Impact of disturbance on spatio-temporal dynamics of carbon dioxide efflux on forest floor in tropical sal forests of the Eastern Ghats

Abstract

Understanding soil carbon dynamics in tropical forests is essential for developing sustainable forest management strategies and strengthening climate change mitigation efforts. This study examined soil respiration and carbon turnover across three moist deciduous sal forest types of the Eastern Ghats, India: pure sal forest (PSF), sal-dominated moist mixed forest (SDMDF), and mixed forest without sal (MDFWS). Seasonal in-situ measurements of total, autotrophic, and heterotrophic soil respiration were conducted across three forest types, along with the measurements of soil temperature, moisture and vegetation attributes. Correlation, regression and principal component analysis (PCA) were used to identify the major environmental and biotic controls of soil respiration and carbon turnover. Seasonal patterns revealed higher soil temperatures during summer and maximum soil moisture during the monsoon period. Soil respiration closely followed moisture availability, reaching peak levels during the monsoon and declining during winter. Among the forest types, MDFWS exhibited the highest mean soil respiration (1.14 g cm−2 d−1), followed by SDMDF and PSF. Annual soil carbon efflux ranged from 28.80 to 49.83 Mg C ha−1 y−1, with autotrophic (root) respiration contributing a greater proportion than heterotrophic respiration. Mean residence time of soil organic carbon was highest in PSF (3.73 years) and lowest in MDFWS (1.09 years), indicating faster carbon turnover in mixed forests lacking sal dominance. Soil respiration was positively associated with soil moisture and tree density, while it showed a negative relationship with soil temperature. Multivariate analyses identified soil moisture as the primary determinant of soil respiration variability, underscoring the critical role of monsoonal precipitation and forest structure in regulating ecosystem carbon fluxes. These findings demonstrate that forest composition and hydrological conditions strongly influence soil carbon dynamics and ecosystem functioning. The study highlights the importance of conserving and sustainably managing tropical sal forests to enhance carbon retention, strengthen climate resilience, and support long-term environmental sustainability and sustainable development goals in forest-dependent landscapes of India.