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There were no significant differences between watershed qualities for total area (ha) of low-prairie (F1,51 = 1.20, p = 0.278), wet-meadow zone (F1,51 = 1.79, p = 0.187), shallow-marsh zone (F1, 51 = 2.00,p = 0.163), deep-marsh zone (F1,51 = 1.25 p = 0.268). and fen zone (F1, 51 = 0.65, p = 0.422).

Communities

Number and area

Basins in poor-quality watersheds tended to have slightly fewer communities per basin (Table 3).

Table 3. Numbers of surveyed wetland plant communities among basin classes in good- and poor-quality watersheds and mean numbers of communities per basin, 1992-1993

Watershed quality basin classa	1992		1993		Mean no. communitiesb per basin
	Basins	Communities	Basins	Communities
Good
Temporary	8	13	6	7	1.4
Seasonal	7	13	6	12	1.9
Semipermanent	6	15	6	18	2.8
Poor
Temporary	7	7	6	8	1.2
Seasonal	6	10	6	12	1.8
Semipermanent	6	14	6	15	2.4
Total	40	72	36	72

Of the communities, 80 (57%) were in wet-meadow zones, 42 (30%) in shallow-marsh zones, and 18 (13%) in deep-marsh zones (Table 4).

There were no significant effects of year, watershed quality, or zone on mean area of communities (ANOVA: all p > 0.11). Total area of the 140 analyzed plant communities was 176 ha, including 91 percent (160 ha) in good-quality watersheds and 9 percent (16 ha) in poor-quality watersheds.

Water depth

Water depth varied with year and zone (F2,36 = 4.44, p = 0.019; Table 5), but there were no significant watershed quality effects. Increased precipitation resulted in higher water depths in 1993 (F1,49 = 6.49, p = 0.014). Depths were higher in zones of greater water permanence (F2,36 = 20.54,p = 0.001).

Standing dead vegetation

Percent of standing dead vegetation did not vary by year or watershed quality (F1,49 = 0.35, p = 0.555; Table 5). However, greater amounts of standing dead vegetation were found in zones of greater water permanence (F2,36 = 6.78,p = 0.001).

Table 4. Number and least-squares means(+ or - SE) of community areas among Stewart and Kantrud(1971) wetland zones in good- and poor-quality watersheds, 1992-1993

Watershed quality Zone	1992		1993
	na	Mean area(ha)	n	Mean area(ha)
Good
Wet-meadow	24	0.74 (0.54)	23	2.84 (0.59)
Shallow-marsh	13	0.59 (0.81)	13	2.20 (0.99)
Deep-marsh	5	0.60 (1.88)	9	3.48 (1.08)
Total	42		45
Poor
Wet-meadow	17	0.40 (0.66)	16	0.08 (0.66)
Shallow-marsh	8	0.28 (1.55)	8	0.42 (0.93)
Deep-marsh	3	0.02 (1.63)	1	0.37 (2.65)
Total	28		25
Grand Total	70		70

^a n=Number of communities; least-squares means are based on fewer (see Table 2). ^a Wetland basins classified according to original sample draw.
^b Averaged across zones.

Litter

Depth (cm) of litter varied with watershed quality, zone, and year (F2,36 = 4.70,p = 0.015). Depth of litter was higher in zones of greater water permanence and in zones in poor-quality watersheds (Table 5). Effects of watershed quality alone were non-significant.

Unvegetated bottom

Percent unvegetated bottom varied with year (F1, 49 = 4.53, p = 0.038) and quality (F1,49 = 10.03, p = 0.003; Table 6). Greater amounts of unvegetated bottom were found in sample wetland basins in poor-quality watersheds and lesser amounts occurred in all wetlands during the wetter year of 1993.

Open water

Greater amounts of open water occurred during the wetter year of 1993 (F1,49 = 5.12, p = 0.028; Table 6), and in zones of greater water permanence (F2,36= 6.06, p = 0.0328), but effects of watershed quality alone were non-significant.

Table 5. Least-square means(+ or - SE) water depth, percent standing vegetation, and litter depth of plant communities^a of wet-meadow, shallow-marsh, and deep-marsh zones in wetlands in good- and poor-quality watersheds, 1992-1993

Watershed quality Zone	Water-depth(cm) Year		Standing dead vegetation(%) Year		Litter depth(cm) Year
	1992	1993	1992	1993	1992	1993
Good
Wet-meadow	2.2 (2.8)	3.6 (3.0)	6.6 (1.1)	2.0 (1.2)	0.3 (0.3)	0.2 (0.4)
Shallow-marsh	7.9 (4.2)	23.4 (5.1)	8.0 (1.6)	3.1 (2.0)	0.2 (0.5)	1.7 (0.6)
Deep-marsh	26.3 (9.8)	44.4 (5.6)	17.0 (3.7)	10.5 (2.1)	0.0 (1.2)	1.3 (0.7)
Poor
Wet-meadow	0.4 (3.4)	8.1 (3.4)	2.1 (1.3)	1.5 (1.3)	1.0 (0.4)	0.0 (0.4)
Shallow-marsh	2.9 (8.0)	37.0 (4.8)	0.1 (3.0)	0.6 (1.9)	2.7 (1.0)	0.0 (0.6)
Deep-marsh	28.7 (8.4)	38.8 (13.6)	8.0 (3.2)	3.8 (5.2)	6.7 (1.0)	0.0 (1.7)

