FOREST SURVEY 5 



only an average portion of the stand may be measured. The laws of 

 averages, or of sampling are applied to solve nearly every problem in 

 Forest Mensuration, in order to bring the cost of the field work within 

 practical limits. 



When Mensuration deals with the growth of trees and stands, and 

 of whole forests, its purpose is to predict what will occur in the future. 

 It bases these predictions upon the results which have occurred in the 

 past, under conditions judged to be similar to those which will affect 

 these future stands. The laws of growth of trees, and especially, of 

 stands composed of great numbers of trees competing with each other 

 for existence and supremacy, can only be approximated on the basis of 

 probabilities and averages. The results of living forces cannot be 

 predicted with mathematical accuracy, and the study of growth par- 

 takes of the nature of research rather than of routine measurement of 

 definitely determinable quantities. 



Neither Forest Mensuration nor Forest Surveying produces any 

 physical change or improvement in the forest, as does the application of 

 silviculture, protection, and lumbering. The achievements of forestry 

 depend upon the amount and character of the actual work done along 

 these latter lines. Misdirected work, done at the wrong time or place 

 and in the wrong quantity, or by too expensive a method when com- 

 pared with results, means waste, inefficiency, and ultimate ruin and 

 bankruptcy of the enterprise. The data supplied by mensuration and 

 supplemented by forest finance are the balance wheel of forest industry. 

 But the necessity of restricting the funds expended upon the mere col- 

 lection of data to as small a per cent as possible of the total budget of 

 expenditures, reserving the greater portion for the operations which 

 effect actual change in the forest, is obvious and justifies the use of meth- 

 ods based on averages rather than extreme mathematical accuracy. 



7. Forest Survey. Forest Survey is the general term applied 

 to the project of gathering all the quantitative data required regarding 

 a specific forest property. It includes a survey and maps of the area, 

 thus locating the property and its subdivisions, a measurement of the 

 volume and character of the timber, and it may cover other resources 

 such as land classification, waters, forage, game, and fish. Forest 

 Surveying and Forest Mensuration deal with the principles and methods 

 of accomplishing this work. The Survey itself is the enterprise or 

 project of securing the data. Accuracy in the results of a forest survey 

 is judged, not on an absolute standard, but in relation to the balance 

 between utility of the results and the cost of obtaining them, and is 

 therefore always a relative term. 



