Retrieval forest stock volume of large plantation in South China using RADARSAT-SAR

摘要

Estimation of forest stem volume in large area using remotely sensed data has remains difficult due to poor understanding relationships of forest stand parameters and remote-sensing spectral response. Recent studies have show that SAR can be used to investigate forest attribute, especially in tropic forest where there is so much cloud that good quality optic remote sensing is not easily available. The goal of this research was to assess the efficiency of SAR data for forest plantation management and the sensitivity of stem volume to RADARSAT-SAR data. Based on field survey data of the large managed plantation and GIS, the ability of RADARSAT-SAR data in extracting forest stock volume was analyzed in this paper. Results show that RADARSAT-SAR Backscatter coefficient has a relatively good logarithmic correlation with forest stock volume, tree height and diameter at breast height for the six species. The investigation of response of tree height and diameter at breast height to backscatter also shows that backscatter coefficient is affected by tree height much more than by diameter at breast height for Eucalypt, but for pine trees, backscatter coefficient is affected by diameter at breast height much more than by tree height. Inversion results of stem volume show that stem volume can be estimated for such plantation but had limitations. The estimation results obtained are not accurate enough for forest management purposes at the forest stand level. However, the approximate volume estimates derived by the method can be useful in areas where no other forest information is available.