8 



FOREST commissioner's REPORT. 



C — Method of Computing; Growth, and Yield of Second 

 Growth in Spruce and Pine. 



Each of the two previous Maine forestry reports contained a descrip- 

 tion of the method of tree measurement adopted by the United States 

 Forestry Division for the use of its field agents. Few, perhaps, will 

 take interest in this matter on its own account, but work of this nature 

 is so fundamental to the results of this report that it must be once more 

 explained. 



The schedule of field measurements annexed careful attention will 

 I think, make perfectly plain. The figures refer to a spruce tree that 

 grew up on a very old burn on township I, K. XTV, just east of Moose- 

 head Lake. In getting these data an ax, a foot rule, a four-foot stick and 

 caliper measure are the tools used. The tree desired is looked over 

 standing, note being taken of its thrift and relation to other trees. Then 

 it is felled and measurements taken of main features, — breast diameter, 

 height, and relative length of trunk and crown. The diameter of the 

 tree at every four feet is also measured, which gives its shape and vol- 

 ume. The tree next, if it is at the observer's disposal, is cut into desired 

 lengths for the detail count and measurement of its yearly rings. This 

 gives, as will be seen, a clew to the history of its development and 

 growth. 



In order to understand these detail measures it is necessary to hold in 

 mind one principle. The yearly wood growth of a tree is deposited imme- 

 diately under the bark. A thin layer is thus formed each year over the old 

 wood and reaching out beyond it at the top of the tree. Now supposing 

 that the deposit of rings is entirely regular— that one ring and onlj' one 

 ring is grown each year — which is for practical purposes the case, — it is 

 seen that the number of rings at the stump of a tree gives its age, 

 while the rings at any section above tells how many years were taken to 

 grow the lieight that is above the point selected. Subtraction of one 

 from the other therefore tells how many years the tree took in growing 

 fi-om the height of the stump to the height of the section. 



Position: Cbown Partly Free; Surrounding Species: Spruce, Pine, 



Birch and Poplar. 



