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Chapter 5: Vegetation

5.20: Vegetation Near Plum Lakes

The large shallow water area of Oak Lake and Plum Lakes is a relic of glacial Lake Hind; as the glacial lake dried out these remnants were left. Part of the Plum Lakes exists in the northwest 1 and northeast 2. Almost all the northern two-thirds of the photo was recently covered by water, and in addition to the Plum Lakes, several other small relic lakes remain 3 some bounded by low dikes 4. Emergent aquatic vegetation is visible in several of the shallow lakes 5. The slightly higher land has been reclaimed for agriculture—in this case hay growing. At the time the photo was taken the hay harvest was complete, and hay piles can be seen scattered throughout the area 6. Numerous trails cross this area 7.

The southern third is quite different, being covered by sand dunes which result from lake deposited sands being blown into dunes. Some well-defined ridges 8 can be identified. There are a few bare sand patches 9 but almost all the dunes are stabilized by vegetation—mainly deciduous trees and grass. The deciduous trees had lost their leaves by the time the photo was taken; consequently their shadow shape 10, their medium-grey tone, and mottled texture can identify the trees. Grass, on the other hand, is light grey with a smooth texture 11. On the dune ridges, microclimate variations result in different vegetation covers: on wetter northeast-facing slopes, trees dominate, whereas drier southwest-facing slopes are grass-covered 12. Two dugouts 13, probably supply grazing cattle in the sand hills. Apart from some trails there is little evidence of human activity, other than farming.

Figure 5.20: Vegetation Near Plum Lakes

Figure 5.20: Vegetation Near Plum Lakes

Figure 5.20

Vertical air photograph: A20288-22

Flight height: 9,330 feet a.s.l.; lens focal length: 152.17 mm

Date: October 30, 1967

Scale: 1:16,000 (approx.)

Location: Townships 7 and 8; Range 24 WI

Map sheets: 1:250,000 62F Virden

1:50,000 62F/10 Pipestone