Detection of Spruce Defoliation with Microwave Radar Techniques

Results achieved from microwave radar backscattering measurements of defoliating spruces are presented. Individual spruces were measured in an unechoic chamber and in outdoor conditions and the natural defoliation was simulated by gradually removing the needles of the trees. The instruments included 5, 10 and 35 GHz channels (multi-polarized). Additionally, helicopter-borne measurements of natural defoliation were carried out. The experimental results show the potential of microwave remote sensing for the detection of forest damage. The best correlations between radar signatures and defoliation were achieved using the 10 GHz linearly polarized channels.