Periodical Literature. 207 



In this last respect, the author claims, the yield tables in their 

 present form do not fulfill their function, because the data are 

 insufficient. As regards grouping the data in relation to time no 

 fault is to be found, for intervals of five years, as used in the 

 best tables, are for practical purposes sufficient. But when the 

 data for older stands are compared from site class to site class, 

 there being usually five site classes made, the differences become 

 eventually too great for practical purposes, since for a felling 

 age position of, say, 100 years, the difference from site class to 

 site class may be 1,500 to even 3,000 cubic feet, leaving too wide 

 intervals without data. Hence, the author proposes supplement- 

 ary tables at least for older stands above sixty years, which he 

 illustrates by such tables worked out for Scotch Pine from data 

 furnished in Schwappach's tables. 



Table I gives the range of average heights in each site class 

 in relation to age. Table II gives with five year intervals the 

 timberwood in relation to the average heights. Table III gives 

 for age classes in periods of 10 and 20 years the periodic loss 

 in each site class by thinning. Table IV does the same for dif- 

 ferent average heights. Table V is an increment table. In 

 Table VI also increment relations to age and height are elabo- 

 rated in such a manner as to permit an estimate of present and 

 future yields. Tables VII and VIII serve for diameter estimates, 

 the first giving actual diameters related to age and height, the 

 second expressing the same percentic progression for various 

 growth periods. 



This may be illustrated by an example. 



The average diameter of a 70 year stand, with average height 

 60 feet, hence according to table I belonging to site class III, is, 

 according to table VII, 8 inches. If the aim of the management 

 is to produce 12 inch diameters, then the diameter increment 

 required to the felling time must be 50 per cent. According to 

 table VIII, this will require 50 years ; and from table II it can 

 be found that the cut will be 5,700 cubic feet. 



Die Normalertragstafeln im Dienste der Forsteinrichtung. Zeitschrift f. 

 Forst-u. Jagdwesen, January, 1909, pp. 14-27. 



14 



