EFFECT OF SALVAGE LOGGING AND CHECK DAMS ON SIMULATED HYDROLOGICAL CONNECTIVITY IN A BURNED AREA

This study assessed the effect of a wildfire and different post-fire practices (salvage logging, skid trails and check dams) and vegetation recovery (eight scenarios) on the hydrological connectivity (HC) in 11 sub-catchments (SubCs; 330 ha) affected by a wildfire (213 ha) in 2012 in Spain. According to the Landsat 8 Operational Land Imager/Thermal Infrared Sensor images, moderate, high and extreme burn severity affected 42.1% of the area. HC was calculated with an updated version of the Borselli index. Within the burned area (BA), HC increased in all SubCs after the wildfire (PostF-1), the salvage logging and the new skid trails (PostF-2), and the development of new gullies (PostF-3). Check dams reduced connectivity but did not prevent the general trend. Afterwards, the incipient (PostF-4 and PostF-5) and future vegetation recovery made slightly decrease HC. In the three forestry SubCs with check dams and large BA (67% of the study area), connectivity markedly increased (11.4%, 18.2% and 22.9%) during the three first post-fire scenarios. In the three SubCs with urban areas and small BA (5%), HC decreased a little because the linear elements connected the hillslopes between them. In the three SubCs with urban areas and large BA (12%), HC increased less than in the forestry SubCs (3.0%, 8.2% and 9.1%). In the two forestry SubCs without check dams and small BA (16%), the increment of connectivity was low (2.5%, 4.6% and 6.3%). Monitoring of check-dam siltation and of the actual vegetation regrowth is necessary to minimize the off-site consequences of high HC. Copyright (C) 2017 John Wiley & Sons, Ltd.