A Phytosociological Study of the Woody, Forest Vegetation of the Cypress Hills
Newsome, Richard D.
The Cypress Hills are a prominent landmark on the Canadian Great plains. Their sudden and considerable rise above the general landscape brings with it an equally abrupt vegetal transformation from tawny, semi-arid prairies to green, mesic forests and other, more luxuriant grasslands. The composition of these highland forests and prairies is dissimilar to that of the surrounding vegetations and has its nearest counterpart 200 miles away in the Rocky Mountains of Alberta and in the Aspen Grove Region adjacent to the Boreal Forest. This outlier is relict of at least early post glacial time and covers a landscape that, in part at least, was spared glacial occupation. The forces which isolated these relicts have eliminated all but 6 tree species of which Pinus contorta var. latifolia (lodgepole pine) and Populus tremuloides (trembling aspen) are by far the most abundant. Picea glauca var. albertiana (white spruce) and Ponulus balsamifera (balsam poplar) are common but less abundant, and Betula papyrifera var. subcordata (white birch) and Acer negundo (Manitoba maple) are rare. For convenience, the first 4 species will be referred to as pine, aspen, spruce and balsam poplar respectively. Particularly noticeable is the absence of the genus Abies, an important constituent of most coniferous regions. Festuca scabrella is the most abundant grass of this elevated prairie and, together with Potentilla fruticosa, is largely responsible for its physiognomy. Numerous spring-fed streams emanate from these uplands, providing the only available surface water for many miles. The lush vegetation of the Cypress Hills sustains this brook flow by stabilizing its watersheds and is, in turn, sustained by these same waters. Man, attracted to the hills by the timber and grazing land they offer, and needing this source of water, has sought to exploit their resources and to manage them for his own purposes. The variety and inconstancy of past management efforts attests to a lack of basic knowledge concerning the relationships of this vegetation to its components and to its habitat. A working knowledge of the climate, soils and vegetation of the Cypress Hills has yet to be synthesized. The purpose of the present study has been to examine the distribution of the woody, forest species in an attempt to determine the basic interrelations between the forest communities. This is a preliminary analysis of limited scope, designed to test methods and to clarify problems in preparation for a more comprehensive study. The field work was conducted during the summer 1961. Quantitative data were gathered from 26 stands, distributed to include as much variation as occurs in composition, slope, exposure, altitude and topographic position.