A model-based approach for the estimation of carbon sinks in European forests

Man’s knowledge of ecosystems is in constant evolution. This is a consequence of the increased understanding of the underlying biology, but also of the increased collaboration between disciplines that in the past did not interact in the same way and intensity as they do today. In fact, more and more ecosystem scientists are building on what now may be considered solid foundations laid out by disciplines such as biology, ecology, physics, and also computer science (see, for instance, Waring and Running 1998; Patil and Myers 1999). A good understanding of ecosystem processes is vital as it leads to models, which, in turn, provide us ways to predict the possible future behavior of ecosystems under changing conditions. Most models include fluxes of carbon, water, and nitrogen, and are able to provide estimates of gross primary production (GPP) and net primary production (NPP) of carbon per unit area. In the past decade, the numbers of sites where canopy fluxes of carbon and water were measured increased exponentially (Baldocchi et al. 2001) and net ecosystem exchange (NEE) became available as well. Hence, modelers were recently provided with calibration and validation data for the complete process of ecosystem carbon exchange, up to net ecosystem production (NEP=NEE) and even net biome productivity (NBP; see Fig. 9.1)