Two-wave Laser Method for Monitoring the Species Composition of Forest

Abstract

Today the monitoring of forests is one of the actual tasks of environmental control. The most important problems of monitoring of forest resources are mapping of forests, determining species and age composition of forests and analysis of sanitary condition of forests.An effective method of monitoring the state of vegetation (including forests) is optical aerospace sensing. The methods of optical sensing of vegetation cover are currently passive, for the most part.However, passive methods are available to use for daylight only. Therefore, laser methods which can be used in wide range of light and atmospheric conditions are of interest.In this article there was carried out the comparative analysis and selection of the most effective sensing wavelengths in atmospheric transparency windows for two-waves laser method for determining forest areas with prevalence of coniferous or deciduous wood species.As an information index (coniferous or deciduous wood species) in this article the ratio of reflection coefficients of parcels of forest at two wavelengths was used. Pairs of wavelengths 1,54μ and 0,532μ; 1,54μ and 0,355μ are the most relevant for detecting forest areas with prevalence of coniferous or deciduous wood species.For quantitative assessment the efficiency of the laser method mathematical modeling was carried out. The results of mathematical modeling show that that the wavelengths of 0.532μm and 1.54μm are the most effective and provide scanning with probability of correct detecting ~ 0.99 and with false-alarm probability ~ 0.04.However, in terms of eye safety it’s better to choose wavelengths of 0.355μm and 1.54μm, because they allow to solve satisfactory the problem of determining forest areas with prevalence of coniferous or deciduous wood species with probability of correct detecting ~ 0.9 and with false-alarm probability ~ 0.14.