200 proceedings: botanical society 



ance due to cutting. In practical forest management each formation 

 was shown to present distinct problems in which the kind or degree 

 of cutting is the controlling factor. The correct solution of these 

 problems involves an intimate knowledge of the range of conditions 

 under which the climax type can succeed. Direct seeding of forest 

 trees on ground not recently occupied by the climax forest has usually 

 resulted in failure. 



Dr. J. V. Hoffman called attention to the successions in the forests 

 of Washington and Oregon. Two types of succession were distin- 

 guished: (1) A type in which the production, distribution, germina- 

 tion of seed, and the establishment of seedlings are important. This 

 type is dependent therefore on the presence of seed trees and progresses 

 into an unoccupied area only 150 to 300 feet during each generation. 

 The resulting forest is composed of trees of uneven age. (2) A type 

 dependent primarily on the viability of seed and in no way dependent 

 on remaining seed trees. The seeds produced by the old stand retain 

 their viability when the forest is destroyed and germinate to form a 

 new forest of the same type and of even-aged trees. 



Mr. A. W. Sampson discussed succession as a factor in the manage- 

 ment of the range lands of the Forest Service. Succession, or the 

 alternation in the vegetative personnel of an area was found to occur 

 whenever the natural conditions of the environment had been ap- 

 preciably changed. Where the vegetative cover had been disturbed 

 more or less seriously on pasture and range lands, and the disturbing 

 factors subsequently eliminated or their intensity decreased, the vege- 

 tation, through successive invasions, gradually became more like the 

 original. 



In the administration of the range on National Forests with a view 

 of maintaining a maximum forage cover, a clear recognition of the 

 successional stages represented by the more conspicuous species is 

 important. Certain species occur 'early and others late in the suc- 

 cession leading to the development of the climax or ultimate type. 

 The conspicuous appearance of species which occur early and which 

 are usually of little or no value for grazing, shows clearly that the 

 pasture is being improperly used and that a change must be made in 

 the management if the remaining desirable species are to be preserved. 

 Studies of the growth requirements, the life cycles of the more impor- 

 tant species, and the successional stages make possible the initiation 

 of systems of management favorable to the invasion and succession 

 of the species desired. 



Mr. E. O. Wooton discussed the succession due to protection of a 

 badly overgrazed area on the foothill slopes and adjacent sloping plains 

 of the northwest side of the Santa Rita Mountains in southern Arizona. 

 Quadrat collections were made at various stations at intervals during 

 a period of eleven years. From this data the following successional 

 stages were recognized: (1) Small weedy annuals in spring and an- 

 nual grasses in summer and fall. (2) Short-lived perennial grasses. 

 (3) Long-lived perennial grasses and a few species of perennial herbs 



