OF YIELD TABLES GENERALLY. 95 



Separate yield tables must be prepared for 



{a.) Each species. 



(/>.) Each method of treatment, as high forest, coppice wood 



and combination forest. 

 (t\) Each quality of locality. 



The volume is given divided into the different classes of 

 wood, as timber, firewood, fagots, etc. The volume of thin- 

 nings, or intermediate yields generally, is entered separately 

 from that of final yields. 



Yield tables are prepared only for "normal" woods, that is 

 to say, for woods, which are fully stocked, taking into considera- 

 tion the species, quality of locality, and the adopted method of 

 treatment. Such woods are produced, if no extraordinary 

 influences have interfered with their progress, such as natural 

 phenomena, faulty treatment, etc. 



3. Local and General Yield Tables. 



If a yield table has been prepared for a particular district of 

 limited extent, it is called a local yield table ; if for a whole 

 province or county, a gencrcd yield table. 



The question, what territorial limits should be assigned to 

 the applicability of a yield table, is still under discussion, but 

 so much is certain, that, in the preparation of such tables, a 

 considerable extent of country can be thrown together without 

 incurring any appreciable inaccuracy. It has been proved, for 

 instance, that yield tables prepared for North-Germany are 

 quite applicable to the south and centre of England, 



4. QucdiUj Classes. 



Localities of different quality, or yield capacity, produce 

 woods, which follow in their development different laws. The 

 law of increment of the one cannot be evolved out of that of 

 the other. The preparation of each yield table should, there- 

 fore, be based on data obtained from localities of precisely the 



