Balancing biodiversity and economics: Using robust Pareto-optimisation to quantify ecological–economic trade-offs in German mixed beech forests

Biodiversity loss threatens forest ecosystem stability and functioning, while measures to enhance biodiversity trade-off with economic performance. Native tree-species mixtures are promoted to support associated taxa but usually underperform economically compared to non-native species, both in pure and admixed stands. Quantifying ecological-economic trade-offs remains challenging due to uncertainties in economic and biodiversity indicators. Using empirical data on economic (land rent/annuity) and biodiversity indicators (species richness) of five forest taxa from Central German forests, we applied multicriteria optimisation to forest stand-type compositions. We assess the compositional shift of pure (beech, spruce, Douglas-fir) and mixed stand types (beech-spruce, beech-Douglas-fir) under increasing biodiversity targets, accounting for uncertain indicator provision. Stand-type portfolios became more diversified with increasing biodiversity targets. Biodiversity-economic trade-offs were efficiently reduced by incorporating Douglas-fir (in pure and mixed stands) into the portfolio. However, enhancing biodiversity created economic loss, underscoring the need for financial compensation schemes.