Northern Prairie Wildlife Research Center
Improving Prairie Pond Counts with Aerial Video
and Global Positioning Systems
Methods: BGS Aerial and Gound Surveys
The U.S. Fish and Wildlife Service conducted the aerial BGS 9-24 May 1992. The
observer, using pond criteria in the standard operating procedures, counted
the number of ponds within 200 m on the right side of the flight line (Anonymous
1977). The Canadian Wildlife Service conducted the ground BGS within 2 days
following the aerial BGS. Ground crews inspected all wetland basins within the
400 m width of an air-ground segment that were identified on recent (<10 yr
old) 1:12,000 scale aerial photographs.
Ground crews classified wetland basins as Type I, III, IV, and V freshwater
and wetland basins according to Shaw and Fredine (1956), and artificial basins.
Water level in each basin was classified according to the following definitions
in the standard operating procedures (Anonymous 1987:III 15-16):
- Dry -
- Surface water has disappeared completely due to seepage, evaporation,
or drainage.
- Vestigial -
- Water occurs only as small pools or puddles within the central vegetative
zone of the wetland and can be expected to dry up within a matter of days.
- Recessional -
- Water levels have receded within the central zone but still cover a fairly
extensive area. In Open Water type of wetlands there is a drawdown mudflat
between the water edge and the emergent vegetation. In Emergent Deep marshes
and Shallow marshes, a fairly wide band of the central zone is dry.
- Intermediate -
- In Open Deep marshes and Shallow Open Water wetlands, the central open
water zone is completely flooded and the water extends into the inner edge
of the emergent vegetation. In Emergent Deep marshes and Shallow marshes,
the water extends throughout most of the central zone.
- Full -
- The wetland is filled to the outer limit of the wet meadow zone.
- Flooded -
- Water has spilled out of the wetland proper and floods the upland vegetative
communities in the basin.
- Overflowing -
- Water is at full supply level (FSL) of the basin and is spilling over.
FSL can vary greatly from basin to basin. In some basins it is at the level
of the outer edge of the wet meadow zone and in others, FSL is so high that
it will never be attained (e.g., terminal wetlands).
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