G30 Forestry Quarterly 



after having made them comparable. To do this, it is necessary 

 to determine by graphical or calculatory interpolation the develop- 

 ment of stands of the same height — the height development having 

 been recognized as the best criterion of site. Calling the height 

 at 100 years of age the index height, being an index of stand and 

 site quality, he determined the progress of height development 

 from yield tables for stands with different index heights. He 

 finds that stands which have the same height at 100 years have 

 approximately the same heights at other ages no matter whether 

 grown in Russia, Sweden, North Germany, Black Forest, Alps or 

 Rhine valley. Differences appearing in the table are much 

 smaller than those which are met in a confined locality on the 

 same site, hence cannot be due to climatic influence. A table 

 of average heights, which the author claims would do service 

 equally well in Germany, France, Siberia, Canada, Japan and 

 China, has been figured out from the yield tables, smoothed out 

 according to Weber's law which determines the decreasing rate 



of height growth as 1 : , x being age diminished by the duration 



1.0^" 



of the juvenile stage, and p a growth per cent derived from the 

 yield tables. This table also enables one to compare the different 

 yield tables, no matter what site class differentiation has been 

 made. 



We can give only a sample of this table. 



In Age 



Stand Index Height at 100 Years 

 if the Stands have a Height of 



10 11 12 13 14 15 etc. meter 



30 24 26 27 29 31 2>3 



40 19 21 22 24 25 27 



50 16 17 19 20 21 23 



e. g., when a 50-year stand has a height of 15 m it will be 23 m at 

 100 years, or if 13 m then 20 m. 



Thus everywhere the same trend of height curves furnishes the 

 possibility to make uniform site classifications by the index height 

 — a purely objective classification found in the stand itself inde- 

 pendent of the estimator. 



Next, it is found that the development of form factors is in all 

 regions the same: One can therefore everywhere determine the 

 volume for the same age and height and same treatment of stands 



