4.5 Driving factors for oasis changes

The inter-annual variations of driving factors during 1990 and 2020 were displayed in Figure 8. the average monthly temperature in growing season ranged from 15.64 ⁰C and 22 ⁰C to 20.15 ⁰C and 25.79 ⁰C. The mean temperature in growing season ranged from 19.22 ⁰C to 23.07 ⁰C, with a slight upward tendency. Precipitation decreased obviously from 1990 to 2020, and the variations in growing season ranged from 1.44 mm and 16.99 mm to that of between 2.77 mm and 6.24 mm. In growing season, precipitation expressed as significant decreased tendency. The four human driving factors- population, total power of agricultural machinery, production of raw coal and total output value of plantation industry, all showed upward tendency over the study period. The production of raw coal and the total output value of the plantation industry were increased dramatically after 2005.