Vegetation change on a northeast tidal marsh: Interaction of sea-level rise and marsh accretion
- Connecticut College, New London (United States)
Increasing rates of relative sea-level rise (RSL) have been linked to coastal wetland losses along the Gulf of Mexico and elsewhere. Rapidly rising RSL may be affecting New England tidal marshes. Studies of the Wequetequock-Pawcatuck tidal marshes over four decades have documented dramatic changes in vegetation apparently related primarily to differential rates of marsh accretion and sea-level rise though sediment supply and anthropogenic modifications of the system may also be involved. When initially studied in 1947-1948 the high marsh supported a Juncus gerardi-Spartina patens belting pattern typical of many New England salt marshes. On most of the marsh complex the former Juncus belt has now been replaced by forbs, primarily Triglochin maritima, while the former S. patens high marsh is now a complex of vegetation types-stunted Spartina alterniflora, Distichlis spicata, forbs, and relic stands of S. patens. The mean surface elevation of areas where the vegetation has changed is significantly lower than that of areas still supporting the earlier pattern (4.6 vs. 13.9 cm above mean tide level). The differences in surface elevation reflect differences in accretion of marsh peat. Stable areas have been accreting at the rate of local sea-level rise, 2.0-2.5 mm/yr at least since 1938; changed areas have accreted at about one half that rate. Lower surface elevations result in greater frequency and duration of tidal flooding, and thus in increased peat saturation, salinity, and sulfide concentrations, and in decreased redox potential, as directly measured over the growing season at both changed and stable sites. These edaphic changes may have combined to favor establishment of a wetter, more open vegetation type. Similar changes have been observed on other Long Island Sound marshes and may be a model for the potential effects of sea-level rise on New England tidal salt marshes. 39 refs., 4 figs., 1 tab.
- OSTI ID:
- 6470553
- Journal Information:
- Ecology; (United States), Vol. 74:1; ISSN 0012-9658
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
SEA LEVEL
ENVIRONMENTAL EFFECTS
WETLANDS
DAMAGE
COASTAL REGIONS
ECOSYSTEMS
LONG ISLAND SOUND
MARSHES
MASSACHUSETTS
PEAT
PLANTS
REDOX POTENTIAL
SALINITY
TIDE
AQUATIC ECOSYSTEMS
ATLANTIC OCEAN
DEVELOPED COUNTRIES
ENERGY SOURCES
ESTUARIES
FOSSIL FUELS
FUELS
LEVELS
MATTER
NORTH AMERICA
ORGANIC MATTER
SEAS
SURFACE WATERS
USA
540210* - Environment
Terrestrial- Basic Studies- (1990-)
560400 - Other Environmental Pollutant Effects