Modeling Leaf Optical Properties:prospect

Abstract

Introduction Higher plants have proliferated a wide range of internal leaf structures, and yet they demonstrate ecological convergences in similar ecosystems, which are widely interpreted to indicate evolutionary constraints on optimized leaf properties. Plant leaves are the primary photosynthesizing organs, significantly affecting important planetary biogeochemical cycles. The mechanisms of how leaf chemistry, structure and orientation interacts with the light environment, however, remains incompletely understood. Leaf optical properties, have been extensively studied for 150 years, although primarily for Angiosperms. It is well established that the reflectance and transmission spectrum of leaves is a function of both the concentration of light absorbing compounds (chlorophylls, carotenoids, water, cellulose, lignin, starch, proteins, etc.), and the internal scattering of light that is not absorbed or absorbed less efficiently. Quantitative relationships between optical characteristics and plant biochemical properties (which themselves depend on many environmental and species factors), have been established empirically, such as response to leaf aging or environmental stresses, which are well known to reduce chlorophyll content, which in turn, increases both the reflectance and transmittance in the visible spectrum. More recently, radiative transfer models of leaf biophysical processes have been used to directly estimate biochemical composition and structural characteristics. An extensive review of the literature, and available optical models is available ONLINE.