Shorebird loss increases soil CO₂ emissions in coastal wetlands under restoration

Countries worldwide are increasingly adopting nature-based solutions (NbS) to tackle the challenges of global climate change. One recently proposed NbS is wildlife conservation, yet the impact of wildlife on carbon emissions in ecosystems under restoration remains poorly understood. We assessed the role of shorebirds in regulating the carbon cycle of a coastal wetland under vegetation restoration, using a long-term field experiment that simulated the exacerbation of ongoing shorebird loss through shorebird exclusion. We found that compared to control treatments, shorebird exclusion significantly increased soil CO₂ emissions by 105% on average over four years, an impact that was particularly pronounced in seasons (spring and autumn) when migratory shorebirds were abundant. The impact of shorebird exclusion on CO₂ emissions was mainly driven by the release of crab bioturbators from predator control, with CO₂ emissions increasing strongly as crab bioturbator abundance increased. Largely owing to increased soil CO₂ emissions, shorebird exclusion significantly increased ecosystem respiration and net ecosystem exchange and reduced soil carbon sequestration, although it did not affect gross ecosystem photosynthesis, litter decomposition, microbial biomass carbon, or dissolved organic carbon. Our findings underscore the substantial, but previously overlooked role shorebirds play in regulating the carbon cycle of coastal wetlands under vegetation restoration. Conservation of shorebirds and other predators of soil bioturbators may be a valuable NbS to help curb global warming.