
Table 4. Comparison of characteristics of plant species seeded to those found in stands of seeded nesting cover 
in the prairie pothole region, 1977-79. 
Years 
Species 1977 1978 1979 combined 
seeded (N = 99) (N = 135) (N = 130) (N = 159) 
Characteristic N % N % N % N % N % 
Origin 
Native 3a 30 54 55 78 58 77 59 96 60 
Introduced 7 70 45 45 57 49 53 4] 63 40 
Growth habit 
Perennial 8 80 65 65 80 60 79 61 96 60 
Annual 0 0 95 95 41 30 36 28 48 30 
Biennial 2 20 9 i) 14 10 15 12 15 9 
Life-form 
Forb 3 30 75 75 108 80 103 79 126 79 
Grass 7 70 19 19 20 15 19 15 24 15 
Brush-shrub 0) 0 3 3 3 9 4 3 4 3 
Succulent 0 0 ] ] 0 () 0) () l ] 
Tree 0 0 1 1 4 3 4 3 4 3 





aCultivars of native species. 
Table 5. Comparison of frequency, cover, and composition for three major life-forms of plant species 
in seeded nesting cover aggregated for 1977-79. 



Percent Relative Percent 
Percent canopy Relative canopy species Importance 
Life-form frequency cover frequency cover composition value 
All grasses 45.4 48.9 44.6 52.0 80.8 177.4 
All forbs 52.3 44.9 53,2 47.4 19.1 119.7 
All shrubs 2.3 0.6 2.2 0.6 0.1 2.9 
The trend in stand structure relative to age occurred in a 
similar fashion for shrubs, forbs, and grasses when ex- 
pressed either in mean number of species, percentage 
canopy cover, or percentage composition (Fig. 7A-C). 
Shrub species had higher relative cover and composition 
during the first growing season and then nearly constant 
values in later years. Mean number of shrub species was 
nearly constant in all years. Grasses increased in number 
of species, canopy coverage, and species composition until 
the fourth growing season and remained nearly constant 
in later years. Forbs decreased in number of species, 
canopy coverage, and species composition until the fourth 
growing season and remained nearly constant in later 
years, 
The contrasting expression in canopy cover, number of 
species, and species composition between grass and forb 
species appeared to indicate an almost reciprocal relation 
for these two major life-forms (Fig. 7D-F). In every age 
class this reciprocal expression suggests that for every 
quantifiable increase in the structure of grasses, forbs 
expressed an opposite quantifiable decrease in their struc- 
ture and vice versa. This relationship was more or less con- 

stant, even though the total biomass may increase or de- 
crease during the same time. 
Age-related vegetation characteristics of stands. —The 
mean number of plant species for stands by age classes for 
groups of annuals, biennials, perennials, families, genera, 
species, introduced species, and native species were com- 
pared (Fig. 8A-J). The change in mean numbers of species 
for these groups was generally greatest during the first 
three growing seasons or age classes than during age 
classes 4 through 9. 
Vegetative Characteristics of Selected Species Groups 
Frequency, canopy cover, and composition were com- 
pared for three selected species groups: (1) 5 species com- 
prising SNC, (2) 17 species of greater problem weeds of 
cropland, and (3) 15 species of regulated noxious weeds 
within the region (Table 6). 
Seeded nesting cover species.—In relation to the 115 
plant species occurring in at least one quadrat in the 321 
stands, the 5 species of SNC made up 49.8 % of the relative 
frequency, 75.0% of the relative canopy cover, and 
