b BULLETIN 1113, U. S. DEPARTMENT OF AGRICULTURE. 
Table 1. — Precipitation and seasonal evaporation at 10 field stations in the 
northern Great Plains for the 5-year period from 1916 to 1920, inclusive. 
Station. 
Alti- 
tude 
(feet). 
Precipitation (inches). 
Seasonal. 
i 
Annual. 
Nor- 
mal 
Maxi- 
Mini- 
Aver- 
Maxi- 
Mini- 
Aver- 
an- 
nual .2 
mum. 
mum. 
age. 
mum. 
mum. 
age. 
11.38 
9.22 
10.15 
15.07 
10.31 
12.96 
17.05 
13.89 
5.82 
10.18 
18.21 
8.35 
12.81 
15.77 
13.18 
6.39 
10.11 
15.91 
7.85 
12.74 
14.96 
20.56 
8.44 
12.78 
25.89 
13.32 
17.03 
15.20 
17.53 
10.57 
13.29 
20.26 
13.53 
16.66 
17.55 
14.88 
4.85 
8.57 
19.24 
7.56 
11.68 
13.67 
15.63 
4.77 
10.74 
19.87 
9.90 
16.44 
16.61 
9.87 
5.31 
7.88 
15.14 
12.22 
13.62 
13.84 
12.41 
5.28 
8.60 
17.38 
8.56 
13.52 
14.72 
15.59 
8.53 
11.62 
19.09 
12.39 
14.79 
13.60 
Evap- 
oration, 
seas- 
onal 1 
(inches). 
Mandan, N. Dak.. 
Dickinson, N. Dak. 
Hettinger, N. Dak. 
Newell, S. Dak 
Ardmore, S. Dak.. 
Havre, Mont 
Moccasin, Mont 
Huntley, Mont 
Sheridan, Wyo. 3 . . . 
Archer Wyo 
1,750 
2,543 
2,253 
2,950 
3, 557 
2,505 
4,200 
3,037 
3,790 
6,017 
35.460 
34.158 
32. 762 
34. 174 
37. 274 
35.727 
35. 335 
34.256 
35. 525 
36.845 
1 Seasonal precipitation and evaporation are for the 6-month period from Apr. 1 to Sept. 30, inclusive. 
2 Mean annual precipitation is the average of the entire record. 
3 Sheridan data, except mean annual precipitation, are for the four years from 1917 to 1920, inclusive. 
F(G. 2. — The Yellowstone River valley at Pompeys Pillar in southern Montana, showing 
native growth of western cottonwood, box elder, and green ash in the river bottom 
and yellow pine on the adjoining hills. 
NOTES ON TREE SPECIES. 
In determining the adaptability of any tree species for planting 
on the open prairie of this region, its ability to resist drought and 
extreme cold is a factor of prime importance. In this area of limited 
moisture, late spring frosts, and early autumn frosts it is found that 
many of the species adapted to shelter-belt use have a comparatively 
short growing season. Their leaves are not put out until spring is 
well advanced and terminal buds are generally set in late summer. 
It naturally follows that the native tree growth found along the 
rivers and in the coulees and on certain groups of hills throughout 
