Spanish ecosystems contain a great richness of species in spite of being subjected to ancestral human exploitation. The article stresses the importance of the traditional agricultural-forestry-pasture systems in the maintenance of biological diversity. Specifically analyzed is the role of one of the characteristics of these systems, namely the spatial configuration of the landscapes. That is, the relative spatial position occupied by their elements in the territory. In many cases, this characteristic is the result of an historic and continued optimization of natural resources management. The configuration of the landscape affects the horizontal flow of energy and nutrients, thus conditioning the ecosystems' possibilities of organization and modifying their production values and biological diversity. This has been shown in two studies carried out with very different approaches in two very different Spanish agricultural-forestry-pasture systems (caserios and dehesas). In both cases, spatial configuration of their landscape determines changes in the biological diversity values of the vegetation. In the particular case of the dehesas, their peculiar configuration is a crucial factor in understanding the efficiency of the nutrient use and the exceptionally high biological diversity factors of their pastures. While some environmental policies give priority to the conservation of large habitats with uniform little altered landscapes, the article stresses the importance of understanding the heterogeneity and configuration of the agricultural-forestry-pasture landscapes as an example in the quest for productive systems of high naturalistic value. This is particularly important in the case of the unprotected Spanish spaces (over 90% of the territory), when the idea of sustainable development needs to be applied.