Large cemetery trees are vital for ecosystem services and tree-related microhabitats: A study from Karlsruhe city, southwest Germany

Urban trees play vital roles in climate regulation, improving air quality, sequestering carbon, and supporting biodiversity. However, the ecological significance of cemetery trees remains understudied. We analyzed 200 large trees from five common broadleaved species across three cemeteries in Karlsruhe, Germany. Field measurements assessed tree size, crown health, pruning, and tree-related microhabitats (TreMs). Using i-Tree Eco v6, we then estimated carbon storage and sequestration, oxygen generation, pollutant removal, and transpiration from these inputs. We employed species comparisons, ordination, generalized linear models, and Spearman correlations to explore differences and relationships among these ecosystem services. Results showed species differed in ecosystem service profiles, reflecting complementary ecological roles rather than one species dominating all services. Larger DBH (diameter at 1.3 m height) correlated positively with TreM richness, abundance, and leaf-area-dependent services. Crown dieback was linked to higher TreM abundance but reduced leaf area, pollutant removal, and transpiration. TreM richness and abundance significantly positively correlated with carbon storage, though not with carbon sequestration or oxygen production. A positive relationship was observed between TreM richness and a composite of canopy-mediated ecosystem services. These findings suggest that large, structurally diverse cemetery trees can jointly store carbon and host various microhabitats, though annual physiological regulating ecosystem services may not always complement TreM diversity. Due to their high ecological value, cemetery trees should be conserved as much as possible, and conservation efforts should balance tree health, habitat continuity, and public safety.