Airborne radar scatterometer for estimation of stand heights

This paper presents the results of an analysis of radar airborne scatterome ter data obtained over an Austrian black pine (Pinus nigra Arnold ssp. nigr icans Host.) forest in Lozere, France. This system provides vertical soundi ng inside canopy from which can be derived tree height estimations. The obj ective of this paper is to analyse the validity of these measurements and, then, to study the interest of this kind of sensors for better forest manag ement. The mean and top height estimations give very good results with a re lative error of about 6%. The radar measures the back scatter coefficient o f the vegetation from which can be estimated other parameters such as stem volume or basal area. The radar backscatter coefficient is found to be sens itive to the biomass in a low to intermediate range of values (0-200 m(3)/h a), particularly when the canopy backscattering is separated from the groun d echo. The estimation of stem volume using a regression with both tree hei ght estimations and backscatter measurements gives satisfying results. Fina lly, we discuss the interest of this kind of sensor data for an improved an d detailed forest management giving an example of application on the evalua tion of the variability of the local site index within a stand.