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Table of Contents
Foreword
Preface
Glossary

Chapter 5: Vegetation

5.9: Natural Vegetation Surrounding the Red River Plain

This Landsat image shows radiation from the earth’s surface in three wavelength bands: 0.5 to 0.6 micrometres (green), 0.6 to 0.7 micrometres (red), and 0.8 to 1.1 micrometres (infrared). Printing was done so that objects reflecting large amounts of infrared radiation were imaged as red. At the time the image was obtained (September 17, 1973) this applied to trees, shrubs, and grasses growing in the area. Water bodies range from very dark blue to light milky blue, the latter being the case where there is a large suspended sediment load. In the northeast, the Winnipeg River 1 flows through a series of expansions, the largest being Lac du Bonnet 2, before entering Lake Winnipeg 3. The southern end of Lake Manitoba 4 is seen in the west, and in the Interlake region the Shoal Lakes (west 5, east 6, and north 7) as well as many smaller lakes can be seen.

Three main areas of natural vegetation can be identified. In the southeast, mainly on the Canadian Shield 8, is an area of provincial parks and forests. In the extreme east the vegetation is broadleaf forest with an area of mixed-woods bordering it. This area also has numerous areas of “poorly drained lowland bogs with their black spruce-sphagnum communities, and of granite rock outcrops with their thin, often only 15 cm thick, organic soils (folisols) dominated by jack pine to the north and white, red and jack pine to the southeast. Some of the acid sphagnum peat in the Agassiz Forest bogs near Beausejour and Hadashville [9 and 10 on the image] is harvested for horticultural purposes.”[i] The continuity of this forest/bog area is broken by clearing for agriculture only along the Whitemouth River 11, the Brokenhead River 12, and the upper reaches of the Seine River 13.

The second area is the Interlake region 14 between lakes Winnipeg and Manitoba. Here the natural vegetation is categorized as aspen parkland[ii] with aspen (Populous tremuloides) being the dominant tree. The thin poorly drained soils of the area are at best marginal for agriculture, so there has been little clearing except for a spur projecting along the west coast of Lake Winnipeg 15.

In the third area in the southwest on the Pembina Hills 16, the redness is less uniform because of agricultural clearing. In this area small patches of broadleaf forest occur on the higher ground with the rest being aspen parkland.[iii]

Delta marsh 17 at the south end of Lake Manitoba and Netley Marsh 18 at the south end of Lake Winnipeg show up as lattice works of vegetation surrounded by water. These marshes are subject to frequent water level changes and therefore have not been reclaimed for agriculture, in contrast to the marshes that used to exist on the Red River plain further south. At the end of the nineteenth century the plain, which extends from Portage la Prairie in the west 19 to the Canadian Shield in the east 20 and from Lake Winnipeg in the north to well south into the U.S.A. 21, was covered by marshes. They have almost all been drained for agricultural use, and as the active growth period for crops was past when this image was obtained, little of the plain is shown in red.

There are, however, a few exceptions. In the north, Oak Hammock Marsh 22 “has been maintained as an important wetland and staging area for migratory waterfowl by regulating water levels and practicing periodic draw down.”[iv] It is imaged as red, but there is little indication of standing water. Another red area northeast of Winnipeg 23 results from woodland in Birds Hill Provincial Park, and the red area south of the Assiniboine River in western Winnipeg 24 indicates the presence of treed parks. Also, several river courses can be located on the basis of linear red zones: in the west the Assiniboine 25, La Salle 26, and Boyne 27; in the south the Red 28 and the Rat 29; and in the east the Seine 13 and Brokenhead 12.

The emphasis here is on interpretation of natural vegetation, but three cultural features should be mentioned: Winnipeg is located at the junction of the Red and the Assiniboine rivers 30; the white areas 31 northeast of Winnipeg are gravel pits into the Birds Hill esker; and the Red River Floodway which bypasses the city to the east 32 is red because of grasses growing on its banks.

Figure 5.9: Natural Vegetation Surrounding the Red River Plain

Figure 5.9: Natural Vegetation Surrounding the Red River Plain

Figure 5.9

Landsat I image. September 17, 1973

This is a colour composite of bands 4- wavelength 0.5 to 0.6 micrometres (green); 5-wavelength 0.6 to 0.7 micrometres (red) and 7-wavelength 0.8 to 1.1 micrometres (infrared)

Scale 1:1,000,000 (approx.)

Notes

[i] Scott, op.cit. 1996, 50.

[ii] Scott, op.cit. 1996, figure 4.2, 45.

[iii] Scott, op.cit. 1996, figure 4.2, 45.

[iv] Scott, op.cit. 1996, 49.