LEAF AREA INDEX ESTIMATION IN THE MONARCH BUTTERFLY BIOSPHERE RESERVE

Abstract

Leaf area index is the main biophysical variable used to model many plant processes. In this work a method is proposed to obtain a leaf area index map of the Monarch Butterfly Biosphere Reserve based in the adjustment of a radiative transfer function between the leaf area index, estimated in some sample points using hemispherical photographs, and the corresponding radiometrical data of a SPOT (satellite pour l’observation de la Terre) image. Before the adjustment of the radiative transfer function, data were corrected with respect to the slope effect. In order to adjust a function, several vegetation indices were calculated and linear and non linear functions were tested, and a linear combination of SPOT bands was chosen (r = 0.608, RMSE = 0.493). The transfer function was applied to the forest image corresponding to the Monarch Butterfly Reserve to obtain a leaf area index map of a date near the declaration of biosphere reserve. This work was performed in the context of the VALERI (validation of european remote sensing instruments) international project.