Abstract

Saproxylic beetles are among the most important forest invertebrates associated with dead and decaying wood, yet many species are threatened by the loss of old-growth forest structures. We investigated the microhabitat use, demography and dispersal of two saproxylic longhorn beetles, Rosalia alpina (Linnaeus 1758) and Morimus asper funereus Mulsant 1863, in a system of 12 habitat patches within a forest reserve in Triglav National Park, Slovenia. We examined 30 potentially suitable trees and marked 68 individuals of M. a. funereus and 37 individuals of R. alpina. Generalised linear mixed models showed contrasting habitat preferences between the two species. M. a. funereus strongly preferred standing, dying beech (Fagus sylvatica) trees with large diameters, whereas R. alpina showed no significant preference for any studied tree category and displayed a patchy distribution. These patterns suggest ecological niche differentiation and possible resource partitioning between the species. The best-fit POPAN open population model (φtlin ptlin btlin+tlin2) estimated the population size of M. a. funereus at 144 individuals (95% confidence interval 88–199), with high but gradually declining survival and peak recruitment in early August. For R. alpina, a population size estimate was not possible due to sparse recaptures; however, an extensive area of contiguous beech forest near the study area extends the suitable habitat for both species. M. a. funereus made predominantly short-distance movements (maximum 34 m), whereas R. alpina undertook less frequent but substantially longer movements (maximum 457 m), indicating greater dispersal ability. Our results highlight the importance of structurally diverse old beech forests with abundant dead and dying trees for the persistence of both species and suggest that differences in habitat use and mobility may reduce direct competition in sympatry.

Keywords

Saproxylic beetles, habitat, demography, mark-release-recapture, forest reserve

Fulltext

Microhabitat use and co-occurrence patterns of Rosalia alpina and Morimus asper funereus (Coleoptera: Cerambycidae) in an old-growth beech forest, Triglav National Park, Slovenia