Spatial Optimization in Forest Planning Using Different Fragmentation Measures
Habitat fragmentation is a key biodiversity issue in forest planning at the landscape level. More consideration is needed in assessing the choice of the landscape index in spatial forest planning optimizations. The objective of this study was to evaluate the effects of four different landscape indices on the fragmentation when applied to forest planning optimization problems. The indices were included in a long-term planning problem from a case study area in Northern Sweden, with both timber production and biodiversity goals. The results show that different spatial indices affect the landscape structure differently and that the effect of the index is very dependent on the available area of habitat. For mean distance between patches and shape index, for example, very good index values were achieved, but at the cost of total area of habitat. Moreover, the optimization algorithm chose small and regular-shaped patches, which had a positive effect on the index value, but a negative impact on the overall fragmentation pattern. This is an important result for the practical application of landscape indices to forest planning situations: by only tracking the numerical changes in landscape configuration, the detrimental effects of the optimization setup on fragmentation as a whole may be overlooked.