WOOD-LIM · Above and belowground wood formation thermal limits

The timing and duration of the growing season of plants determine biomass production and strongly influence the global carbon and water cycles. However, predicting growing season start and end in woody species remains challenging due to limited knowledge of the fundamental factors controlling wood formation throughout the season, particularly belowground. Earlier research shows different thermal thresholds for trees and shrubs. The central hypothesis of the project is that the thermal limit of roots is close to freezing, and therefore lower than that of stems. Moreover, thermal limits are expected to vary little between trees and shrubs when taking into account the buffering effects of microclimate. The project will mainly focus on stem and root wood formation and its kinetics to evidence the timing of wood formation and the mechanism behind it. To achieve this, the project will combine in-situ monitoring of trees and shrubs along an altitudinal gradient, providing different thermal conditions with controlled experiments testing root temperature thresholds in the most common European woody species. the implication of phytohormones and carbohydrates for wood formation temperature threshold will be investigated. Ultimately, the research will provide a foundation for bottom-up assessments of woody species’ responses to climate change. The project outputs will be directly relevant for policymakers, offering key insights for forest management and the optimisation of ecosystem services, including timber production and climate change mitigation.