File:The ecology of delta marshes of coastal Louisiana - a community profile (1984) (20526779174).jpg

Title: The ecology of delta marshes of coastal Louisiana : a community profile
Identifier: ecologyofdeltama00goss (find matches)
Year: 1984 (1980s)
Authors: Gosselink, James G; National Coastal Ecosystems Team (U. S. )
Subjects: Marsh ecology -- Louisiana; Wetlands -- Louisiana
Publisher: Washington, DC : National Coastal Ecosystems Team, Division of Biological Services, Research Development, Fish and Wildlife Service, U. S. Dept. of the Interior : Corps of Engineers, U. S. Dept. of the Army
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

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VEGETATION TYPES: ^â 1- FRESH MARSHES INTERMEDIATE MARSHES BRACKISH MARSHES SALINE MARSHES â NL>N-MARSH AREAS Figure 35. Vegetation zones in the Mississippi River Delta marshes (Chabreck and Linscombe 1978). Chabreck': data are for the coastal marshes of the whole state. There is some difference in the species found in the western chenier plain compared to the delta, but these are minor. More impor- tant is that the species list is a com- posite from many different, sites. No one site would be expected to contain all the species, especially in the intermediate and fresh marshes. Each major zone is actually a complex mosaic of many sub- associations. The primary zones are, as the names indicate, determined by the salinity tolerance of the plants. Within each zone detailed mosaics result from much more complex factors including soil nutrients and elevation (hence flooding frequency and duration). For example, a 90-km^ site in the intermediate marsh in the Barataria basin was mapped from aerial imagery, and intensive ground surveys were conducted. Six plant associations were identified using statistical clustering techniques (Figure 38), and even more complex visual patterns are seen in the aerial imagery. The observed patterns seem to result from the interaction of brackish water entering the marsh from the east and south, and fresh upland runoff from the west, com- bined with slight elevation differences (Sasser et al. 1982). Vegetation studies in the Atchafalaya basin fresh marshes show the importance of elevation and exposure to direct river flow versus stagnating backwater flooding in controlling the species distribution (Johnson et al., LSU Center for Wetland Resources; unpublished). Greenhouse studies on salt marsh species from the delta clearly show differences in the ability of different species to tolerate flooding (Parrondo et al. 1978). In these studies, although S^. alterniflora and S. cynosuroides appeared to be equally weTl adapted to salt, the latter was far less tolerant of flooding (Figure 39). The greenhouse studies quantify qualitative observations that S^. cynosuroides is found in slightly elevated locations in the marsh. 39

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