28 TRANSACTIONS OF ROVAL SCOITISH ARBORICULTURAL SOCIETY. 



3. The State Forests of Saxony. 



( IVith Illustrations.) 



{Continued from Vol, xxvii., p. 187.) 



By A. D. HoPKiNSON. 



Rotation. — Eighty years is about the average rotation for 

 spruce in Saxony, but no hard and fast regulations are laid 

 down that as soon as a wood reaches that age it must be cut 

 and not before. Many considerations affect the age at which 

 " stands " are cut, and tend to make it vary from the normal. 

 Two of the chief of these are the production and maintenance 

 of normal age-classes, and the uniformity of the " Cutting Series." 

 If, for instance, a " stand " rather under the normal age 

 comes in the middle of a cutting series, then it is generally cut 

 in order that the regularity of the series may not be broken 

 (see Fig. 3). The average rotation, eighty years, is the 

 average economic rotation, and is obtained by calculating 

 several soil expectation values for different rotations, and 

 taking the maximum as being the most advantageous financial 

 rotation. To obtain the necessary data accurately for working 

 out the soil expectation values, a number of investigations 

 were carried out to find both mass and worth increments in 

 typical woods. 



Regulation of Yield. — This subject takes us back to the days 

 of Cotta, if we are to understand how the somewhat complex 

 method at present in operation in Saxony arose. Cotta was a 

 strong supporter of the " Fldchenfachwerk " system, or system 

 of determination of yield by area, whereas G. L. Hartig, his 

 famous contemporary, strove energetically to introduce in 

 Prussia the more complicated " Massenfac/nverk,'^ or system of 

 determination of yield by volume. Neither of these have 

 survived in their original forms, although the former has a 

 much greater bearing on modern management than the latter. 

 Latterly Cotta changed his views somewhat, and became a 

 supporter of the system of determination of yield by combined 

 area and volume, but area played always the more important 



part in his calculations, and the simple formula 0, = ^ (where 



a = annual area cut, A = total area, and R = rotation in years) 



