3. RESULTS
Carbon Erosion Comparing the topo sequences reveals an average carbon
content of 1.07% in healthy soils, while the average does not exceed
0.8% in fire-affected soils. The C/N ratio, which is an indicator of
soil functionality, plays a crucial role. An elevated C/N ratio
(>12) signifies slow organic matter degradation, while a
low C/N ratio (<8) indicates excessive soil activity.
The C/N ratio in Galite is generally low in both treated cases (healthy
and burnt), primarily due to the rapid decomposition of organic matter,
resulting in significant nitrogen production during decomposition
(considered as a fertilizing effect).
The low C/N value (3.98) in the burned areas seems plausible. Regarding
nitrogen, the situation is more complex. In absolute terms, nitrogen is
less abundant on the soil surface after a fire because almost all the
nitrogen in the burning fuel is lost through volatilization. However,
many studies have shown a significant increase in mineral nitrogen in
the soil after fire. Research indicates that a few hours after
controlled burning in Aleppo Pine forests, the amount of mineral
nitrogen in ammonium form in the top two centimeters of soil is four
times higher than before the fire, while nitrate-form mineral nitrogen
had decreased. It’s worth noting that the ashes are poor in mineral
nitrogen. Christensen (1977) measured that less than 1% of the total
nitrogen found in the ashes was in a mineral form, with 99% being in
organic form. This immediate production of ammonium nitrogen in the soil
does not appear to be related to ash input but is likely due to the
heating of the surface soil layers and the hydrolysis of proteins.
However, these ashes, which become incorporated into the soil, serve as
a potential source of mineralizable nitrogen. The mineral elements
contained in the ashes deposited on the soil are vulnerable to losses
through erosion (wind or runoff) and leaching into deeper layers beyond
the biologically active zones. These losses can vary based on slope,
post-fire weather conditions, and soil characteristics. (Table 1)
Table 1: Descriptive Statistics of Natural Sample Topo sequences