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The control and maintenance of species composition of mixed stands is a highly relevant objective of forest management in order to provide multifunctionality and climatic resilience. In contrast to this requirement there is, however, an evident lack of quantitative methods for mixture regulation. In this context, we propose an approach for the regulation of mixture proportions that has been implemented in a forest management model. The approach considers species-specific growth characteristics and takes into account the mixing effect on stand density. We present five exemplary simulations that apply the regulation. Each simulation maintains one of five desired species compositions. In these simulations, we consider the species European beech and Norway spruce under good site conditions, thus representing the most prominent mixed stands in Central Europe. Based on this model experiment, we analyze the potential benefit of controlled mixing regulation for achieving desired levels and combinations of ecosystem service provision, in particular productivity, diversity, and groundwater recharge. We found that a constant 50% basal area share of beech (equivalent growing space share of 80% to 70% depending on stand age) provided the most balanced supply of ecosystem services. Prominently, groundwater recharge considerably decreased when beech basal area shares were held below 50%. We discuss the ecological and practical implications of the regulation approach and different mixing shares.

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In the field of assessing forest ecosystem service provision and biodiversity, there seems to be a gap between an existing large body of valuable expert knowledge and its application. We propose fuzzy logic evaluation systems as a contribution to closing that gap. With this method-focused pilot study, we explored the potential of fuzzy logic for assessing the provision of different ecosystem services in a simulation case study, covering a large forest landscape in Southern Germany. Based on expert knowledge and available literature, we designed a fuzzy logic evaluation system for biodiversity, and the ecosystem services balanced wood production, storm and bark beetle damage resistance, and recreation value. This evaluation system was applied to 100-year simulation outcomes for three contrasting forest management scenarios in the landscape of interest. While the results of the case study in general support the idea of a multifunctional forest management, fuzzy logic turned out pronouncedly useful as a method. This is due to its potential to make otherwise unused expert knowledge applicable and transparent in a formal evaluation process. Based on our results, we discuss the approach related to its potential for interdisciplinary integration of knowledge, for revealing tradeoffs and synergies, and participative planning processes.

Introduction: Changes in socio-economy and climate are affecting the demand of wood products globally. At the same time, society requires that forest supporting structures like biodiversity are maintained and preserved while the demand for wood products is also covered. Management support systems, like forest simulation models, that are able to analyze connections as well as quantify trade-offs between forest structure management and biodiversity indicators are highly sought. However, such models are generally developed for the local plot or stand scale only and ecosystem-scale analyses are missing. In this study, we analyzed ways to interpret results from the single-tree forest simulator SILVA from the local to the ecosystem scale. We also analyzed the impacts of forest management on biodiversity using two species diversity indicators, the species profile index and the species intermingling, for scenarios adapted from the GLOBIOM model in the case study "Augsburg Western Forests", a high productive region in South-Germany. In order to evaluate diversity tendencies across the ecosystem, we applied a moving window methodology. Results: The relevance of scale for the interpretation of management effects on species diversity was shown and clear differences between scenarios revealed. The differences between scenarios were particularly visible when comparing the two diversity indicators, especially because the species profile index focuses on vertical and horizontal information and the species intermingling focuses mainly on horizontal structures. Under a multifunctional scenario, biodiversity values could be preserved at all scales in the vertical dimension. However, under a bio-energy-oriented scenario diversity at the local scale was reduced, although at the ecosystem level, and only in the horizontal dimension, diversity remained at relatively high values.Conclusions: With this work, we can conclude that integrative modeling, with multiple scenarios, is highly needed to support forestry decision making and towards the evolution of forest management to consider the ecosystem scale, especially when the optimization of diversity is a management priority.