Effect of Salvage Logging and Check Dams on Simulated Hydrological Connectivity in a Burned Area

Abstract

AbstractThis 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 © 2017 John Wiley & Sons, Ltd.