Standardisation of Instruction. 371 



IV. Increment of Trees and Stands. 



Differentiation in direction, height, diameter, basal area, form, volume ; 

 in time ; current — periodic — average. 



Stages of development: Infantile or seedling; juvenile or brushwood; 



adolescent or polewood ; virile or young timber ; senile or old timber. Brief 



, . r • , r 1 400, 200, 100. _ 



quizz on methods of ascertamment and formulae, — 3 — Borggreve 



^ nd a a 



modification for stands. Quantitative — qualitative increment. 



Laws of progress of increment, and relation of species and site to incre- 

 ment, illustrated by curves and yield tables. Discussion of construction 

 and value of yield tables. 



V. Determining the Rotation. 



Definition of maturity : Natural — technical (size) — financial. 



Definition of rotation: Normal or average felling age chosen as a guide 

 vs. actual felling age. 



Considerations influencing choice of felling age, silvicultural — techno- 

 logical — managerial. Rotation of maximum volume — of most profitable 

 diameter limit — of maximum gross value — of maximvmi net money yield; 

 forest rent and soilrent theories briefly explained. Formulas of financial 

 rotations. Index per cent, its ascertainment and use. Rotations in use for 

 different species and silvicultural systems; their justification. 



VI. Determination of Felling Budget. 



Felling Budget, the amount of material to be harvested, area, volume, 

 number of trees of stated size, value. 



Determined upon one of three premises : 



a. Removal of merchantable part of growing stock at once — lumberman's 

 method — exploitation — varying with market conditions and immediate 

 financial considerations alone. 



b. Removal of exploitable stock with increment distributed in harvests 

 during given time — conservative lumbering — limited exploitation — involv- 

 ing more far reaching financial calculation and crude silvicultural practice. 



c. Preparing at once for sustained yield management of crop production 

 under normal forest idea (forest management proper). 



Budget regulation for sustained yield management has two objects in 

 view: secure a budget of proper size (interest of the present), and secure 

 approach to normal conditions (interest of the future) ; this involves 

 always compromises : budget regulation a guide, not a force. 



Bases for budget regulation and their relation : Area, age classes, 

 diameter classes, volume, value. Importance of thinnings in influencing 

 all these factors. Various methods described as historically developed, 

 with examples and problems. 



1. Schematic Methods. 



a. Simple Division. 



Area Division — Stock Division — Tree size Division. 



b. Periodic Allotment. 



Area allotment — Stock allotment — Combined allotment. 



2. Normal Stock (Formula) Methods. 



Austrian — Hundeshagen — Heyer — Other modifications. 



3. Individualizing (Age class) Methods. 



Saxon — Judeich modification — other modifications. 

 Brief Review. Advantages and disadvantages of various methods com- 

 pared and application to different silvicultural systems. 



24 



