The cost of restoring carbon stocks in Brazil's Atlantic Forest

Abstract Knowing which restoration approach provides the best returns on investment for accumulating carbon is essential to foster restoration planning, financing, and implementation. Here, we explored the cost‐effectiveness and drivers of aboveground and soil carbon accumulation in restored forests across an agricultural landscape of Brazil's Atlantic Forest. The recovery of aboveground and soil carbon stocks, as well as the implementation and land opportunity costs, was assessed across chronosequences (10–60 years) of second‐growth forests and mixed‐species tree plantings and old growth, reference forest remnants. Plantations accumulated approximately 50% more aboveground carbon than second‐growth forests throughout the chronosequence. When controlling for soil clay content, soil carbon stocks were higher in reference than in restored forests, but they were comparable between plantations and second‐growth forests. After 60 years of stand development, recovery of total carbon stocks in both restoration approaches reached only half of the average stocks of reference forests. Total cost‐effectiveness for carbon accumulation, including both implementation and land opportunity costs, was on average 60% higher for second‐growth forests than for plantations (15.1 and 9.4 kgC US$ −1 , respectively). Although tree plantations initially showed higher rates of carbon storage than second‐growth forests, their higher implementation and land opportunity costs make them less cost‐effective for carbon farming. Our results further suggest that, at current pricing levels, carbon markets alone have a limited potential to up‐scale restoration efforts in Brazil's Atlantic Forest.