ESTIMATING THE VOLUME. 69 



to measure the volume on the sample plot as accurately as 

 possible. 



5. Merits of the Method of Sample Plots. 



The method of sample plots works quickly, and it affords 

 a great saving of time and expense as compared with the 

 measurement of whole woods. On the other hand, its accuracy 

 depends on the degree, to which the sample plot represents 

 an average of the whole wood. Hence, it only yields accurate 

 results in regular grown young and middle-aged woods, less 

 so in old- irregularly stocked areas, or where the (quality 

 changes frequently. The method is chiefly useful, where 

 extensive areas have to he assessed, or where the value of 

 the produce is small, in fact where a high degree of accuracy 

 is either impossible to attain, or not required. Where only 

 small areas have to be measured, or where the value of a 

 forest has to be ascertained for the purpose of sale — in fact, 

 when a high degree of accuracy is wanted— the whole wood 

 should be measured. 



Section III. — DETEiniiNAXioN of the Volume by Estimate. 



Instead of measuring the trees on the whole or a part of the 

 area, the volume can be estimated in various ways, of which 

 the following deserve to be mentioned : — 



1. Estimating the Volume of the Wood as a Whole. 



This method, being the oldest and roughest of all, consists 

 of going through the wood and estimating the volume, either 

 of the whole wood, or per unit of area, if the total area is 

 known. The estimator must consider differences in the density 

 of stocking, the average volume per tree, the differences in the 

 quality of the locality, and, if for the whole wood at once, its 

 area or number of trees. It stands to reason, that the method 

 requires great experience and practice on the part of the 

 estimator, and even then considerable mistakes may be made. 



