32 
IOWA ACADEMY OP SCIENCE 
shelterbelts. The rapid growing species— willow, cottonwood, 
boxelder and soft maple — predominate. Occasionally the fol- 
lowing species are planted: red and white cedar, Scotch pine, 
white pine, hardy catalpa and white elm. 
ECOLOGICAL DISTRIBUTION OP TREES. 
The ecological distribution of trees in the vicinity of Council 
Bluffs was determined on Mosquito and Pony creeks, two small 
streams near Council Bluffs. The soil area is the Marshall 
silt loam. Plot I on Mosquito creek south slope, trees from six 
to ten inches in diameter; Plot II, draw north slope, including 
a part of the bottom; Plot III, divide between two draws with 
slope to the west. Unless otherwise stated the area on which 
the percentage distribution was determined was 100 feet each 
way. 
Percentage of Trees, Mosquito Creek, Council Bluffs, Marshall 
Silt Loam. 
Name of Species 
Plot No. 1 
Percentage 
Plot No. II 
Percentage 
Plot No. Ill 
Percentage 
Praxinus americana 
8.1 
0 
0 
Ulmus americana 
13.6 
4.54 
13.28 
Ulmus fulva 
13.5 
9.08 
13.28 
Quercus rubra 
10.8 
11.35 
4.76 
Quercus macrocarpa 
24.3 
15.87 
57.16 
Ostrya virginiana 
0 
24 97 
0 
Tilia americana 
10.8 
24.97 
0 
Juglans nigra 
8.1 
6.81 
0 
Celtis occidentalis 
2.7 
0 
0 
Carya cordiformis 
2.-7 
0 
9.52' 
Cornus asperifolia 
2.7 
0 
2. . 
Rhamnus lanceolata 
2.7 
0 
0 
Gymnocladus dioica 
2.2 
2.27 
0 
The undergrowth here was chiefly goldenrod {Solidago’ 
ulmifolia) , blue grass {Poa pratensis) , blue violet {Viol<i cucul- 
lata), dogwood {Cornus asperifoUa), buckthorn {Rhamnus Ian- 
ceolata) and some snowberry (Symphoricarpos occidentalis) . 
