Dynamic change of soil moisture and their relationship with climatic factorsin the Jarud Banner of Inner Mongolia

In order to reveal the dynamic change of grassland soil moisture and the effects of climate changes, the inter annual variations of soil moisture and the relationships between soil moisture and climatic factors were analyzed using historical climate date and soil moisture from 1983 to 2012 in the Jarud Banner of Inner Mongolia. The results showed the soil moisture in all the soil layers including 0-10, 10-20, 20-30, 30-40, 40-50 and 0-50 cm gradually decreased from 1983 to 2012 which suggested that grassland become more and more drought. The decrease of soil moisture included 3 stages. The first stage was from 1983 to 1987 when the soil moisture ranged from 15% to 30% which was the higher moisture stage. The second stage was from 1988 to 1999 when the soil moisture ranged from 5% to 15% which was transition stage from higher moisture to lower moisture stage. The third stage was from 2000 to 2012 when the soil moisture ranged from 2% to 10% which was the lower moisture stage. There was negative relationship between temperature, sunshine hours and soil moisture and positive relationship between precipitation, relative humidity, evapotranspiration and soil moisture.