The results showed that among the 27 sampling sites, the salt content in
rhizosphere of herbaceous
halophytes increased at
7 sites and decreased at 20 sites. The variation of soil salt content in the RUE micro-area of shrubby
halophytes was related to the growth status of the plants. The salt content in
rhizosphere decreased a little at the early stage of plant development, but that in RUE micro-area tended to increase and accumulated most quickly at the site of the canopy edge soil.An obvious variation of salt components was found in the RUE micro-area of different types of halophytes. The Na +/K + ratio tended to decrease in succulent halophytes and salt secrete halophytes. Among 53 sampling sites, only 14 sampling sites had a higher ratio of Na +/K + in rhizosphere soil than in background soil, and only 10 sampling sites had a higher ratio of Na +/K + in canopy-under soil than in background soil. However, the Na +/K + ratio in the canopy edge soil of Tamarix and Nitraria tended to increase when they grew weakly. By contraries, the Na +/K + ratio in the rhizosphere was higher than that in background soil at 3 of 4 sampling sites of Phragmites australia , which indicated that the Na +/K + ratio in the rhizosphere of exclude halophytes tended to increase. The variation of SO_4 2- /Cl -ratio in the RUE micro-area was different in the 3 types of halophytes. For salt secrete halophytes, it decreased obviously in rhizosphere soil, canopy-under soil and canopy-edge soil; for succulent herbaceous halophytes, it tended to increase in rhizosphere soil; and for succulent shrubby halophytes, it tended to decrease in rhizosphere and in canopy-under soil, and tended to increase in canopy-edge soil. The SO_4 2- /Cl - ratio had no big change for exclude-halophytes. The reduction of the salts in rhizosphere of herbaceous halophytes was mainly because of their plant uptake, and the accumulation of salts in the RUE micro-area of shrubby halophytes was because the salt absorbed from the around soil returned to the RUE micro-area again. Because of the selective uptake by plant, the salt component varied with different types of halophytes. Most halophytes except Phragmites australia take more Na +, and hence the Na +/K + ratio in the rhizosphere tends to decrease. The SO_4 2- /Cl - ratio in the RUE micro-area of salt secrete halophytes trended reduce, mainly because this type of halophyte can secrete more Cl - with its growth.