Computer Program for Determining an Optimum Solution in Long-Term Forest Exploitation Process

In the paper we describe a possible usage of dynamic programming, based upon Bellman’s principle, in order to obtain the optimum solution of a predefined long-term forest exploitation process. In this process measures and activities are introduced at each step within the iterative solution process, and their effects on the intermediate results and the final solution are stated in the form of mathematical relations. The whole forest area which is taken into consideration is divided into a number of homogeneous parts — segments. For each of these segments, five special functions are imposed by means of which we direct (guide) the process within a number of time intervals, either years or decades. These functions are: (F1) the maximum possible tree growth capacity, (F2) exploitation capacity, (F3) the quality of the existing tree specimens, (F4) level of administration — care for improved growing conditions, and (F5) stage in segment development, based upon the age (oldness) of the tree specimens in it. The functions help to optimize exploitation endeavours. At each step of the iterative solution process four possible activities can be imposed: (A1) no activity at all, (A2) exchange of the existing tree specimen with a new one, (A3) rarefying, and (A4) restoration. The exploitation policy is defined by a sequence of chosen activities during the iterative process. The stated functions, activities and time intervals are part of the mathematical model and dynamic programing process respectively. The problem and the corresponding computer program can be extended by incorporating some additional functions and activities. Program prototype in FORTRAN was written and tested on DEC-10 computer at the University of Ljubljana, Yugoslavia. In the paper we also comment the problems which are associated with dynamic programming applied to such type of problem.