The most obvious effect that a forest fire leaves behind is the disappearance of the forest. But many other elements of it can be affected, including the soil. The soil is a thin and thin layer, which is essential for life, and whose loss is practically irreversible.
Back to the question What impact does fire have on the ground and on forest recovery? Two types of impact must be distinguished in order to respond to it:
Direct Impact: The generated by the heat emitted by burning itself (duration and intensity of the fire) to the ground
Indirect Impact: The absence of vegetation cover and mulch, which previously were responsible for protecting the soil against erosion.
Effect direct Burning usually has a special incidence, at least temporary, on the biology of the soil, very sensitive even at moderate temperatures. Remember that the soil is home to a quarter of the Earth's biodiversity and it is essential for the functioning of ecosystems. Other soil properties can be directly affected by heat, such as structure and organic C, related to soil hydrology and climate change. Fortunately, the high thermal inertia of the soil determines that this direct effect is superficial.
As effect indirectWe will highlight that a burned forest can no longer fulfill its protective function of the soil against rain and, as a result, it is common to see an increase in runoff * and soil erosion, in addition to the ashes that covered it, more or less less rich in organic C and nutrients, which generates the progressive impoverishment of the forest ecosystem. These effects also affect downstream, even in unburned areas. A reiteration of the burning and erosion processes can lead to soil loss, rock outcropping and, therefore, hinder vegetation recovery.
* Runoff: Rainwater that circulates over the soil surface when its infiltration capacity is exceeded.
Author David Badia Villas, Higher Polytechnic School of Huesca (University of Zaragoza)