4G0 Forestry Quarterly 



the field. Quite a few crown measurements were taken during 

 the last two summers and this fall a new method occurred to 

 me. In riding through these Yellow pine stands after a light 

 snowfall, I noticed that the open spots underneath the trees 

 (that were free from snow) corresponded very nearly to the 

 projected crowns of the individual trees. This observation re- 

 sulted in a very easy way of measuring crown diameters and 

 the areas of the crowns as projected on the ground. The follow- 

 ing table shows the results of these observations: 



TABLE 3 

 Average Diameter Area of Projection 



Diameter Breast High of Crown 



Group Inches Sq. Ft. 



6-10 inches 8 100» 



11-20 inches 15 348^ 



21-30 25 1038 



31-40 35 1536 



Over 40 1925 



Applying these figures to the various classes of stands based 

 upon number of trees per acre, we get the density of our Yellow 

 pine stands in tenths based upon an ideal acre. 



TABLE 4 

 Total Trees 



per Acre Total Area Crown Density 



Density All Diameters Projected Crowns in Tenths 



Class {From Table 2) Sq. Ft. per Acre Based upon Ideal 



1 6.8 8,581 .23 



II 14.4 12,652 .36 



III 17.9 15,014 .42 



IV 26.1 19,141 .55 



V 39.7 28,168 .81 



Average 14.8 13,107 .38 



Maximum 80.0 29,050 .83 



Ideal 34,848 1.00 



The ideal acre is an acre (43,560 sq. ft.) of Yellow pine, in 

 which 10 per cent, or 4356 sq. ft. is allowed for the young stuff 

 below 5 inches D.B.H., and an additional 10 per cent, or 

 4356 sq. ft., is allowed for "other species," the remaining 80 per 

 cent, or 34,848 sq. ft., being taken up by the Yellow pine over 

 5 inches D.B.H. considered in this study. This assumes that the 

 trees utilize every square foot of sunlight, there being no over- 

 topping. This is largely true in the case of Yellow pine, on 

 account of its intolerance. The projected crown area of the 



2 Average area per tree, fifty-year Scots pine No. 1, diameter 8 inches, is 

 94 square feet. 



3 Average area per tree 120-year Scots pine No. 1, diameter 16 inches, is 

 283 square feet. 



