A sub-continental assessment of responses to climate extremes in ancient beech forests (Fagus sylvatica L.) from the cell to the ecosystem

• Applicant: Professor Dr. Emanuele Ziaco
• Subject Area: Forestry ; Physical Geography
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 524835176

Rising temperatures and changing seasonal precipitation, accompanied by frequent and stronger hydroclimatic extremes, are expected to impact European temperate forests beyond their physiological limits. To understand how single trees and forest ecosystems may respond to these unprecedented conditions, the mechanistic linkages between tree hydraulic functioning and secondary growth need to be specified. The retrospective characterization of wood functional traits, and their association with annual growth rings along sub-continental ecological gradients, provides a space-for-time approach to study species vulnerability to varying levels of environmental stresses.The research proposed here focuses on beech (Fagus sylvatica L.), one of the most important tree species in Europe and highly threatened by anthropogenic climate change. We intend to study four unique old-growth beech forests identified as UNESCO World Heritage Sites, located in the center of the habitat in central and northern Germany, and toward the western and southern limits on the Iberian Peninsula and in Italy, respectively. We will produce annually resolved time-series of basal area increments and xylem functional traits and compare these with remote-sensed vegetation indexes to i) characterize long-term anatomy-growth responses to past hydroclimate variability, ii) upscale signals from the single tree to the forest level, and iii) estimate the vulnerability of beech stands to climate extremes. The sensitivity of xylem functional traits to past extremes is assessed by highlighting directional shifts in trait distribution, considering pre- and post-event periods. The link between functional traits and ecosystem processes is evaluated by comparing the spectral properties of time series of cellular parameters and forest Gross Primary Productivity using state-of-art techniques of sub-seasonal signal enhancement.Wood anatomical traits have developed into suitable indicators of long-term plant physiology and health status. Integrating their climatic sensitivity with ecosystem functioning provides a conceptual framework to predict geographical patterns of species vulnerability in future climatic scenarios. By comparing beech stands across Europe, characterized by natural disturbance regimes, the proposed research will further our understanding of forest resilience to climate change accounting for the species’ potential to respond to hydroclimatic extremes.

• DFG Programme: Research Grants
• Co-Investigator: Professor Dr. Jan Esper