51 



-' (?+ t) 



»■ 100 



so that p = = loo ( ^ ^ j—J 



T\ hen there has been no increase in height, 



2*30 X diameter incremeDfc 200 5 



" Actual diameter (£ 



Another simple formala to use is that of Schneider, by which 

 /> = y— , J) being the actnal diameter in inche, exclusive of the 



barkj and « the number of annual rings in the last inch of growth. 



2 . . 



— is obviously equal to one year's increase of diameter, and this 



figure can consequently be used in Ereymann's formula above. 



Both Breymann's and Schneider's formula give only the rate 

 of increase per cent, of the basal area, and the rate of increase' 

 per cent, of volume must be obtained therefrom in different cases 

 as follows : — 



(a) In the case of trees possessing vigoron? upward growth 

 and standing in a leaf-eanopy, by multiplying by If. 



{b) In nearly- all other case? of canopied trees, by multiplying 

 by a factor varying from li to H- 



(c) In the case of isolate*! trees without any multiplication at 

 all in many instances. 



■ E. Stem analjas, ot the determination of tlie conrse of fhe increment of the 

 stem during the whole term of ils life. 



If any tree forms annual rings, the observation of these rings 

 enable us to trace its life-history, to say when it was suffering from 

 suppression, from insect ravages, from the effects of fire, frost 

 and from other retarding caases, when it enjoyed comjJete im- 

 , mnnity from such injurious inflnences, and was a dominant 

 stem growing vigorously, and so on. A longitudinal section 

 passing through every point of the axis of the stem would 

 show all this at a glance, but such a section is practically imfws- 

 sible to make ; the stem must be cut across into a number of sec- 

 tions, and the required information sought thereon. The sections 

 may be made at every 6 feet, but as a tree grows fastest 

 when yonng, the lower sections may be longer (up to 10 and 

 even 14 feet in the case of quick-growing trees), while the upper 

 ones may be made shorter. The first cross-cut should be made at 



