QUANTITY INCREMENT. 



179 



between wood and bark all over the stem, branches and roots. 

 As a general rule the stem or trunk is the most important part 

 of the tree ; hence the forester is specially interested in the 

 height and diameter growth. 



It has been explained in Volume I. of this Manual, p. 161, 

 that the energy of height growth differs not only according to 

 species, but also, in the case of one and the same species, 

 according to the locality and method of treatment ; besides, 

 there is in this respect a great difference between seedlings 

 and coppice shoots. 



Generally speaking, in the case of seedlings the height 

 growth during earliest youth is, in temperate climates, com- 

 paratively slow ; it then increases rapidly, remains steady for a 

 time, then decreases, and ceases altogether, or nearly so. 



The periods when the current annual and mean annual 

 height increment show their maxima are of special interest to 

 the forester, but the data at present available give wide limits 

 for those periods. Taking the various quality class es together 

 the following table gives the limits of the periods and the mean 

 year of the maximum height growth : 



On the whole, the culmination occurs earlier : 



(1) In the case of light- demanding species, and 



(2) In the better localities. 



In the case of teak, the current annual height increment 



N 2 



