Nutrient Cycling: The Ash-bed
Despite the losses (which may be as high as 400 kg/ha for N in eucalypt forests) during fire,
nutrient availability in topsoils is, at least temporarily, increased.
In addition to the nutrients added in ash, surface soils are heated, which releases nutrients from soil organic matter.
Heating also 'sterilises' the soil, resulting in a changed soil microflora.
Each of these changes contributes to increased plant growth following fire.
This aerial photo demonstrates the 'windrow' effect in pine plantations. Prior to planting, the residue of the previous harvest is bulldozed into mounds and burnt. Seedlings planted along these lines benefit from the nutrient enhancement produced by the burn and grow better than the surrounding trees.