SOIL RESPIRATION IN FOREST ECOSYSTEMS: COMBINATION OF A MULTILAYER APPROACH AND AN ISOTOPIC SIGNAL ANALYSIS

摘要

One of the key questions in climate change research relates to the future dynamic of soil CO2 efflux (Fs). This efflux represents the most important CO_2 emission component of terrestrial ecosystems. However, it remains the largest source of uncertainty about carbon cycling within ecosystems because of the complexity of processes involved: multiple sources, manifold and variable driving factors (Moyes et al, 2010). Spatial and temporal variability of F_s are widely reported in the literature (Ekbladet al, 2005 ; Luo & Zhou, 2006). This variability results from variations in the intensity of biochemical and transport processes. This intensity is controlled by the climatic and edaphic conditions such as temperature, soil water content, substrate availability/quality, soil type etc. The variability is hampering spatial and temporal extrapolations required to estimate the Carbon balance at global scale. For now, most models developed to explain the observed variability are based on empirical approaches which do not identify the fundamental processes governing F_s. Therefore, such models cannot be used to describe climate change impact on F_s.