The production of phytoliths in China's grasslands: implications to the biogeochemical sequestration of atmospheric CO₂.

摘要

Among the most promising approaches of long-term atmospheric CO₂ sequestration is terrestrial biogeochemical carbon sequestration. One of the most promising terrestrial biogeochemical carbon sequestration mechanisms is the occlusion of carbon within phytoliths, the silicified features that deposit within plant tissues. Using phytolith content-biogenic silica content transfer function obtained from our investigation, in combination with published silica content and above-ground net primary productivity (ANPP) data of China's grasslands, we estimated the production of phytoliths and phytolith-occluded carbon (PhytOC) in grasslands. The results show that the average above-ground phytolith production rates of China's grasslands (10.9 106 t yr-1 or 1.45% of world grasslands) are much lower than those of other grasslands (e.g. North American nonwoody grasslands) mainly because of much lower ANPP. Assuming a median content of PhytOC of 1.5%, the average above-ground PhytOC production rates of China's grasslands and world grasslands are estimated to be 0.6 106 t CO₂ yr-1 and 41.4 106 t CO₂ yr-1, respectively. The management of grasslands to maximize ANPP has the potential to result in considerable quantities of phytoliths and securely bio-sequestered carbon.