EFFECTS OF FIRE INTENSITY AND SLOPE ON SURFACE SOIL EROSION FOLLOWING A PRESCRIBED FIRE IN OLD PINUS NIGRA STANDS

As a practical forest fuel-reduction technique, prescribed fires have been implemented in many countries regardless of their potential impact on surface soil erosion process. Greater runoff and surface soil erosion (rill and inter-rill) after these forest fires is facilitated by the lack of vegetative ground cover on the soil surface and the degradation of soil physical characteristics. Here, the effects of different forest surface fire intensities and slope levels on surface soil erosion were studied by using 5-m x 2-m runoff plots. Specifically, three prescribed (controlled) burn sites, one on a high (53%) and two on low (11% and 12%) slope areas in old stands of Pinus nigra trees, were subjected to high (1596 kW/m) and low (567 kW/m and 797 kW/m) fire intensities. The experimental field study was conducted in 2013-2015 in the Kunduz Province, Vezirkopru District in Samsun, Turkey. To achieve replication within each site, three runoff plots were installed within each burn site, and three other runoff plots in their adjacent control (i.e., unburned) areas. A total of 18 surface runoff plots were located on the ground to collect the water samples, which were measured for their volume and picked up after each severe precipitation event, or monthly when runoff had accumulated in the collecting buckets. Results showed that surface soil loss occurred even with the effects of low intensity of fire under high slope level; however, the effects were not marked with significant differences in the low-slope areas regardless of fire intensity. Therefore, our study suggests that surface prescribed forest fires could be used as a management tool to reduce the build-up of forest fuel loads, especially in those low-sloping areas with a low potential of surface soil erosion.