June, 1922] HANSON — • PRAIRIE INCLUSIONS IN FOREST 
333 
located on the very steep north slope, just below the shrubs, which formed 
a zone extending for two or three meters in width from the crest. The 
dominant tree was Quercus macrocarpa; Ulmus fulva, Hicoria cordiformis, 
Toxicodendron radicans, Parthenocissus quinquefolia, and Celastrus scandens 
formed the open undergrowth. The shrubs in the zone between this forest 
and the prairie were Rhus glabra, Cornus femina, Zanthoxylum americanum, 
Symphoricarpos symphoricarpos, and Toxicodendron radicans. 
Factor Readings 
1. Evaporation 
The evaporating power of the air was measured from May 10 to Sep- 
tember 7 in the above-described stations by means of Livingston's standard- 
ized cylindrical atmometers without rain correctors. The table gives the 
average daily evaporation for the periods between readings and the daily 
average for the entire season. 
Table i. Daily Amounts of Evaporation during Periods between Readings, and the Daily 
Average for the Season: Peru, Nebraska, igiy 
Period 
High 
Prairie 
Low 
Prairie 
Dogwood- 
Bur Oak 
Shrub 
Prickly Ash- 
Dogwooa 
Shrub 
Red Oak- 
Hickory 
Forest 
Bur-Oak 
Forest 
May 10-18 
33.0 CC. 
31.5 CC. 
21.7 CC. 
25.6 CC. 
22.7 CC. 
24.7 CC. 
May 18-26 
17.8 
14.4 
10. 0 
94 
8.3 
10.5 
May 26-June 2.. . . 
54 
2.4 
1.7 
I.I 
1.8 
2.3 
June 2-12 
12.7 
8.8 
5-3 
4.8 
4.2 
4.9 
June 12-19 
25.0 
24.6 
13.2 
137 
11.8 
134 
June 19-July 4. . . . 
16.0 
157 
7.2 
8.8 
7.0 
8.2 
July 4-10 
16.1 
16.3 
6.8 
6.8 
6.8 
7.2 
July 10-17 
18.4 
15-3 
8.3 
8.1 
7.6 
8.3 
July 17-26 
22.9 
20.0 
7.2 
6.6 
5.8 
8.2 
July 26-Aug. 2 . . . . 
40.6 
36.2 
237 
21.4 
■ 18.2 
22.0 
Aug. 2-9 
14.4 
9.8 
4.8 
57 
37 
4.8 
Aug. 9-16 
18.2 
14.0 
54 
5-0 
4.2 
5-2 
Aug. 16-22 
13.8 
9.2 
3-1 
3.1 
3-3 
4.2 
Aug. 22-31 
26.1 
19. 1 
10.6 
9-9 
97 
II. 2 
Aug. 31-Sept. 7. . . 
20.5 
16.2 
6.3 
7.2 
5-9 
8.1 
Daily average May 
lo-Sept. 7 
20.6 
16.9 
9.0 
9.1 
7-9 
9.5 
The table shows that the evaporation for the season was greatest in the 
high prairie with 20.6 cc. daily average loss, next in the low prairie with 
16.9 cc, followed by bur-oak forest with 9.5 cc, shrubs with 9.1 cc, and 
least in the red oak-hickory forest with 7.9 cc. The greatest evaporation 
occurred in the high prairie because this station was more directly exposed 
to the sun and wind. The bur-oak forest station showed a greater evapora- 
tion loss than the shrub stations because the growth was much more open 
in the former, thus allowing freer circulation of the air and reducing to a 
