Canadian Forestry Journal, August, 10 IS 



1837 



of the overtopped softwood is di- 

 rectly dependent upon openings in 

 the upper canopy. It is an undeni- 

 able fact that these openings are 

 more readily and quickly seized by 

 the closing together of the surround- 

 ing hardwood crowns than by the 

 growth of the softwood from beneath. 

 The effect of these openings is I he 

 acceleration of the growth of the 

 understory softwoods, and the closing 

 together of the crowns retards it. 

 This continues until the individual 

 softwood tree is able, by its height, 

 to thrust its own crown into the 

 opening and to seize it for itself. 



The Effect of Cutting 

 The pulp man, however, is not 

 interested in the time required by 

 a tree to reach a place in the main 

 canopy. The length of time covered 

 by the period of iniiial suppression 

 is variable and represents not so 

 much a defmite period of time as a 

 condition to be endured in the young 

 growth of all softwoods in mixture 

 And as such it should be regarded in 

 the predictions of growth. The lum- 

 berman is not so much concerned 

 with the age of the trees remaining, 

 as with their size, their number and 

 their subsequent growth. Suppose 

 that it does take 100 years to grow 5 

 inch Spruce or Balsam tree in virgin 

 mixture. That is of very little con- 

 sequence provided that there are 

 enough of them and that in the 

 period before the next cutting, 50 

 years perhaps, they will increase 

 their diameter by 8 inches, making a 

 total of 13 inches, a supposition not 

 beyond expectation with either Spruce 

 or Balsam. Increase in the rate of 

 growth of all trees is the immediate 

 effect of cutting. In illustration of 

 this, Figure No. 1 is submitted, 

 which shows the average diameter 

 growth on the stump before and 

 after cutting. It is based on the 

 measurement of 313 Red Spruce trees 

 on Brandreth Park in the Adirondack 

 Preserve, New York State. 



The recovery of a tree from sup- 

 pression is dependent upon the pro- 

 portionate size of the crown and the 

 development of the roots. It is 

 not to be thought that the immediate 



effect of the removal of the overwood 

 and the entrance of the crown into 

 the light is a corresponding increase in 

 growth. Even when the tree is but 

 lightly shaded, it takes some little 

 time for it to make full and complete 

 recovery and show an acceleration of 

 growth. The removal of the over- 

 wood has not the same effect as if 

 the trees came up into the light 

 through the processes of growth, and 

 a period of readjustment is necessary, 

 before they begin to show an increase 

 in the rate of growth. 



The recovery is slowest on the 

 biggest trees and most rapid on the 

 smaller members of the underwood. 

 Yet even with the smaller trees it 

 takes from 4-5 years for the tree to 

 make recovery and show an accelera- 

 tion of growth. With the bigger 

 trees this time is longer. Attention 

 is called to Figure No. 2 in 

 illustration of the period of read- 

 justment in Spruce after cutting. 

 While this figure is made out on the 

 basis of height growth only, it will 

 be understood that curves based on 

 either diameter of volume growth for 

 the same period would show exactly 

 the same trend. This study is based 

 on the measurements of 316 Red 

 Spruce trees at Wanakena, N.Y. 

 The first few years after the cutting 

 there is no acceleration or increase 

 in the rate of growth. It will be 

 noticed that the recovery and accel- 

 eration of growth was quickest with 

 the smallest sized trees. 



Need of Light and Room. 

 In reality, the whole process of 

 growth hinges upon the release and 

 development of the individual tree. 

 The development of the unmer- 

 chantable portion of the stand can 

 only be accomplished by giving the 

 component individuals their requis- 

 ite light and room. In the meantime 

 there is a potential forest immediately 

 available represented by the 4, 5, b, 

 and 7 inch trees now present in the 

 stand, on which the lumberman 

 can depend for his wood supply until 

 the small suppressed material can 

 make the expected recovery, and 

 begin to take its place in the actual 

 productive portion of the stand. 



