ABSTRACT
The scientific community is being urged to invest more time and economic resources to improve current estimates of global and regional carbon budgets (Scurlock et al. 1999). Carbon gains are considered either as an intermediate service (Fisher et al. 2009) or as supports of provision and regulating services (MA 2005). In addition, net primary production (NPP), an estimate of ecosystem carbon gains, is often considered the most integrative descriptor of ecosystem function (McNaughton et al. 1989). NPP estimates are derived from biomass harvesting, flux tower measurements, remote sensing, and model simulation (Ruimy et al. 1995; Sala et al. 2000; Still et al. 2004). Biomass harvesting is expensive and not exempt from errors and methodological problems. These methods are limited in their spatial and temporal coverage. Given the linear relationship between the fraction of solar radiation absorbed by vegetation and spectral vegetation indices (Sellers et al. 1992), Monteith’s model (Monteith 1972) offers the possibility of estimating seasonal variation in carbon gains from remote sensing data (Potter 1993). Monteith’s model states that carbon gains (Equation 6.1) of vegetation cover are a function of the quantity of incoming photosynthetically active radiation (PAR), the fraction of this radiation intercepted by vegetation (fPAR), and the light use efficiency (LUE; Still et al. 2004). The flux estimated using the Monteith’s model included net and gross primary production and net ecosystem exchange (NEE) (Ruimy et al. 1999; see Equations 6.2 and 6.3).
