ABSTRACT
Concerns about the rising carbon dioxide (C02) concentration in the atmosphere (0.5% yr'1) and the projected warming of world climate have hastened studies of carbon (C) dynamics within known C reservoirs and the fluxes of C 0 2 from these reservoirs to the atmosphere. During the last three decades, a wealth of data regarding C 0 2 evolution in various ecosystems has been collected and several global C budgets have been constructed. A constant observation of these budgets is an apparent imbalance of the global C cycle, giving rise to the so-called “missing C,” the amount of C (1.2 to 1.8 Pg C) needed to balance the cycle. A 1992 report to the Intergovernmental Panel on Climate Change (IPCC) states that estimates of C fluxes to the atmosphere from land-use changes remain among the most uncertain figures in the global C cycle (Watson et al., 1992). It has been suggested that temperate region forests may represent an additional sink not fully accounted for in global C budgets. The capacity of this sink has been estimated at 1.37 Pg C y r1 (Sedjo, 1992). There are indications that this sink can be enhanced due to forest regrowth, C 0 2 fertilization and atmospheric N deposition effects (Hudson et al., 1994; Thomley et al., 1991). Conversely, cyclical events like fires can greatly reduce the role of forests as C sink. Nabuurs et al. (1997) estimated that about half of the C sink of European forests (0.101 Pg C yr'1) can be lost due to fire-related emission of C 0 2 (0.06 Pg C yr-1).
