Modeling Brdf And Radiation Regime Of Boreal And Tropical Forest

Monitoring forest evolution and functioning with remote sensing depends on canopy BRDF (Bidirectional Reflectance Distribution Function) sensitivity to parameters of interest. A radiative transfer model (DART, Discrete Anisotropic Radiative Transfer) is used to investigate the behavior of visible and near infrared BRDF and the PAR (Photosynthetically Active Radiation) environment of two tropical (Sumatra) and boreal (Canada) forests. In any case, BRDF directional anisotropy is very large, which can make difficult the detection of phenomena such as deforestation. Comparison of simulated and measured (PARABOLA, POLDER) BRDF stressed (1) the potential of the DART model, and (2) the importance and difficulty to use accurate field data, Differences in tropical and boreal forest architectures induce distinct PAR transmission and 3-D APAR. Their influence on canopy photosynthesis is illustrated with the coupling of DART with a leaf functioning model.