Abstract
- Retention forestry is promoted as a conservation-oriented management strategy to sustain forest biodiversity by preserving key structural elements, such as single old trees and deadwood. However, the effectiveness of this approach in conserving the diversity of spiders as generalist predators remains unclear, particularly because the effect of structural elements under retention forestry on spiders may be mediated by its effect on prey availability.
- We sampled spiders (Araneae) and potential prey (Diptera, Hemiptera, Collembola) in 55 1-hectare plots across mixed temperate forests of the Black Forest, Germany. We used pitfall traps targeting species active on the forest floor. We studied spider abundance, taxonomic diversity, ecological diversity (combined measure of functional and phylogenetic distance) and community composition along gradients of forest structure (canopy cover, proportion of conifers, stand structural complexity, volume of lying deadwood, herb cover and understorey plant richness). We also looked at how potential prey abundance varied with forest structure and cascaded to their predator.
- Spider richness increased with stand structural complexity. Abundance declined with increasing proportion of conifer and increased with understorey plant richness. Ecological diversity was not significantly related to forest structural variables.
- Prey abundance increased with structurally complex stands and tended to decline the proportion of conifers. Higher prey abundance was positively related to spider abundance and partly accounted for lower spider abundance in high proportion of conifer stands. Community composition shifted with canopy cover and conifer gradients, and functional trait identity varied with canopy cover, volume of lying deadwood and stand structural complexity.
- Synthesis and applications. Our findings suggest that retention forestry practices, which maintain structural complexity through spatial and vertical heterogeneity, integrate deadwood and support diverse plant communities, may support spider richness and shape dominant ecological strategies while influencing predator populations through prey availability. Managers aiming to enhance biodiversity in managed forests may benefit from prioritising structural complexity and understorey diversity, while considering potential trade-offs associated with stand compositions. These findings provide an evidence-based foundation for integrating principles of structural complexity, resources availability and trait-based filtering into forest management and conservation strategies.
Fardiansah, R., Rehling, F., Cordeiro Pereira, J. M., Heidrich, L., Stör, J. L., Rothacher, J., Müller, J., & Klein, A. M. (2026). Structural complexity and prey availability shape spider communities under retention forestry. Journal of Applied Ecology, 63(5), e70415. https://doi.org/10.1111/1365-2664.70415