A solution method for uneven-aged management applied to Norway spruce

The uneven-aged management problem is to determine the management regime fo r an existing stand over an infinite time horizon, without ever clearcuttin g it. A new solution method to solve this problem is presented and demonstr ated on simulated Norway spruce stands with different initial stand structu res. Diameter distributions were used as a convenient way to describe these structures. The method, which puts much effort into determining the timing of harvest activities, is based on Tabu search and greedy heuristics. The growth dynamics were described with a single tree simulator. Different prob lem approaches for this problem were adopted to maximize the net present va lue (NPV) of harvested trees, with or without steady-state constraints. Wit h no such constraints, a finite time horizon approximates the general manag ement problem, while the steady-state constraints involved fixed and equili brium endpoints. The fixed endpoint was a reverse J-shaped diameter distrib ution, and its purpose was to mimic the structure of a virgin stand. Analys is of economic efficiency, productivity. and managerial implications were m ade. With the method used and for the endpoint problems, the conversion str ategy, conversion length. and steady-state diameter distribution were deter mined simultaneously. The Kolmogorov-Smirnov measure was used to describe t he similarity between diameter distributions and was put directly into the constraints. The infinite approximation is suggested as the best problem fo rmulation as it, in contrast to a steady-state approach, does not assume th at a resource system reaches a climax, eliminates the need to define a diam eter class width, and involves no fixed cutting cycles. The even-aged manag ement problem, which is to determine the best period for clearcutting and t he best thinning regime that precedes the clearcut, while recognizing the s oil expectation value, was analyzed for comparison. The method is flexible, independent of the kind of growth simulator used, and can, for example, be directly applied to a diameter class model.