Table 6. Least-square means(+ or - SE) of percent unvegetated bottom and percent open water in plant communities^a of wet-meadow, shallow-marsh, and deep-marsh zones in wetlands in good-and-poor-quality watersheds, 1992-1993

Watershed quality Zone	Unvegetated bottom(%)Year		Open water(%)Year
	1992	1993	1992	1993
Good
Wet-meadow	2.0 (2.4)	0.9 (2.6)	4.3 (3.6)	3.2 (3.9)
Shallow-marsh	10.9 (3.5)	1.0 (4.3)	8.3 (5.4)	35.6 (6.5)
Deep-marsh	12.4 (8.3)	0.5 (4.7)	1.7 (12.5)	34.6 (7.1)
Poor
Wet-meadow	46.5 (2.8)	15.2 (2.8)	0.6 (4.3)	18.4 (4.3)
Shallow-marsh	-b	19.4 (4.0)	2.8 (10.2)	36.5 (6.1)
Deep-marsh	-	17.3 (11.6)	9.1 (10.7)	40.4 (17.5)

^a Sample sizes for communities as in Table 4; least-squares means are based on fewer(see Table 2).
^b Least-square means were poorly estimated for poor quality shallow-and deep-marsh zones in 1992; observed means are 43.7, 0.0, and 0.0 for wet-meadow, shallow-marsh, and deep-marsh zones, respectively.

Plant species richness

We recorded 298 plant "taxa" during the study. These were 217 wetland pteridophytes and spermatophytes (73%) listed for the northern plains (Reed 1988) and 50 upland spermatophytes (17%) listed in the National List of Scientific Plant Names (U.S.D.A. 1982). Also included were 31 (10%) other "taxa" formulated for the study. These were certain non-vascular plants including the macroalgae Chara spp., two liverworts (Riccia fluitans and Ricciocarpus natans), and the aquatic moss Drepanocladus spp. Also included were unidentified plants (e.g., Gramineae unidentified) seen only in early growth stages. A list of plants recorded on the study areas is available from the authors.

Total taxa recorded was higher in all zones of basins in good-quality watersheds (Table 7). Ratios of total taxa recorded in good- versus poor-quality watersheds varied from a low of about 1.6:1 in wet-meadow zones to a high of about 3.4:1 in deep-marsh zones. When unadjusted for community size, taxon richness varied by zone (F2,36 = 17.35, p = 0.0001) and watershed quality (F2,49 = 3.94, p = 0.053), with richness higher in wet-meadow zones and shallow-marsh zones in good quality than in similar zones of poor-quality. As a partial test of the effects of community size, we eliminated from the data set 17 communities in good-quality watersheds larger than the largest communities in poor-quality watersheds (1.43 ha). Effects of zone remained significant (F2,28 = 15.09,p = 0.0001), whereas effects of watershed quality were not significant (F1,46 = 2.59, p = 0.114). The only significant correlation between taxon richness and community size was for communities of deep-marsh zone within good-quality watersheds (r = 0.77, P = 0.0013).

Table 7. Total plant taxa and least-squares means(+ or - SE) taxon richness for communities in wet-meadow, shallow-marsh, and deep-marsh zones in wetlands in good- and poor-quality watersheds, 1992-1993^a

1992
	Good-quality			Poor-quality
Zone	nb	No.taxa	Mean taxon richness	n	No. taxa	Mean taxon richness
Wet-meadow	24	173	23.8 (1.7)	17	104	11.1 (2.0)
Shallow-marsh	13	90	12.0 (2.5)	8	47	1.7 (4.8)
Deep-marsh	5	31	2.4 (5.9)	3	15	0.0 (5.1)
Total communities	42			28
1993
	Good-quality			Poor-quality
Zone	nb	No. taxa	Mean taxon richness	n	No. taxa	Mean taxon richness
Wet-meadow	23	166	25.4 (1.8)	16	89	14.8 (2.0)
Shallow-marsh	13	74	12.8 (3.1)	8	49	8.2 (2.8)
Deep-marsh	9	47	7.4 (3.4)	1	8	9.5 (8.3)
Total communities	45			25

^a Means unadjusted for community area. Some taxa common to more than one zone.
^b n=Number of communities; least-squares means are based on fewer (see Table 2).

Plant types

Perennial native plants dominated all zones of basins in good-and poor-quality watersheds (Table 8). We found greatest numbers of these plants (116 taxa) in wet-meadow zones of basins in good-quality watersheds during the wetter year of 1993. We observed smallest numbers (7 taxa) that year in deep-marsh zones of basins in poor-quality watersheds. Mean number of native perennials varied by zone and watershed quality (F2 36 = 2.79, p = 0.075). Wet-meadow zones in good-quality watersheds had greater numbers of native perennials than those in poor-quality watersheds. This relation also held when we eliminated 17 communities in good-quality watersheds larger than the largest communities in poor-quality watersheds from the data set (F2,28 = 2.76, p = 0.081). Ratios of native perennials to introduced perennials varied by watershed quality and zone when adjusted as above for community size (F2 28 = 3.37, p = 0.049). With this adjustment, the ratio of native perennials to introduced perennials was marginally greater in good-quality watersheds than in poor-quality watersheds for wet-meadow zones only. We found greater numbers of introduced perennials in basins in good-quality watersheds. Ratios of native annuals to introduced annuals, when adjusted for community size, did not vary by zone or watershed quality.