Spatial and temporal dynamics of soil moisture and salinity in typical plant communities of Sangonghe Basin

Soil moisture, salinity, ground water table and salt concentration were measured monthly in seven typical plant communities for one year in Sangonghe basin of Xinjiang. Temporal dynamics of soil water and salinity during growing season were compared within these communities. The dominant species in each of these communities were Suaeda physophora, Reaumuria soongorica, Anabasis aphylla and Kalidium foliatum, Tamarix ramosissima, Alhagi pseudalhagi and Haloxylon ammodendron respectively. Results show that soil water content and salinity were significantly different among all these communities. In the edge of alluvial fan and low reaches of the river, ground water table was high, soil profile was moist, and salt concentrated in the soil upper layers and surface. Soils were all saline with dominant species of T. ramosissima, A. aphylla and K. foliatum . In the plain area, communities were dominated by R. soongorica and S. physophora Ground water table was generally low, but soil surface and up layer contained high salt concentration. Soil here belonged to strong to medium salinized soil. In ecotone, ground water table increased due to the irrigation in the nearby oasis. From soil surface to deep layers, water content increased gradually with no salt accumulation for all the layers. Vegetation in ecotone was stable and dominated by A. pseudalhagi . In intervale of desert, ground water table was very deep and soil was very dry throughout of the profile. There were no significant differences in vertical and temporal change of soil moisture. Communities were dominated by H. ammodendron . Spatial and temporal dynamics of the soil moisture and salinity caused community subrogation, and were the two main factors that affected distribution and succession of plant communities.