Carbon sequestration potential and cost-benefit analysis of hybrid poplar, grain corn and hay cultivation in southern Quebec, Canada

Fast‐growing trees provide opportunities for carbon (C) sequestration. This study compared the C sequestration potential and cost benefit of four cultivation systems in southern Quebec, Canada. The systems studied included two hybrid poplar cultivation systems, a hybrid poplar and hay intercropping system (111 trees ha⁻¹) and a hybrid poplar plantation (1,111 trees ha⁻¹), and two agricultural systems, grain corn and hay. The C sequestration potential was estimated using the net primary productivity (NPP) approach, which relied on literature values and average yields for the study region. We used the NPP approach to quantify C fixed annually in above‐ and below‐ground biomass, to determine the annual plant residue input to soil from litter, root turnover and root exudates, to estimate the fraction of plant residues stabilized in soil organic C, and to provide a reference value or estimate of C sequestration potential. Costs and benefits of the cultivation systems were assessed using replacement chain and equivalent annual annuity approaches, with alternate discount rates. Estimated C sequestration potential was highest for hybrid poplar grid plantation > hybrid poplar hay intercrop > grain corn > hay. Economic benefits, not accounting for potential benefits of C sequestration, were greatest for grain corn > hay > hybrid poplar‐hay intercrop > hybrid poplar grid plantation. We conclude that economic valuation of C sequestration potential is necessary to improve the apparent profitability of tree‐based cropping systems in Quebec, Canada. And if afforestation with hybrid poplar is considered as an option for increasing C sequestration on Canadian farms, government policies such as C‐trading programs would be necessary to increase the financial attractiveness of hybrid poplar cultivation.