Selection of Forest Stands for Stem Volume Retrieval From Stable ERS Tandem InSAR Observations

Environmental factors influence the accuracy in stem volume retrieval using European Remote Sensing Satellite (ERS) tandem synthetic aperture radar (SAR) interferometry. Some forest stands are more sensitive than others to heterogeneity of environmental properties, forest properties, and noise. It is shown that the consistency of coherence observations between different image pairs or the consistency of the estimated stem volume can be used to sort forest stands according to increasing errors in stem volume estimates associated with varying forest properties. Fifteen ERS tandem pairs were used to determine the relative root mean square error (RMSE) of stem volume estimated from C-band SAR interferometry. The test site, Tuusula in Finland, contains 210 forest stands with stem volumes up to 539 m³/ha. RMSE varies between 17% and 63% depending on number and type of stands included in the retrieval accuracy analysis. The more homogeneous forest stands with larger area and higher stem volumes of spruce and pine are those with highest retrieval accuracy