41 



obtaiDing other information of equal imjDortance becomes clearer. The 

 success of conducting the other inquiries relating to the forest, with a 

 view to working out an adequate plan for its management, depends 

 upon knowledge of the sylvicultural possibilities of the species com- 

 prising it. The question, for instance, of how far the actual annual 

 growth of the forest differs from the annual growth possible for the 

 locality, under the given conditions and species or the age at which 

 the cutting should be made in order to insure that possible annual 

 growth, can be properly answered when the requirements of the species 

 composing the forest and the rate at which those species grow at 

 various ages and under various situations is known. In Europe the 

 sylvicultural requirements of forest trees have been ascertained in an 

 experimental, or rather historical, way. The forest districts into which 

 the state forests were divided at the beginning of the epoch of forest 

 regulation kept records registering the results attained by their forest 

 trees under the various situations and treatment. These records, 

 together with the casual and experimental observations organized 

 later on by the European foresters, have accumulated a good deal of 

 valuable and sound data, the systematic teaching of which has attained 

 the rank of a science known under the name of sylviculture. It has 

 taken Europe almost two centuries to work out its sylviculture. It 

 would take the United States, with ten times as many species of 

 economic value as are found in Europe, considerably more time to work 

 out its sylviculture should it ignore the progress made in forestry 

 science, and in spite of it follow the slow historical method of investi- 

 ating timber growth. 



It has been shown in the preceding pages that the progressive devel- 

 opment of a single tree may be determined in an analytical way. The 

 European foresters apply that analytical method for the examination 

 of the average sample trees. The analysis of a few individual trees is 

 sufficient to enable the forester, with the general knowledge he possesses 

 of the rate of growth of the particular species, to determine the factor 

 of the locality, i. e., to determine in what way the locality affects the 

 general law of growth of the species. But when the sylvicultural 

 requirements of a species are totally unknown, an analysis of a few 

 individual trees is scarcely sufficient even to indicate the rate of growth 

 of the species. To be sure, by analyzing a large number of trees taken 

 on various sites and under various situations the rate of growth of the 

 species could be determined, but if each of the number of individual 

 trees were to be analyzed separately, as is done usually by European 

 foresters, the work would be too cumbersome. It was thought neces- 

 sary, therefore, in the work for the Division of Forestry of ascertaining 

 the rate of growth of our species, to modify the European analytical 

 method so as to make it more applicable for the thorough investigation 

 of timber growth. 



According to the analytical method as employed by the European 



