Are biodiversity patterns of saproxylic beetles shaped by habitat limitation or dispersal limitation? A case study in unfragmented montane forests

Abstract

Understanding the processes that shape biodiversity patterns is essential for ecosystem management and conservation. Local environmental conditions are often good predictors of species distribution and variations in habitat quality usually positively correlate to species richness. However, beside habitat limitation, species presence-absence may be constrained by dispersal limitation. We tested the relative importance of both limitations on saproxylic beetle diversity, using forest continuity as a surrogate for dispersal limitation and stand maturity as a surrogate for habitat limitation. Forest continuity relies on the maintenance of a forest cover over time, while stand maturity results in the presence of old-growth habitat features. Forty montane beech-fir forests in the French pre-Alps were sampled, under a balanced sampling design in which forest continuity and stand maturity were crossed. A total of 307 saproxylic beetle species were captured using flightinterception traps and Winkler-Berlese extractors. We explored the response of low-versus high-dispersal species groups to forest continuity and stand maturity. Saproxylic beetle diversity increased significantly with stand maturity and was mostly influenced by variables related to deadwood diversity at the stand scale and suitable habitat availability at the landscape scale. Surprisingly, no evidence of dispersal limitation was found, as diversity patterns were not influenced by forest continuity and associated variables, even for low-dispersal species. Our study demonstrates that in an unfragmented forest landscape, saproxylic beetles are able to colonize recent forests, as long as local deadwood resources are sufficiently diversified (e.g. tree species, position, diameter and/or decay stage).

The impact of even‐aged and uneven‐aged forest management on regional biodiversity of multiple taxa in European beech forests

“…Higher amounts of dead wood in UEA forests may not lead directly to higher saproxylic beetle diversity compared to the EA forests, which provides higher light availability and air temperatures in specific stages. In any case, our results further support the claims that reduced habitat connectivity (Janssen et al., ), extinction due to unsuitable habitats (Grove, ) or lack of niches (Brunet et al., ) are very unlikely to operate as important filters for biodiversity in the EA system in comparison to UEA.…”

Trade‐offs between carbon stocks and biodiversity in European temperate forests

“…Sampling of forest structure is described in detail in Burrascano, Sabatini, and Blasi, (), Janssen et al (), Márialigeti, Tinya, Bidló, and Ódor (), Paillet et al, (), Sabatini et al, (), and Sitzia et al, (), and synthesized in Supporting Information Table S3. In short, we sampled living trees in plots ranging from 491 to 2,827 m 2 in area using a diameter at breast height (DBH) threshold of 10 cm.…”

Congruence across taxa and spatial scales: Are we asking too much of species data?

“…Birds were sampled by point counts (see Bouvet et al, ). Finally, saproxylic beetles were sampled by window‐flight interception traps, emerging traps and Winkler extractors (see Janssen et al, ). We checked and homogenized species lists for plants by using The Plant List (http://www.theplantlist.org); we used ITALIC for lichens (Nimis & Martellos, ), Index Fungorum for fungi (http://www.indexfungorum.org/names/names.asp), Hodgetts () for bryophytes, and several online resources for animals (http://www.fauna-eu.org/; http://www.gbif.org/; http://www.organismnames.com/; https://inpn.mnhn.fr/accueil/index).…”