Modelling the impact of stand type, tree traits, and temperature on norway spruce survival under bark beetle attack in Germany

Forests provide vital ecosystem services such as carbon sequestration , water regulation, and habitat diversity. However, climate change and bark beetle infestations threaten forest stability, particularly in Norway spruce ( Picea abies ) monocultures . This study examines how stand type (mixed vs. pure spruce stands), tree characteristics (e.g., diameter, height, crown area), and mean annual temperature influence the survival of Norway spruce under bark beetle attack. Using field data from the German Forest Inventory (2012–2022) on over 100,000 trees, we compared survival rates in mixed stands and monocultures through chi-squared tests, logistic regression, Kaplan-Meier analysis, and Cox proportional hazards models. Results reveal that Norway spruce in mixed stands have significantly higher survival rates under bark beetle attack—on average 10 % higher than monocultures—while survival rates are similar without beetle pressure. Stand type and mean annual temperature emerged as key predictors of Norway spruce survival. These findings highlight the role of diverse stand compositions in enhancing forest resilience, supporting adopting mixed-forest management practices to mitigate climate change impacts and biotic stressors. • Models survival of over 100,000 Norway spruce trees during bark beetle outbreaks. • Uses logistic regression and survival models to assess survival dynamics. • Shows higher survival rates for spruce in mixed stands compared to monocultures. • Demonstrates that mixed spruce forests are more resilient to bark beetle outbreaks. • Supports theoretical models of mixed forest dynamics through survival analysis.