The influence of tree species, stratum and forest management on beetle assemblages responding to deadwood enrichment

Deadwood harbours a diverse community of saproxylic beetles but has become rare as a result of intensive forest management. The lack of this key-resource has yet largely unmeasured consequences for the distribution of saproxylic species, their overall abundance and guild composition. In order to investigate these effects we established a large field experiment by enriching freshly cut beech and spruce deadwood of different size in the canopy and on the ground beneath beech and spruce trees in age-class and extensively managed forests. Flight Interception Traps (FITs) were used to collect attracted arthropods. Sampling was performed monthly from April to September and resulted in a total of 7542 beetles sorted to 371 species of which 5502 specimens (73%) and 180 species (49%) were saproxylics. All beetles as well as saproxylic assemblages taken separately showed substantial differences in species and guild composition between Fagus and Picea and the canopy-ground stratum but not between wood diameter classes. Indicator analysis identified 21 beetles indicative for beech and 27 species indicative for spruce. This assortment is largely supported by ecological data. In respect to vertical stratification 13 beetles (61.9%) were indicative for beech canopy but only 5 species (18.5%) for the spruce crowns. Difficult to interpret are results comparing forest management types. A respective effect was detected only in beech crowns. Forty-nine endangered species (13% of the total) were collected of which 76% were saproxylics (representing 80% of all endangered beetles). (C) 2014 Elsevier B.V. All rights reserved.