Characteristics of phytolith-occluded organic carbon sequestration in typical plant communities in the Songnen grassland, China

Abstract

Phytolith-occluded organic carbon (PhytOC) sequestration is an important contributor to long-term carbon storage in grassland ecosystems. In this study, 28 typical plant communities of the Songnen grassland in China, consisting of Poaceae, Cyperaceae and Asteraceae community types, were selected for the analysis of phytoliths and PhytOC. The phytolith content, carbon content of phytolith, and PhytOC in biomass in each community were then measured. In addition, the statistical relationships between these three were analyzed, and the relationship between the percentage of phytoliths and PhytOC sequestration potential was determined so as to explore the PhytOC sequestration mechanism. Our principal results are as follows: (1) The annual PhytOC yield of Songnen grassland is 1.67 kg CO2 hm−2 yr−1. (2) In 28 communities, there are significant negative correlations between the contents of phytoliths and PhytOC (R2 = 0.943, P < 0.05) and between the contents of phytoliths and PhytOC biomass (R2 = 0.312, P < 0.05). However there is a significant positive correlation between the carbon content of phytolith and PhytOC in biomass (R2 = 0.652, P < 0.05). (3) Short-cell phytoliths make a greater contribution to PhytOC sequestration, and we speculated that this is due to the formation process of short-cell phytoliths and their high productivity in this grassland. Furthermore based on the above, we proposed some management measures to increase the PhytOC sequestration rate of the entire ecosystem.