SlLVICULTURAL RELATIONS 



In any effort to increase the utiliza- 

 tion value of wood, testing and selection 

 Assume essential and immediate impor- 

 tance. Fundamental, however, to the 

 general program of forestry and wood 

 use is the problem of control of wood 

 quality at its source. Its solution must 

 be found in the conditions of tree 

 growth, and at this point the research 

 of the Laboratory makes close contact 

 with silvicultural experiments and prac- 

 tices in the field. 



Growth and quality 

 of wood 



The wide variations in strength, hard- 

 ness, shrinkage, and other properties of 

 wood produced within a tree species as 

 a result of growth under different con- 

 ditions have prompted the Laboratory 

 to investigate the possibilities of im- 

 proving wood quality at the source, 

 that is, while the tree is growing. 

 Wood grown under different natural 

 conditions or under conditions artifi- 

 cially modified with respect to soil, 

 moisture, density of stand, and asso- 

 ciated species, is tested and compared 

 in order to find the best conditions to 

 produce the best type of wood for given 

 uses. Although many years are re- 

 quired to grow trees of merchantable 

 size, a change in growth conditions, 

 such as may be effected by removal of 

 ^neighboring trees, drainage, or pruning, 

 ^ls reflected in the character of the an- 

 nual growth rings subsequently formed, 

 thus affording a ready means of com- 

 paring wood before and after the change 

 was made, the other variables remain- 

 ing unchanged. The resulting infor- 



mation can be beneficially applied to 

 second-growth timber which is still in 

 the formative stage. For instance, 

 softwoods make their best development 

 as to strength and other desirable prop- 

 erties when spaced moderately close, 

 whereas the quality of hardwoods is 

 sustained or improved by increased 

 opening up of the stand. 



Identification 



Families, genera, and many individual 

 species of wood may be identified as 

 readily by cell and pore arrangement as 

 by the botanical characteristics of the 

 tree. The specialized service provided 

 by the Laboratory in wood identifica- 

 tion is widely used. About 3,000 sam- 

 ples per year are identified. Frequently 

 important questions of use and even 



M-29644-F 



Width of annual rings and quality o£ the 



wood are correlated with factors of climate 



and soil affecting growth of the tree. 



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