.^84 



Illinois Natur.vl History Survey Bulletin 



2b, Art. 5 



estimated ground space covered li\ tliese 

 plants was 157.*) square inches, table 5, 

 an estimation computed in the following 

 manner. There were 20 rosettes of Soli- 

 dayo ni'iiioralis 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 

 (if this species were small and covered 

 about 0.5 square inch each, or a total of 

 121). 5 square inches. The total ground 

 space of iS\ 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 .irea. 

 The estimated ground space of these 

 plants was 0.82 square inch (167x 

 (I.(I04'I)- The estimated ground space for 

 all the nongrass species was 157.9 siiuare 

 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 Phegle> prairie was 

 1,403.3 square inches (91 square decime- 

 ters I, 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. — In the central mil- 

 acre of this unpastured prairie, Aiidrnpo- 

 gon scopariiis covered 1,781 square inches 

 (115 square decimeters), or 28.39 per 

 cent of the milacre; Buuteloua ciirtipen- 

 dula and A. girardi 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 2*). 6 square inches of 

 the milacre as computed from the map b\ 

 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 Snlidago 

 nemoralis covered 32.0 square inches 

 (64x0.5). The remaining 248 plants. 



Table 5. — (jroiind space or areas {square 

 inches) occupied at (ifound surface hy ^rass 

 plants, plants other than jjrasses, and bare 

 loess in the central milacre of Sampson and 

 of Phegley prairies. 



Type of Plant Growth 



Hunch grasses 



Plants other than gra.sses 



.All plant.s 



Rare loess 



Sampson 

 Prairie 



1,820,3 



63.8 



1,884.1 



4,388.5 



Phegley 

 Prairie 



1,245,4 



157.9 



1,403.3 



4,869.3 



Table 6. — Per cent of the central milacre of 

 Sampson and of Phei*le> hill prairies occupied 

 at ground surface hy bunch grasses, plants 

 other than grasses, and bare loess. 



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. There 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, Atidrnpogon 

 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. 



