The production and accumulation of phytolith-occluded carbon in Baiyangdian reed wetland of China

Phytolith, the opal of amorphous silica formed in plant tissues, is present in most plants (mainly Poaceae, Cyperaceae and so on). The carbon bio-sequestration within the phytoliths of plants, one of the most promising approaches of long-term CO2 sequestration, is a significant mechanism of long-term biogeochemical carbon sequestration. This study analyzed the production and accumulation of phytolith-occluded-carbon (PhytOC) in Baiyangdian reed wetland of China. The plant phytolith extraction was undertaken with microwave digestion procedures and the soil phytolith extraction was based on the method of heavy liquid separation. The determination of the carbon content of phytoliths was based on phytolith-Si dissolution methods. The production flux of PhytOC for aboveground reed was 3.7-4.2 g CO2 m−2 a−1 and the accumulation flux of PhytOC for soil layer (0-15 cm) of soil deposition was 0.03 g CO2 m−2 a−1. The results imply that PhytOC content in reed dry biomass mainly depends on the content of the silicon taken up by the plant and the occluded carbon content of phytoliths during the plant growth. In Baiyangdian reed ecosystems, the rate of PhytOC for aboveground reed is about 6.77-7.69 × 108 g e CO2 a−1, and the accumulation rate of PhytOC for 0-15 cm soil layer is around 5.49 × 106 g CO2 a−1. Assuming the plant-area (5.7 × 108 ha) of global wetland with the similar maximum flux (0.054 t e CO2 ha−1 a−1) of reed PhytOC sequestration of atmospheric CO2, about 3.08 107 tone CO2 every year would be sequestrated by wetland ecosystem. The appropriate management of reed wetlands to maximize ANPP and select plant species with high-phytolith content or high-efficiency of phytolith occlusion of carbon has the potential to result in considerable production and accumulation quantities of PhytOC in reed wetland ecosystems.