Carbon storage in silvopastoral systems: a global review and meta-analysis

Abstract

Understanding how effectively silvopastoral systems (SPS) enhance carbon storage compared to other land use systems is crucial to developing grazing systems that can integrate production and carbon storage goals. We conducted a systematic review of 265 publications to identify global trends in SPS carbon research and a meta-analysis of 104 publications to evaluate the effect of SPS on carbon storage compared to open pastures and forests. The review indicates major gaps in Asia, Oceania and Africa, and highlights a need for greater attention to comparing tree, ground vegetation, and tree litter carbon between SPS and forests. The meta-analysis showed SPS with planted trees had 41.7% lower stand-level tree carbon than planted forests, whereas stand-level tree carbon in SPS with native trees was 63.9% lower than in native forests. SPS with either planted or native trees had similar ground vegetation carbon to open pastures. SPS with native trees had 28.9% higher soil organic carbon (SOC) in the topsoil (0 – 30 cm) than open pastures and a comparable topsoil SOC relative to native forests. In contrast, these native systems had 22.8% lower SOC in the subsoil (30 – 100 cm) than native forests, whereas SPS with planted trees had similar SOC up to 100 cm depth compared to open pastures and planted forests. Our findings suggest SPS can enhance carbon storage in grazing landscapes. Integrating livestock into native forests can increase SOC compared to open pastures, while establishing SPS with planted trees can maintain comparable SOC levels to open pastures and planted forests.