1921] CURRENT LITERATURE 407 
shown that grazing results in retrogression, the more stable or climax forms 
being gradually eliminated and their place being taken by plants character- 
istic of more primitive successions. The key to the situation, therefore, is 
forms. If such invasion is detected in time, grazing may be reduced or wholly 
abandoned for a time, thus giving the more desirable species charaeteristic 
of the higher successional stages an opportunity to reestablish themselves. 
The region under consideration in this paper is the neighborhood of the Great 
Basin Experiment Station in the Manti National Forest. Here four major 
successional stages are recognized: the first or early weed stage, characterized 
by ruderals; the second or late weed stage, with foxglove (Pentstemon pro- 
cerus), sweet sage (Artemisia discolor),.and yarrow (Achillea lanulosa) as 
leading species; the mixed grass and weed stage, with porcupine grass (Stipa 
minor) and yellow brush (Chrysothamnus lanceolatus) dominant; and the sub- 
climax or wheat-grass (A gropyron spp.) stage. The wheat-grasses constitute 
the climax herbaceous cover and are desirable range grasses i 
sheep do well here. Retrogression tothe firs 
astrous. If grazing is permitted here, all vegetation may disappear and 
finally the soil itself, through the action of erosion, in which event recovery 
is difficult or even impossible. In the treatment of the different vegetationa] 
stages, the writer considers in detail the conditions of growth and reproduction, 
the soil water content, the root relations of the characteristic species, the 
effect of disturbing factors, palatability, and forage production. All-in-all 
this is one of the most important papers in the field of applied ecology, and 
may well serve as a model to investigators everywhere. 
The studies resulting in Sampson’s paper on the effect of grazing on 
aspen reproduction were also carried on in the Manti National Forest. This 
paper recommends that an attempt be made to work out a proper balance 
between the production of meat and timber. As the aspen does not reproduce 
effectively in its own shade, it is recommended that the timber be cleancut, 
and that the new growth be exempted from grazing or be grazed moderately 
by cattle rather than by sheep, which are much more destructive. When the 
new shoots reach a height of 45 inches (which results generally in about three 
years), they are effectively out of the reach of sheep, so that from then on 
to timber maturity grazing by sheep may be permitted. cee 
Another paper resulting from studies in the Manti National Forest is 
the one by Sampson and WEYL on range preservation and erosion control. 
Overgrazing in this region, especially by sheep, has resulted in such a serious 
