Wildfire impacts on morphology and habitat diversity in two Mediterranean streams

This study pretends to evaluate stream morphology and habitat diversity long-term impacts (four years after) of wildfires on two Mediterranean streams. Four sites were selected on a stream with a more flat valley and three sites were selected on a stream with a more v-shape valley. During 2007 River Habitat Survey protocol, with some modifications to emphasise the wildfire effects on river morphology, was applied to these seven sites. Within drainage basins of each site, wildfire severity (traits of fire on the trunks) and post-fire recover of the vegetation (new branches after the fire and general physiological status of trees and shrubs) in respective drainage areas were evaluated. This evaluation was done along a set of transepts perpendicular to the river, from the river margin until the top of the slope. River Habitat Survey protocol was also applied in two additional river sites with drainage areas not affect by wildfires. Debris dams, trash-lines, point bars, and deposition areas, originated by large woody debris, were responsible for an increase on habitat diversity, conducting to higher values of the Habitat Quality Score (more than 40). Higher impacts on river morphology were observed to areas subjected to medium wildfire intensities, because, under these situations, production of large woody debris to be potential exported to streams is higher. Effects of wildfires tend also to be slightly higher on v-shape valleys than on more flat valleys