Tree, Shrub, and Herb Succession and Five Years of Management Following the Establishment of a New Electric Transmission Right-of-Way through a Mixed Woodland

摘要

A five-year study on vegetation succession was undertaken following the construction of a new electric transmission right-of-way (ROW) in Delaware, USA, that utilized both clear and selective cutting methods. Integrated vegetation management (IVM) methods were used as secondary interventions and compared against control sites. Restrictions have been imposed by regulatory agencies declaring that only selective clearing of targeted incompatible tall-growing trees and retention of existing compatible low-growing trees and shrubs is permitted for new ROW construction. Permanent upland quadrants were established for this study that compared tree, shrub, and herb populations following clear-cut and select-cut tree removal, and integrated vegetation management and no treatment interventions. Baseline data were gathered prior to construction and changes were documented for species numbers, diversity, stem count, and relative density. The management of desirable species and their relative value to wildlife are considered. Results show that IVM interventions triggered vegetation succession from mature woodland trees to low shrub/herbaceous communities as successfully in the clear-cut as in the select-cut quadrants. Total species numbers remained relatively stable but reflect a substitution of trees for herbaceous species while shrub species numbers remained relatively constant. The environmental effects of electric transmission ROW establishment and various vegetation management techniques upon plant species succession are discussed.