Risk-sensitive planning support for forest enterprises: The YAFO model

YAFO is a planning-support tool for the development of management plans under uncertainty focusing on the forest enterprise level. Based on existing stand data, the software provides the calculation of management scenarios (felling plans) for single stands that are optimized with respect to financial considerations and ecological constraints. Under these constraints, YAFO predicts timber stocks, harvest amounts and financial returns for each simulation period. The YAFO package consists of an optimization module, that has been programmed using the modelling software AIMMS. In addition, it contains two Excel-based spreadsheet files - an import and evaluation module and a risk analysis module. The YAFO model calculates financially optimized management scenarios by means of the net present value development of single stands. Optionally, the objective function can also consider risks and uncertainties due to natural calamities and timber price fluctuations, using the value at risk approach or risk utility functions. Nonlinear programming algorithms are used as solution techniques. As YAFO provides the additional flexibility to switch between two timber grading options on stand level, effects of timber price scenarios on grading can be analyzed. Due to its modular design, it can be easily adopted to individual data bases.