YIELD OF VOLUNTEER SECOND GROWTH 501 



crown classification, taken in connection with the character of the sites, 

 brings out some useful facts. The number of dominant, or A, trees 

 is hardly significant, since it is largely a matter of accident how many 

 individuals have been free from suppression from the start. The 

 sudden drop in the number of B trees (overtopped, but still thrifty) 

 between the twenty and the forty year age seems to indicate that any 

 attempt at a profitable improvement cutting must be made before the 

 twentieth year. In fact, considering conditions on Plot III, the cutting 

 would probably have to be made even earlier. This plot represents soil 

 of quality I — a site distinctly more favorable for hardwoods than for 

 pines. The figures show that suppression proceeded here much more 

 rapidly than on the lighter, sandier soil of Plot II. The 413 trees in 

 class C were all dead, for the most part about twenty years old and 

 between 10 and 15 feet in height. These were almost exactly the gen- 

 eral dimensions of the 15 trees in Plot II, which, nevertheless, though 

 completely overtopped, would most of them have survived from five to 

 ten years longer on the poorer soil. It seems fair to conclude, then, 

 that if a young mixed stand is to yield a substantial percentage of white 

 pine it must be treated for release and improvement not later than the 

 twentieth year, and still earlier on good soils. 



Similar but less well-marked conclusions can be drawn with respect 

 to some of the more valuable hardwoods in such mixed stands, but, 

 being more difficult of decisive statement and less important in deter- 

 mining the final value of the stand, they are not here considered. 

 Again, it should be noted that the several plots are not sufficiently uni- 

 form, either as to site or stocking, to make absolute comparisons pos- 

 sible. The results, however, are sufficiently large to be. in spite of this, 

 conclusive. 



T.\BLE 5. — Summary of Comptitations for all Plots on Basis of Yield per Acre 



at 60 Years 



Final volume without improvement cutting 

 Plot Age Xo. trees Saw timber, bd. ft. Firewood, cds. 



II 20 356 12,956 (pine. 60 per cent) 12.40 



III 40 284 13,880 (pine, 60 per cent) 22.68 



I\' 50 320 12,820 (pine, 55 per cent ) 8.30 



Fin.il volume with improvenunt cutt.UK Intermediate 



Firewood, Firewood, 

 Pli)t Arc N'o. tiooi Saw timber, bd. ft. cds. cds. 



II _'u 4^4 32,320 (pine, 85 percent ) 9.00 11.40 



HI 40 368 17,356 (pine, 75 per cent) 17.00 6.28 



I\' 30 ii2 16,064 (pine, 60 per cent ) 2.30 7.IJ 



III 'I'ahle 5 are stated the liiial yields for each of the tlirce plots on 

 an acre basis, including the vohime oi nii.xed wood in cords derived 

 from the improvement ctilling. which, under average market con- 



