Vegetation composition along a New England transmission line corridor and its implications for other trophic levels

Transmission line corridors in forested landscapes provide important early successional habitats for a taxonomically rich array of native plant and animal life, including populations of rare species. We measured plant diversity and cover for 27 randomly selected paired powerline and woodland plots along a 140-km rights-of-way corridor that extended from northern Connecticut into southern New Hampshire. Mean plant richness was significantly higher in powerline plots (x¯ = 49.8 species) than in woodland plots (x¯ = 29.5 species). Powerline plots with the greatest richness were those that included a maintenance road or other areas of disturbed, open soil. Three hundred and twenty-six plant species were recorded in powerline plots, more than twice the number found in woodland plots (n = 157). Powerline plots had higher invasive plant cover than the woodland plots, but non-native invasive species cover was low (<2%) in both powerline and woodland plots. Cover of clonal species was greater in the powerline plots (mean values of 12.0% ±1.2 vs. 4.0% ±0.6). Northern powerline plots in our study, maintained exclusively by mowing, had a higher proportion of tree cover than southern plots that were maintained by mowing plus spot-application of herbicides. No differences were found in the proportional cover of all woody plants, clonal species, or invasive species among the two management types. We include a discussion of host-specialized Lepidoptera, oligolectic bees, and other wildlife that are dependent on vegetation composition and structure found along transmission line corridors in the Northeast.