植物生态系统中的植硅体闭蓄有机碳及其在全球土壤碳汇中的重要作用

植硅体闭蓄有机碳（phytolith—occluded organiccarbon，PhytOC）是封存在植硅体中的有机碳。在土壤环境中受到具有高度抗分解能力的植硅体的保护，它可以长期（数千年至万年以上）封存在土壤剖面中，从而成为陆地土壤长期（万年尺度）固碳的重要机制之一。以千年的时间尺度来衡量，估计全球土壤有机碳的平均积累率为2．4g·m^-2．a^-1，其中PhytOC积累贡献了15．0％～37．0％。通过选择种植高产PhytOC的植物物种来增加短期和长期碳汇的途径是存在的。大多数的农作物如大麦Hordeumvulgare，玉米Zeamays，水稻Oryzasativa，高粱Sorghumvulgare，甘蔗Saccharumofficinarum和小麦Triticumaestivum已知是植硅体的生产者。估计全球上述作物每年生产的PhytOC高达（5．08～12．01）×10^6t.a^-1。综述了植物生态系统中PhytOC的形成机制与特征、积累率、提高土壤PhytOC积累率的农学措施及其在全球土壤碳汇中的重要作用。

PhytOC in plant ecological system and its important roles in the global soil carbon sink

As a substantial component of soil organic carbon occluded within phytoliths, PhytOC is a result of biomineralization within plants and highly resistant to decomposition in the soil environment. PhytOC accumulation rates have contributed about 15.0%-37.0% to the estimated global mean long-term soii carbon accumulation rate which is 2.4 g.m-2.a^-1 over the last 10 000 years. There are ways to enhance both short and longterm carbon sequestration by cultivation of high PhytOC-yielding plant species of agricultural crops. Most of the economically important agricultural plant species such as barley, maize, rice, sorghum, sugarcane and wheat, are producers of phytoliths. It was estimated that the above-mentioned crops globally produced PhytOC of （5.08-12.01）x106 t＇a-1. The paper reviewed the formation mechanism, characteristics and accumulation rate of PhytOC in the plant ecological system, the agronomy measures to improve the accumulation rate and its important role in the global soil carbon sink.