28 BULLETIN 141, U. S. DEPAETMEXT OF AGRICULTURE. 
by the consumption of the herbage the fire risk to the timber may be 
greatly minimized. 
Being unable to reproduce in its own shade, aspen must be well 
opened up either by heavy thinnings or by clear-cutting, preferably 
the latter, if the lands are to be fully restocked. 
When the logging is done on sheep range, or on a combination 
sheep and cattle range, the forthcoming reproduction will be destroyed 
almost to the last sprout if the areas are even moderately grazed by 
sheep during the first three years following the cutting. To avoid 
destruction of the young aspen cover, then, only three courses are 
open: (1) Entire exclusion of grazing for three successive seasons 
following logging, (2) exceedingly light grazing by sheep, and (3) 
moderate grazing bv cattle. 
Obviously, the first of these possibilities does not appeal either to 
the timbemian or the stockman. The entire exclusion of grazing 
animals means increased fire risk and additional fire patrol, the cost 
of which must be met by the timberman. For the stockman whose 
farm operations generally, including to a large extent the marketing 
of the crops produced, are dependent upon the grazing afforded in the 
aspen type, entire exclusion of stock may spell ruin. 
The second possibility, very fight grazing by sheep, would upon 
first thought appear to meet the requirements, and guarantee estab- 
lishment of the reproduction. But the sheepman who will graze 
his sheep very lightly over the choicest of forage, such as .invariably 
becomes established on clear-cut or heavily thinned aspen lands, 
has not yet been discovered. Naturally the sheepman's interests 
he in the production of the maximum mutton and wool consistent 
with sustained forage yield; he has little interest in the production of 
timber. Since the standards of grazing intensity vary with the 
individual, what may be declared as very-light cropping by the 
average stockman-might be classed as moderately heavy by the 
grazing expert or the silviculturist. Furthermore, the intensity of 
the grazing, at least so far as the stockman is concerned, would, of 
course, be judged by the extent of cropping of the herbaceous cover 
rather than by the seriousness of the browsing of the aspen reproduc- 
tion, whereas, owing to the tendency of sheep to browse rather than 
graze, the aspen would probably be badly damaged before much 
of the herbage would be consumed. Accordingly only the very 
lightest grazing, coupled with the most expert handling of the flocks 
during the first three seasons, could be expected adequately to protect 
the reproduction, and exceedingly few herders would be qualified to 
assume such responsible management. 
This brings us to the third course open to avoid the destruction of 
the young aspen cover: viz. moderate grazing by cattle. The aspen 
type occupies lands of moderate elevation usually characterized by 
