Early secondary succession in a southeastern U.S. alluvial floodplain.
Species number, turnover and early successional patterns were examined over the first 5 yr of old-field succession in a former bottomland hardwood forest in Louisiana. Number of species, measured by walk-through surveys, increased up to year 3, but decreased in years 4 and 5. Species turnover in 20 quadrats indicated that species invasions remained high throughout the study, while losses of species were initially high but declined. Detrended Correspondence Analysis (DCA) on species cover in each year showed the existence of a compositional gradient that could be significantly related to relative altitude (an indirect measure of the hydrological gradient), in years 2-5. DCA of the pooled 5-yr species cover data showed greater compositional changes in lower altitude quadrats, and those higher altitude quadrats dominated by the woody vine (Campsis radicans) remained similar over time.