The Sciences Underlying Forestry. 29 



others deteriorate the old crop, calling for knowledge not merely 

 of their names, but of the conditions which favor their develop- 

 ment and the means of preventing it. It will be observed, then, 

 that botanical studies form a prominent part through three years 

 of the curriculum. 



As must have become apparent from the reference to the rate 

 of growth as influenced by the factors of site, the knowledge of 

 these factors, soil and climate, general and local, and their rela- 

 tion to plant life is indispensable. The study of geology and 

 meteorology as far as they explain this relationship, as far as they 

 teach the chemico-physical basis for wood production, and form 

 a criterion for the adaptation of species to various conditions is 

 required. 



The Germans have segregated the portions of these sciences, 

 which contribute towards an understanding of these relation- 

 ships as a special branch called "Standortslehre." 



Especially the subject of soil physics, only lately developed 

 into a science, furnishes much useful information to the forest 

 grower. It is now a well substantiated fact that wood growth 

 is much less dependent on the mineral constituents of the soil, 

 than other vegetable growth, and especially the agricultural food 

 and fruit crops, that trees live and thrive literally on air, and 

 from the soil derive mainly the necessary water ; hence the physi- 

 cal conditions of the soil, which influence the water conditions 

 are of much more moment than the chemical composition ; hence 

 also manures are not required, and conservation of favorable 

 water conditions is the main concern of the forest owner. 



Since limitation is wisdom it is wise to confine the geological 

 and mineralogical studies to such small portions as are neces- 

 sary for a general understanding of how and what soils are 

 formed from different rocks, and secure depth of knowledge only 

 regarding soil physics. A more elaborate introduction to the 

 geological history and dynamic geology may be of general edu- 

 cational interest, but it is not required by the practitioner who 

 is concerned only with what has relation to tree life. 



There is one other branch of natural sciences which has con- 

 cern with tree life, namely zoology. Animals feed on plants, 

 hence become enemies to the forester's business. Especially does 

 he find a limited number of insects which can become trouble- 

 some and call for protective measures. He should know them 



