iTREE

iTREE-Long-term variability of tree growth in a changing environment – identifying physiological mechanisms using stable C and O isotopes in tree rings

Context

Trees play are a critical role in the carbon cycle – their photosynthetic assimilation is one of the largest terrestrial carbon fluxes and their standing biomass represents the largest carbon pool of the terrestrial biosphere. Understanding how tree physiology and growth respond to long-term environmental change is pivotal to predict the magnitude and direction of the terrestrial carbon sink.

iTREE is an interdisciplinary research framework to capitalize on synergies among leading dendro-climatologists, plant physiologists, isotope specialists, and global carbon cycle modellers with the objectives of reducing uncertainties related to tree/forest growth in the context of changing natural environments. Cross-cutting themes in our project are tree rings, stable isotopes, and mechanistic modelling.

Objectives

We will (i) establish a European network of tree-ring based isotope time-series to retrodict inter-annual to long-term tree physiological changes, (ii) conduct laboratory and field experiments to adapt a mechanistic isotope model to derive plant physiological variables from tree-ring isotopes, (iii) implement this model into a dynamic global vegetation model, and perform subsequent model-data validation exercises to refine model representation of plant physiological processes and (iv) attribute long-term variation in tree growth to plant physiological and environmental drivers, and identify how our refined knowledge revises predictions of the coupled carbon-cycle climate system.

Hence iTREE will result in a seamless understanding of the responses of terrestrial ecosystems to long-term environmental change, and ultimately help reduce uncertainties of the magnitude and direction of the past and future terrestrial carbon sink.