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Vegetation - Stratified Random Sampling
1999 Results

1999 Results in La Grange Pool of the Illinois River

Sampling Efforts

Sampling for La Grange Pool 1999 stratified random sampling (SRS) began on June 16, 1999, and ended August 6, 1999.  Of the 550 sites targeted for sampling, 538 sites were sampled (Figure 9).  Twelve sites were not accessible and were not sampled.

Submersed Aquatic Vegetation

The status of submersed aquatic vegetation (SAV) in La Grange Pool in 1999 was the same among the strata sampled.  There was no SAV recorded at any of the sites sampled during the SRS in any of the strata.  River stage near Havana was at or above flood stage from mid-April through June, making growing conditions less than desirable for SAV (Table 6; Figure 10).  However, several small- to medium-sized beds of sago pondweed were observed during an informal survey of the lower half of the reach in September.  Other medium-sized beds of coontail were also observed in smaller isolated backwater lakes during SRS.

Rooted Floating-Leaf Vegetation

 American lotus was the only rooted floating-leaf species recorded in La Grange Pool.  This species was recorded in both contiguous and isolated backwater lakes (0.2% and 0.1% cover, respectively).  American lotus covered  0.1% of La Grange Pool.

Table 6.  Percent frequency, cover, and standard error of rooted floating-leaf vegetation in La Grange Pool, Illinois River, 1999.

Common name (Scientific name)	Contiguous backwater n = 190		Isolated backwater n = 188		Main channel border n = 120		Secondary channel n = 40		La Grange Pool n = 538
	Freq	Cov	Freq	Cov	Freq	Cov	Freq	Cov	Freq	Cov
lotus, American (Nelumbo lutea)	0.5 ± 0.5	0.2 ± 0.2	0.5 ± 0.5	0.1 ± 0.1	-	-	-	-	0.5 ± 0.5	0.1 ± 0.1
all rooted floating–leaf species	0.5 ± 0.5	0.2 ± 0.2	0.5 ± 0.5	0.1 ± 0.1	-	-	-	-	0.5 ± 0.5	0.1 ± 0.1

 

Image Preview	Figure - Description
	Figure 9. Aquatic area strata and sampling points in La Grange Pool, Upper Mississippi River System, 1999.
	Figure 10. Sites where species were recorded in La Grange Pool, Upper Mississippi River System, 1999.  Species: American lotus (Nelumbo lutea).

 

Content manager: Danelle Larson

April 5, 2002
Page Last Modified: April 17, 2018