706 JOURNAL OF FORESTRY 



browsed or trampled ; most of the injuries from browsing or trampling 

 were confined to seedlings less than 1.5 feet in height. 



"The relative mortality of seedlings of different sizes is shown in 

 Table 3. During the first few years seedlings succumb very easily to 

 slight injuries, because of their small size, shallow root system, and the 

 lack of woody matter in their stems. The loss due to grazing decreased 

 from about 20 per cent for seedlings in their first year to 11 per cent 

 for those in their second and third years. By the end of the third year 

 they are from 8 to 4 inches high (depending on species and site), their 

 stems have become woody and fairly tough, and their roots penetrate 

 the soil for a foot or more, so that they are not easily uprooted by 

 trampling nor exposed to drying by the loosening of the soil. Injury 

 from grazing is so slight after this that there is no need for closing 

 reproduction areas to sheep after the third year, though it may be de- 

 sirable to graze such areas lightly for a few years more, until the 

 seedlings reach a height of 6 inches. . . . 



"Where the forage is composed largely of tender herbaceous vege- 

 tation reproduction is more subject to damage than where there are 

 shrubs or dense tufts of perennial grasses or weeds to protect the 

 seedlings 



"Taking the combined areas as a whole, more than three times as 

 many seedlings were killed by other causes as were killed by sheep- 

 grazing and five times as many were injured." 



The author attempts the valuation of damage by a more or less novel 

 method. Correlating height growth and number of killed and injured 

 in each size class, a mortality or number decrease table and curve is 

 constructed, and from this is determined the "average number of seed- 

 lings per acre at different ages necessary to insure a stand of 100 trees 

 per acre of any of the three species at 150 years, if ordinary grazing 

 every year is permitted." 



The difficulty lies in determining what the normal stand should show, 

 without which the method has little or no value. In actual cited cases 

 the full stand at 150 years varies from 40 to 230 trees. 



"If 40 trees per acre are assumed to constitute a full stand, but 0.4 

 as many seedlings as are indicated in Table 16 will be needed; but if 

 200 trees per acre are assumed, the figures in the table should be 

 doubled. If a full stand of Douglas fir is taken as 167 trees, the figures 

 should be increased by two-thirds for Douglas-fir stands. Assuming 

 250 trees per acre as normal for lodgepole pine at maturity (140 years), 

 the figures in Table 16 should be multiplied by 2.5 — that is, there should 

 be approximately 3.700 seedlings the first year;" and the author con- 

 cludes : 



