PG Thesis
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Item Spatial variation of carbon stocks and its turnover in the mangrove systems of Kerala(College of Climate Change and Environmental Science ,Vellanikkara, 2023-12-07) Aryadevi, J S.; Sandeep, SA study of 625 individuals from six mangrove species in Kerala found that A. marina dominates the mangrove forest, accounting for 38% of the tree count. Other species include A. officinalis, R. mucronata, B. cylindrica, R. apiculata, and S. alba. The northern zone has the highest diversity value and lowest Simpson index value. The total AGB of six mangrove species in Kerala is 1852.42 t ha-1, with the northern zone having the highest biomass at 827.73 t ha-1. R. mucronata has the highest AGB in the northern zone, followed by A. marina in the southern zone. Avicennia species dominate over half of the basal area. The study also found that soil bulk density increased with soil depth, with the lowest value in the northern zone and the highest in the southern zone. The pH levels in mangrove habitats vary, with the central zone having the highest pH (7.62). Organic carbon content varies among soil profiles, with the top soil in the central zone having the highest organic C level (2.05%). Estimated total organic C stock is 434±60.99 t ha-1, with the north zone having the largest deposit (181.96±16.14 t ha-1). The amount recorded in the southern zone is the lowest (111.93±18.06 t ha-1). Future predictions show that, temperature and rainfall significantly impact mangrove growth and productivity in Kerala over a 27-year period. Temperature rises by 0.74°C and rainfall increases by 13.63%, with temperature having the greatest influence in DNDC modelling. From 2022 to 2050, SOC is expected to increase at a rate of 0.3 to 1% per year, with an increase of 0.4% from 2022 to 2030 and 0.25% from 2030 to 2040 and 2040 to 2050. Temperature and precipitation positively correlate with SOC, with higher temperatures and rainfall increasing soil carbon mineralization and lowering SCS. Tree C in mangroves is experiencing a 0.2% decline annually, with no effect from RCP 4.5. The study shows a decline in GPP from 2022-2050, due to increased atmospheric CO2 concentrations. The trend towards reducing tree respiration is increasing, with a 0.04% increase expected between 2040-2050. Climate change is predicted to positively impact SCS by 2050, but its severity is concerning, as rising temperatures and precipitation pose risks to mangrove ecosystems' future. Key words: Mangrove, SOC, DNDC modelling