An investigation of soil/vegetation relationships in southeastern Manitoba
Anderson, Sheila Margaret
One of the main objectives of this work was to obtain a detailed description of forest vegetation on mineral soils in southeastern Manitoba, as little botanical information is available on this area. Because of the cooperation of the Manitoba Soil Survey in the field, correlations could be made between forest vegetation and soil type. This relationship between forest vegetation and soil type is significant in many aspects of forest management. Accounts of climate, geology and soils are given, followed by a description of the forest vegetation. The important role of recurrent fires in the development of forest vegetation in southeastern Manitoba is emphasized. Early literature on the south-east is considered in order to compare the vegetation of nearly one hundred years ago with that of the present day. Three very broad forest-soil types are recognised: 1. The coniferous, hardwood, and mixed stands on the Podzol and Grey Wooded Soils developed on sandy moranic till, duned sand and glacial Sandy outwash. 2. The coniferous, hardwood and mixed stands on the Bisequa Grey Wooded and Grey Wooded soils developed on glacial outwash or aeolian and lacustrine deposits over calcareous boulder till. 3. The hardwood stands on the Grey Wooded Soils and Degraded Blacks on calcareous boulder till or calcareous boulder till with a thin mantle of lacustrine sand or clay. Each group has characteristic assemblages of species in the minor vegetation. These three groups can be subdivided according to drainage class. In the first group coniferous stands which are composed of jack pine (Pinus banksiana) for the most part with some red pine (Pinus resinosa) in places, are found on the freely drained sites and a few imperfectly drained sites. The latter sites commonly support hardwood stands or mixed jack pine and hardwood. Aspen (Populus tremuloides), Balsam poplar (Populus balsamifera), and white birch (Betula papyrifera) are the commonest hardwoods in the area. In the second group jack pine forms pure stands in some sites but is usually found mixed with aspen or birch. Either of the latter species may form pure stands in these sites. There is an indication from the stands examined that the hardwood stands on the freely drained sites in this group would be succeeded by jack pine if left undisturbed for a sufficient length of time. Hardwood stands of aspen, birch, and balsam poplar are dominant on the soils of the third group. The early literature suggests that the red and white pines were more widespread a century ago. The red pine probably occurred with jack pine on the sandy soils and white pine (Pinus strobus) on the calcareous boulder till soils. A brief consideration or indicator species points to a need for intensive studies before arriving at any definite conclusions on the interpretation of vegetation.