Document: KEV-3-76-24

Patterns of tree species in early succession along point bars of southeastern USA rivers.

ROBERTSON, K.M.* and C.K.AUGSPURGER

University of Illinois, Urbana, IL 61801 USA ¹

Abstract:
During riparian primary succession on point bars, trees often become established at some distance from the channel, where there frequently is a gradient from high to low elevation from the upstream to downstream ends of the point bar. We hypothesized that factors associated with this gradient cause an associated pattern of tree species, and we predicted that successional forests on comparable rivers in the southeastern U.S.A. coastal plain would consistently show such a pattern. On each of eight rivers from North Carolina to Texas, ten river bends were surveyed. At each bend, trees of each species in the earliest stage of succession were censused on the point bar at an upstream, middle, and downstream transect, where elevation was measured. Elevation patterns on all rivers corresponded to the expected gradient. On five of the eight rivers, the importance (density + basal area) of more than half of the 11 to 13 common species differed significantly among point bar locations. For each of these species, the relative location on the point bar was the same among rivers. Factors other than elevation may have caused three rivers to deviate from the predicted pattern of tree species. In summary, variables associated with elevation patterns characterizing the geomorphology of point bars of rivers in the southeast U.S.A. appear to influence the spatial pattern of establishment of a majority of tree species on most of the rivers studied.

Keywords: southeast,trees,water

This abstract is being presented at: 10:30 AM in session:
Oral Session #20: Riparian Ecology.