Abstract:In order to study the dynamics of soil water potential of plantations in Bashang area, in this experiment, Zoysia japonica was taken as control, Populus simonii Carr. and Pinus sylvestris var. mongolica, which were typical plantations in Bashang area, were selected to study the soil water potential value and variation coefficient in different time and space in growing season, and the soil water potential variation under sunny days and rainfall in growing season. The results showed that: (1) The change trend of the soil water potential of plantation and grass was the same, the soil water potential was higher at the early and late stages of growing season, and the soil water potential entered the fluctuating and declining period at the middle stage, but different vegetation entered the fluctuating period at different time, and that of P. sylvestris var. mongolica was later than that of P. simonii Carr. and Z. japonica. In addition, the lowest soil water potential of P. simonii Carr. was -1 257.24 kPa at 70 cm, that of P. sylvestris var. mongolica was -747.97 kPa at 10 cm, and that of Z. japonica was -830.11 kPa at 30 cm. The maximum variation coefficient of soil water potential of P. simonii Carr., P. sylvestris var. mongolica and Z. japonica appeared at 10 cm in September, 10 cm in July and 30 cm in July, with values of -155.9%, -208.0% and -183.6%, respectively. On the whole, the variation coefficient was greater in the middle of growing season than that at early and late stages, and that in surface layer was greater than that in deep layer. (2) In sunny days, there was a significant correlation between the maximum value of soil water potential difference of plantations and grasslands and the daily mean temperature. With the increasing of daily mean temperature, the maximum of soil water potential difference also increased. In typical sunny days, the atmospheric temperature fluctuated up and down in the day, and the soil water potential fluctuated with a lag, which was most obvious in the shallow soil during the growing season. (3) There was a correlation between different rainfall and soil water potential difference. With the increasing of rainfall, the soil water potential difference also increased. Under typical rainfall events, the soil water potential of moderate and heavy rainfall profiles rose rapidly, and fluctuated under light rainfall events. From the perspective of different vegetation, grass was more intense than artificial forest. To sum up, the soil water potential of P. sylvestris var. mongolica in the growing season entered into the fluctuating period at the latest, with the largest fluctuating range. The response of soil water potential of Z. japonica was the most sensitive to atmospheric temperature and rainfall. The results were of great significance for guiding the construction of local plantations and efficient management of water resources.