Characteristics of plant calcium fractions for 25 species in Tengger Desert

Little attention has been paid to plant calcium fractions in the desert. To address the characteristic of the calcium fractions of desert plants, we collected 25 plant species in Tengger Desert, observed the calcium crystals using an optical microscope and determined water soluble calcium, acetic acid soluble calcium, and hydrochloric acid soluble calcium. To do so, we used sequential fractionation procedures to probe the relationships among different functional groups, different growth forms, or different successional stages. The results showed that the psammophyte, the late successional plants, and the drought-resistant shrub and semi-shrub all held considerable calcium oxalate crystal compared to the grassland plants, the early successional plants, and the perennial herb. With the proceeding succession, the acetic acid soluble calcium decreased gradually, and the hydrochloric acid soluble calcium increased gradually. The perennial herb had more water soluble calcium, while shrub held greater hydrochloric acid soluble calcium. The grassland plants held more water soluble calcium, while psammophyte had greater hydrochloric acid soluble calcium. This implies that the plants that are relatively sensitive to drought hold more calcium ion, while the drought-resistance plants hold more calcium oxalate. Thus, the plant calcium components are in close relation to plant drought-resistance, and of important significance in plant physiology of the desert.