GROWTH ON AREAS OF IMMATURE TIMBER 451 



first, because number of trees per acre at these ages does not in any way 

 indicate the future yield, since this is determined by the number that 

 survive; second, because the area rather than the number will determine 

 the future yield. On a plot of 100 square feet there may be one hundred 

 seedlings; yet if fully stocked at maturity not more than one tree would 

 be able to survive from this number. Such counts on plots serve only 

 to determine the extent to which reproduction is becoming established 

 and do not give the data needed for growth predictions. 



Age Classes Based on Size. Immature timber may be divided into 

 at least three classes for purposes of growth study; seedlings, saplings 

 and poles. Seedlings are trees under 3 feet high.^ Saplings include 

 trees from 3 feet high to 4 inches D.B.H. Poles are trees from 4 to 12 

 inches D.B.H. 



Saplings may be divided into 

 Small — from 3 to 10 feet high. 

 Large — from 10 feet high to 4 inches D.B.H. 



Poles may be divided into 



Small— from 4 to 8 inches D.B.H. 

 Large — from 8 to 12 inches D.B.H. 



Methods for Seedlings and Saplings. In determining the quantity 

 of reproduction and immature timber present on an area, in order to 

 predict its growth by comparison with a yield table, the procedure 

 will depend upon the form of the forest. In even-aged stands, areas 

 stocked with seedlings in sufficient numbers can be entered by mapping 

 them as fully stocked. Danger of destruction is chiefly by fire, and for 

 this, correction can be made when fires occur. But in many-aged 

 stands, suppression must be considered. Depending upon the silvical 

 characteristics of the species and the behavior of the seedlings, the object 

 should be to record only the area of mature forest which will result from 

 the present stocking. Seedlings which are suppressed wiU be ignored. 

 Those which grow in openings and are thrifty will be regarded as prob- 

 able survivors. In rather open, group-selection - forests like yellow 

 pine, the areas stocked in this manner are easily distinguished. With 

 species such as spruce, seedlings starting under shade and not in open- 

 ings should be disregarded altogether, both because of suppression, 

 and because their age will be prolonged b}^ this cause and they wiU 

 not become an economic factor in the stand till a later period (§ 263). 



With saplings, the establishment of the stand in many-aged forests 



^ Standard definitions, Society of American Foresters. 



^ Group-selection, a forest composed of trees of all ages intermingled in small 

 fairly even-aged groups. 



