An Investigation of some ecological characteristics of four Calligonum species in Yazd province

The distribution and establishment of plant species is affected by plant characteristics and environmental conditions. The species of Calligonum genus, belonging to Polygonaceae family, have a wide distribution in arid and semi-arid climates. In this study, the distribution and qualitative characteristics of four species of Calligonum (C. stenopterum, C. persicum, C. bungei, and C. polygonoides) were investigated. In each habitat, four soil profiles were dug and soil properties including soil texture, EC, pH, lime, gypsum, SAR, and organic matter were measured. Results showed that all species needed a light soil texture, loamy-sand, with relatively high gypsum and lime content and a slightly alkaline pH. Very low canopy cover indicated a low humidity condition as well as the sever lack of organic matter in soil. Very low rainfall, large temperature differences between summer and winter, and a long dry season (10 12months) were the characteristics of the study habitats. The number of frost days in the habitats of C. stenopterum and C. persicum was lower as compared to the habitats of C. bungei and C. polygonoides, providing the conditions for growth of C. stenopterum and C. persicum, which are exclusively native to this region of Iran.