Impacts of climate change on Kobresia pygmaea phenophase at different altitude regions in Qinghai Plateau

Impacts of climate change on phenophase of Kobresia pygmaea at high (4 175.0 m) and low (3 500.0 m) altitude regions in the Qinghai Plateau were studied by analyzing the observation data obtained from Qumalai and Henan meteorological stations from 1989 to 2010. The results showed that during the past 22 years the air temperature had an increasing trend at both high and low altitudes, the warming amplitude of mean minimum temperature was larger at high altitude than that at low altitude, while the warming amplitude of mean maximum temperature was larger at low altitude than that at the high altitude. The air temperature change in growth season (April to September) showed a same trend at two meteorological stations. There was a significant correlation between air temperature of the growth season and annual air temperature. It was found that days of green stage, growth period and withering period of K.pygmaea at two meteorological stations showed interannual fluctuations, the fluctuations at high altitude were bigger than those at low altitude. The first day of green stage had a delaying tendency with increasing altitude, 3.3 d per 100 m. In contrast, the growth period had a shortening tendency with increasing altitude, 2.5 d per 100 m. At high altitude regions, average phenophase of K.pygmaea was advanced 6-25 d, and growth period was prolonged 3 d. At low altitude regions, withering period was advanced 1 d, while other phenophase was delayed 1-9 d, and growth period was prolonged 6 d. The growth of K.pygmaea at high altitude was influenced easier than that at low altitude by climate change. Its habitat was more fragile at the high altitude region.