Carabidocoenoses and Fragments of Forests : exploring the Carabid Landscape

Sammanfattning: Epigeic ground beetles (Coleoptera: Carabidae) were sampled between 2021-06-28 and 2021-07-09 using pitfall traps in the Swedish counties Värmland and Gävleborg. The structural properties of the landscapes surrounding these points were estimated from the Swedish Environmental Protection Agency’s national land cover databases and the Swedish Forest Agency’s data for all formally protected and high conservation value forests using patch-based configurational metrics. Their effects on the diversity of carabids were investigated using generalized additive models. An optimum in explanatory power and model fit was observed at around 452 ha landscapes. In accordance with area-heterogeneity trade-off principles, carabid diversity maximized at intermediate levels of patch shape complexity. No statistically significant response to patch type interspersion could be observed however. Habitat-wise core areas did not affect carabid diversity uniformly. Some increased diversity linearly positively or negatively with increased abundance, while others produced curves or waves. The ratio between total core and ecotone area affected carabid diversity negatively linearly above 1. The results indicate that this approach is useful for investigating landscape ecological processes and therefore developing practical landscape level management strategies. Not only are the configurational parameters of habitat patches significant for carabid communities, they produce completely different responses. As the conservational values of landscape structures gain more attention, solutions to novel issues are demanded. Here I present the first steps in developing a fruitful investigative approach. Finally, discussions on carabid ecology and improvements to both sampling and modeling are presented, and future avenues of inquiry and considerations for management recommended.