Trial Plantings of Perennial Plants on Electric Transmission Line ROWS in North Louisiana

Kenneth W. Farrish, Charles E. Rowell, and James M. Dyer

Trial plantings of small trees, shrubs and low growing perennial herbaceous plants were made on three electric transmission rights-of-ways (ROWs) in north Louisiana. The purpose of the plantings was to ascertain the opportunities and constraints from using planted perennial plants to both improve ROW aesthetics and wildlife values, and produce a stable vegetation community requiring less maintenance. The goal of the project was to establish selected species in three height growth zones to achieve the desired bowl-shaped vegetation canopy. Small tree species were planted on the ROW edge next to the adjacent forest. Shrub species were planted in a zone between the small trees and the area directly under the transmission lines. Perennial herbaceous species were planted under the transmission lines. Small tree survival was good over three growing seasons of the study. However, growth of the trees was disappointing. Above and below ground competition from the adjacent large forest trees appeared to restrict growth of the planted trees. The shrub species made better growth, probably because of their greater distance from the forest. Wax myrtle and Lespediza did particularly well. Survival, however, after three growing seasons was mixed for the shrub species. The perennial herbaceous plantings were completely unsuccessful. The project demonstrated that while aesthetics of the ROWs may be enhanced with group plantings of small trees and shrubs, establishing the desired bowl-shaped vegetation canopy using plantings in forested landscapes of the region will be difficult to achieve at reasonable cost.

Keywords: Rights-of-way plantings, perennials, aesthetics, vegetation management, trees, shrubs, group plantings, wildlife values