ABSOLUTE FORM QUOTIENT 355 



average form class in the stand. The form class varied considerably 

 within the same stand, especially in uneven-aged and open stands. 



We believe, however, that in ordinary cruising it will be possible to 

 judge the average form class outside bark of the stand by eye with 

 sufficient accuracy. Density is a good criterion of the average form of 

 the trees in the stand. Poor density gives lower form class and good 

 density higher form class. In the East, form class 80 was only found 

 in a partially overcrowded stand of red pine and then only in individual 

 trees, the average being 75 inside bark and 73.3 outside bark. Another 

 red pine stand with normal density gave form class 69 inside bark 

 and 68 outside bark, and another fine looking red pine stand of full 

 density had form class 71 inside bark and 70 outside bark. Jack pine 

 of full density gave form class 68.7 inside bark and 67.3 outside bark. 

 A plot of white pine, spruce, and balsam gave the following average 

 form classes : — 



White pine 68.8 inside bark, 68.4 outside bark 



Balsam 68.0 inside bark, 6S.0 outside bark 



White spruce 65.8 inside bark, 65.9 outside bark 



The following form class figures inside bark have been found to rep- 

 resent the average at Petawawa : 



Overcrowded stands 75 outside bark 



Very good density 70 outside bark 



Good density 65 outside bark 



Open 62.5 outside bark 



Very open 60 outside bark 



The large trees in even-aged stands have as a rule a somewhat 

 lower form class than the smaller ones. 



The Swedish investigators have found that the average form class of 

 the stand coincides closely with the form class of the average tree in 

 the stand. Whether or not this is the case here we are not yet able to 

 say, but the indications seem to point that way. 



All taper series and volumes referred to in this article are based on 

 the inside bark measurements. It is, of course, necessary to first study 

 the stem form of trees inside bark so that the laws of taper of the wood 

 stem may be ascertained. The bark generally lowers the form class 

 and the relation between the form class inside and outside bark can 

 only be arrived at after very extensive bark studies. Such investiga- 

 tions must be concentrated for each species upon the thickness of bark 

 at breast height and ui)on the taper of the bark with increasing height 



