REPRODUCTION OF WESTERN YELLOW PINE. 69 



secured from the 1913 seed crop alone. Extensive observations by 

 the writer and others warrant the statement that wherever an area 

 well provided with seed trees has been adequately protected against 

 sheep grazing and fire for 10 years or more reproduction is making 

 substantial progress. The average period for complete restocking 

 has been placed at 20 years. On adverse sites or under unfavorable 

 conditions with respect to coincidence of seed crops and rainfall, the 

 period may be longer, whereas under favorable conditions it may be 

 greatly shortened. 



Results during the past 10 years show that as far as cutting alone 

 is concerned the method practiced by the Forest Service is reasonably 

 sure of success. The persistent failure of cut-over lands to restock 

 has been due not to the method of cutting but to the disregard of 

 other silvicultural requirements, principally control of ground cover 

 and protection against sheep. This, however, does not prove that 

 the present method of cutting can not be improved upon. Can better 

 results be secured by leaving more trees, or are we leaving more trees 

 than necessary? The evidence obtainable from old cuttings is con- 

 flicting, due to varying conditions of site, seed supply, and grazing. 

 Studies of the large stand of seedlings which originated in 1919 

 throw additional light on the subject. 



Table 19 gives the results of seedling counts in cut-over and virgin 

 stands in which the number of possible seed trees ranges from 2 to 

 20 per acre and where the distribuion varies from widely scattered 

 single trees to the other extreme, in which nearly all occur in large 

 groups. Pronounced variations in seed crop, soil, and ground cover 

 have made it necessary to classify the areas into several groups. On 

 account of the abundant rainfall in 1919, which created almost ideal 

 conditions for germination, variation in seed supply was by far the 

 greatest factor during the first season. In the second and third sea- 

 sons, however, the influence of site came into play in determining 

 survival. 



Group I covers the cut-over region in the bunch-grass type, in 

 which sample plots 3a and 3b are located. An unusually heavy 

 seed crop prevailed over this entire region in 1918. Even small 

 trees down to 12 inches in diameter, if growing in the open, were 

 loaded with cones. For this reason the heavy cuttings on which 

 only a few small trees are left show up to much better advantage 

 than would be the case under normal conditions. It is at once 

 apparent that the number of seedlings is at least in a general way 

 related to the number of seed trees. The " timber rights " section, 

 with its four trees per acre (very few above 15 inches diameter breast 

 high) is so far down the scale as to leave no doubt as to the 



