Native: Vegetation 
5i 
and pinyon pine-juniper communities by a large amount. The 
mean annual temperature ranges from 40° to 47°, while that for 
the summer months is never below 60°. The frostless season is 
very rarely below 75 days, the usual length being from 85 to 125 
days. The average date of the last spring frost is usually between 
May 20 and June 1, although in the southwestern counties, it may 
frequently come as late as the middle of June. 
TABLE XVIII.—PRECIPITATION IN YELLOW PINE FOREST ZONE. 
Station 
Altitude 
County 
Mean Annual 
Total from Oct. 
to May (inc.) 
% from Oct. 
to May (inc.) 
% from June to 
Sept, (inc.) 
Mean Annual 
Snowfall 
Castle Rock. 
6220 
Castle Rock. . 
19.40 
12.80 
64.33 
35.67 
62.8 
Fremont Exp. Sta. 
8850 
El Paso. 
18.08 
90.7 
Ft. Lewis. 
7610 
La, Plata, .... 
19.46 
Georgetown . 
8550 
Clear Creek . 
15.62 
7.87 
50.39 
49.61 
93.6 
Gold Hill . 
7200 
Boulder . 
20.19 
10.23 
50.67 
49.33 
.... 
Husted . 
6596 
El Paso . 
14.79 
51.0 
Idaho Springs . 
7543 
Clear Creek . 
15.74 
8.89 
50.52 
49.48 
67.0 
Monument. 
7200 
El Paso. 
24.36 
8.25 
33.46 
66.54 
82.0 
Pagosa Springs . 
7108 
Archuleta . . . 
21.15 
11.08 
52.39 
47.61 
84.0 
Tacoma . 
7300 
La Plata .... 
21.57 
16.37 
75.94 
24.06 
87.0 
Average. 
. 19.04 
10.70 
53.95 
46.05 
77.4 
Relation to Agriculture .—The yellow pine forest community 
forms a vegetative belt in our mountains varying in width, and 
with an altitudinal range of approximately 6,000-8,000 feet in 
northern Colorado, and 7,000-9,000 feet in the southern sections. 
Throughout much of this area, the slopes are too steep to culti¬ 
vate, or the soil is stony and shallow; moreover, many cultivated 
areas are as yet inaccessable, except to the stockman. In fact, a 
very large percentage of the area is economically adapted only to 
grazing and timber growing. 
The presence of the yellow pine forest is quite a reliable index 
of temperature conditions favorable to the maturing, most seasons, 
of wheat, oats, barley and rye. Oats and barley are the two most 
common small cereals of this belt, and in seasons that are consid¬ 
erably below the average in length, are cut for forage. Potatoes 
