Figure 1: Surface NDVI calculated from the red and near-infrared band of the POLDER instrument with the atmospheric correction algorithm 6S (Vermote et al, 1996), and NDVI simulated with the 4-Scale model for four boreal forest sites: Old Black Spruce (OBS), Young Jack Pine (YJP), Old Jack Pine (OJP) and Old Aspen (OA). The parameters in Table 1 are used as inputs for the model.