142 Journal of Agricultural Research voi. iii, No. 2 



It will be seen that both before and after grazing the more abundant 

 seedlings were of mountain bunch-grass, smooth wild rye, short-awned 

 brome-grass, sickle sedge, little bluegrass, and western porcupine grass. 

 Table X shows that before grazing there was an average for all quadrats 

 of 155.3 seedlings per square meter. After grazing (Table XI) this was 

 reduced to 80.5 seedlings, a loss of 48.2 per cent. A comparison of the 

 height and root development of the same seedling species at medium and 

 high elevations discloses the fact that the shorter and later growing season 

 of the high range had not been conducive to the rapid development made 

 by the seedlings in the lower and warmer, though drier, situations. 

 Though the high ranges were grazed much more moderately, the loss 

 was practically the same as on the lower ones. 



The factors responsible for the heaviest loss of seedlings through grazing 

 were (i) superabundance of soil moisture, (2) lack of soil moisture, (3) 

 abnormally dense seedling stands, and (4) irregular topography. 



In wet situations the roots did not penetrate as deeply as in the more 

 compact and drier soils, and so were more easily disturbed. Although 

 in some cases the seedlings recovered, the loss on *he moist soils was 

 relatively large, in fact occasionally five times that on the dry soils. 



In excessively dry situations the loss from grazing was often serious, 

 owing to the relatively weak growth made by the seedlings and their 

 poor recuperative power. In some places practically the entire seedling 

 stand was destroyed. Doubtless many of the seedlings whose destruc- 

 tion was charged to grazing would have perished in any event from 

 drought, though the stand as a whole was not affected by this factor. 

 The lack of \ngor in individual plants where the stand was unusually 

 dense often caused a heavy loss. Quadrats with from 250 to 500 seed- 

 lings almost invariably suffered more than the contiguous plots which 

 carried a sparser stand. In general, it may be said that more than 200 

 seedUngs to a square meter is a heavier stand than most situations can 

 support permanently. Competition is most severe between plants of the 

 same species, since each plant makes the same demand upon the habitat. 

 Where a dense stand occurred it was usually of a single species. 



The loss from trampling was much more severe on steep slopes than 

 on level situations. This was largely the result of the coarser texture 

 of the soils on steep slopes and of the greater extent to which they are 

 shifted by grazing. Moreover, because of the lack of soil moisture on 

 many of the steeper slopes, the plants growing there are generally less 

 vigorous than those growing in more level places. 



TIME AND INTENSITY OF GRAZING AFTER THE FIRST YEAR 



Though the information here presented shows that the range upon 

 which deferred grazing was practiced suffered heavy loss of seedlings 

 when moderately grazed, it should not be concluded that in order to 



