Claws and Effect : how Small Carnivore Richness Responds to Habitat Diversity and Ecological Productivity

Sammanfattning: Species distribution and composition research has gained significance in light of global warming and its impact on biodiversity. Understanding the factors shaping species richness is crucial for wildlife ecology and conservation. Previous studies have shown a general pattern of positive correlation between terrestrial species richness and primary productivity. However, the productivity-species richness relationship varies across regions and spatial scales. Additionally, the link between habitat diversity and species richness remains ambiguous, with studies reporting both positive and negative correlations. This thesis focuses on small carnivores, a diverse group with ecological importance and vulnerability to climate change. I aimed to address the knowledge gaps in what shapes the species richness of small carnivores in Europe. I hypothesize that small carnivore species richness increases with study area productivity and habitat richness. I also hypothesize a positive relationship between small carnivore species richness and decreasing habitat evenness. To test these hypotheses, I employed a multi-scale and multi-species hierarchical modelling approach, estimating the species richness of small carnivores across 64 sites in Europe. These estimates were then used in a meta-analysis that tested the correlation between species richness, productivity, habitat richness and habitat evenness. The occupancy model performance confirms the accuracy of species richness estimates based on expected associations between species' site-use probabilities and environmental covariates. The result of the meta-analysis found a weak association between productivity and species richness but no association between species richness and habitat richness or evenness. While the productivity-species richness relationship shows uncertain results, previous research suggests the presence of additional factors influencing the correlation. The link between habitat diversity and small carnivore richness is inconclusive, with contrasting findings across different studies and definitions of habitat diversity. In conclusion, this study provides insights into the species richness of small carnivores in Europe and their relationships with productivity and habitat factors. However, further investigations are required to understand the complex interactions among productivity, habitat diversity, and species richness. Accounting for indirect effects through trophic levels and considering habitat fragmentation and connectivity will enhance future studies. Understanding these factors is vital for effective conservation and management strategies for small carnivores in the face of global change.