Speaker
Description
International commitments promote large-scale forest restoration as a nature-based solution to mitigate climate change through carbon (C) sequestration. Accumulating evidence suggests that mixed compared to monospecific planted forests may store more C, exhibit greater stability to climate extremes, and provide a wider range of ecosystem services. However, experimental studies that thoroughly examine the control of tree diversity on multiple C stocks and fluxes above- and belowground are lacking. To fill this gap, we leverage data from the Sardinilla experiment in Panama, the oldest tropical tree diversity experiment which features a gradient of one‐, two‐, three‐ and five‐species mixtures. Over 16 years, we measured multiple above- and belowground C stocks and fluxes, ranging from tree aboveground C, over leaf litter C production, to soil organic carbon (SOC). We show that tree diversity significantly increased aboveground C stocks and fluxes, with a 57% higher gain in aboveground tree C in five-species mixtures compared to monocultures (35.7±1.8 vs 22.8±3.4 Mg C ha-1) 16 years after planting. In contrast, we observed a net reduction in SOC (on average -11.2±1.1 Mg C ha-1) and no significant difference in tree-derived SOC (SOC3) stocks between five-species mixtures and monocultures (13.0±0.9 vs 15.1±1.3 Mg C ha-1). The positive effects of tree diversity persisted despite repeated climate extremes and strengthened over time for aboveground tree growth. Increased tree growth in mixtures enhanced leaf litter and coarse woody debris C fluxes to the soil, resulting in a tightly linked C cycle aboveground. However, the only link between above- and belowground C stocks and fluxes was between leaf litter C inputs and SOC3 which was positively affected by diversity. Our study elucidates the mechanisms through which higher tree diversity enhances the climate mitigation potential of tropical forest restoration. Restoration initiatives should prioritize mixed over monospecific planted forests.
| Status Group | Senior Scientist |
|---|
