Sustainability nexus in China's forestation initiatives

The broader impacts of forestation on sustainability under growing land resource pressure remain poorly understood. In this study, we develop a "Sustainability Nexus" framework that leverages an integrated assessment model, an ecosystem service model, and a biodiversity model to evaluate how forestation policies may intensify land competition and reshape ecosystem services, food security, energy transitions, emission mitigation cost, and water consumption. Taking China as a case study, we find that the 30.7% forest cover goal can deliver a gross carbon sink of 18.1 Pg C this century, yet land conversion offsets nearly two-thirds of this gain, leaving a net land use, land use-change, and forestry sector carbon sink of only 5.6 Pg C. While forestation reverses national habitat loss, decreases renewable energy demand by 1.5%, lowers the shadow carbon price by 3.2%, and reduces irrigation water consumption by 2.4% and fertilizer inputs by 5.9%, it simultaneously raises food and bioenergy prices, placing an additional 34.4 million people at risk of hunger. These findings underscore the need to explicitly account for sustainability nexus in forestation planning. Synergistic agricultural measures will be critical for maximizing co-benefits and mitigating unintended trade-offs in future land-based mitigation strategies.