Upper Midwest Environmental Sciences Center
Vegetation - Stratified Random Sampling
1999
Results
1999 Results in Pool 4 of the Upper Mississippi River
Sampling Effort
Sampling began June 15 and ended July 27, 1999. Of the 550 sites targeted for sampling at the beginning of the season, 547 were sampled while three were not sampled because of inaccessibility (Figure 1).
Submersed Aquatic Vegetation
The status of submersed aquatic vegetation (SAV) in Pool 4 varied among the strata sampled. Isolated backwaters had the highest frequency of SAV (Table 2; Figure 2), followed by contiguous backwaters of lower pool, secondary channels of the lower pool, upper pool contiguous backwaters, lower pool main channel borders, upper Lake Pepin, upper pool main channel borders, lower Lake Pepin, and secondary channels of the upper pool. In general, lower pool contained significantly more SAV than upper pool (48.9% and 18.5%, respectively). The SAV covered about 38% of the shallow water areas poolwide.
Of the nine strata sampled in Pool 4, only three (isolated backwaters and both lower pool contiguous backwaters and secondary channels) supported a rich diversity of species (10 or more species per strata). Two strata (lower pool main channel border and lower Lake Pepin) supported moderate species diversity (seven species each). In the upper portion of the pool, all of the strata had few or no species (zero-one species) with the exception of upper pool contiguous backwaters that had five species. A total of 15 SAV species were recorded in the entire pool; however, most species were found either in lower pool strata or isolated backwaters. Coontail was the most abundant species found poolwide, followed closely behind by sago pondweed and Canadian waterweed. Wildcelery was most abundant in lower pool contiguous backwaters and secondary channels of the lower pool.
Rooted Floating-Leaf Vegetation
Of the three rooted floating-leaf species present in Pool 4, only two were recorded in 1999; white waterlily and American lotus. Poolwide, the percent frequency of all rooted floating-leaf species was fairly sparse (9.5%), but primarily dominated by white waterlily (8.5%). Isolated backwaters had the highest percent cover of rooted floating-leaf vegetation that consisted entirely of white waterlily. The only stratum that harbored American lotus was the lower pool contiguous backwater. Aside from isolated backwater sites, rooted floating-leaf species were only recorded in contiguous backwaters of both lower and upper pool, and secondary channels of the lower pool. All other strata were void of rooted floating-leaf species.
Content manager: Danelle Larson
Page Last Modified: April 17, 2018