Agroforestry strategies to sequester carbon in temperate North America

Information on carbon (C) sequestration potential of agroforestry practices (AP) is needed to develop economically beneficial and ecologically and environmentally sustainable agriculture management plans. The synthesis will provide a review of C sequestration opportunities for AP in temperate North America and the estimated C sequestration potential in the US. We estimated carbon sequestration potential for silvopasture, alley cropping, and windbreaks in the US as 464, 52.4, and 8.6 Tg C yr(-1), respectively. Riparian buffers could sequester an additional 4.7 Tg C yr(-1) while protecting water quality. Thus, we estimate the potential for C sequestration under various AP in the US to be 530 Tg yr(-1). The C sequestered by AP could help offset current US emission rate of 1,600 Tg C yr(-1) from burning fossil fuel (coal, oil, and gas) by 33 %. Several assumptions about the area under different AP in the US were used to estimate C sequestration potential: 76 million ha under silvopasture (25 million ha or 10 % of pasture land and 51 million ha of grazed forests), 15.4 million ha (10 % of total cropland) under alley cropping, and 1.69 million ha under riparian buffers. Despite data limitation and uncertainty of land area, these estimates indicate the important role agroforestry could play as a promising CO2 mitigation strategy in the US and temperate North America. The analysis also emphasizes the need for long-term regional C sequestration research for all AP, standardized protocols for C quantification and monitoring, inventory of AP, models to understand long-term C sequestration, and site-specific agroforestry design criteria to optimize C sequestration.