Impact of Soil Water Availability on Carbon Sequestration in Tree Biomass and Soil in Arid Region of India

Arid regions have low capacity to sequester carbon due to low soil water availability and plant growth. However , considering the large extent of such areas total capacity of carbon sequestration may be important. One-year-old planted seedlings of E. camaldulensis , A. nilotica and D. sissoo were maintained at different water regimes by re-irrigating the seedlings at 36.2 mm (T₁) , 26.5mm (T₂) , 20.2mm (T₃) , 18.1mm (T₄) and live saving irrigation (T₅) When the soil water content decreased to 7.56% , 5.79% , 4.44% , 3.23% and drying of leaves (T₅) in the respective treatments. Carbon content both in dry biomass and soil increased with age of the seedlings , but it decreased with decreasing irrigation quantity. A negative carbon balance was observed in T₅ at 12 months age. At the age of 48 months , carbon content varied from 14.91 to 0.72 kg seedling^-1 in E. camaldulensis , 8.67 to 1.74 kg seedling^-1 in A. nilotica and 12.42 to 0.36 kg seedling^-1 in D. sissoo. Carbon density was high under A. nilotica and low under E. camaldulensis. The study suggests that severity of soil water stress affected carbon sequestration whereas , enhanced availability of soil water through irrigation increased carbon storage in biomass and soil. Therefore , there is scope to increase carbon sequestration in dry areas through rain water management and supplying additional irrigation during availability of water.