The impact of species introduced to control tree invasion on the vegetation of an electrical utility right-of-way

Abstract

Utilities must remove trees from their rights-of-way on a frequent basis. Many use selective removal methods that leave the nontarget ground cover intact. It is thought that this ground cover will inhibit the subsequent establishment of trees, thus reducing future maintenance needs. An alternative approach is to plant highly competitive species that are able to produce stable communities. This paper describes a project set out to determine if seeding such cover crops would affect the composition of the right-of-way vegetation, and to what extent the resulting community would affect the time course of succession towards a forest. Four cover crops (Festuca rubra L., Dactylis glomerata L., Lotus corniculatus L., and Coronilla varia L.) were evaluated for a 5-year period. The cover and abundance of all vegetation was assessed annually, and the ordination program DECORANA was used to investigate the changes in the vegetation over time. To provide a measure of the effect of the crops on tree growth, 1-year-old transplants of Fraxinus pennsylvanica Marsh. and Acer saccharum Marsh and unrooted cuttings of Populus ×canadensis Moench. were planted into each plot. Dactylis has the largest effect on the vegetation. This grass reduced forb biomass by 70%, producing a community with significantly lower species richness. The time trajectories of the ordination indicate that this treatment is changing the overall development of the plant community. In addition, the survival of the Fraxinus and Populus planted into the Dactylis plots was reduced to 75 and 0% of the unseeded controls. These results indicate that some crops are capable of altering the community composition in the early stages of development, and may inhibit the establishment of trees. Key words: power corridor, vegetation control, competition, interference.