Impact of post-anthropogenic forest fire on soil carbon dynamics and physicochemical properties in tropical dry deciduous Sulia Reserve Forest, Odisha

Anthropogenic forest fire is an emerging cause for forest degradation, which primarily alters soil physicochemical characteristics and carbon content. For assessing these effects, the current study compares soils of unburned (as CON), managed (as MAN) planted locations (Shorea robusta, Tectona grandis), and burned (as BUR) locations of Sulia Reserve Forest of Nayagarh, Odisha. Soils were collected from below surface litter (BSL) (0 to 5 cm), top soil (TS) (5 to 15 cm), and sub-soil (SS) (15 to 30 cm) randomly from selected patches. Samples were analysed for colour, texture, pH, bulk density (BD), water holding capacity (WHC), electrical conductivity (EC), potassium (K⁺), and nitrogen (N). Also, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and Fourier transform infrared spectroscopy (FTIR) were utilised to study the soil mineralogical and surface properties. In comparison to unaffected locations (CON and MAN), the BUR soil showed increased levels of EC, OC (oxidisable carbon), TOC (total organic carbon), SOM (soil organic matter), K⁺, and available nitrogen (AN). However, suppression in total nitrogen (TN) was observed for BUR locations in BSL samples. In BUR, the range of EC (0.12–0.29 S/m), OC (1.8–2.8%), TOC (2.5–3%), and SOM (4–6%) demonstrated variability in soil physicochemical properties. The BUR soils reflect significant changes in feldspar, haematite, and kaolinite. The results also highlight the C alteration and enhancement of nutrients (K⁺ and N) availability in BUR soil. The assessment demonstrates complex behaviours of soil properties due to forest fire within a dry deciduous forest and emphasises a location specific management plan to conserve the natural resource.