860 
Journal of Agricultural Research 
Vol. XXVIII, No. o 
Table VI .—Soil moisture and evaporation data on six different sites at elevations 
of 7,500 to 7,700 feet on Big Cottonwood watershed, Wasatch National Forest, 
Utah, season of 1920 
Total soil moisture at different dates of sampling 
Site 
Depth of 
soil sample 
June 
9 
June 
16 
June 
23 
July 
3 
July 
14 
July 
29 
Au¬ 
gust 
9 
Au¬ 
gust 
18 
Au¬ 
gust 
30 
Sep* 
tem- 
ber 28 
Inches 
Per 
Per 
Per 
Per 
Per 
Per 
Per 
Per 
Per 
Per 
cent 
cent 
cent 
cent 
cent 
cent 
cent 
cent 
cent 
cent 
Northern aspect, brushy.... 
0-6 
9.0 
6.0 
61 
5.1 
3.6 
9.1 
14.2 
8.8 
17.0 
21.5 
6-12 
10.9 
8.1 
8.6 
15.0 
6 6 
9.8 
10.2 
9.5 
12.1 
23.2 
Average... 
10.0 
7.0 
7.4 
10.0 
5.1 
9.4 
12.2 
9.2 
14.6 
22.4 
Western aspect, Ceanothus- 
0-6 
10.0 
11.5 
5.7 
4.2 
4.4 
7.9 
9.2 
9.3 
18.0 
20.5 
oak. 
6-12 
10.0 
15.2 
9.9 
7.8 
4.4 
5.7 
7.1 
7.6 
12.9 
13.5 
Average... 
10.0 
13.4 
7.8 
6.0 
4.4 
6 8 
8.2 
8.4 
15.4 
17.0 
Northeastern aspect, open, 
0-6 
20.2 
16 6 
8.8 
9.3 
4.8 
10.1 
16 6 
11.0 
30.9 
35.4 
grassy. 
6-12 
23.0 
21.2 
13.5 
12.1 
10.3 
9.7 
11.1 
11.7 
28.2 
30.1 
Northeastern aspect, asp- 
Average... 
21.6 
18.9 
11.2 
10.7 
7.6 
9.9 
13.8 
11.4 
29.6 
32.8 
0-6 
28.9 
23.9 
20.8 
19.5 
10.2 
18.6 
21.7 
9.4 
28.1 
36 5 
en. 
6-12 
24.7 
27.1 
23.1 
16 6 
12.2 
13.2 
14.2 
10.4 
16 2 
25.5 
Average... 
26 8 
25.5 
22.0 
18.0 
11.2 
15.9 
18.0 
9.9 
22.2 
31.0 
Canyon bottom, scattered 
0-6 
13.8 
11.3 
10.0 
7.5 
5.5 
12.3 
18.1 
8.5 
24.3 
23.5 
aspen. 
6-12 
27.9 
13.3 
15.4 
13.5 
7.3 
9.8 
12.5 
9.4 
19.5 
21.6 
Average... 
20.8 
12.3 
12.7 
10.5 
6 4 
11.0 
15.3 
9.0 
21.9 
22.6 
Southern aspect, sage- 
6-6 
7.4 
5.4 
6.6 
6.9 
3.4 
11.0 
14.5 
6 0 
15.8 
17.2 
Ceanothus-oak-aspen. 
6-12 
16 4 
11.7 
11.5 
10.2 
6 5 
9.1 
11.1 
7.6 
13.8 
19.4 
Average... 
11.9 
8.6 
9.0 
8.6 
5.0 
10.0 
12.8 
6.8 
14.8 
18.3 
Wilting 
coeffi¬ 
cient a 
Mean 
daily 
evapora¬ 
tion 
E b 
S. M. 
E ft 
S. M, 
mean of 
1919 and 
1920 
Per cent 
13.6 
11.3 
12.4 
} 10.9 
Cc. 
10.86 
0.95 
1.40 
18.65 
1.98 
2.89 
17.9 
14.5 
16 2 
14.7 
12.6 
13.6 
16.2 
13.5 
14.8 
} 12.4 
15.12 
0.88 
1.67 
9.96 
0.54 
1.02 
19.13 
1.28 
1.62 
20.90 
1.79 
2.89 
Site 
Depth of 
soil sample 
Seasonal 
average 
of soil 
moisture 
Northern aspect, brushy. 
Western aspect, Ceanothus-oak. 
Northeastern aspect, open, grassy. 
Northeastern aspect, aspen. 
Canyon bottom, scattered aspen. 
Southern aspect, sage-Ceanothus-oak- 
aspen. 
Inches 
0-6 
6-12 
Average... 
0-6 
6-12 
Average... 
0-6 
6-12 
Average— 
0-6 
6-12 
Average— 
0-6 
6-12 
Average— 
0-6 
6-12 
Average— 
Per cent 
10.0 
11.4 
10.7 
10.1 
9.4 
9.8 
16.4 
17.1 
16.8 
21.8 
18.3 
20.0 
13.5 
15.0 
14.2 
9.4 
11.7 
10.6 
• Determined in the Biophysical Laboratory, Bureau of Plant Industry, United States Department of 
Agriculture by the Briggs and Shantz centrifugal method. 
b Evaporation divided by the mean seasonal moisture content of the soil at a depth of 6-12 inches. 
SAP-DENSITY DATA 
The object of this study was to attempt a correlation of the major vegeta- 
tional types with the cell-sap density of representative plants. The procedure 
therefore involved a systematic sampling of each of the well-marked types. 
In the Ephraim Canyon investigation six such types were recognized: (1) grease- 
wood-shadscale, (2) sagebrush, (3) pinion-juniper, (4) oak brush, (5) aspen-fir, 
(6) spruce-fir. In the main Wasatch Mountains eight major vegetational types 
or associations were considered: (1) stream-bank, (2) sagebrush, (3) juniper, 
(4) western yellow pine, (5) chaparral, (6) lodgepole pine, (7) aspen-fir, (8) 
spruce-fir. With the exception of the stream-bank association, these types form 
