Postfire vegetation responses and soil erosion of burned surfaces time series (1983-2003) in northeastern Patagonia, Argentina?.

DEL VALLE, H. F.; ROSTAGNO, C. M.; DEFOSSÉ, G. E.

Ghent

Workshop; 4th International Workshop on Remote Sensing and GIS Applications to Forest Fire Management; 2003

Ghent University ? EARSeL

The northeastern region of Patagonia is a shrubby steppe dedicated to sheep ranching since the beginning of the century. In some areas, however, sheep ranching has been abandoned for different reasons, allowing the recovery of the vegetation, increasing then the fuel load and horizontal continuity. In this study, we evaluated the vegetation response and soil erosion to fire in 58 burned surfaces between January 1983 and February 2003 (99,497 hectares). A post-fire land cover map was developed based on classes derived principally from Landsat TM & ETM images (unsupervised and supervised classification). ERS/SAR and SIR-C images were considered to be sensitive to surface morphology at the scale of interest in soil erosion processes.  Polarization signatures (Sir-C versus ERS) were used to support the visual and digital analysis of identifying the scattering mechanism that characterizes some burned surfaces test. Relationships between fire severity and slope azimuth, and slope magnitude + azimuth combinations were studied also using field observations and digital terrain models (obtained by interferometric techniques). There were stronger relationships between fire severity and slope azimuth classes than with slope magnitude and combinations, associated with grazing patterns in rolling plain landscapes.