Canopy structure parameters derived from multi-angular remote sensing data for terrestrial carbon studies

Recent studies have highlighted the importance of vegetation structure, both in the context of landscape dynamics and with regard to ecosystem productivity. This paper addresses the feasibility to retrieve information on canopy structure on the basis of quasi-simultaneous multi-spectral and multidirectional remote sensing measurements from space. After a brief summary of both active and passive remote sensing approaches that are commonly used to address vegetation structure retrievals, this contribution focuses on the state-of-the-art in physically based interpretations relating the anisotropy of multi-directional reflectance measurements to the structure and heterogeneity of the underlying surface. New sets of ecology-oriented parameters are identified that permit a geophysical interpretation of the directional signature of the surface leaving radiation field. The availability of such terrestrial surface structure information, at the within-pixel scale and for the entire globe, will undoubtedly lead to better estimates of ecosystem productivity, carbon stocks and fluxes, as well as changes thereof.