Finding equilibrium in continuous-cover forest management sensitive to interest rates using an advanced matrix transition model

Abstract

Continuous-cover forestry is a management alternative that seeks to provide more diverse forests for continual multi-purpose benefits. Whether there is an economically-optimal equilibrium of uneven-aged forest can be tested deterministically by varying interest rate i. To answer this question, optimisation focused on maximising the net present value for the long-term period was performed using the Subplex algorithm integrated within a density-dependent stand-level matrix transition model. A regular-grid inventory of mixed uneven-aged forests in the West Carpathians, Central Slovakia, was used to parameterise the model. The results showed that a steady state can be reached that is characterised either by a near equilibrium at an i of 1% and higher, or by a continuous fluctuation at an i of 0% and 0.5%. When starting optimisation with a real stand situation with i of 2% and higher, deviations from an equilibrium state appeared both at the beginning and end of the optimisation run. The conclusion is therefore to only interpret the middle-stabilised sequence from the long-term optimisation results as a real equilibrium. Considering the individual target diameter specific for crown size and stem quality of trees within the extended matrix model improved the financial results by 7%. Crown size, representing tree vigour and growth potential, was more important for the improvement of financial results compared to stem quality related to timber price.