Storage and Stability of Phytolith-occluded Carbon in Three Typical Coniferous Forests at Mt. Funiu

  Objective  Sequestration and stability of phytoliths and phytolith-occluded carbon (PhytOC) in plant organs, ground litter, and soil in three typical coniferous forests at Mt. Funiu in Henan province were analyzed to better understand the long-term carbon fixation in the eco-system.

  Method   Contents of phytoliths, C in phytoliths, PhytOC, and SiO₂ in the plant organs, ground litter, and 0-50 cm soil in Cedrus deodara, Sabina chinensis, and Platycladus orientalis forests at Mt. Funiu were collected according to the mass balance method.

  Result  The contents of phytoliths, C in phytoliths, PhytOC, and SiO₂ in various organs of the trees and soil of the forests in the area varied significantly. The phytolith contents in the plant organs ranged 1.49-3.27 g·kg⁻¹ for C. deodara, 1.44-2.56 g·kg⁻¹ for S. chinensis , and 1.86-2.90 g·kg⁻¹ for P. orientalis, while the PhytOC at the C. deodara forest, 0.030-0.114 g·kg⁻¹, at the S. chinensis forest, 0.036-0.085 g·kg⁻¹, and at the P. orientalis forest, 0.038-0.083 g·kg⁻¹. The production fluxes estimated by this study indicated that the soil PhytOC storage at the S. chinensis forest was 1.64 t·hm⁻², which was higher than 1.17 t·hm⁻² at the C. deodara forest and 0.77 t·hm⁻² at the P. orientalis forest. The estimated PhytOC turnover time for the S. chinensis forest soil was 1 813.16 a, which was significantly longer than 218.78 a for the C. deodara forest soil or 556.44 a for the P. orientalis forest soil.

  Conclusion  Significant variations existed on the phytolith content in the plant organs and the PhtyOC production rate and turnover time of the soil at the 3 forests. By optimizing and/or re-establishing the coniferous S. chinensis forest in the mountain, the biogeochemical carbon sink of the environment could be significantly enriched.