PARENT SESSION
Contributed Oral Session 58: Forest Ecology: Riparian Areas
Tuesday, August 9, 1:30 PM - 5:00 PM, Meeting Room 514 A, Level 5, Palais des congrès de Montréal

Primary succession of riparian broadleaf woodlands in Zoar Valley Canyon, New York, USA.

Diggins, Thomas^*,1, Fairchild, William ¹, Pfeil, Erin¹, Kolenick, Joseph¹, ¹ Youngstown State University, Youngstown, OH, USA

ABSTRACT- The understanding of riparian primary succession in the eastern United States has been incomplete because ecologically mature stages are all too often altered by timber harvest and/or land clearing. During 2002-2005 we studied riverside forest structure and species composition in the Zoar Valley Canyon of 6th order Cattaraugus Creek, NY, where a complete chronosequence includes rare un-logged riparian old growth. We catalogued trees >1 cm diameter at breast height (DBH) in 65 square quadrats (30-m and 10-m for raised terraces and floodplains, respectively) on 19 streamside flats along 11 km of river. Ordination (non-metric multidimensional scaling) of quadrats clearly distinguished younger floodplains from raised terraces that are no longer inundated. Ordination also discriminated suspected late-successional old growth from transitional woodlands within terraces. On-going quantification of stand ages during 2005 is providing a direct gradient analysis to augment ordination. Vegetation structure and species composition were highly divergent among floodplains, suggesting multiple pathways of early succession possibly related to colonization from adjacent stands. In contrast, later succession converged markedly to a more cohesive shade-tolerant old-growth stage, loosely reminiscent of the climatic monoclimax theorized by Clements.

Key words: Succession, Riparian, Forest, Floodplain