Soil PhytOC accumulation of Masson pine forests in Southwest China

The accumulation of phytolith-occluded organic carbon (PhytOC) in soils is great significance for carbon sink of terrestrial ecosystems. To clarify the accumulation law of soil PhytOC in Masson pine forests and to elucidate whether forest management significantly influences the accumulation of PhytOC in soils, soil PhytOC accumulation of the typical Masson pine forests in Southwest China karst area were studied. We tested the hypothesis that forest age obviously affects soil PhytOC accumulation in Masson pine forests and mature Masson pine forests have higher soil PhytOC accumulation than young Masson pine forests. The followed results and conclusions were obtained: (1) Soil phytolith and PhytOC content range of 0–30 cm soil profile in the karst Masson pine forests was 9.67–12.81 g·kg^− 1 and 0.17–0.25 g·kg^− 1, respectively. (2) Forest stand condition significantly influenced soil PhytOC accumulation in the Masson pine forests. With increasing stand age, soil PhytOC accumulation rose remarkably in the Masson pine forests. (3) Soil physical and chemical properties largely influenced the soil PhytOC accumulation. The calcium-rich, high Si and alkalescent soils in Southwest China karst area were propitious to the preservation and accumulation of PhytOC. (4) There were huge potential of soil phytolith carbon sequestration of Masson pine forests in Southwest China. Forest management measures changing stand density or canopy density is of great significance in increasing soil phytolith carbon sink of Masson pine forests and should be paid more attention for increasing carbon sink of terrestrial ecosystems.