INTREE · How and when does climate influence carbon sink activity? Multi-temporal analysis of wood formation in conifers

How and when does climate influence carbon sink activity? Multi-temporal analysis of wood formation in conifers

Wood is the main terrestrial biotic reservoir for long-term carbon sequestration. The amount of carbon stocked in the tree stem each year is highly variable, in relation to short- and long-term climate variability, variations in the stand dynamics (inter-tree interactions), and biotic and abiotic stress factors that influence tree physiology and growth processes. Better understanding of the mechanisms behind such variability would be critical for predicting future carbon sequestration by forests under global change. Different approaches can be used to study environmental influence on tree radial growth (carbon sequestration). The tree-ring width analysis provides long-term information on environmental influence on tree growth at annual resolution. Direct xylogenesis observations inform on the timing of different phases of xylem (wood) cell formation, at the weekly scale. A third approach, the quantitative wood anatomy in tree rings, allows to retrospectively analyze of xylem anatomical traits along tree-ring series. The INTREE project developed intra-ring quantitative wood anatomy and applied it to different tree species, constrained by different environmental drivers. In connection with outcomes from the other two approaches (xylogenesis observations and tree-ring analyses), this provided new information on how environmental variability (temperature, precipitation, drought, defoliator insects) affects xylem formation processes at different time scales and in different environments (project Objective 1). Research conducted in the project demonstrated that the amount of carbon in conifer tree rings is sensitive to variability in the anatomy of xylem cells (Objective 2). In particular, defoliation caused by insects can alter xylem cell formation and anatomy, causing strong reduction in the amount of carbon stored yearly in the tree stem (Objective 3). This calls for further quantitative investigation on how environmental-driven variations in xylem anatomy can influence the tree-ring biomass, which is the fundamental element for assessing forest biomass variations and climate change impacts on terrestrial carbon cycle.

Data: CORDIS, © European Union