Effects of fire intensity on soil chemistry in a eucalypt forest

Abstract

Soil samples taken in the Wombat State Forest in Victoria, at depths of 0-2, 2-5, and 5-10 cm before and after burning fuel loads of 0 (unburnt control), 15, 50, 150, and 300 t ha-1 were analysed for pH, exchangeable cations and cation exchange capacity, available and total P, organic carbon and soil moisture, over a 2-year, 2000 mm rainfall period. Short term responses (up to 6 months) occurred in levels of exchangeable NH4+, K+, and Mg2+, and long term changes (2 years or longer) over the period of the study were observed for pH, available and total P and exchangeable ca2+ at the 0-2 cm soil depth for the burnt treatments. Following burning (and 108 mm of rain), changes in soil chemical parameters were strongly correlated with fuel load and the quantity of fuel burnt. Changes through the 0-10 cm profile for the various chemical parameters are described, together with seasonal variations. For similar yellow podzolic soils, measurement of soil pH may be a useful criterion for monitoring soil chemical changes following slash and fuel reduction burning, provided that accurate estimates of fuel loads, composition and amount burnt can be established.

Effects of a Wildfire on Selected Physical, Chemical and Biochemical Soil Properties in a Pinus massoniana Forest in South China

“…Adams and Boyle [86] reported that a month after a wildfire, available K in the soil of a Quercus rubra-Populus grandidentata forest was significantly higher than pre-fire levels, but the increases were almost gone after a further three months. Tomkins et al [87] found soil K to increase for six months following fire in a Eucalyptus forest. Heavy rainfall one month after the wildfire in the study area may have led to the observed decrease in exchangeable K because of the loss of a high-density-charged fraction such as organic matter, which can lead to K being lost by particulate transport of ash, runoff, or erosion [36].…”

Competition for nitrogen by three sympatric species of Eucalyptus

“…The soil is primarily yellow podsolic soils derived from Ordovician sedimentary rocks and the climate is cool temperate with the majority of the 900-925 mm of annual rainfall in winter and spring. Details on soil chemistry have been published previously (Tomkins et al, 1991).…”

Journal of Range Management, Volume 56, Number 3 (May 2003)

“…Several studies on the effect of fire on soils have shown changes in soil nutrient levels resulting mainly in total N losses, but short-term increases in available N and other nutrients (Biederbeck et al 1980, Kutiel and Naveh 1987, Fenn et al 1993, Saa et al 1998. Soil chemical properties such as exchangeable Ca++, Mg++ and K+, and pH also increase after fire (Tomkins et al 1991). Microbial biomass is considered an agent of transformation of soil organic materials, and a labile reservoir of nutrients such as N, P, and S (Jenkinson and Ladd 1981).…”