Etude pluriannuelle de l'allocation du carbone assimilé par deux écosystèmes forestiers et de la variabilité climatique sur les sites ICOS de Hesse (France) et de Vielsalm (Belgique)

Abstract

Forest ecosystems actively participate in climate change mitigation by absorbing CO2. This study estimates the annual allocation of carbon by two forest ecosystems in western temperate Europe (France and Belgium), and its efficiency in relation to fluxes between the ecosystem and the atmosphere. Both sites consist of a mixed forest of different ages with varying woody species diversity and are part of the European research programme ICOS. This study identifies the inter- and intra-annual variability of carbon allocation in biomass, through the use of forest inventories, allowing the calculation of a carbon quantity in the total dry matter and/or in the total woody aboveground biomass. In parallel, the influence of this varability on main climatic parameters were analyzed. Both forests behave as a carbon sink, allocating on average 437,2 gC/m².year for Hesse and 356,4 gC/m².year for Vielsalm. The efficiency of this carbone storage is on average 21% for both sites, with a decrease since 2018. On an annual scale, the woody aboveground biomass accumulations for four main species in Vielsalm are correlated with a delayed effect of the intense weather conditions of the previous years. While for Hesse, relationships are significant but may vary under several intense climatic conditions.