70 



3. General and special schemes.— Tlie prescriplion of the 

 possibility involves the formulating of a general scheme or 

 framework on which the Tihole working ot the forest is built 

 up and a special scheme or statement of the fellings to be 

 made during a limited period. It has in some cases been 

 imagined that the general scheme might be dispensed with 

 and the fellings prescribed in what has been called a " preli- 

 minary working* plan." This is, however, a mistaken notion. 

 A forest exploitation must have a definite purpose which 

 cannot be arrived at without considering what is to be the 

 constitution of the normal growing stock to be created. This 

 necessitates the determination of the exploitable age and the 

 drafting of a general scheme of working for that age. 



Thus, suppose the worhing-plan fcr l.CCO acres of sal forest to he — treatment hj 

 the selection-method with the ohject of growing sal trees of two feet in diameter and 

 lequirins 100 years to attain that size ; the possihility being 1,000 trees a year. 

 These prescriptions constitute the general scheme. The regulation of the fellings for 

 a certain time, say for 10 years (that period havixig been adopted as the felling rota- 

 tion) and their allocation to definite areas or blocks, each about one-tenth of th& 

 total area, would form the special scheme or statement of fellings for the first felling 

 rotation. A better example is, hcwever, afforded in the method of snccessive regener- 

 ation fellings in which the periodic blocks and the order in which they are to be 

 regeneiated are prescribed in the general scheme, while the special scheme prescribes 

 in detail the fellings to be made in each blcok during one period only. 



4. ProTisional worliing sclieme.— The possibility is based on 

 the condition of the existing crop ; and as this crop is prac- 

 tically always abnormal, being either insufficient or super- 

 abundant or irregularly arranged, the possibility also exhibits 

 corresponding divergencies frcm Ihe normal standard. 



Thus, a coppice of 500 acres is to be exploited at 20 years. Tlie nonnal annnal 

 felling woiild extend ever 25 acres of coppice 20 years <lcl. Bnt, if there were no 

 crops of, Fsy, 10 to 15 years old, it would not be possible during the first rotation to 

 follow the normal plan: either the area occripied by the crops aged from !16to20' 

 years shoDld furnish tie feHings for the first 10 years, ard then a larger area would 

 be felled, or crops of a lower age than 20 years should be felled during some years. 



It has by some been considered necessary to distinguish 

 between the actual scheme applied and the ideal one ; and 

 the former has, in consequence, occasionally received the 

 special name of provisional working scheme. This is, 

 however, hardly necessary ; because, in the great majority of 

 cases, the only scheme with which we have to deal is provi- 

 sional, and there can, therefore, be no confusion. 



5. Preparatory period.— The length of time required in 

 order to constitute the forest according to the normal condi- 

 tion is sometimes called a ^preparatory period. It is neces- 

 sary to adopt a preparatory period where the age-classes are 

 defective or irregularly arranged, where it is desired to hasten 

 the felling of over-mature material, or where immediate 



