Soil carbon alterations of selected forest types as an environmental feedback to climate change

The soil organic carbon (SOC) and its various fractions vary significantly under different forest categories and understanding these variations is important for assessing the carbon balance and dynamics of these systems. These factors or indicators can depict the extent of vulnerability of forest systems as potential sources or sinks of carbon(C). The study was conducted in four typical forest types in the Chinnar wild life sanctuary of Idukki district, Kerala, India, a part of the high ranges of Southern Western Ghats. The results showed that there were obvious variations in the content and stock of SOC among the forest categories. Maximum SOC content was observed in Shola Forest (SF) site whereas the minimum in Riparian Forest (RF). The prominence of subsoil layer (10-30cm) as a better C sink was recognized for the entire forest types, irrespective of its category. Variations in the labile and non labile C counterparts were significant among the categories and similar variational trends were observed between the Particulate organic carbon(POC) and water stable aggregates (WSA) proportion for various forest systems. The various soil carbon fractions indicate different aspects of soil carbon dynamics and sequestration, with the more active (labile) carbon component reacting more sensitively to landuse changes as observed in thorny forest (TF) site. The proportion of carbon labile, micro aggregation and potential carbon mineralization (PCM) were comparatively high in TF site making it a vulnerable soil carbon pool. Significant positive correlations were observed between the soil carbon sink indicators like SOC, POC, and macro aggregation. The soil carbon source indicators like PCM and micro-aggregation showed significant negative correlation with the sink indicators. The study thus highlights the role of selected parameters or factors as potential indicators of soil carbon pool vulnerability in forest ecosystems. Understanding the mechanisms and factors of SOC dynamics in forest soils is important in their role as natural sinks for C sequestration in the climate change perspective.