ESTIMATING TREE DENSITY IN OAK SAVANNA-LIKE DEHESA OF SOUTHERN SPAIN FROM SPOT DATA

The main objective of this study was to establish a method of estimati ng tree density in savanna-like vegetation systems using the highest s patial resolution available from satellite data (SPOT-1 panchromatic = 10 m resolution) based on the assumption that for sparse trees on a c ontrasting herbaceous background, spatial filters may provide a direct mapping of tree cover. The study was performed in the 'dehesas' oak-w oodland of southern Spain. This particular landscape is characterized by the presence of scattered evergreen oak trees (Quercus ilex and Q. suber) whose density ranges from 0 to 80 even-aged mature trees per he ctare which gives the appearance of a savanna-like vegetation. Tree de nsity can be accurately estimated by SPOT-1 panchromatic data after nu merical filtering. This method allows the mapping of tree density of t he dehesas, a key parameter reflecting the functional vegetation-soil- climate equilibrium which exists for both woody and herbaceous strata.