Native Vegetation 
55 
of the lodgepole pine zone. The isotherm 60° for the summer 
months is approximately co-extensive with the lower limit of this 
community, and its upper limit has a summer average of 53.6°. The 
frostless season is seldom longer than 75 days, and very frequently 
much shorter. 
Except in a few localities, the annual precipitation is above 18 
inches, and in places as high as 25 to 28 inches. Where lodgepole 
pine and yellow pine grow under equal precipitation amounts, the 
former will usually occupy exposures that are cooler and moister. 
TABLE XX.—TEMPERATURE, LODGEPOLE PINE FOREST ZONE. 
Station 
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Ashcroft . 
9583 
35.7 
17.8 
33.4 
53.4 
34.7 
61 
July 1 
Sept. 1 
103 
Breckenridge. 
9524 
32.6 
16.4 
30.9 
51.7 
36.5 
35 
• • • 
Crested Butte . 
8867 
33.1 
12.7 
• • • • 
.... 
• • • • 
• • • 
109 
Cripple Creek . 
9396 
• • • • 
• • • • 
• • • • 
• • • • 
• • • 
• • • 
Dillon . 
8800 
33.9 
13.4 
113 
Dumont . 
8000 
43.0 
112 
94 
Frances . 
9300 
40.3 
23.6 
37.6 
58.5 
41.9 
110 
May 31 
Sept. 20' 
94 
Fraser . 
8671 
31.3 
12.9 
111 
Fremont Exp. Sta . . 
8850 
40.7 
83 
June 18 
Sept. 9 
103 
Long’s Peak (near) 
8600 
28.2 
22.8 
53.8 
53.4 
43.2 
62 
June 29 
Aug. 30 
102 
Hermit . 
9843 
31.7 
11.8 
45 
110 
White Pine. 
9500 
33.3 
15.7 
31.1 
50.9 
35.9 
32 
100 
Average. 
34.9 
18.4 
33.4 
53.6 
38.4 
67 
June 20 
Sept. 9 
104 
Lodgepole pine, as a strongly developed plant association, in¬ 
dicates temperature conditions too low for the maturing of the 
small cereals, for the profitable growth of alfalfa, potatoes, peas, 
and any but the most hardy vegetables. Some of the hardier small 
fruits are raised for home use along its lower edge; timothy and 
alsike clover are grown now and then. Excellent growths of al¬ 
falfa and potatoes, and small grains are frequently grown in the 
sagebrush strips or oakbrush land that touches the lodgepole pine 
association, but, as a rule, an increase of but 200 to 300 feet in ele¬ 
vation is sufficient to bring about temperature conditions unfavor¬ 
able to these crops. It is at the very upper limit of agricultural 
possibilities, that the greatest care needs be exercised in the se¬ 
lection of areas for cropping purposes. Just here, exposure counts 
for the most, and here too, a hundred feet difference in altitude 
may be the deciding factor in making for a success or a failure in 
the growth of a crop. A growth of lodgepole pine tells one that 
he is approaching, or is beyond, the upper altitudinal limit of 
