Effects of different post-fire rehabilitation practices on erosion processes, water quality, and soil properties: The case of the 2021 Manavgat fire area

Approximately 64% of Turkey's forested areas are classified as high-risk zones for wildfires. Between 2017 and 2021, wildfires burned a total of 189.443 hectares, with 2021 marking the most extensive fire season in the country's history. Following such events, salvage logging is commonly conducted to prepare the site for ecological rehabilitation. Subsequently, various restoration strategies are applied, including natural regeneration, artificial regeneration, or passive recovery. However, the ecological impacts of these post-fire practices remain insufficiently studied. This study investigates the effects of salvage logging and different rehabilitation treatments on soil properties, surface runoff, sediment and nutrient transport, and water quality at the micro-watershed scale. The study area is located in the Manavgat region, severely affected by the 2021 wildfire. Three burned micro-watersheds (Watersheds 1, 2, and 3), with similar geomorphological and climatic characteristics, and an unburned control watershed were selected. From October 2022 to May 2023, salvage logging operations—tree felling, skidding, transport, and forest road construction—were conducted simultaneously in all burned watersheds. In May 2023, rehabilitation methods were implemented: Watershed 1 was left to regenerate naturally (YADD-H1), Watershed 2 underwent seeding and mulching (YADG-H2), and Watershed 3 was treated with contour tilling and afforestation (YAYG-H3). During both the salvage logging and rehabilitation period, soil samples were collected periodically from each watershed. Additionally, runoff, sediment yield, nutrient concentrations (in water and sediment), and water quality parameters were monitored during rainy seasons. In the salvage logging phase, the presence of a vegetated riparian zone in Watershed 1 significantly reduced sediment and nutrient transport compared to the other two watersheds. During the rehabilitation period, YADG-H2 showed improved infiltration in the second year, leading to decreased runoff, sediment transport, and nutrient losses, along with improved water quality. In contrast, although YAYG-H3 initially exhibited low runoff and sediment yield, a decline in infiltration during the second year and the development of rills and gullies resulted in sharply increased sediment and nutrient transport and water quality degradation. No substantial changes in runoff, sediment yield, or water quality were observed in YADD-H1. In conclusion, riparian vegetation effectively reduced sediment and nutrient export during salvage logging. Among the rehabilitation methods, YADG-H2 yielded the most favorable outcomes by the second year. In contrast, YAYG-H3 produced the least favorable results due to increased erosion and declining infiltration.