Beta-diversity in central European forests decreases with elevation due to changes in local community assembly processes, not just the number of species available. By analyzing forest data, researchers found that as elevation increases, the variety of species between different areas decreases more than the variety within each area. This suggests that factors like environmental conditions and species dispersal play a role in shaping forest diversity patterns. The study shows that understanding how different species are distributed across communities can help explain why beta-diversity decreases with elevation in temperate forests.