Field root ecology and contribution of dominant vegetations in rhizoliths formation in Badain Jaren Desert, China

Abstract

Background Carbonate rhizoliths are a kind of vegetation root fossils. The rhizoliths occur in Badian Jaran Desert, China. The studies on the relationships between the rhizolith formation and modern vegetation and their roots ecology are rare, and the rhizoliths formation mechanism still remains unclear. Aims The relationships were studied, focusing on roots ecology, local geomorphology and soil under the super arid climate background of the desert. Methods Field preliminary examinations and exploration, digging, and logical comparison methods were used for the three dominant vegetations, Artemisia blepharolepis, Psammochloa villosa and Phragmites australis. Results Woody shrubs of Artemisia blepharolepis have tap and lateral roots; herbaceous grasses of Psammochloa villosa and Phragmites australis have monopodial and linear rhizomes. These roots mainly distribute in moist or wet shallow soil under the dry sand layer of about 10-20 cm depth, which is an open system with active exchanges of water and air of atmosphere. The rhizoliths always were found at Artemisia shrub sites and match the characteristics of Artemisia roots. Conclusion The dead roots of Artemisia released some special biochemicals that triggered carbonate mineralization with the CO2 gas released during root decomposition. Roots structures and depths do not have direct controls for root mineralization. However, local characters of geomorphology and soil had played key roles in rhizolith formation, with the dead roots together. Descriptive studies of ecology of desert vegetation have revealed important questions about rhizoliths mechanisms. Detailed study of the biochemicals, local soil and geomorphology are needed to better understand the origin of rhizoliths.