Inhibition of Seedling Survival under Rhododendronmaximum

In the southern Appalachian mountains Rhododendron maximum L. (R.m.) is the dominant subcanopy evergreen species. Approximately 30 million hectares of the southern Appalachian mountains are occupied by R.m. This subcanopy evergreen shrub forms extensive thickets, near streams and on north slopes, reaching a height of 3-6 m. On north-facing slopes these thickets form a mosaic of -40% cover. There is clear evidence that the coverage of R.m. thickets has been increasing over the past 30 yr. For example, the area occupied by R.m. thickets in the Coweeta basin has increased from 14.8% in 1976 to 31.7% in 1993 (Dobbs, 1995). The increase in abundance of this species is a concern for forest managers because recruitment of canopy tree seedlings under R.m. thickets is substantially inhibited. Several studies over the past 50 yr document the extent of seedling inhibition and the potential for inhibition of canopy tree productivity by R.m.