Restoration or Disturbance: Assessing the Impacts of a Salmon Habitat Restoration Project on Riparian Vegetation Composition

Abstract

Invasive plant species can threaten the biodiversity and resilience of riparian ecosystems. A vegetation assessment of the riparian zone beside the Stoney Creek Off-Channel Habitat Project compared with a non-restored site and a previously replanted site showed that the sites were significantly different in their vegetation composition. All three sites had several invasive species of concern playing dominant roles in the ecosystem with the most common two species being English ivy (Hedera helix) and Himalayan blackberry (Rubus discolor). The previously restored site had significantly lower levels of invasive English ivy than the non-restored site. The non-restored site had greater total foliar cover than the other sites, but this was mostly covered by invasive species. The project site was only significantly different from the reference sites by having greater ivy levels on trees and a higher number of red alders (Alnus rubra). These results, along with the qualitative differences noted in the composition of the Off-Channel habitat from the previously restored stream area, suggests that further restoration and replanting needs to take place around the Off-Channel habitat area