Phytolith-occluded organic carbon (PhytOC) is a form of long-term storage of soil organic carbon, which is of great significance for soil carbon sequestration. Taking six land use patterns in southwest China as the research object, including coniferous and broad-leaved mixed forest, bamboo forest, orchard, dry land, paddy field, and grassland, we compare the distribution of the PhytOC content under the different land use patterns in different depth sections of 0-20, 20-40, 40-60, and 60-100 cm. In addition, we estimate the storage of phytOC and analyze the carbon sequestration characteristics of the terrestrial ecosystems. According to the results, the soil organic carbon and phytolith mean content in the bamboo forest were the highest in the soil profile, at 16.75 g·kg-1 and 59.66 g·kg-1, respectively. In all soil layers, the phytolith content of the bamboo forest soil was significantly higher than that in other land use patterns (P<0.05). The average content of soil phytOC in the six land use patterns ranged from 0.55 to 1.96 g·kg-1, and the phytOC content of each layer of bamboo forest was higher than that in other land uses. The total carbon storage of phytOC in the bamboo forest soil, at 23.45 t·hm-2, was significantly higher than that of other soil use methods (P<0.05). Statistical analysis showed that soil silicon had a significant positive correlation with the soil phytolith and the soil phytOC (P<0.01). The soil phytolith and phytolith carbon content in different land use patterns generally showed a decrease with an increase in soil depth, and a certain surface enrichment phenomenon was noted.
Keywords: Jinyun Mountain; land use patterns; phytolith-occluded organic carbon; soil organic carbon; storage of PhytOC.