Wetland loss dynamics in southwestern Barataria basin, Louisiana (USA), 1945?1985

Evers, D. Elaine; Gosselink, James G.; Sasser, Charles E.; Hill, John M.

doi:10.1007/bf00215318

Cited by 26 publications

(13 citation statements)

References 10 publications

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“…Thus, there is an implication that these wetlands did not exist in the 1940s, which suggests further that the last 50 years have seen significant changes in the vegetation and substrate structure of Louisiana's floating marshes. This is not surprising in light of hydrologic modification (Gosselink 1984) and the magnitude of degradation and loss of non-floating marshes during the same period in coastal Louisiana marshes (Britsch and Kemp 1990;Dunbar et al 1992;Evers et al 1992;Gagliano et al 1981;Sasser et al 1986). At this point it is not clear whether the thin mat habitat type is a transitional community in a degradation trend toward open water, or a Possible relationships among floating marsh types that occur in Mississippi River delta marshes (Sasser 1994a).…”

Section: Floating Marsh Types and Their Interrelationshipsmentioning

confidence: 99%

Vegetation, substrate and hydrology in floating marshes in the Mississippi river delta plain wetlands, USA

et al. 1996

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In the 1940s extensive floating marshes (locally called 'flotant') were reported and mapped in coastal wetlands of the Mississippi River Delta Plain. These floating marshes included large areas of Panicum hemitomon-dominated freshwater marshes, and Spartina patens/Scirpus olneyi brackish marshes. Today these marshes appear to be quite different in extent and type. We describe five floating habitats and one non-floating, quaking habitat based on differences in buoyancy dynamics (timing and degree of floating), substrate characteristics, and dominant vegetation. All floating marshes have low bulk density, organic substrates. Nearly all are fresh marshes. Panicum hemitomon floating marshes presently occur within the general regions that were reported in the 1940's by O'Neil, but are reduced in extent. Some of the former Panicum hemitomon marshes have been replaced by seasonally or variably floating marshes dominated, or co-dominated by Sagittaria lancifolia or Eleocharis baldwinii. Nomenclature: Nomenclature follows RK Godfrey and JW Wooten (

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Section: Floating Marsh Types and Their Interrelationshipsmentioning

confidence: 99%

Vegetation, substrate and hydrology in floating marshes in the Mississippi river delta plain wetlands, USA

et al. 1996

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“…Louisiana contains 27% of coastal marshes of the continental US (Louisiana 6 × 106 ha and continental US 22 × 106 ha of fresh and saline marsh) (Field et al 1991). The problem of land loss in these coastal marshes is well-documented (Craig et al 1979, Gagliano et al 1981, Scaife et al 1983, Sasser et al 1986, Walker et al 1987, Evers et al 1992, Boesch et al 1994. Louisiana is undergoing the most severe wetland loss in the United States, with loss rates estimated from 6,000 to 12,450 ha yr-1 (Britsch and Kemp 1990, Turner 1990, Britsch and Dunbar 1993.…”

Section: Introductionmentioning

confidence: 99%

Long-term vegetation change in Louisiana tidal marshes, 1968–1992

et al. 1999

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The Louisiana coastal marshes form some of the most extensive wetlands within the continental United States. The problem of land loss in these coastal marshes is well-documented, but very little is known about possible changes in vegetation composition that might be associated with this loss. We analyzed vegetation data collected from 1968 to 1992 in the tidal wetlands of Terrebonne parish and described five vegetation types that occur in this region. Our data did not show the predicted change to more salt-tolerant vegetation. This is probably due to the influence of the Atchafalaya River in the study area. However, we documented a large change in the dominant vegetation of the fresh marsh. Panicum hemitornon-dominated marshes occupied 51% of the study area in 1968 and only 14% in 1992. This vegetation type was replaced with Eleocharis baldwinii-domJnated marshes (3% in 1968 to 41% in 1992). This change occurred adjacent to an area of significant conversion to open water. Based on limited available data from the literature, we ev',duated three potential driving factors in this change-grazing, water-level increase, and water quality-but could not determine the cause of change definitively.

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“…An accretionary deficit caused by a lack of sediment input from the Mississippi River, acting in combination with a high rate of subsidence-induced sea-level rise, is most often cited as the main cause of land loss in Louisiana (DeLaune et al 1983, Salinas el al. 1986, Penland and Ramsey 1990, DcLaune et al 1992, Evers et al 1992, Boesch et al 1994). In addition, human activities such as canal dredging and the creation of associated spoil banks also promote wetland loss (Turner et al 1994).…”

Section: Introductionmentioning

confidence: 99%

Altered hydrology effects on Louisiana salt marsh function

1999

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A marsh subject to "structural marsh management," which changes natural wetland hydrology, was found to be functionally impaired when compared to an adjacent unimpounded reference marsh. The "managed" marsh had much lower sedimentation rates and tidal amplitude. Also, net annual primary production was lower in the managed marsh relative to the reference marsh. In light of the great importance of sedimentation, as well as primary production, to vertical accretion and maintenance of the salt marsh surface, our findings support the contention that structural marsh management (SMM) inhibits marsh surface accretion. Even so, much of the Louisiana coast has been proposed for this form of management in an effort to protect it from loss. However, our results show such management activities in the salt marsh could likely increase sediment aggradation deficits and wetland loss, especially in areas subject to high rates of subsidence or sea-level rise, such as Louisiana. Further research is needed to evaluate whether the results shown here are typical for saline SMM sites. In the absence of such research, the u~e of SMM in salt marshes is not presently recommended.

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Wetland loss dynamics in southwestern Barataria basin, Louisiana (USA), 1945?1985

Cited by 26 publications

References 10 publications

Vegetation, substrate and hydrology in floating marshes in the Mississippi river delta plain wetlands, USA

Vegetation, substrate and hydrology in floating marshes in the Mississippi river delta plain wetlands, USA

Long-term vegetation change in Louisiana tidal marshes, 1968–1992

Altered hydrology effects on Louisiana salt marsh function

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