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▼ Latest Research Findings: Plant and Animal Response to Right-of-Way Treatments

Results of more than six decades of ecological research on Pennsylvania electric transmission rights-of-way demonstrate that plant communities can be selectively managed to support reliable electric service and a diverse plant community for wildlife habitat.

The Pennsylvania State Game Lands 33 (SGL33) research project in central Pennsylvania began in 1953 in response to public concern—particularly from hunters—about the impact of vegetation management practices on wildlife habitat within electric transmission rights-of-way. Today, SGL33 is the site of the longest continuous study measuring the effects of herbicides and mechanical vegetation management practices on plant diversity, wildlife habitat, and wildlife use within a right-of-way. Similar studies have been conducted at a companion site, Green Lane Research and Demonstration Area (GLR&D), in southeastern Pennsylvania since 1987. Both projects provide invaluable information for understanding the response of plants and animals to vegetation management on rights-of-way.

Right-of-way vegetation management justification documentation for pollinators 

The original research objectives of the project remain the same today.

  1. Compare the effectiveness of commonly used vegetation management practices on controlling trees incompatible1 with management objectives for right-of-way function.
  2. Developing tree-resistant plant cover types.
  3. Determine the effect of vegetation management practices on wildlife habitat and select wildlife species of high public interest.

Management Practices: The Wire Zone-Border Zone Method

Since the mid-1980s, the wire zone–border zone integrated vegetation management approach has been applied at SGL33 and GLR&D sites. With this approach, the zone located directly under transmission lines (wire zone) is managed for a plant community of grass, forbs and low shrubs to minimize reinvasion of tall-statured trees and shrubs that could interfere with power lines. The ‘wire zone’ adjoins a narrow ‘border zone’ of low- to medium-sized shrubs where the right-of-way meets the natural forest.

Long-term studies conducted on SGL33 and GLR&D sites have shown economic, aesthetic and wildlife habitat benefits associated with integrated vegetation management practices on transmission line rights-of-way. This information is critical to help right-of-way managers implement proper vegetation management practices that meet needs of their industry, the public, and wildlife. Future research will be shaped based on the needs of the utility industry to address conservation issues, new vegetation management techniques, and concerns generated by the public and scientific community.

1In this document the term ‘incompatible’ vegetation indicates tall-growing trees that are not compatible with management objectives for right-of-way function.