PhytOC stock in forest litter in subtropical forests: Effects of parent material and forest type

Organic carbon (C) occluded in phytolith (PhytOC) is stable in the soil for millennia and can be an important contributor to long-term C storage in forest ecosystems. In order to understand the effect of parent material and vegetation type on the production of PhytOC in plant litter in subtropical forests in China, we investigated the PhytOC concentration and stock in plant litter in four forest types, moso bamboo (Phyllostachys edulis Moso), Chinese-fir (Cunninghamia lanceolata), evergreen broadleaf and mixed conifer-broadleaf forests, established on three parent materials (rhyolite, sandy shale and tuff). This study showed that: 1) both parent material and forest type significantly affected phytolith concentrations in litter, and there was a significant interaction between parent material and forest type. Plant litter in the moso bamboo forest developed on rhyolite and tuff had the highest phytolith concentrations followed by moso bamboo forest on sandy shale; 2) forest type but not parent material affected PhytOC concentrations in litter, with the highest in the moso bamboo forest; 3) both parent material and forest type significantly affected PhytOC stock in litter, without a significant interaction between the two factors. The moso bamboo forest had the highest PhytOC stock in its litter; and 4) the PhytOC stock returned to the soil in moso bamboo, Chinese-fir, evergreen broad-leaf and mixed coniferous forests was (mean ± SD) 14.66 ± 4.69, 2.87 ± 2.19, 6.22 ± 2.46 and 4.84 ± 1.82 kg ha−1, respectively. Considering the area of the four respective forest types, the amount of C that can be entered into the soil in the form of PhytOC in litter was 2.08 × 105, 1.19 × 105, 5.68 × 105 and 2.75 × 104 t CO2-e, respectively, and therefore it indicates a great potential in long-term C storage.