384 
estimated ground space covered by these 
plants was 157.9 square inches, table 5, 
an estimation computed in the following 
manner. ‘There were 29 rosettes of Soli- 
dago nemoralis that were clustered into 
five groups or patches. The five patches 
occupied 36.59 square inches in the cen- 
tral milacre. The remaining 241 rosettes 
of this species were small and covered 
about 0.5 square inch each, or a total of 
120.5 square inches. The total ground 
space of §. nemoralis for the milacre was 
157.09 square inches. The remaining 167 
individuals of 13 species were small and 
averaged only 0.08 inch (2 mm.) in di- 
ameter, or 0.0049 square inch in area. 
The estimated ground space of these 
plants was 0.82 square inch (167 x 
0.0049). The estimated ground space for 
all the nongrass species was 157.9 square 
inches (10 square decimeters), or 2.52 per 
cent of the quadrat, tables 5 and 6. The 
total ground space for all plants in the 
central milacre at Phegley prairie was 
1,403.3 square inches (91 square decime- 
ters), or 22.37 per cent of the quadrat. 
There remained 4,869.3 square inches, or 
77.63 per cent of the quadrat, that was 
bare loess, tables 5 and 6. 
Sampson Prairie —lIn the central mil- 
acre of this unpastured prairie, 4ndropo- 
gon scoparius covered 1,781 square inches 
(115 square decimeters), or 28.39 per 
cent of the milacre; Bouteloua curtipen- 
dula and A. gerardi together occupied 
39.3 square inches (3 square decimeters), 
or 0.63 per cent of the plot, tables 4 and 
6. ‘The three bunch grasses covered at 
ground level 1,820.3 square inches (117 
square decimeters), or 29.02 per cent of 
the milacre. 
The ground space for the remaining 
487 plant individuals of 10 species was 
computed in the same manner as was the 
ground space for the plants in Phegley. 
Lecidea, which grows over the surface of 
the loess, occupied 29.6 square inches of 
the milacre as computed from the map by 
use of a planimeter. The Agave and 
Opuntia were each about 0.625 inch in 
diameter at the ground surface; the three 
plants occupied approximately a square 
inch. The 64 small rosettes of Solidago 
nemoralis covered 32.0 square inches 
(64x 0.5). The remaining 248 plants, 
Ittinois NATURAL History SURVEY BULLETIN 
Vol. 26, Art. 5 
Table 5.—Ground space or areas (square © 
inches) occupied at ground surface by grass © 
| 
F 
a 
plants, plants other than grasses, and bare © 
loess in the central milacre of Sampson and 
of Phegley prairies. 
SAMPSON | PHEGLEY 
Type or PLanr GrowTH 
PrairiE | PRAIRIE 
Bunch grasses..........-. 1,820.3 | 1,245.49 
Plants other than grasses. . . 63.8 157, 9a 
All plantee i). 0 esi dese 1,884.1 | 1,403.3 
Bareiloess..<. vgestoween 4,388.5 | 4,869.3 
Table 6.—Per cent of the central milacre of 
Sampson and of Phegley hill prairies occupied 
at ground surface by bunch grasses, plants 
other than grasses, and bare loess. 
SPECIES OR TYPE OF SAMPSON | PHEGLEY 
PLant GrowTH Prarri£é | PRAIRIE 
Andropogon scoparius...... 28 .39 17.64 
Andropogon gerardi........ 0.16 0.00 
Bouteloua curtipendula..... 0.47 221 
All bunch grasses..:...... 2) 29902 19.85 
Plants other than grasses... 1.02 2.52 
All plants, osc aaa 30.04 22.37 
Bareloess 4. soe eee 69.96 77 .63 
all small, covered 1.2 square inches. The 
nongrass species together occupied 63.8 
square inches (4 square decimeters), or 
1.02 per cent of the quadrat, tables 5 and 
6. The total ground space for the plants 
in this milacre of ungrazed prairie was 
1,884.1 square inches (122 square deci- 
meters), or 30.04 per cent of the charted 
area. [here remained 4,388.5 square 
inches or 69.96 per cent of the quadrat 
not occupied at ground level by plants. 
Foliage Area or Crown Cover.— 
Foliage area, crown area, or crown cover 
is considered here as the area that would 
be mapped if the crowns of the plants 
were projected on the ground surface di- 
rectly below. Although foliage area was 
not mapped in the field, it was estimated 
in the following manner. 
In the Sampson prairie, Andropogon 
scoparius had a large foliage area, fig. 11. 
The aspect of this grass in Sampson was 
similar to its aspect at Northeast Mere- 
dosia, where a sample was collected for 
separation. Foliage area of this sample 
was mapped. A factor of approximately 
2.7 was derived when foliage area of the 
sample was divided by its ground space. 
