Plantations are efficient sequesters of carbon and can mitigate the predicted rise in atmospheric CO2 concentration and future climate change. Trees can capture atmospheric CO2 through photosynthesis and store it in biomass with a turnover time of several decades. The present investigation was undertaken to study the carbon stock in biomass of important plantation species of clonal and seedling origin in the Southern agro-climatic zone of Tamil Nadu. The existing stands of three different ages of a tree plantation were selected from within the available plantations on farmlands, and data on girth and height were recorded for all the trees. The results revealed that the total carbon stocks (537.8 Mg ha-1) was maximum under Eucalyptus clonal plantation of >6 years. Aboveground biomass was greater than belowground biomass, accounting for 79% of total biomass in Casuarina clonal plantation of > 5 years. Biomass carbon stock in Melia increased from 49.8 Mg C ha-1 in 1 to 4 years plantation to 95.5 Mg C ha-1 in >7 years old plantation. The findings explain the ability of clonal plantations of Casuarina and Eucalyptus in accumulating maximum biomass carbon stock.

Soil organic carbon (SOC) plays an important role in soil fertility and is of paramount importance for its contributions to mitigation and adaptation to climate change. The present study was undertaken to estimate the SOC stock and soil properties in important plantations of the Southern zone in Tamil Nadu. Four different species were selected for the study viz, Eucalyptus, Casuarina, Melia and Teak. In all the plantations selected for estimation of biomass, composite soil samples were collected at three different depths; i.e., 0-15, 15- 30 and 30-45 cm. The soil samples were analysed for the carbon stock and various properties such as pH, Electrical conductivity, Organic carbon, Available N, Available P, Available K. Among Eucalyptus plantations, clonal plantation of >6 years sequestered the highest amount of soil carbon (19.8 Mg ha-1) at 30 cm depth. SOC stock was maximum in Casuarina plantation of > 5 years (23.3 Mg ha-1). Among the different Melia plantations, maximum SOC stock was observed in Melia plantation of 5 to7 years old (15.6 Mg ha-1), and in Teak plantations, SOC stock was highest in plantations of > 15 years old (22.1 Mg ha-1). The soil pH and Electrical conductivity significantly differed among the plantations and decreased with an increase in the age of plantation. Nitrogen availability was highest (303.98 kg ha-1 ) in >5 years of Casuarina clonal plantation at 0-15 cm depth. Among the plantations the available potassium was high in surface soils (0-15 cm) of >5 years Casuarina clonal plantation (329.50 kg ha-1). The data generated in the present study would provide valuable information on the scope of afforestation and reforestation projects for sustaining the livelihoods of the farming community and also will encourage them to contribute to mitigating global carbon emissions and expanding forest and tree cover.