Manitoba displays a large range of vegetation types that are arranged with a climatically determined north/south zonation. Grass-covered areas in the south give way to parkland and forested areas further north and eventually to shrub tundra in the extreme northeast.
In southern and west central Manitoba, agriculture, grazing, forestry and urban development have drastically altered the natural vegetation, but vast areas in the north and northeast are in near pristine state. Vegetation that often obscures the earth’s surface is clearly shown on air photos; particularly useful are colour infrared images that can detect stressed areas. Wetlands cover about 40 percent of Manitoba and do not conform to the climatically determined zonal distribution of vegetation. They occur in all parts of the province and provide distinctive ground cover well shown on air photos.
Individual animals are too small to appear on all except very large-scale images. However, some animals (e.g. beaver) profoundly affect drainage systems.
5.29: Peat Plateaus and Sloping Fens Near the Mouth of the Hayes River
In this area the coastal plain is being rapidly uplifted. Peat covers a discontinuous veneer of recent over- bank alluvial deposits over marine silt and clay or wave-modified till. The Hayes River 1, transporting a large sediment load, is braided with in-channel islands: RainbowIsland 2, SealIsland 3, and FishingIsland 4. The Nelson River can be seen in the upper left corner 5. Wanatawakaw Portage runs from near RainbowIsland to the Nelson River.
Oval peat plateaus are well-developed 6. The regular outlines of these plateaus suggest that they are actively expanding over the surrounding fens, many of them eventually coalescing (as at 7). Collapse scars can be detected on the centre of some of the plateaus 8. The streaked pattern 9 of the gently sloping fen is created by sheet runoff in the spring and by ground water flow. The light tones also reflect vegetation responses to water quality. Dark tones indicate fairly nutrient-rich fens, with tamarack (Larix laricina) and shrubs in the sedge. Light areas are located down- slope from peat plateaus 10 where these interrupt the regional flow and the water is coming off the peat plateau. Here the water is poor in nutrients and more acid. The poorer nutrient and oxygen status, as well as the low PH values, produces a poorer fen with fewer trees and shrubs.[i]
The north bank of the Hayes is retreating rapidly under the combination of thermal and fluvial erosion, and a pile of debris 11 can be seen at the base of a bank failure.
Figure 5.29: Peat Plateaus and Sloping Fens Near the Mouth of the Hayes River
Vertical air photograph: A14219-106
Flight height: 30,000 feet a.s.l.; lens focal length: 152.15 mm
Scale: 1:60,000 (approx.)
Date: July 5, 1954
Location: Township 91; Range 10 E
Map sheets: 1:250,000 54C Hayes River
1:50,000 54C/15 GillamIsland
[i] Interpratation from Mollard and Janes op. cit., 1984, 131.