Water is a restrictive factor for plant growth and ecosystem stability in arid and semiarid areas. The dynamics of water availability in soils and water use by plants are consequently critical to ecosystem functions, e.g. maintaining a high resistance to the changing climate. Plant water use strategies, including water-use efficiency(WUE) and the main water source that a plant species utilizes, play an important role in the evaluation of stability and sustainability of a plantation. The water use strategies of desert plants(Tamarix chinensis, Alhagi sparsifolia, Elaeagnus angustifolia, Sophora alopecuroides, Bassia dasyphylla and Nitraria sphaerocarpa) in three different habitats(saline land, sandy land and Gobi) in Dunhuang(located in the typical arid area of northwestern China) were studied. The stable isotope of oxygen was used to determine the main water source and leaf carbon isotope discrimination was used to estimate the long-term WUE of plant species in the summer of 2010. The results suggest that: 1) the studied desert plants took up soil water below the depth of 80 cm; 2) T. chinensis in the three habitats used deeper soil water and T. chinensis in the Gobi site had higher WUE than those in the saline land and the sandy land. The results indicated that desert plants in Dunhuang depended on stable water source and maintained high WUE to survive in water limited environments.
In this paper,we reviewed the progress in the application of stable isotope techniques to the study of soil salinization.As a powerful technique,stable isotopes have been widely used in the studies of soil water evaporation,the dynamics of soil salinization and salt-tolerant plant breeding.The impact of single environmental factors on plant isotope composition has been the focus of previous studies.However,the impact of multiple environmental factors on plant isotope composition remains unclear and needs to be carefully studied.In order to gain insights into soil salinization and amelioration,especially soil salinization in arid and semiarid areas,it is essential to employ stable isotope techniques and combine them with other methods,such as located field observation and remote sensing technology.
