Comparative analysis on the socio-ecological and economic potentials of traditional agroforestry systems in the Sikkim Himalaya

Five different traditional agroforestry systems viz. farm-based, forest-based, Alnus-cardamom, forest-cardamom, and Albizia-mixed-tree-mandarin were studied in the Sikkim Himalaya in order to evaluate and compare stand nutrient dynamics, N-2-fixation, and cost-effectiveness in relation to social and ecological resilience to the increasing externalities such as climate change. Overall soil nutrient availability was highest in Alnus-cardamom systems, followed by Albizia-mandarin systems. N-2-fixation in Alnus-cardamom systems was highest (95 kg ha(-1)), followed by forest-based systems (59 kg ha(-1)), and lowest in forestcardamom agroforestry systems (9.5 kg ha(-1)). Annual economic return was highest from Alnuscardamom (US$ 1895), followed by forest-cardamom (US$ 1275), and Albizia-mandarin systems (US$ 1166). Output-input ratio was highest in Alnus-cardamom (12.05), and lowest in forestbased agroforestry (4.21). Climate change has primarily manifested itself as unpredictable or shorter duration of rainfall events. Exposed or abandoned agricultural land lacking tree cover decreases the retention time of soil water content, thereby drying of local springs/ streams at lower altitudes. Crop productivity of large cardamom between traditionally suitable altitudes has declined by 10 - 20 % in the past 3 - 4 years. Farmers have perceived a shift in phenological calendar, most notably in the flowering period of plants. The future socio-ecological and economic resilience of this research lies in the collective design and implementation of an integrated agroforestry scheme, considered by farmers, scientists, agricultural extensions agents, and policymakers alike.