— 170 



for a stand with " b " grade : 



43.6145 



^ ^„ ^ , t Probable % Diff. ±3.2% 



for a stand with " c " grade : 



46.1913 



^ ,,,„ t Probable % Diff. ±3.3% 



Dc=44.63e 



The following diagrams (Plate XXII) show the comparison between 

 the theroetical and the observed results. 



(d) On the Average Height. 



In the preceding part, we have investigated the height curve of test 

 trees in a given stand and asserted that the height curve may be re- 

 presented by the formula: 



Oi _ b] 



and Ti=ae ^2— be 



Hence if we put x—D, then we get 



_^ 

 h=v2=be 

 This last equation shows that the trend of the height of test tree corres- 

 ponding to the average diameter with respect to the age, will be expressed 

 by the formula: 



h=be * 



Hence if the height of the test tree corresponding to the average diameter 



of a stand corresponds to the average height of the given stand calculated 



from the formula: H=-^^, the fluctuation of the average height of a 



In 



stand will be expressed by the equation 



R=be * 

 However it is generally recognised that the average height of a stand is 

 greater than that of a test tree corresponding to the average diameter, 

 but from the diagrams which- we have shown in the previous part, we 



