Short-term spatio-temporal spring grassland fire effects on soil colour, organic matter and water repellency in Lithuania

Abstract

Abstract. The aim of this work was to study the short-term effects (first 9 months after the fire) of a low-severity spring boreal grassland fire on soil colour, soils organic matter (SOM) and soil water repellency (SWR) in Lithuania. Three days after the fire we designed a plot of 400 m2 in a control (unburned) and unburned area with the same geomorphological characteristics. Soil water repellency analysis were assessed through the 2 mm mesh (composite sample) and in the subsamples of all of the 250 samples divided into different soil aggregate fractions of 2–1, 1–0.5, 0.5–0.25 and < 0.25 mm, using the Water Drop Penetration Time (WDPT) method. The results showed that fire darkened the soil significantly during the entire study period due to the incorporation of ash/charcoal into the soil profile. Soil organic matter was significantly higher in the first two months after the fire in the burned plot, in comparison to the unburned plot. Soil water repellency (SWR) of the composite sample was higher in the burned plot during the first two months after the fire. However, considering the different aggregate fractions studied, the SWR was significantly higher until 5 months after the fire in the coarser fractions (2–1 mm, 1–0.5 mm) and 7 months after in the finer (0.5–0.25 mm and < 0.25 mm), suggesting that the leachability of organic compounds is different with respect to soil aggregate size fractions. This finding has implications for the spatio-temporal variability of fire effects on SWR. SOM was significantly negative correlated with SWR (composite sample) only in the two months after the fire. These results demonstrated that in the first two months the hydrophobic compounds produced by fire were one of the factors responsible for the increase in SWR. Subsequently repellent compounds were leached, at different rates, according to particle size. The impacts of this low severity grassland fire were limited in time, and are not considered a~threat to this ecosystem.

Short-term changes in soil Munsell colour value, organic matter content and soil water repellency after a spring grassland fire in Lithuania

“…In this burned plot it is very likely that the direct impacts of fire (e.g. temperature) were minimal since IAF no significant differences were observed in soil moisture between the burned (14.17 % ± 2.83) and unburned (13.59 % ± 2.82) plots (Pereira et al, 2012b). In this case, since the temperature impact on the topsoil was probably minimal, the observed increase of SWR in the burned plot can be attributed to the indirect effect of ash deposition on the topsoil.…”

Soil organic matter quality and composition in a postfire Scotch pine forest in Tolyatti, Samara region

“…As identified by previous works, fire has an important impact on soil properties (Certini, 2005(Certini, , 2014Mataix-Solera et al, 2011;Jain et al, 2012;Bergeron et al, 2013;Guénon et al, 2013;Dymov and Gabov, 2015;Maximova and Abakumov, 2015;Pereira et al, 2015;Pereira, Rein, and Martin, 2016;Keesstra et al, 2016;Van Eck et al, 2016). After a fire, there is an accumulation of ash on the topsoil (Pereira et al 2014), leaching of some nutrients into deeper horizons (Bodi et al, 2014), over-compaction of the surface, accumulation of crusts, and transformation of soil structure (Mataix et al, 2011).…”

“…Pyrogenic processes are widely distributed phenomena, significantly affecting pedogenesis and numerous environmental processes (Vasil' evskaya, 1986;Certini, 2005Certini, , 2014Cerdà and Doerr, 2008;Certini et al, 2011;Pereira et al, 2014Pereira et al, , 2015. Numerous groups are studying the role of forest fires in the natural dynamics of forest cover because fires are the most important environmental factor determining the structure and dynamics of forest development and, hence, the environmental status of a forest.…”

A simple water balance model adapted for soil water repellency: application on Portuguese burned and unburned eucalypt stands

“…Fire can also be a major factor for the occurrence of SWR (e.g. Bodí et al, 2013;Ferreira et al, 2004;Keizer et al, 2008;Pereira et al, 2013), but fire effects can be highly variable, depending mainly on the soil heating regime, the type of organic matter consumed and the amount of oxygen available during burning (Doerr et al, 2009), with ashes playing an important role (Bodí et al, 2014); in some cases, fires could decrease SWR (e.g. Cerdà and Doerr, 2005).…”