Interaction Networks Help to Infer the Vulnerability of the Saproxylic Beetle Communities That Inhabit Tree Hollows in Mediterranean Forests

Abstract

Insect populations are facing unprecedented changes in many ecosystems worldwide. However, do these changes make insect communities more vulnerable? The study of interaction networks can help to answer this question. We assessed the adequacy of network tools to address the long-term variation (after 11 years) of diversity patterns of the saproxylic (wood-dependent) beetle communities that inhabit tree hollows in three representative Mediterranean woodland types. To explore saproxylic communities’ vulnerability to microhabitat loss, we simulated hollow extinctions and recreated feasible future threat scenarios based on decreasing microhabitat suitability. Contrasting responses in diversity patterns among woodland types were found, whereas interaction patterns generally showed substantial temporal variations in the way that saproxylic beetles interact with tree hollows (less interconnected and specialized networks). Network procedures evidenced increased saproxylic communities’ vulnerability, and this situation could worsen in potential future scenarios with decreased microhabitat suitability. The valuable information that ecological networks provide should be considered for improving management and conservation programs.