Eco-physiological dynamics behind the inter-tree bud-burst timing variability in temperate deciduous forests.

Bud-burst is a crucial phenological event in deciduous trees, as it controls the start of the growing season, water uptake and the tree energy balance. However, current models do not predict bud-burst timing accurately. One reason for this is related to the inter-tree variability in bud-burst timing, which is generally overlooked. Earlier research highlighted the correlation between inter-tree variability in bud-burst timing and the inter-tree variability in the previous year's autumn phenology and tree size. Yet, we currently do not know the eco-physiological bases behind these dynamics. My project tackles the new hypothesis that inter-tree variability in bud-burst timing in deciduous forests is driven by inter-tree variability in non-structural reserves of carbon and nitrogen. Moreover, as bud-burst timing and reserve dynamics are species-specific and affected by local climate, these dynamics are expected to vary spatially. I will target populations of beech, oak and birch within the temperate oceanic European zone, with the majority of the research taking place in Belgium. The results obtained will be integrated into the model ORCHIDEE, strongly improving predictions of bud-burst timing in deciduous forests. The newly developed version of ORCHIDEE will be used to make simulations of long-term forest growth and carbon stocks. My project will thus fundamental understanding of tree functioning, which is essential to assess forests' ecosystem services.

Keywords:PHENOLOGY, CARBON SINK, NUTRIENT AVAILABILITY, TREES

Disciplines:Ecophysiology and ecomorphology, Biology of adaptation, Plant ecology, Forestry management and modelling