Post-fire soil nutrient dynamics in a tropical dry deciduous forest of Western Ghats,India

Background: The effect of forest fire on soil is complex and relatively less understood than its above ground effect.Understanding the effect of fire on forest soils can allow improving management of valuable forest ecosystems as adequate and proper information is very important for efficient management. We have studied the recovery of soil properties after fire, using a chronosequence approach(two, five and fifteen years after fire and control). Soil samples were collected from each plot of four fire patches(B0, B2, B5 & B15) from three different depths viz. 0–10(Top), 10–20(Middle), and 20–30 cm(Bottom).Results: Soil organic carbon was lower than unburned plots after the fire and could not recover to the level of unburned plot(B0) even in 15 years. Total N, available P, and extractable K were lower 2-years and 5-years after the fire but are higher than unburned plot after 15-years. Available nitrogen(NO_3^- and NH_4^+) remain unchanged or higher than B0 in burned patches. Soil pH, Bulk Density, Water Holding Capacity, and Electrical Conductivity was lower initially after the fire. Forest fires have affected soil properties considerably. The response of soil properties varied with years after fire and soil depth.Conclusion: Forest fires occur very frequently in the study area. Significant quantities of carbon and total nitrogen are lost to the atmosphere by burning of litter, duff, and soil OM. Because nitrogen is one of the most important soil nutrients, the recapture of N lost by volatilization during a fire must receive special attention. Long-term studies are required to better understand the recovery of soil nitrogen.

Effect of forest fire on tree diversity and regeneration potential in a tropical dry deciduous forest of Mudumalai Tiger Reserve, Western Ghats, India

Introduction:The study was conducted in Mudumalai Tiger Reserve,in the Western Ghats to understand the effect of a single fire event on tree diversity and regeneration status.Four forest patches were selected which were unburned,2-year-old burn,5-year-old burn,and 15-year-old burn.Three 0.1 ha square plots were laid randomly in all four patches and analyzed for tree diversity,stand structure,and regeneration of tree species.Results:A total of 4129 individuals of tree species were recorded in field surveys,comprising 3474 seedlings,121 saplings,and 534 trees.Totally,40 tree species were recorded in study plots,from which 28 species were seedlings,16 species were saplings,and 37 species were at tree stages.Conclusions:Tree diversity decreased in 2-year-old and 5-year-old burnt plots and was reached to the level of unburnt plots in 15 years of interval.Stems of small size classes started increasing after the fire.Seedling density increased linearly in subsequent years after fire but sapling and tree density recorded less than control in B2 but was higher in B5 and B15.The overall fire affected diversity,but regeneration showed a positive trend.