Toward low-carbon management of Spartina alterniflora ecological restoration project in China: A multi-objective spatial optimization balancing carbon footprint and economic cost

Spartina alterniflora is a highly invasive plant species in China's coastal wetlands, posing severe threats to ecosystem functioning and biodiversity while generating substantial environmental and economic burdens during large-scale control efforts. However, the carbon footprint and cost trade-offs of alternative restoration projects remain poorly understood at the national scale, limiting the design of sustainable management strategies. Moreover, no spatially explicit decision-support framework currently exists to jointly optimize restoration methods and biomass treatment pathways under heterogeneous regional contexts. Here, we integrate life cycle assessment with multi-objective spatial optimization to evaluate the carbon footprint and engineering cost of four widely applied S. alterniflora restoration methods, including mowing–plowing, mowing–shading, mowing–flooding, and mowing–plowing–planting, in combination with four straw treatment methods. Carbon emissions and costs were quantified per hectare and spatially optimized. Results show that mowing–plowing exhibits the lowest carbon footprint (4.64 t CO 2 -eq ha −1 ), whereas mowing–flooding produces the highest emissions (9.82 t CO 2 -eq ha −1 ) due to intensive electricity consumption. Straw management substantially reshapes project-level emissions, with biogas production providing net carbon offsets and landfill disposal causing high emissions (100.73 t CO 2 -eq ha −1 ). Spatial optimization identifies province-specific restoration portfolios that balance national carbon emissions (0.41 Mt CO 2 -eq) and economic cost (3.68 × 10 9 CNY), with mowing–flooding dominating in Shanghai and Jiangsu and mowing–plowing prevailing in most other provinces. This study provides a spatially explicit decision-support framework for low-carbon and cost-effective coastal restoration, offering advances in spatial planning for sustainable invasive species management under China's dual-carbon goals.