Northern Prairie Wildlife Research Center
Zamuda (1976) reported a maximum V. americana density of 280 rosettes/m2 in August and a seasonal mean of 200 rosettes/m2 for the Pamlico River Estuary, North Carolina. Donnermeyer (1982) measured a maximum density of 214 rosettes/m2 in Navigation Pool 9 of the Upper Mississippi River. After sampling rosette densities along six transects within V. americana beds in Navigation Pool 7 of the Upper Mississippi River in 1980-83, C. E. Korschgen (unpublished data) determined densities of 50-253 rosettes/m2. Table 6 shows the variability of V. americana biomass in various Wisconsin locations.
A maximum winter bud density of 233/m2 and a mean of 55/m2 were reported for the lower Detroit River; the maximum and mean winter bud (wet weight) biomass was 68.7 g/m2 and 16.6 g/m2, respectively (Hunt 1963). When Hunt's biomass data was converted to dry weight by using a conversion factor of 30.2% dry matter (C. E. Korschgen, unpublished data), the Detroit River had a maximum and mean winter bud (dry weight) biomass of 20.8 g/m2 and 5.0 g/m2, respectively. Donnermeyer and Smart (1985) reported a maximum winter bud density of 158 g/m2 and a maximum and mean (dry weight) biomass of 30.1 g/m2 and 20 g/m2, respectively. Variation of winter bud biomass for the years 1980, 1983, and 1984, of 36 g/m2, 32 g/m2, and 47 g/m2 (oven dry weight), respectively, was found (C. E. Korschgen, unpublished data) in Lake Onalaska, Wisconsin (Navigation Pool 7, Upper Mississippi River). The variations may be attributable to annual changes in density of V. americana or sampling error.
U.S. Department of the Interior |
U.S. Geological Survey
URL: http://www.npwrc.usgs.gov/resource/plants/wildcel/product.htm
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