Trees are essential to urban biodiversity, providing key ecosystem services and enhancing the resilience of urban environments. However, urban trees often have short life spans, and urban forests frequently lack age diversity—particularly mature and senescent habitat trees, which are scarce or entirely absent. These older trees support the highest levels of biodiversity, yet they are frequently removed, posing a significant threat to biodiversity conservation, ecosystem service provision, and ultimately, ecosystem resilience.

Our research project, “Habitat Trees: Home for Biodiversity”, investigated the biological communities supported by habitat trees. The aim was to better understand tree-associated biodiversity and to develop practical strategies for tree management and conservation.

We assessed biodiversity across various taxonomic groups—including microorganisms, invertebrates, vertebrates, lichens, and mosses—while also considering vertical stratification, tree-related microhabitats (TreMs), seasonal variation, tree species, and other structural characteristics. Our findings show that habitat trees can host thousands of species from multiple taxonomic and functional groups, including rare and protected species. Many of these organisms are vertically stratified and associated with specific structures such as TreMs, which are often removed in urban contexts, leading to significant biodiversity loss.

This knowledge is critical for implementing biodiversity-conscious tree management, as interventions like pruning or branch removal can have substantial ecological impacts. Our findings are being integrated into urban forestry practices by developoing standardized approach for identifying and mapping habitat trees and for creating ecological networks that acknowledge their conservation value.