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In a general way if we say a forest is caught by fire then this fire is termed a forest fire or wildfire. When a wildfire occurs then we imagine only harm to forest flora and fauna. That is true in a way but it depends on the severity of the fire. When a forest is caught by fire then its severity depends on how much longer it affects the area. Surface fire burns the surface of the forest floor, and they are easy to control in comparison to crown fire and ground fires. Understanding the impact of fire on soil characteristics is crucial for improving soil management in burnt forest ecosystems. Because a surface fire's maximum soil temperature is lower than a crown fire's, which has a great quantity of heat emitted during the burning of vegetation, it is anticipated that surface fires will not significantly alter the properties of soil (Campbell et al., 1995). Comparatively, to moderate to high-intensity crown fires, the condition of soil characteristics following low-intensity surface fires has, however, received less research (Certini, 2005). The objective of the study was to find out which chemical property of soil is most affected by a surface fire in forested land. We predicted that surface fire would have an impact on soil chemistry, but that such changes may be reversed quickly after the fire.

Numerous studies, such as those by Schoch and Binkley (1986) and Fisher and Binkley (2000), claimed that although low-intensity fires can reduce the amount of nutrient pools, they can also boost soil fertility because they chemically transform nutrients trapped in dead plant matter.

Carter and Foster (2003) discovered that the impact of fire on nutrient productivity is related to fire intensity. They reported that while high-intensity fires (which are also more likely to be of high severity) tend to decrease site productivity, low-intensity fires can increase site productivity because the chemical nutrients from the burned vegetation are released, potentially creating an environment that is favourable for growth.

Other scientists and researchers also found the same conclusion as above when a fire affects a forest. From the above point of view, the soil properties are affected by fires whether it’s low or high-intensity fires

Study Area

Figure 1. Location of Kota range in Ramnagar Forest Division
Methodology
For the study of this paper, a random sampling method was carried out for determining the soil’s chemical properties (pH, Nitrogen, Phosphorous, and Potassium). A total of 20 samples were collected from the burnt site and unburnt site via two methods, zig-zag pattern and square box pattern. In a zig-zag pattern, we follow a zig-zag path and randomly collect samples, in the square box method a burnt and unburnt site has been chosen and then an imaginary square is formed. 4 samples were collected from all four corners and one sample is collected from the middle part.


These samples were collected after one week of fire (month of March 2021) and again after seven months in October 2021. Samples were analyzed in the district soil testing laboratory situated in Bhimtal, District Nainital, (Uttarakhand). The properties which were studied in the lab were soil pH, available Nitrogen, Phosphorous, and Potassium.

Soil pH was recorded by using pH meter adjusting pH = 4, pH = 7, pH = 10 by using buffer solution. Available Nitrogen was determined through the Potassium Permagnet method (Subbiah and Asija). Total phosphorus content was calculated by the method of Bray and Kurtz (Ülgen & Ateşalp, 1972). Potassium was calculated using an Automatic Absorption Spectrophotometer (AAS).

Mean values of top and lower soil properties are shown under the following tables and variations among the seasons are shown in charts.

Table 1. pH values recorded

Chart 1. pH values showing variation
Table 2. Available Nitrogen values 


Chart 2. Available Nitrogen Values showing variation
Table 3. Phosphorous values 


Chart 3. Phosphorous values showing variation
Table 4. Potassium values


Chart 4. Potassium values showing variation
According to ANOVA results of soil samples, surface fire affects all properties which were pH, Nitrogen, Phosphorous, and Potassium in top soil i.e. 0-6 cm below in a significant manner. While some properties were not significantly affected or not affected by the fire while we go down the soil depth i.e. 6-12 cm.
Table 5. The summary of two-way ANOVAs on the effect of fire and soil depth on chemical properties of soil. F values are shown for each factor for each analysis, and statistical significance of each factor in the model is given (ns, not significant; * P < 0.05; ** P < 0.01; *** P < 0.001, **** P < 0.0001)

According to the result analysis, we found out that there is a significant increase in the pH of soil after a fire. With pH, other properties which were studied are available Nitrogen, Phosphorous, and potassium. Study results indicated that soil Nitrogen and Potassium values are decreased but not in a very significant manner with depth. While Phosphorous is also decreased and showed significant changes like pH on topsoil.
 After the monsoon when second samples were collected from the same site, the values of some properties are recovered while some didn’t. Soil pH was recovered and came back to its slightly normal values. That may be because water content from rainfall help to reduce the alkalinity of the soil. Other properties like Nitrogen and Potassium were not changed even after the fire. While soil Phosphorous was not recovered fully from the fire. This may be because, during a fire, Phosphorous which is an organic matter may have been lost as gas or liberated as phosphate salts that are hardly soluble in the soil (Fisher and Binkley, 2000). 

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