Plant species diversity in managed and unmanaged forests was studied in five national parks in Italy. The researchers compared plant richness and composition in beech-dominated unmanaged stands and managed high forests. They found that species composition differed between the two types of forests, but richness and beta-diversity did not. Plant richness may increase with more forest structural diversity, like deadwood and canopy variation. Deadwood accumulation influenced beta-diversity, while canopy diversification had a weaker effect on species richness. Overall, unmanaged forests had different plant species compositions but not significantly higher species richness and beta-diversity compared to managed forests.