164 THE THEORY AND PRACTICE OP WORKING PLANS 



SECTION FOUR 



CONTROL AND REVISION OF WORKING PLAN 



No working plan can remain alive and useful unless it is 

 revised at frequent, more or less regular intervals. These 

 re\'isions incorporate all the changes which have taken place 

 during the working period. Such renewals may be made at 

 fixed intervals of say ten years, or at irregular intervals, as 

 is commonly the case where re\dsed data or changes in prevail- 

 ing market conditions, etc., necessitate modification of the 

 original plan. 



Since the working period is usually ten years, the working- 

 plan document is usually revised every decade. But under 

 very intensive conditions more frequent re\^sion may be justi- 

 fied, even to the extent of every five years. On the other hand, 

 a plan should not, ordinarily, go without re\ision for more than a 

 decade, even though the working period be longer, e.g., two 

 decades, or even four, as in Prussia and Austria, respectively. 



Especially under the kaleidoscopically changing conditions 

 in most parts of America is it desirable to have frequent revisions 

 so that the working plan may really " work " and not become 

 obsolete within the working period. Special revisions before the 

 end of the working period are, of course, necessitated when- 

 ever, through storm, purchase, or the Hke, a substantial change 

 is caused in the size, character, or composition of the forest. 



The record of the progress of the work on the forest as 

 outlined by the working plan is called the working plan control. 

 This control operates as a check on the execution of the working 

 plan. In European practice these records are kept by maps 

 and books. The entries are made periodically or at the time 

 of completing each of the various projects. The books (called 

 " Control Books ") may conveniently be divided into two 

 parts: I, the cutting and planting record; II, the general or 

 " history " book. The former may conveniently take the 

 following form (page 165). 



