Species diversity of Louisiana chenier woody vegetation remnants

The cheniers of southwestern Louisiana are linear arrayed ridges up to 3 meters high and 450 meters wide. These prehistoric shorelines now stand as relict "islands" surrounded by coastal marsh. Although the chenier woodlands were once extensive, most have now been converted to rangeland, roads and homesites, and therefore presently exist as remnants. The woody species in six remnant sites were sampled in order to determine species diversity and importance High numbers of the introduced species, Sapium sebiferum (L) Roxb., resulted in species diversity in the two Little Chenier sites being significantly lower than those on Grand Chenier, Tiger Island and Pecan Island. This appears to be due to a higher level of habitat destruction in the Little Chenier than in the other cheniers Importance values suggest a high degree of heterogeneity among the sites chosen for study For example, Quercus virginiana L Celtis laevigata Willd, Cephalanthus occidentalis L and Sapium were each the most important species in at least one of the sampled sites An ordination of the six sites suggests that only three sites form an ecologically meaningful cluster and the remaining three sites are clearly segregated from all others. The ordination pattern may be due primarily to varying levels of habitat destruction as a result of historic anthropogenic activity.