A simulation-based approach to assess forest policy options under biotic and abiotic climate change impacts: A case study on Scotland's National Forest Estate

The future provision of forest goods and ecosystem services is dependent, among other factors, on climate change impacts, forest management, and response to forest policies. To assess policy implementation targets for Scotland's National Forest Estate under climate change, we simulated forest growth through the 21st century - with and without the abiotic impacts of climate change, and with and without the biotic impacts of an important fungal disease. Eight different forest management trajectories were simulated under a climate projection, to assess the future provision of forest ecosystem goods and services. Climate change was represented by the IPCC RCP 4.5 projection, and the biotic impact of Dothistroma needle blight was predicted using a new vulnerability matrix. Indicators of three important goods and services: timber production, standing biomass, and biodiversity were measured in the simulation of forest growth and reported at decadal intervals using dynamically linked forest models. We found that both a broadleaved species trajectory and a Forest Enterprise Scotland selected species trajectory would improve standing biomass and biodiversity, but slightly reduce timber volume. Dothistroma needle blight could reduce standing biomass (by up to 3tha−1) and timber volume (by up to 5m3ha−1), but the predicted impact is dependent on the type of forest management trajectory. Our findings show opportunities for diversifying forest management and tree species – and at the same time supporting forest policy to improve forest resilience under uncertain climate change and Dothistroma impacts. The forest simulation has been used to demonstrate and evaluate national strategic delivery of multi-purpose forest benefits in Scotland, and how species and management might be targeted regionally in Forest Districts, to maintain achievable national targets for timber production, carbon sequestration, and biodiversity under climate change.