Thesis assessed the ability of indirect estimation of nitrogen using the link with leaf traits retrieved from PROSPECT-5 model inversion; evaluated the feasibility of retrieving nitrogen through recalibrating PROSPECT- 5 by incorporating the effects of leaf protein and cellulose + lignin on leaf reflectance and transmittance; tested if nitrogen can still be retrieved if canopy structural effects were corrected for the canopy BRF; investigated to what extent nitrogen can be retrieved by linking a recalibrated PROSPECT-5 and canopy reflectance models such as INFORM.