764 



XLVI. VERBENACEAE 



plans, shows the estimated rate of growth in girth in different localities. Except 

 in the case of the Mawku working circle of the Upper Chindwin division, these 

 figures do not include bark thickness, for which about 2 in, should be added 

 to the girth in each case. Nor is any allowance made for the time required 

 for a natural seedling to estabhsh itself ; this period is usually placed at ten 

 years, though one working plan allows fifteen years. It has been considered 

 best to reduce all the figures to the same level by omitting the period allowed 

 for the seedling stage, which is at the best a very rough estimate, and probably 

 varies under different conditions. In the earlier working plans, notably those 

 of Zigon and Tharrawaddy, Pressler's borer was largely employed to estimate 

 the rate of growth, and the figures obtained are probably less reliable than in 

 most of the other working plans, where the rate of growth has been estimated 

 from ring-countings. It may be noted that the figures given refer to trees 

 which have grown up under natural conditions without any tending, and the 

 rate of growth is probably slower than might be expected in regularly 

 tended natural crops. In Tharrawaddy and Zigon the rapid growth in the 

 alluvial plains forests as compared with the hill forests is noticeable. This is 

 not the case in Insein, where the soil of the plains forests is not so well drained 

 as that of the Tharrawaddy and Zigon divisions, and consists in places of 

 laterite. 



Central Provinces. The following statement showing the rate of growth 

 in girth over bark and in height has been compiled from measurements made 

 in different localities in the Central Provinces between 1909 and 1914 : 



Tectona grandis : rate of growth in girth and height in natural forest. Central 

 Provinces ; measurements made from 1909 to 1914, 



Mr. J. W. Best i has recorded the following summary of measurements 

 of over 4,000 felled teak trees, in two local quality classes, in the Hoshangabad 

 forests : 



^ Ind, Forester, xliv (1918), p. 408. 



