6533b81ffe1ef96bd1278877

RESEARCH PRODUCT

Saproxylic beetle assemblages of three managed oak woodlands in the Eastern Mediterranean

subject

description

Oak woodlands belong to the natural vegetation in most Mediterranean regions but have suffered from a long history of woodland devastation and overgrazing. The remaining woodlands have been managed in different ways, and we expected this to have effects on the fauna associated with trees. We investigated three different sites in the Eastern Mediterranean with flight-interception traps to analyse the impact of woodland management on dead wood and tree structures and the relevance for saproxylic beetle assemblages. Our results show significant differences in trunk diameter, stein density and dead wood diversity between the three sites. Old oaks in semi-open woodland are characterised by diverse stages of dead wood and harboured most saproxylic species (74 species out of a total of 98) and most individuals. With regard to rarefied species richness, we found that coppice woodland with a high stem density and medium-sized trees has the most diverse beetle assemblage (19.7 species per 100 individuals). Species richness was in general strongly associated with the diameter of the oaks, but, surprisingly, was also of the same level as species numbers reported from studies in Central Europe. The large number of singletons, which made tip 40 % of the entire sample, may indicate a considerable number of species that were not trapped. We discuss the impact of different management options on tree shape and woodland structure, issues which are also important for the saproxylic beetle assemblage associated with Mediterranean oaks. We conclude that oak woodlands in the Middle East - and especially those woodlands that have been used and managed in a sustainable way - represent a valuable resource for insect diversity. Oak woodlands belong to the natural vegetation in most Mediterranean regions buthave suffered from a long history of woodland devastation and overgrazing. The remaining woodlandshave been managed in different ways, and we expected this to have effects on the fauna associatedwith trees. We investigated three different sites in the Eastern Mediterranean with flightinterceptiontraps to analyse the impact of woodland management on dead wood and tree structuresand the relevance for saproxylic beetle assemblages. Our results show significant differencesin trunk diameter, stem density and dead wood diversity between the three sites. Old oaks in semiopenwoodland are characterised by diverse stages of dead wood and harboured most saproxylicspecies (74 species out of a total of 98) and most individuals. With regard to rarefied species richness,we found that coppice woodland with a high stem density and medium-sized trees has themost diverse beetle assemblage (19.7 species per 100 individuals). Species richness was in generalstrongly associated with the diameter of the oaks, but, surprisingly, was also of the same levelas species numbers reported from studies in Central Europe. The large number of singletons,which made up 40 % of the entire sample, may indicate a considerable number of species thatwere not trapped. We discuss the impact of different management options on tree shape andwoodland structure, issues which are also important for the saproxylic beetle assemblage associatedwith Mediterranean oaks. We conclude that oak woodlands in the Middle East – and especiallythose woodlands that have been used and managed in a sustainable way – represent a valuableresource for insect diversity.