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Arid Land Geography ›› 2022, Vol. 45 ›› Issue (6): 1881-1889.doi: 10.12118/j.issn.1000-6060.2022.094

• Biology and Environment • Previous Articles     Next Articles

Characteristics of precipitation and response of soil moisture to precipitation pulse in meadow steppe: A case of Ergun City in Hulunbuir steppe

ZHANG Cunhou1(),DUAN Xiaofeng1,YANG Liping1,YUE Kun1,ZHANG Li2()   

  1. 1. Centre of Ecology and Agricultural Meteorology, Inner Mongolia Weather Bureau, Hohhot 010051, Inner Mongolia, China
    2. Meteorological Information Centre, Inner Mongolia Autonomous Region Weather Bureau, Hohhot 010051, Inner Mongolia, China
  • Received:2022-03-10 Revised:2022-06-21 Online:2022-11-25 Published:2023-02-01
  • Contact: Li ZHANG E-mail:zhangcunhou2004@163.com;beht@foxmail.com

Abstract:

The regulation of structure and function in an ecosystem is largely affected by soil moisture, and the grassland ecosystem is more sensitive to soil moisture than other ecosystems. The change of soil moisture is determined by precipitation, so how does precipitation affect grassland soil moisture? What is the response law to the precipitation of grassland soil moisture? These are the key problems in the benign development of grassland ecosystems. However, there have been few reports on the response of soil moisture to precipitation in the meadow steppe in north China. To reveal the characteristics of precipitation and the response of soil moisture to precipitation pulse, the Hulunbuir meadow steppe was taken as the research object, dynamic change, transformation process of precipitation, and soil moisture were analyzed. The influence characteristics of different scale precipitation processes on soil water were explored and the critical values of rainfall, which could cause each layer of soil moisture (0-50 cm) of the meadow steppe were determined based on the data of precipitation and soil moisture from Ergun Animal Husbandry Meteorology Experiment Station. The relationship models between precipitation and soil water increment were established to invert soil water content, which could significantly reduce the spatial uncertainty of refined drought assessment and provide a scientific basis for local government to fight drought and reduce the disaster. The response regularity of soil moisture to precipitation pulse at different depths was revealed in the meadow steppe. The results showed that (1) the precipitation showed a trend of “decreasing first and then rising”, and the annual precipitation showed a single-peak distribution. (2) The weather was dominated by no precipitation, and the precipitation was dominated by small-precipitation events in a meadow steppe. The heavy precipitation events were characterized by low occurrence frequency and large precipitation, whereas the small-precipitation events were the opposite. (3) The critical values of precipitation that can cause the response of 0-50 cm soil moisture were 8.1 mm, 10.1 mm, 19.0 mm, 27.9 mm, and 31.6 mm, respectively. The probability of light rain only causing 0-10 cm soil moisture response was 28.6%, whereas moderate rain could not cause 40-50 cm soil moisture response. (4) Precipitation was extreme significantly negatively correlated with the lag time when soil moisture reached the maximum value in 0-10 cm and 10-20 cm, and was significantly negatively correlated with the lag time when soil moisture reached the maximum value in 20-30 cm. The lag time of soil moisture reaching the maximum value in each layer of 0-30 cm accords with the power function relationship with precipitation. (5) There was a significant positive correlation between precipitation and soil moisture increments of 0-50 cm. Precipitation was linear with soil moisture increments of 0-10 cm and 10-20 cm, and polynomial with soil moisture increment of 20-30 cm, 30-40 cm, and 40-50 cm. The model test results showed that the simulation effect of soil moisture increment models in each layer of 0-30 cm was better.

Key words: soil moisture, precipitation events, pulse response, critical value, hysteresis effect, meadow steppe