Combining spatial and other objectives in forest design

The paper presents a forest planning model for Northern Germany with an objective function which includes an economic, even flow and spatial component. The spatial modeling approach followed in this analysis relies on specific geographic relations among neighboring stands, including the distance between stand centroids and the length of the common boundary between adjacent compartments. To our knowledge, this is a new and more realistic approach in spatial optimization when compared with earlier approaches. The geographic data are derived from a GIS system and stored in a database. The database also includes details of all management regimes and the corresponding objective function coefficients. The method is first applied in a relatively small forest with only 41 compartments. The Simulated Annealing algorithm is used to identify the optimum combination of management regimes. Solutions are presented for different objective function components. When the even flow and spatial components were added in the objective function, the economic objective was only moderately reduced. The method is then also applied using a bigger example, a forest with 591 compartments. The results, obtained within a reasonable processing time, were similar and, because of the large number of compartments, the even flow was perfectly balanced.