878 JOURNAL OK KORKSTRV 



areas. This further study has revealed much information on the habits 

 of regeneration and forest succession in yellow pine that was not evi- 

 dent at first. It is the object of this paper to present the facts of this 

 study in their relation to the method of cutting now being practiced on 

 timber sales and to the method which it is believed our present knowl- 

 edge justifies. Only the pure yellow pine forest is considered. The 

 observations upon which these remarks are based were made in Oregon 

 and Washington, but it is believed that the forest conditions found here 

 prevail generally in the western yellow pine region and that the con- 

 clusions herein expressed will apply generally, except possibly in parts 

 of the Southwest. 



In general the pure yellow pine forest* is characterized by open, 

 irregular and uneven-aged stands with a preponderance of mature and 

 overmature trees. In addition there is generally an excellent ground 

 cover of advance reproduction made up partly of dense groups of seed- 

 lings here and there in the openings of the forest, but mostly of uni- 

 formly distributed and suppressed little seedlings struggling along 

 directly under the overwood. This latter form of reproduction, which 

 has generally been unnoticed, is small and inconspicuous, but has a 

 great power of recovery which, after the overwood is cut, enables it to 

 make a wonderfully dense and even stand of flourishing saplings. 



While the virgin forest is very evidently uneven-aged, there is on the 

 whole, and contrary to general opinion, an exceedingly unbalanced 

 representation of the age classes, in which mature and overmature 

 trees preponderate and young trees are only negligibly represented. 

 This was studied very intensively on two 20-acre sample plots on cut- 

 over land in the W^hitman Forest, upon which were secured the ages 

 of all the trees above four inches in diameter breast height that had 

 stood on the areas, and the ages of a representative proportion of the 

 tree growth under this size. Upon correlating and averaging the data 

 it was found that of all the trees over 4 inches in diameter, 9 per cent 

 fell in the class 20-100 years, 22 per cent in the class 100-200 years, 

 45 per cent in that 200-300, 6 per cent in that 300-400, 15 per cent in 

 that 400-500, and 3 per cent in that 500-600. Thus 69 per cent of all 

 the trees above reproduction size were between 200 and 600 years old. 

 This means that only a small proportion of the stand was under 200 

 years — the maximum rotation age usually considered in yellow pine. 

 On sample plots totaling 417 acres taken in other localities, but upon 

 which the trees were classified by diameter only, it was found that 67 



