vs sewage or agricultural runoff). With chronic fertilization the global warming potential of the increased N2O emissions may be enough to offset the global cooling potential of the C sequestered by salt marshes.
Mangrove forests have the potential to export carbon to adjacent ecosystems but whether mangrove-derived organic carbon (OC) would enhance the soil OC storage in seagrass meadows adjacent to ...mangroves is unclear. In this study we examine the potential for the contribution of mangrove OC to seagrass soils on the coast of North Sulawesi, Indonesia. We found that seagrass meadows adjacent to mangroves had significantly higher soil OC concentrations, soil OC with lower δ
C, and lower bulk density than those at the non-mangrove adjacent meadows. Soil OC storage to 30 cm depth ranged from 3.21 to 6.82 kg C m
, and was also significantly higher at the mangrove adjacent meadows than those non-adjacent meadows. δ
C analyses revealed that mangrove OC contributed 34 to 83% to soil OC at the mangrove adjacent meadows. The δ
C value of seagrass plants was also different between the seagrasses adjacent to mangroves and those which were not, with lower values measured at the seagrasses adjacent to mangroves. Moreover, we found significant spatial variation in both soil OC concentration and storage, with values decreasing toward sea, and the contribution of mangrove-derived carbon also reduced with distance from the forest.
Acquiring in situ data of tidal flooding is key for the successful restoration planning of intertidal wetlands such as salt marshes and mangroves. However, monitoring spatially explicit inundation ...time series and tidal currents can be costly and technically challenging. With the increasing availability of low-cost sensors and data loggers, customized solutions can now be designed to monitor intertidal hydrodynamics with direct applications for restoration and management.
Tidal wetlands, such as tidal marshes and mangroves, are hotspots for carbon sequestration. The preservation of organic matter (OM) is a critical process by which tidal wetlands exert influence over ...the global carbon cycle and at the same time gain elevation to keep pace with sea-level rise (SLR). The present study assessed the effects of temperature and relative sea level on the decomposition rate and stabilization of OM in tidal wetlands worldwide, utilizing commercially available standardized litter. While effects on decomposition rate per se were minor, we show strong negative effects of temperature and relative sea level on stabilization, as based on the fraction of labile, rapidly hydrolyzable OM that becomes stabilized during deployment. Across study sites, OM stabilization was 29 % lower in low, more frequently flooded vs. high, less frequently flooded zones. Stabilization declined by ∼ 75 % over the studied temperature gradient from 10.9 to 28.5 ∘C. Additionally, data from the Plum Island long-term ecological research site in Massachusetts, USA, show a pronounced reduction in OM stabilization by > 70 % in response to simulated coastal eutrophication, confirming the potentially high sensitivity of OM stabilization to global change. We therefore provide evidence that rising temperature, accelerated SLR, and coastal eutrophication may decrease the future capacity of tidal wetlands to sequester carbon by affecting the initial transformations of recent OM inputs to soil OM.
Torio, D.D. and Chmura, G.L., 2013. Assessing coastal squeeze of tidal wetlands. As sea level rise accelerates and land development intensifies along coastlines, tidal wetlands will become ...increasingly threatened by coastal squeeze. Barriers that protect inland areas from rising sea level prevent or reduce tidal flows, and impermeable surfaces prevent wetland migration to the adjacent uplands. As vegetation succumbs to submergence by rising sea levels on the seaward edge of a wetland, those wetlands prevented from inland migration will decrease in area, if not disappear completely. Tools to identify locations where coastal squeeze is likely to occur are needed for coastal management. We have developed a “Coastal Squeeze Index” that can be used to assess the potential of coastal squeeze along the borders of a single wetland and to rank the threats faced by multiple wetlands. The index is based on surrounding topography and impervious surfaces derived from light detection and ranging and advanced spaceborne thermal emission and reflection radiometry imagery, respectively, and uses a fuzzy logic approach. We assume that coastal squeeze varies continuously over the coastal landscape and tested several fuzzy logic functions before assigning a continuous weight, from 0 to 1, corresponding to the influence of slope and impervious surfaces on coastal squeeze. We then combined the ranked variables to produce a map of coastal squeeze as a continuous index. Using this index, we compare the present and future threat of coastal squeeze to marshes in Wells and Portland, Maine, in the United States and Kouchibouguac National Park in New Brunswick, Canada.
PDF
