Analyzing fire-induced water repellency and runoff in forest soil from beech forest: A controlled laboratory experiment

Abstract

Forest fires are a common ecological disturbance affecting soil properties and hydrological processes. In this study, we investigated the impact of fire on surface runoff and soil water repellency (SWR) in beech forest through a laboratory experiment. Our main goals were to quantify the severity of SWR caused by low-intensity fires (simulated at 300°C in a muffle furnace) using contact angle measurements with an optical goniometer and to analyze the relationship between heat-induced alterations in SWR and subsequent surface runoff generated by a rainfall simulator in laboratory conditions. The secondary goal of this study was to propose an innovative laboratory approach as an alternative for fire experiments in real forest environments. We collected six monoliths, each with a forest soil surface layer measuring 20 cm x 15 cm x 10 cm, from the Zvolen-Budča site. These monoliths were heated at 300°C for 20 minutes in a muffle furnace to simulate the impact of low-intensity wildfires. Subsequently, the burnt monoliths and the Control were exposed to artificial rain from a rainfall simulator, and surface runoff was measured. The results showed a significant increase in surface runoff from the burnt monoliths compared to the Control, indicating the impact of fire-induced changes in soil structure and SWR. Additionally, contact angle measurements using an optical goniometer showed increased SWR in the burnt disturbed samples. The findings of our study underscore the significance of the interplay between fire-induced alterations in SWR and surface runoff. They offer valuable insights into the post-fire hydrological responses and erosion risks in forest ecosystems. These insights could help develop effective strategies to mitigate the environmental impacts of forest fires.