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SCIENCE 



[N. S. Vol. XLI. No. 1047 



forest type became the silvi cultural unit 

 which has the same physical conditions of 

 growth throughout and therefore requires 

 the same method of treatment. The manner 

 of growth and the method of natural re- 

 generation once developed for a forest type, 

 hold true for the same type no matter 

 where it occurs. After the relation be- 

 tween a certain natural type of forest and 

 the climate and topography of a region has 

 been established, the forest growth be- 

 comes the living expression of the climatic 

 and physical factors of the locality. Sim- 

 ilarly, with a given type of climate and 

 locality it is possible for the forester to 

 conceive the type of forest which would 

 grow there naturally. The forester, there- 

 fore, may speak of the climate of the beech 

 forest, of the Engehnann spruce forest, of 

 the yellow pine forest. Thus, if in China, 

 which may lack weather observations, we 

 find a beech forest similar to one found in 

 northern New York, we can be fairly cer- 

 tain of the climatic similarities of the two 

 regions. More than that, a type of virgin 

 forest growth may serve as a better indi- 

 cation of the climate of a particular local- 

 ity than meteorological records covering a 

 short number of years. A forest which has 

 grown on the same ground for many genera- 

 tion is the result not of any exceptional cli- 

 matic cycle, but is the product of the aver- 

 age climatic conditions that have prevailed 

 in that region for a long time. It expresses 

 not only the result of one single climatic 

 factor, but is the product of all the climatic 

 and physical factors together. Similarly, 

 the use of the natural forest types for deter- 

 mining the potential capacity of the land 

 occupied by them for different purposes is 

 becoming more and more appreciated. 

 When the climatic characteristics of a cer- 

 tain type of forest, for instance those of 

 Engelmanu spruce in the Rocky Mountains, 

 is thoroughly established, the potential 



capacity of the land occupied by it for 

 agriculture, grazing, or other purposes is 

 also largely determined. 



Observations of the effect of climate upon 

 forest growth naturally brought out facts 

 with regard to the effect of forests upon 

 climate, soil and other physical factors and 

 led to the development of a special branch 

 of meteorology, known as forest meteorol- 

 ogy, in which the foresters have taken a 

 prominent part. "While there are some 

 phases in forest meteorology which still 

 allow room for disagreement, some relation- 

 ships established by foresters are widely 

 accepted. One of these is the effect which 

 forests have upon local climate, especially 

 that of the area they occupy and of contigu- 

 ous areas. Every farmer who plants a 

 windbreak knows and takes advantage of 

 this influence. Another relation is that be- 

 tween the forest and the circulation of 

 water on and in the ground, a relation 

 which plays such an important part in the 

 regimen of streams. Still a third one, as 

 yet beyond the possibility of absolute proof, 

 is the effect of forests in level countries, in 

 the path of prevailing winds, upon the 

 humidity and temperature of far-distant 

 regions lying in their lee. 



If in the field of botany the forester has 

 contributed to the progress of botanical 

 geography and in the realm of meteorology 

 has opened new fields of investigation, his 

 influence in wood technology has been in 

 changing entirely the attitude of engineers, 

 physicists and chemists in handling wood 

 products. The methods of studying the 

 physical, mechanical and chemical prop- 

 erties of wood were, of course, those used in 

 engineering by chemists and physicists; 

 but the forester has shown that wood, un- 

 like steel, concrete or other structural mate- 

 rial, is subject to altogether different laws. 

 Wood, he has shown, is not a homogeneous 

 product, but is greatly influenced by the 



