Identifying plant communities resistant to conifer establishment along utility rights-of-way in Washington and Oregon, U.S.

Abstract

A program to assess the utility of stable, lowgrowing plant communities in suppressing conifer seedling establishment along electrical rights-of-way was initiated in the states of Washington and Oregon, U.S., in 1999. The percentage of cover of all woody species and density of tree stems was described at three sites by sampling 1,376 plots, each 2 x 2 m. We asked if tree seedlings, principally Douglasfir (Pseudotsuga menziesii), were distributed randomly among community types defined by growth form and percentage of cover. Douglas-fir seedlings were not randomly distributed and occurred less frequently within communities already occupied by dense vegetation. This included some, but not all, low-growing communities-e.g., areas of dense grass or shrub communities of moderate to high cover. Douglas-fir seedlings were infrequent within patches dominated by trees and tall shrubs, but these do not fit the low-growing requirement of the program. Of particular concern to vegetation managers was the large number of Douglas-fir seedlings that regrew from an uncut lateral branch.