Abstract
Spatial distribution and edaphic influences on soil organic carbon (SOC) are key determinants of carbon sequestration potential of forest ecosystems. Further, analysis of aggregate-protected soil organic carbon gives an in-depth understanding of the stability of carbon stored in these soils. The present study evaluated the edaphic effects on the soil organic carbon in four different forest systems - tropical evergreen forest, tropical moist deciduous forest, tropical dry deciduous forest and shola forest - in the southern high hills agro-ecological zone of Western Ghats, India. Organic carbon contents in the wet-sieved soil aggregates varied significantly between the different forest systems. The soil organic carbon stocks up to 1 m depth was found to be highest in the shola forest system (441.08 Mg C/ha) and lowest in the dry deciduous forest (138.17 Mg C/ha). An evaluation of the effects of forest type, soil depth and aggregate size on SOC by a fixed-effect model showed that all these factors significantly affected carbon storage in these systems. An assessment of the relative importance and effect of fourteen edaphic factors on SOC content in different forest systems using the random forest model showed that the algorithm could explain 93.68%, 41.72%, 45.53% and 75.2% variability of SOC concentration across shola, dry deciduous, moist deciduous and evergreen systems, respectively. In all the forest systems except in dry deciduous forest, soil texture surpassed all other edaphic parameters and was found to be the primary factor influencing the SOC. The insights on the SOC dynamics and edaphic factors controlling them provide valuable inputs for forest management in the tropics vis – a – vis climate change mitigation.