46 BULLETIN 234, U. S. DEPARTMENT OF AGRICULTURE. 
become old enough to bear fertile seed, usually in 15 or 20 years. 
Planting by this method would require from 125 to 150 seedlings per 
acre, and should cost about $2. 
PROTECTION. 
FIRE. 
Although fire is the principal agent in aiding lodgepole pine to 
maintain its existence in many places, it is also the most destructive 
agent in mature lodgepole-pine stands^.. Besides the active measures 
taken to prevent and extinguish fires, such as lookout stations, 
telephone lines, roads and trails, patrol, and the like, certain coor- 
dinate lines of forest work may be handled in a maimer to insure 
that the fire danger will be kept at the minimum. The most impor- 
tant of these in the case of lodgepole pine is the grazing of live stock, 
particularly sheep. In the lodgepole-pine region fire almost inva- 
riably spreads by means of grass and weeds. A grass fire travels 
very rapidly and soon spreads over large areas. The grass of the 
lodgepole-pine region becomes sun-cured early in July and dries 
very rapidly after summer showers which dampen other inflammable 
material for several days. Thorough grazing on the dangerous areas 
by sheep would dispose of most of the inflammable material. Old 
grass left over from the previous year is particularly inflammable 
and makes a very hot fire. Particularly heavy grazing along trails, 
secondary ridge tops, and certain section lines would be a means of 
securing fire lines at frequent intervals. When grazing in the timber 
sheep trample and wear out the down litter and other debris, greatly 
hastening its decay. 
In addition to the grass which grows in and near the timber, pine 
needles and other debris form an inflammable ground cover. A fire 
in needles alone travels slowly and is easily controlled. Where, 
however, there is also a considerable amount of debris, such as old 
tops and down timber under dense young stands, the heat from below 
sometimes starts crown fires, though this is rare in lodgepole pine. 
Fires on cut-over areas where the brush has been piled and burned 
are easy to control. Where the brush has been well piled and not 
burned there is danger of a hot fire which will kill many green trees 
near the piles. Such a fire is harder to handle, of course, than one on 
a cleaned-up area, but it is by no means as hard to handle as one on 
an area where the slash is left in windrows or scattered over the 
ground. Roads and skidding trails constructed in connection with cut- 
tings and thinnings will act as fire breaks. Much less debris is likely 
to accumulate in the well-spaced, moderately open stands which 
come up after cutting than in the over-dense stands resulting from 
fire. By the time the lodgepole-pine region has been cut over once 
under Forest Service regulations, with the proper amount of grazing, 
the fire danger will have been very much reduced, even though no 
further advance is made in other means of prevention and control. 
