Impact of forest fires on soil physicochemical properties in Himalayan forest ecosystems of Uttarakhand, western Himalaya

Forest fire represents a recurrent disturbance in the Himalayan Forest ecosystems of Uttarakhand, Western Himalaya. The repeated occurrence of large-scale fire events in these forests exerts profound ecological, economic, and socio-cultural impacts. Soil is considered one of the most important natural resource and wildfire alter the nutrient status and composition of the soil. Little information is available on how soil properties such as moisture and pH level, carbon, nitrogen, phosphorus and potassium stock vary along depth-wise before and after fire. In order to address this research problem, soil samples were collected from 0-15 cm and 15-30 cm depths before and after forest fires from mixed, sal, and chir-pine forests of Uttarakhand, India. Principal Component Analysis (PCA) was used to explore the relationship among these different parameters. Before the fire, soil moisture content and organic carbon was highest in mixed forest followed by sal and chir-pine forest and after the fire, both moisture and organic carbon reduced across all forest types. Soil pH was initially slightly acidic in all forest type and after the fire pH of all forest type increased. Nitrogen and Phosphorus content was highest in mixed forest followed by chir-pine and sal forest but after fire, both the nutrients decreased. Potassium content increased after the fire due to ash deposition, and an increase in soil pH and potassium suggests nutrient redistribution. Overall, present study suggested that management of forest fire is essential to mitigate these impacts and restoration efforts to safeguard soil health and maintain ecosystem productivity in the Himalayan region.