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Chapter 5: Vegetation

5.19: Colour Infrared Photo of Vegetation on the Assiniboine Delta Southeast of Shilo

Shown here is part of the Assiniboine Delta where the sands of the delta have been blown into dunes 1 and then stabilized by vegetation. The area, of little agricultural value, has been used as a military training ground for over 50 years. This large-scale colour infrared photo illustrates the usefulness of colour infrared images for identifying vegetation. At the time the photo was taken—late fall—all the deciduous trees had lost their leaves and were therefore not reflecting infrared radiation, but coniferous trees still had needles that reflect infrared and are imaged as red or orange.

Five vegetation types can be identified using the standard criteria for photo identification—tone—including in this case colour, texture, pattern, shape, size, and location. The most obvious vegetation zone is a thick red band trending northwest/southeast across the centre 2. Trees occur in rows indicating that they were planted, and their red colour and triangular shape and shadow indicate that they are coniferous. A field check revealed that they are Scots Pine (Pinus sylvestris L.) which are not native to this area. Near the southern edge of the photo are two small patches (3 and 4) of coniferous trees—red, with triangular shape and shadow. Given their location on the sand dunes, they are probably white spruce (Picea glauca). Isolated individual white spruce 5 can be seen scattered over the area south of the plantation. Also widespread over the whole area, but especially north of the plantation, are orange patches 6 often assuming a circular form 7. This vegetation throws no shadow, so it is not high off the ground. It is creeping juniper (Juniperis horizontalis) that, as its name suggests, spreads horizontally, especially over flat land. Much of the area is covered by vegetation imaged as pale green/almost white 8. Shadows indicate that we are dealing with trees, in this case aspen (Populus tremuloides) that have lost their leaves. Finally, there are extensive areas of pale green, smooth-textured grasslands 9.

The area is crossed by many tracks with a main one along the southern edge of the plantation 10 that leads from Shilo to the central part of the military reserve. Others are trails used by military vehicles. An indicator of how frequently they are used is given by whether they are covered by creeping juniper (as at 11). The only other indicator of human activity is a cluster of buildings north of the plantation 12 that is possibly a rifle range.

Figure 5.19: Colour Infrared Photo of Vegetation on the Assiniboine Delta Southeast of Shilo

Figure 5.19: Colour Infrared Photo of Vegetation on the Assiniboine Delta Southeast of Shilo

Figure 5.19

Vertical colour infrared air photograph: 5901 A37130 1R

Flight height: 11,000 feet a.s.l.; lens focal length: 153.12 mm

Scale: 1:18,000 (approx.)

Date: October 29, 1974

Location: Township 9; Range 16 WI

Map sheets: 1:250,000 62G Brandon  

1:50,000 62G/13 Brandon