Acta Geographica Sinica ›› 2012, Vol. 67 ›› Issue (9): 1246-1254.doi: 10.11821/xb201209009

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Seasonal Variations of Soil Temperature and Moisture at the Upper Limit of Alpine Meadow in North-facing Slope of the Nianqingtanggula Mountains

YU Jiehui1,2, LIU Xinsheng1, LUO Tianxiang1, ZHANG Lin1   

  1. 1. Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, CAS, Beijing 100085, China;
    2. Graduate University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2012-03-30 Revised:2012-06-15 Online:2012-09-20 Published:2012-11-09
  • Supported by:

    The National Key Projects for Basic Research of China, No.2010CB951301; National Natural Science Foundation of China, No.31170451

Abstract: Based on the three-year observations in a plot at the upper limit of the alpine Kobresia meadow (5125 m a.s.l.) on the Nianqingtanggula Mountains in the southern part of Namco Basin in Tibet, we analyzed the seasonal variations of soil temperature and moisture at soil depths of 10 and 30 cm. The results were obtained as follows. 1) The soil thawed in late April and froze in late October. The daily amplitude of soil temperature from June to August, which was 3.8℃ at 10 cm and 1.4℃ at 30 cm on average, reflected the highest values throughout the year. 2) The unfrozen soil water content increased (declined) when the soil began to thaw (freeze). And the soil moisture was relatively high from May to October, which was 2%-6% at 10 cm and 15%-20% at 30 cm. 3) Based on the soil temperature measurements at 10 cm depth, the growing season length for vegetation at the upper limit of the alpine Kobresia meadow was calculated to last 80-87 days, which began in early June and ended in late August or early September. And the average soil temperature and moisture were 6.78±0.73℃ and 4.14±0.91%, respectively. The lowest daily temperature during the growing season was mainly observed between 3℃ and 7℃. 4) Compared with the soil temperature and moisture at the lower altitude of 4980 m a.s.l., those at 5125 m were significantly lower. Also, the number of days of daily minimum temperature < 5℃ in August at the higher altitude was far more than that at the lower.

Key words: soil temperature, soil moisture, the upper limit of alpine Kobresia meadow, seasonal dynamics, growing season length, Nianqingtanggula Mountains