Response of plant species to grazing in the forest region of Saskatchewan

Abstract

Vast areas of central Saskatchewan are occupied by aspen groves, aspen forest and mixed-wood (Rowe, 1959). A part of the aspen forest has been cleared and is now utilized as pastures. These pastures may be referred to as 'wooded', 'bushland' or 'northern wooded' pastures. Though, historically, the utilization of the wooded pastures can be traced back to the times of early settlers, their development as government sponsored pasture dates back to the early 1940's. While the first government community pasture in the grassland zone was established in 1922 at Matador (Moen, 1964), it was not until 1941 that a community pasture was set up at Beaver Hills in the forest zone.

By the early 1950's it became obvious that the livestock industry was being greatly hampered by insufficient grazing facilities. The pastures in the grassland region could not cope with the increasing demand for grazing needs due to low carrying capacity as a result of frequent droughts. In the northern fringe of settlement there were still present vast areas of unutilized submarginal lands under aspen forest. The soil under aspen forest is podzolic, often low in fertility, of sandy texture, stony and poorly drained in low lying areas so that its tillage for cereal crops was not feasible.

The importance of wooded pastures would further increase with the rising demand of beef production. Haase (1964) has outlined the need and importance of increased forage production in Canada. He suggested that an additional 15 million acres of improved land would be needed by 1980. The investigators in various fields discussed effectively the problems and needed fields of study in the establishment of northern wooded pastures in a meeting on "The development of pasture from bushlands in western Canada" under the auspecies of Canada Department of Agriculture in 1964. Perhaps, the most important aspect of the problems that were discussed at the meeting, was the need for understanding the response of vegetation, native as well as seeded, to grazing.

The present study was undertaken primarily to consider the effect of grazing on herbaceous vegetation in wooded pastures. This involved the selection and study of comparable grazed and ungrazed stands under three different 'habitat' types: forest; forest, cleared; and forest, cleared, ploughed and seeded. The study sites were located in areas, potentially capable of supporting aspen forest on podzolic, degraded black or grey wooded soil. Populus tremuloides is the dominant tree species and Fragaria vesca, Lathyrus venosus, Vicia americana, Aster ciliolatus, Galium septentrionale, Thalictrum dasycarpum, Bromus ciliatus, Agropyron subsecundum and Schizachne purpurascens are the common herb species in undisturbed sites. Poa pratensis and Poa palustris are the dominant grasses in cleared areas while Bromus inermis, Agropyron cristatum and Medicago sativa are the most common species in seeded areas.