Conservation of the endangered limestone endemic Salix jejuna : effects of anthropogenic disturbance on habitat and life history

Anthropogenic disturbance has been shown to have negative impacts on the recovery of endangered or rare species. Specific recovery objectives for Salix jejuna, an endangered prostrate shrub endemic to the globally rare limestone barrens habitat of Newfoundland (Canada), include assessing the population dynamics of natural populations, understanding limiting factors, defining threats and mitigating controllable threats where possible. As a large portion of S. jejuna's habitat has been anthropogenically-disturbed, understanding the effects of disturbance on species persistence are central to promoting species recovery. -- An assessment of habitat features revealed that anthropogenically-disturbed substrates were more homogeneous than undisturbed, natural substrates, with more gravel, less exposed bedrock, decreased soil moisture, and increased nutrient content. Populations resident on anthropogenically-disturbed habitats tended towards a more "annual" dynamic, with a greater proportion of seedlings, lower levels of clonal growth, and a younger median age compared with populations on naturally-disturbed substrates. Therefore, specific recovery plans for S. jejuna should include the elimination of continual disturbances such as off-road vehicle use and the active restoration of disturbed habitat to restore natural ecosystem processes, to reflect adjacent undisturbed natural habitat, and to promote the clonal reproductive traits of natural populations