Carbon Sequestration Potential of Biomass Production along Highways in China.

In response to climate change, China is making great efforts to increase the green area for carbon sequestration. Road verges, as marginal land with favorable conditions for plant growth and ease of transportation, can be used for biomass production, but the biomass production and carbon sequestration potential have not been assessed. Here, we mapped the biomass production potential of road verges in China by combining a biomass model and Geographic Information System and then evaluated the effect of road runoff and CO fertilization on the production according to the runoff coefficient and vehicle emission inventory. Nationwide, road verges can produce 15.86 Mt C yr of biomass. Road runoff contributes to a biomass production of 1.26 Mt C yr through increasing soil water availability, which mainly occurs in arid regions. The CO fertilization effect by vehicle emission is considerable in Eastern and Southern China, contributing to a production of 0.09 Mt C yr. Life cycle assessment shows that major road verges in China have a carbon sequestration potential of 6.87 Mt C yr currently. Our results revealed that road verges can make a significant contribution to carbon neutrality under proper management.