TECTONA 765 



Tectona grandis : rate of growth of natural teak, Hoshangabad, Central 



Provinces. 



Local quality I Local quality II 



(i. e. trees attaining a height of over (i. e, trees attaining a height up to 



50 ft. in 40 years). 50 ft. in 40 years). 



Jlean girth at 4^ ft. Mean girth at 4| ft. 



Age. Mean height. from ground. Mean height. from ground, 



years. ft. in. ft. in. 



5 14 7 11 3 



10 21 13 18 6 



15 27 17 22 9 



20 33 21 26 11 



25 38 25 29 15 



30 43 30 32 17 



35 47 33 34 20 



40 50 37 36 22 



45 53 40 38 25 



50 56 45 40 27 



55 58 47 42 30 



60 60 50 44 32 



65 62 52 45 34 



70 62 54 . 47 35 



75 62 55 48 37 



80 62 56 48 38 



85 62 56 49 39 



90 62 56 49 39 



95 62 56 



100 62 56 



Bombay. The statement on p. 766 which shows the average rate of growth 

 in girth, has been compiled from measurements recorded in Bombay working 

 plans. In each case bark thickness has been included ; where this has not 

 been definitely given in the working plans it has been taken to be 0-25 in. 



(b) Taper of logs. Mr. H. F. Blanford ^ has worked out, from numerous 

 measurements in the Mohnyin and Mosit forests. Upper Burma, the taper of 

 bottom logs 25 ft. in length, with the view of arriving at an estimate of the 

 minimum girth of trees to be felled in order to produce ' Europe squares ', 

 that is, sound, straight timber, free from sap wood, at least 12 in. square and 

 18 ft. in length, and averaging not less than 25 ft. in length. These measure- 

 ments show that the taper increases slightly with age. Allowing for sap wood 

 and bark, the minimum girth at the thin end of the log, in order to produce 

 these squares, is 6 ft. The measurements of taper show that a breast-height 

 girth of 7 ft. 9-7 in., or in round figures 8 ft., is necessary to produce a girth 

 of 6 ft. at 25 ft. above the felling wedge, that is, to produce an average ' Europe 

 square '. Mr. Blanford's measurements are summarized as follows : 



Average taper, i. e. diminution in girth to 



a height of 25 ft. above felling wedge, or 



27 ft. 6 in. from ground. 



Girth at breast height. Mohnyin. Mosit. 



in. in. 



6 ft. to 6 ft. 11 in. . . . 161 141 



7 ft. to 7 ft. 11 in. . . . 19-7 14-4 



8 ft. to 8 ft. 11 m. . . . 23-4 15-7 



9 ft. to 9 ft. 11 in. . . . 260 19-1 



Example : in Mohnyin a tree with a breast-height girth of 8 ft. has a girth at 25 ft. above 

 the felling wedge of 8 ft. -23-4 in. = 6 ft. 0-6 m. 



1 (1) Working Plan for the Mohnyui Reserve, Katha, 1910-11 to 1929-30. 

 (2) Mosit Working Plan, Bhamo, 1910-11 to 1939-40. 



