The effect of fire on nutrients in a pine forest soil

Abstract

The effect of a hot summer fire on soil nutrient contents in the upper 2 cm of Aleppo pine forest with a dense woody understory was studied from September 1985 to May 1986.In comparison with the adjacent unburned forest, total nitrogen decreased by 25% but available forms of nitrogen were much higher. In burned and unburned soils there was a similar trend to increase and decrease in NH~--N, However, while (NO~-+ NO3 )-N decreased in the unburned soil it rose rapidly in the burned ash soil. Total phosphorus increased by 300% after the fire but decreased again 2 months later. Also water-soluble P increased up to November and then decreased to the levels of the unburned soils. The same was true for electrical conductivity and pH, increasing immediately after the fire and then leveling off again.This increase in nutrient levels in the "ash soil" was reflected in the striking increase in shoot and root biomass and in the content of N, P, Mg, K, Ca, Zn and Fe in wheat and clover plants grown in pots in these soils. These nutrient levels were much higher in the wheat plants, which also produced 12 times more seeds in the "ash soil."It seems that fire in these pine forests causes a short-term flush of the mineral elements in the upper "ash soil" layer which is reverted gradually via the herbaceous post-fire to the ecosystem.

Effect of fire on soil C, N and microbial biomass

“…Degradation of soil, which takes place after fire events, is driven by the deterioration of the soil structure [4,16,21], the loss of soil organic matter content [9,12,20,34,40] and the loss of soil mineral nutrients [10,13,14,26]. Soil microbial biomass is also affected through size reduction, impoverishment of speciographic spectra and reduction in catalytic capabilities [1,18,25].…”

Long-term decrease of organic and inorganic nitrogen concentrations due to pine forest wildfire

“…Thus, several authors have also found significant reductions on microbial biomass levels after a wildfire in different ecosystems (Hernández et al, 1997;Mabuhay et al, 2006), and as suggested above, the death of microorganisms due to soil warming and the declining quality and quantity of substrate after fire may explain this decrease (Sparling et al, 1994;Vance and Nadkarni, 1990). Furthermore, most authors have reported an increase in inorganic N pools just after fire (Kutiel and Naveh, 1987;Prieto-Fernández et al, 1993) due to ash deposition and increases in soil pH and temperature that improve mineralization rates after fire (Raison, 1979). However, the decrease of mineral N levels observed in our study several years after the wildfire has also been documented in other studies throughout the world (Chorover et al, 1994;Grogan et al, 2000).…”

Changes in Nutrient Contents of Soil across Different Land Uses in a Forest Reserve

“…Although leguminous plants constitute a significant part of conventional cropping system, leaching and volatilization loss limit the availability of the nutrient (Oyedeji et al, 2016). Kutiel and Naveh (1987) in their study of pine forest soil reported 25% decrease in N following burning. The National Wildlife Coordinating Group (2001) also reported that volatilization loss significantly affected N, and to a lesser extent P. The slow mobility of P in soils may be responsible for its low susceptibility to loss by volatilization.…”