No abstract

Plains rough fescue (Festuca hallii), once a dominant grassland in the Northern Great Plains, has been reduced to a fraction of its original extent by agricultural intensification and energy sector disturbances and has become a threatened community type. Despite thousands of kilometers of pipelines in grasslands, little is documented about long-term restoration outcomes. This research assessed recovery of rough fescue grassland 6-21 years after pipeline construction with topsoil stripping and natural regeneration relative to undisturbed reference sites in south-central Canada. Soil properties varied between pipelines and undisturbed prairie, although most were within theoretical values to support plant growth and development. Vegetation cover, species richness and Shannon diversity and evenness did not differ significantly between pipelines and undisturbed prairie. Multivariate analysis (multi-response permutation procedure) showed plant community composition, and its dominant species differed significantly between pipelines and undisturbed prairie. Bray-Curtis dissimilarity indices showed dominant species and functional species groups on pipelines were more similar to undisturbed prairie than the undesirable species group. Presence of early-to late-successional species and increasing F. hallii with pipeline age indicate restoration was possible with topsoil salvage and replacement, using natural regeneration as a revegetation method, but requires time to develop and restore a typical rough fescue grassland ecosystem.

Lichens that grow on the bark of mature trees were studied at 35 sites along an air pollution gradient east of Edmonton, Alberta. Data on species composition, richness, and cover were recorded in October 1999 in a matrix of sites that extends from a known source of pollutants (the Strathcona Industrial Area) east across Strathcona County. Air pollution is affecting the corticolous lichen community. Lichen species richness and total cover increased with distance from the pollution source. Species richness in areas distant from pollution was roughly twice that in areas near the Strathcona Industrial Area. Xanthoria fallax and Phaeophyscia orbicularis were the most pollution tolerant lichens. Xanthoria hasseana, Ochrolechia arborea, Physcia adscendens, Parmelia sulcata, and Melanelia albertana were rare or absent near the pollution source and common in more distant areas. Most of the 15 species assessed were sensitive to air quality to some degree. Some lichens near the refineries and in Sherwood Park showed abnormal coloration and poor thallus integrity indicative of stress. We discuss implications for human health.