Document: SHA-3-76-4

Riparian zone seedling establishment, dynamics, and the influence of Rhododendron maximum.

TAYLOR, S.F.* ¹, B.D.KLOEPPEL ¹, D.C.COLEMAN ¹, B.BECKAGE ² and J.A.YEAKLEY ³

University of Georgia, Athens, GA, USA ¹
Duke University, Durham, NC, USA ²
Portland State University, Portland, OR, USA ³

Abstract:
The understory shrub Rhododendron maximum is associated with reduced regeneration of tree seedlings throughout the southern Appalachians. Four study sites were used to study natural seedling establishment in riparian zones where R. maximum is a dominant species: One R. maximum artificially removed treatment site, one R. maximum hurricane disturbed treatment site, and two R. maximum control sites. Each study site had ten randomly located 1-m² quadrats. All seedlings were tagged during an initial survey in May 1997 and subsequent seasonal surveys were conducted. During each census, species, density, age, and height were recorded. Abiotic characteristics; aspect, slope, soil moisture, and light availability were measured for each quadrat. Coinciding research on the sites included transects instrumented with tension lysimeters. In the control sites, seedling density averaged 2.9 stems m^-2 and mortality averaged 9.9 stems m^-2. At the treatment sites, seedling density averaged 22.9 stems m^-2 and mortality averaged 10.2 stems m^-2. Mean heights for Liriodendron tulipifera and Betula lenta, which dominated in the hurricane disturbed quadrats, were 10.1 and 20.4 cm, respectively. Acer rubrum and L. tulipifera were prevalent in the artificially removed quadrats with mean heights of 1.0 and 4.5 cm, respectively. The results indicate that seedling establishment and height in riparian zones are strongly influenced by the removal or disturbance of R. maximum and the disturbance of R. maximum results in increased germination, height, and survival of seedlings.

Keywords: riparian, rhododendron, disturbance

This abstract is being presented at: 10:30 AM in session:
RIPARIAN ECOLOGY