94 DETERMINATION OF THE INCREMENT 



sented by curves constructed on the principle, that the succes- 

 sive ages are marked as abscissae, and that the corresponding 

 ordinates represent the height, diameter, basal area, or 

 volume. Such curves indicate the appropriate quantities for 

 any age up to a certain limit, generally the highest rotation 

 likely to be adopted. Instead of employing curves, the data, 

 which they represent, are read off and arranged in tables, and 

 these are called Yield Tables. 



By a yield table is understood a tabular statement, which 

 gives the course of the development of a wood from early youth 

 up to a certain age, either from year to year, or for intervals 

 of a certain number of years. 



2. 01>jeet and Contents of Yield Tahles. 

 Yield tables are used for a great variety of purposes, as : 



{a.) Determination of the volume of woods. 



(/>.) ., ,, ,, increment of woods. 



(f.) ,, ,, ,, quality of localities or of the stock. 



((/.) ,, ,, ,, most profttable species, method of 



treatment and rotation. 

 {e.) ,, ,, ,, value of the soil, growing stock, or 



both. 

 (/.) ,, ,, ., yield of forests. 



In order to meet all these requirements, yield tables should 

 show, per unit of area (acre) : 



(1.) The number of trees. 

 (2.) The mean diameter of trees. 

 (3.) The basal area of trees. 

 (4.) The height of the wood. 



(5.) The volume, which may be found in a fully-stocked 

 wood at successive ages ; also the yield of thinnings. 

 (6.) The current annual and mean annual increment. 

 (7.) The form factors. 



