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.