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 s tand as relict ''islands'' surrounded by coastal marsh. Although the c henier woodlands were once extensive, most have now been converted to rangeland, roads and homesites, and therefore presently exist as remna nts. The woody species in six remnant sites were sampled in order to d etermine species diversity and importance. High numbers of the introdu ced species. Sapium sebiferum (L.) Roxb., resulted in species diversit y in the two Little Chenier sites being significantly lower than those on Grand Chenier, Tiger Island and Pecan Island. This appears to be d ue to a higher level of habitat destruction in the Little Chenier than in the other cheniers. Importance values suggest a high degree of het erogeneity among the sites chosen for study. For example, Quercus virg iniana L. Celtis laevigata Willd., Cephalanthus occidentalis L. and Sa pium were each the most important species in at least one of the sampl ed sites. An ordination of the six sites suggests that only three site s form an ecologically meaningful cluster and the remaining three site s are clearly segregated from ail others. The ordination pattern may b e due primarily to varying levels of habitat destruction as a result o f historic anthropogenic activity.