An analysis of calcium components of Artemisia ordosica plant on sandy lands in different ecological regions
不同生态区域沙地建群种油蒿的钙组分特征

To study the differences in calcium content in the same plant species among different ecological regions, we determined the plant calcium content in Artemisia ordosica, an abundant, widespread species on sandy soils in northwest China. To determine the different plant calcium components, water soluble Ca, acetic acid soluble Ca and hydrochloric acid soluble Ca, we used a sequential fractionation procedure method. Water soluble Ca and acetic acid soluble Ca are physiological active, water soluble Ca contains a Ca ion and part of water soluble Ca salts, and hydrochloric acid soluble Ca is Ca oxalate. In general, the more stressful an environment, the more Ca oxalate the plant contains. In the present study, we collected different life stages and different plant organs of A. ordosica from different sandy soil types, and different ecological regions. As growth stages, we used young plants, adult plants and old plants. The types of sandy soil include shifting sandy soil, semi-fixed sandy soiland fixed sandy soil. The ecological regions we selected were located in Hangjin county (Kubuqi Desert), Wushen county (Mu Us Sand Land) and Alashan Zuoqi county (Tengger Desert) in Inner Mongoilia autonomous region, Yanchi county (Mu Us Sand Land) in Ningxia Hui autonomous region and Yuyang district of Yulin city (Mu Us Sand Land) in Shaanxi province. Our results showed that at organ level, water soluble Ca and acetic acid soluble Ca were significantly higher in leafs than in branches or roots, while hydrochloric acid soluble Ca was significantly higher in leafs and roots than in branches. In relatively wet ecological regions, the plant contained higher water soluble Ca, while in drier ecological regions, plants contained higher levels of hydrochloric acid soluble Ca. Moreover, these higher levels of soluble Ca in areas with higher rainfall mainly existed in the leaves, while the high levels of hydrochloric acid soluble Ca in dry ecological regions was found mainly in the leafs and roots. There was no difference between the different growth stages of the plant, but we found significant differences between different sandy soil types. Comprehensive analysis of the environmental and vegetation conditions suggests that the different calcium components in A. ordosica species were not only influenced by rainfall but also by evaporation, and we find no indication that the calcium content differs between the different growth stages of the plant. To conclude, we find higher water soluble Ca content in plants in less stressful habitats, while we find higher hydrochloric acid Ca levels in more stressful habitats.