LIDAR-based estimation of leaf area index on Holm oak [Quercus ilex L. subsp. ballota (Desf.) Samp.] trees

Abstract

The aim of this paper was to estimate Leaf Area Index (LAI) of Quercus ilex by calculating the laser-intercepted rate through the forest canopy using LiDAR data. LAI was measured in 40 trees with a hemispheric camera (NIKON Coolpix 4500) and coincided with the acquisition of LIDAR data. The LiDAR-derived LAILIDAR was then estimated by applying a value of the inverse of the coefficient of extinction of 1/K = 1.48. The in-field LAI values varied between 1.01 m2 m–2 and 1.61 m2 m–2. From a comparison of the LiDAR-derived to the field-derived LAI, the coefficients of the determination for the coefficient of extinction of 1.48 was R2 = 0.60 (RMSE = 0.16) for quadratic and R2 = 0.62 (RMSE = 0.21) for potential correlations. The change in accuracy was attributed to the density of leaves, the interference by stems, and the vertical number of branches in the forest stands. The LIDAR sensor technique gives a satisfactory result in the obtainment of leaf parameters in Holm oak trees, although its generalisation on field studies depends on its cost and suitability to be applied over large surfaces.