SIBYLA - Náklady

How are the costs of the forestry activities calculated in the growth simulator SIBYLA ?

In the growth model SIBYLA, the costs of the following activities are calculated: cutting, yarding, and wood conversion. In the model, total direct costs are calculated consisting of: wage, material, and social welfare costs. The costs are calculated separatelly for tree species and stand components.

Deriving man-time for basic activities

The calculation of costs is based on the selected Slovak output rates for cutting, yarding, and wood conversion (Standards: 23-2165/234/83-EP Collection 21, 329/90-320 Collection 23, 91/1992-230 Collection 24, 230-318/87-EP Collection 26, 615-OPaM/88 Collection 27).

The basis of the standards is man-time given in man-hours per m³ (Nh.m^-3) of a particular tree species derived from time studies divided into individual methods, technologies, and activities. The man-hours are modified by the wage deduction and wage bonuses depending on the working conditions. Tables 1, 2, and 3 present the inputs for basic activities. The method of man-time determination is simplified for the most common technologies, methods, and procedures. The final man-time (NČ) is derived using the inquiries on relation database tables (Nemec 2003) in SQL (Structured Query Language).

Table 1 Structure of inputs required for the derivation of man-time for cutting

Table 2 Structure of inputs required for the derivation of man-time for yarding

Table 3 Structure of inputs required for the derivation of man-time for wood conversion

Wage costs

Wage costs are derived from the final man-time (NČ) multiplied by tree species volume (V) in m³and by wage tariff (T) in EUR.h^-1:

F^-_mzdy= NČ . V . T

Material costs

a) Material costs for the activities performed with a chain-saw (cutting and wood conversion) are calculated as follows:

F^-_materiál= NČ . K_JMP . M . V

i.e. man-time of the given activities is reduced by the reduction coefficient of compensation for the chain-saw (K_JMP), and multiplied by the material costs per man-hour (M) and realised volume (V).

b) In the case of yarding, material costs are directly derived from the yarded volume (V) and material costs per m³ (M):

F^-_materiál = V . M

Social welfare costs

Social welfare costs are calculated using the wage costs and the coefficient of funds contribution (K_MOSP):

F^-_sociál = F^-_mzdy . K_MOSP

Overall direct costs

Overall direct costs are calculated as a sum of wage, material, and social welfare costs:

F^- = F^-_mzdy + F^-_materiál + F^-_sociál

Wage tariffs T are saved in the code list code_TARIFF, indices K_JMP and K_MOSP can be found in the code list code_INDICES, material costs M are saved in code_MATERIAL,and the final costs are saved in the table Costs in the database of the growth simulator SIBYLA.