Gray birch ecology on an electric powerline right-of-way in Upstate New York

Gray birch (Betula populifolia Marsh.) is an important tree species on powerline rights-of-way (ROWs) in the north temperate zone of North America. It is a pioneer species that can proliferate in the early plant succession environment of powerline ROWs. While a short tree at maturity (10-15 m), it is commonly a danger for the transmission of electricity. On a 17-yr-old 765 kV ROW in New York, stem densities of the gray birch population (trees greater than 1 cm diameter at breast height and approximately 3 m height) averaged 350 ha(-1). The ROW had been last managed with herbicides 11 years previous using an Integrated Vegetation Management approach. Treatments were basal and stem-foliar herbicides applied using non-selective or selective modes as part of a long-term study. Fifty-four gray birch trees from across a 25 km section of ROW were examined for height-age development patterns. Population density and age structure were measured on 11 treatment plots. Tree heights ranged to over 11 m and trees ages from 4 to 13 years. Most of the trees were established within 3 years after treatment. Young powerline corridors that have mesic to hydric moisture regimes are well-suited to birch invasion, particularly with management-related disturbance. Minimizing site disturbance and promoting the development of a tall-shrub community should reduce birch presence in older powerlines.