Unveiling soil temperature reached during a wildfire event using ex-post chemical and hydraulic soil analysis

Fire-induced changes in soil properties depend on age and type of forests

“…3). Martínez et al (2022) presented that most soils showed an initial increase in pH between 300 °C and 500 °C and a subsequent decrease between 700 °C and 900 °C, which is in agreement with our results. The influence of the heating temperature on the change in soil pH is great.…”

“…2), and the mean SOC in the deciduous forest soil was significantly different from the mean SOC in the soils of coniferous forests. SOC decrease with temperature was registered by Certini et al (2011), Garcia-Corona et al (2004, and Martínez et al (2022). Badía et al (2017) found that burning depleted 50% of the SOC content in the air-dried soil and 25% in the wet soil at the upper centimetre.…”

“…The persistence of SWR of the soil from a 30-year-old deciduous forest was strong (mean value of WDPT = 146 s) in the unheated state, severe for temperatures of 50-200 °C, extreme for temperatures of 250-350 °C and it disappeared at 375 °C. Martínez et al (2022) state that fires at 100 and 200 °C do not considerably affect repellency and SOC was not fulfilled because significant changes in WDPT with temperatures between 20 and 200 °C were registered in all three soils. It should be mentioned that deadwood can increase the persistence of SWR (measured in terms of WDPT) depending on the species and rate of decomposition (Blonska et al, 2018).…”

“…At 50 mm depth, the temperature is not likely to exceed 150 °C except with long heating times that occur during smoldering fires (Robichaud and Hungerford, 2000). Wildfires affect different physical, chemical, and hydraulic soil properties, and the magnitude of their effects varies depending on intrinsic soil properties and wildfire characteristics (Martínez et al, 2022).…”

“…It was found for both the drying and wetting branches of soil water retention curves that an increase in soil water repellency resulted in a drop in soil water content at the same matric potential. Martínez et al (2022) estimated the impact of heating temperature (300, 500, 700, and 900 °C for two hours) on the saturated and unsaturated hydraulic conductivity, pH, electrical conductivity, wet aggregate stability, soil water repellency measured in the terms of modified repellency index, RIm, and soil organic matter content were measured in six laboratory heated soils with loam, sandy loam, and sandy clay loam texture. The results showed that wet aggregate stability exhibited a U-shaped trend, opposite to pH and electrical conductivity.…”