ANNUAL INCREMENT OF SPRUCE AND SCOTS PINE. 



53 



Plantation D is about 32 years of age, and is situated on 

 ground which has probably carried timber crops for well over 

 100 years. The aspect is east, at about 300 feet elevation, with 

 fairly good shelter. There is a fairly good surface soil of humus 

 and loam 12 ins. to 14 ins. deep resting on a hard sand subsoil. 

 About three-fourths of the crop is spruce, the remainder being 

 birch with a few Scots pine and larch. The birch are more or 

 less accidental, and are not reckoned in any calculations. 



Plantation I has a northern aspect on a fairly steep slope, at 

 about 300 feet elevation, and is well sheltered. The age of the 

 crop varies somewhat, but may be taken to average 40 years. 

 The soil is fairly good — a yellowish sand, 15 ins. to 18 ins. 

 in depth, with a good surface covering of humus, merging 

 into a harder, stiffer subsoil of the same colour. The crop is 

 mainly spruce with some Scots pine, larch, birch and oak. 



The percentage rate of growth calculated from the figures 

 obtained has been ascertained by Schneider's formula, viz., 



400 

 Percentage = -,; n being the number of annual rings in the 



last inch of radial growth, and d the diameter of the tree under 

 the bark. ;/ has been ascertained by dividing the average annual 



increase in circumference by ' in order to obtain the 



22x2 



increase in radius, and then dividing the figure so obtained into 



one. This method, of course, assumes that the size of the annual 



rings has not altered during the last few years, and it may be 



liable to error owing to this assumption, d has been calculated 



from the circumference, making a suitable allowance for bark. 



Plantation K. 

 Scots Pine. — Observations of five frees 



