B4) Functional connectivity among saprophytic beetles in dead wood patches
Gernot Segelbacher & Nathalie Keller
University of Freiburg, Faculty of Environment & Natural Resources, Institute of Forest Sciences, Chair of Wildlife Ecology and Management
Within managed forests, locations with dead wood are distributed irregularly. It is unclear what maximum distance between such isolated patches still allows functional connectivity, and whether distance effects are modulated by matrix quality.
Study questions and hypotheses
We here investigate species and genetic diversity for saprophytic beetles within patches. Additionally we estimate genetic distance between-patches for three invertebrate dead wood specialists with different dispersal ability (short distance, medium distance and long distance disperser) in order to characterize gene flow among patches as a function of abundance, distribution and isolation of dead wood across the landscape and to infer thresholds for functional connectivity between dead wood patches.
- Species and genetic diversity are positively correlated with patch size, and this effect decreases with increasing connectivity to neighbouring patches.
- Gene flow, and thus functional connectivity, is a function of inter-patch distance, with the effect size depending on the species’ dispersal ability.
Approach and methods
Species are sampled at dead-wood patches of different size and distance. Genetic diversity is quantified using both eDNA approaches for total diversity as well as species specific markers (SNP) for genetic distance. Matrix characteristics (tree species composition, height, horizontal and vertical structuring) is obtained by aerial photographs, the amount of coarse woody debris between patches is quantified by a combination of terrestrial mapping and remote sensing. Based on the resulting functions, quantitative thresholds for patch-size, inter-patch distance and matrix quality is derived, which facilitates the implementation and increase the effectiveness of existing dead-wood concepts in forest management.
Outputs and linkages
B4 samples and provide insect data with B3 for all study plots, which complements the other descriptors of forest biodiversity of the RTG (as described in B2 and quanitified in B4-B6. B4 is linked to A1 and A2 making use of their structural data.
- Braunisch V., Segelbacher G., Hirzel AH 2010. Modelling functional landscape connectivity from genetic population structure – a new spatially explicit approach. Molecular Ecology 19: 3664-3678.