V] GENERAL PRINCIPLES OF PLAN 31 



While the general working scheme gives the framework of the 

 whole proposition, the special plan gives full details regarding 

 everything that has to be carried out in the forest during this 

 first period of twenty or thirty years, during which time all its 

 prescriptions remain in force. This includes a felling table 

 showing exactly what area is to be felled each year, and the 

 order of the annual coupes, if they exist; the nature of the 

 fellings, and a set of cultural rules to guide the operator who 

 carries them out; and lastly the material to be removed. This 

 special plan therefore contains the gist of the whole document. 



32. Duration of plan. 



Now to attempt to make any detailed forecast as to the future 

 condition of a forest after the lapse of a century or two, that is 

 to say any forecast that can be put into figures^ — either as regards' 

 cubic contents or money value — is futile and misleading: if we 

 are wise, we shall avoid mathematics based on unknown future 

 conditions, and be content with a hope that, when that remote 

 time arrives, the forest will be to some extent improved as the 

 result of the wisdom of our present intervention. All calculations 

 of every kind should be limited to the period of twenty or 

 thirty years which has been adopted as the duration of the 

 prescriptions of the plan. No attempt should be made to extend 

 any hard-and-fast regulations for a longer future period, nor 

 should any regulation of the yield be imposed as a binding pre- 

 scription for more than twenty, or, at the outside, thirty, years. 



It will in fact be found to be a wise course to follow if it is 

 always provided that the calculations on which the regulation 

 of the yield is based be revised every ten years, and that the 

 working-plan itself be revised at the end of each period of twenty 

 or thirty years, as the case may be. 



Thirty years seems a short part of the life of a high-forest 

 timber crop, but it is a man's whole working lifetime, and some 

 progress should be made, and some improvements found avail- 

 able for introduction in the plan at the end of this period of 

 inception. 



