A Survey of the natural vegetation and flora along the South Saskatchewan River Valley within and near Saskatoon, Saskatchewan

Abstract

Increasing urbanization is exerting heavy pressure on natural places. This is especially true in urban centres that cover large areas. These centres are expanding to take over more natural areas, causing their degradation. In urban centres with large riparian corridors, this degradation of sites has a substantial effect on the natural conditions expected along these corridors. This study was undertaken to determine the extent of deterioration of riparian habitat along the South Saskatchewan River valley near Saskatoon. The vegetation at 10 locations along the riparian corridor within and near the city of Saskatoon was quantitatively sampled over a two-year period from 1995 to 1996. This added to a previous three-year study that described the flora of the riparian corridor, by qualitatively sampling 23 sites. Of the over 700 species identified in the floristic survey, 495 were found in the quantitatively studied plots. Of these, 22% were introduced species that indicate a negative effect on the natural state of the riparian corridor. Within the study area, several mostly natural and some introduced community types were identified. Those communities that possessed introduced species were most prevalent in the central core of the city, which has been exposed longer and more intensively to human impacts. This centralized disturbance pattern will likely ripple outward from the central core of the city unless mediative measures are taken. Also incorporated within the study, was an attempt to determine the effectiveness of using qualitative zonation as a tool for classifying riparian slope plant communities. It was found that the vertical zonation of a slope was a useful means for the classification of riparian communities. This study revealed the presence of two general types of communities in the study area: upland types and wetland types. The wetland types were: Carex lanuginosa, Agrostis stolonifera, Eleocharis palustris, Phalaris arundinacea, Elaeagnus commutata, Salix exigua, and Alnus tenuifolia. The upland types were: Koeleria gracilis, Carex siccata, Agropyron cristatum, Aralia nudicaulis, Rhamnus cathartica, Amelanchier alnifolia, Caragana arborescens, Rosa woodsii and Populus balsamifera. Data gathered in this study present an information database regarding the current status of natural riparian areas within and near Saskatoon that could be used to assess impacts from existing and future urbanization. With increasing public pressure to maintain natural diversity and health of ecosystems, more effort should be placed on minimizing our impacts on the places we see and use everyday.