Effect of forest fire on soil microbial biomass and enzymatic activity in oak and pine forests of Uttarakhand Himalaya, India

Abstract

Background Forest fire incidences in the Himalayan region of Uttarakhand, India are very common in summers. Pine and oak are the principal and dominant species of Himalayan subtropical forest and Himalayan temperate forest, respectively. Forest vegetation influences the physicochemical and biological properties of soil and forest fire in pine and oak forests may have a different effect on the physicochemical and biological properties of soil. Therefore, the present study was carried out to assess the impact of forest fire on soil microbial properties, enzymatic activity, and their relationship with soil physicochemical properties in the advent of forest fire in the pine and oak forests of the Garhwal region of Uttarakhand Himalaya, India. Results The soil microbial biomass carbon and nitrogen, soil basal respiration, and acid phosphatase activity decreased, whereas dehydrogenase activity increased at burnt sites of both forest types. The overall change in soil microbial biomass carbon was 63 and 40% at the burnt oak forest and burnt pine forest, respectively. Dehydrogenase activity and acid phosphatase activity showed a strong positive correlation with soil organic matter (r = 0.8) and microbial indices, respectively. The ratio of soil microbial biomass carbon/nitrogen was reduced at burnt sites of both forest types. Factor analysis results showed that fire had a significant impact on soil characteristics. The soil basal respiration was linked with macro- and micronutrients at burnt sites, whereas at control sites, it was linked with physicochemical properties of soil along with nutrients. Conclusion Forest fire had a significant impact on soil properties of both forest types. The impact of forest fire on soil microbial biomass carbon was stronger in the oak forest than in the pine forest. Forest type influenced soil enzymatic activity at burnt sites. The bacterial community was dominated over fungi in burnt sites of both forests. Soil microbial indices can be used as a selective measure to assess the impact of fire. Furthermore, forest type plays an important role in regulating the impact of forest fire on soil properties.

Short-Term Effects of Experimental Fire on Physicochemical and Microbial Properties of a Mediterranean Cambisol

“…Regardless, they showed that the effect of wildfires on soil dehydrogenases lasted as long as 13 months. The increased soil dehydrogenase activity following a wildfire was also observed in another study conducted by the same authors in the Himalayan oak and pine forests [52]. On the other hand, some studies showed no changes in the activity of soil dehydrogenases following a wildfire [50].…”

“…Considerable evidence exists regarding the behaviour of soil enzymes following wildfires, especially that of dehydrogenases. They are the major oxidoreductase enzymes involved in the biological oxidation of soil organic matter [50][51][52]. In our study, significant differences were only observed 1MAF, with higher values in the C treatment.…”

“…In our study, significant differences were only observed 1MAF, with higher values in the C treatment. Singh et al [52] found that following a wildfire in tropical dry forests, there was an increase in soil dehydrogenase activity, and the effect was most prominent one month after the wildfire. Regardless, they showed that the effect of wildfires on soil dehydrogenases lasted as long as 13 months.…”

Correlation of Soil Physiochemical Properties, Microorganism Numbers, and Bacterial Communities Following Unburned and Burned Sugarcane Harvest

“…Arocena and Opio [37] reported that a pH decrease was generally caused by the loss of base cations during burning. Te opposite efect was reported by the authors of reference [38], who compared to the control (unburned) sites for pine forest and oak forest, the soil pH levels of burnt pine and oak forests were higher by 0.41 and 0.78 units, respectively. In the current study, the numbers of bacteria, actinomycetes, and fungi decreased.…”

“…Signifcant reductions in nitrogen-related bacteria in the rhizosphere soil and sulfur cycle functions accounted for the continuous efective reduction of the total nitrogen and sulfur contents in the rhizosphere soil of sugarcane along with the decrease in the sugarcane yield and sugar content [40]. However, the authors of reference [38] found that the bacterial population tended to increase after the fre because of more available carbon sources. In the current study, the bacterial structure in the soil changed after burning during sugarcane harvest (Table 2 and Figure 3).…”