engleski

Post–fire management for improving soil quality and hydrological process: a case study in a Mediterranean Croatia

Wildfires in Mediterranean Croatia have increased in recent decades, raising concerns about the adverse effects of fire and the rate of soil and water degradation. Post-fire management techniques, such as mulch application, are commonly used after high to moderate wildfire severity. Local, site-specific solutions are needed to mitigate wildfire effects in this context. This research aims to study the effect of mulches (from on-site sources) on soil and hydrological properties. We hypothesised that mulch application would increase soil quality and reduce erosion and runoff yield. During July 2019, about 900 ha of Pinus halepensins Mil. forest, abandoned grazing and agricultural olive groves (Olea europea L.) were affected by a moderate to high wildfire in the hinterland of Šibenik City (Croatia, 43°45'N 15°56'E, 105 m a.s.l.). Twenty-five days after the wildfire occurrence, unmulched (UM, control) and two mulch treatments (Olea europea leaves (OM) and Pinus halepensis needles (PM) were applied for post-fire stabilisation on Cambisols. One treatment covered an ~10 m2 area with 0.5. kg m2 mulch application which was measured on the experimental plots. Prior to mulch application, 15 (5 per treatment) metal rings (0.2 m2) with connected plastic collectors were set up on sloped terrain (~9°) to monitor erosion and runoff yield. Soil samples were collected every three months, and erosion and runoff yield after major precipitation events during two years. The studied soil properties were: soil water repetency (SWR), soil hydraulic conductivity (SHC), mean weight diameter (MWD), water stability of aggregates (WSA), soil organic matter (SOM), total carbon (TC), total nitrogen (TN), extractable potassium (K2O), and available (P2O5). Our results showed that both mulch treatments reduce runoff generation in addition to UM treatment. The erosion yield was not occurred due to natural soil conditions. A linear decreasing trend was noted for SWR in all treatments. Overall, PM was showed higher efficiency in increasing soil aggregate stability (MWD and WSA), SHC SOM, and TC. OM has mostly increased soil nutrients such as TN, P2O5, and K2O. Bot mulch treatment increased soil quality, but the effect was variable due to the different chemical compositions of the material. The use of native mulch can be recommended because it improves soil quality and reduces runoff ratio. However, consideration should be given to whether they are available in the areas affected by wildfire.

Mulching, on-site, soil quality, runoff, nutrients

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