- 1Max Planck Institute for Biogeochemistry, Jena, Germany
- 2ELLIS Unit Jena, Jena, Germany
- 3Friedrich Schiller University Jena, Jena, Germany
- 4European Commission, Joint Research Centre, Ispra, Varese, Italy
Afforestation is widely considered as a key nature-based strategy for mitigating climate change, due to the carbon sequestration potential of forests. While much focus has been on the benefits of carbon sinks, afforestation also induces biophysical changes that can influence the energy budget and the water cycle. A key atmospheric variable potentially affected by these biophysical changes is vapour pressure deficit (VPD), which has a critical role in terrestrial ecosystem functioning, by affecting plant dynamics, growth and health. Through its role in vegetation dynamics, VPD strongly affects land-atmosphere interactions, water and carbon fluxes, and is critical to understanding how ecosystems respond to environmental changes. However, the atmospheric response of VPD to afforestation remains insufficiently explored, and depends on both temperature and absolute humidity. To this end, we performed high-resolution (5km) convection-permitting simulations over a European domain, coupling a regional climate model (RegCM5) with a land surface model (CLM4.5). We focus on the biophysical impacts of changing vegetation cover to VPD, by keeping the CO2 mixing ratio constant. We analyse the resulting VPD changes and explore how temperature and absolute humidity respond to vegetation changes, both at a local and non-local level. Counterintuitively, despite increases in the forest cover over Europe, the VPD experiences small but consistent increases. This suggests that the evapotranspiration changes from the increased forest cover cannot compensate for the higher temperature-induced capacity of the atmosphere to retain moisture, which is driven by changes in the energy budget. To assess possible negative VPD-induced influences of afforestation, we investigate the implications of the new VPD regimes for different plant functional types (PFTs) across European climate types. Our findings contribute to a more nuanced understanding of the biophysical impacts of afforestation and offer actionable insights for climate change mitigation strategies.
How to cite: Blougouras, G., Caporaso, L., Jiang, S., Reichstein, M., Cescatti, A., Brenning, A., and Migliavacca, M.: Biophysical impacts of afforestation over Europe on atmospheric dryness – a simulation study, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12983, https://doi.org/10.5194/egusphere-egu25-12983, 2025.