Impact of recent climatic change on the yield of winter wheat at low and high altitudes in semi-arid northwestern China

This study analyses data on winter wheat (Triticum aestivum L.) development and climate from Tongwei County (35°13′N, 105°14′E), Gansu, in the semiarid northwest of China during 1981–2005. Two study sites were chosen: one at Tongwei Meteorological Station, situated at 1798 m above sea level at the foot of LuLu Mountain, and the second on the summit of LuLu Mountain at an altitude of 2351 m. The objective was to investigate whether there were significant trends in the change of climate variables, and whether these changes have significantly affected the development and production of winter wheat at different altitudes above sea level. The results showed that, with changes in temperature and precipitation, there was a significant change in the phenology of winter wheat that crop yields increased at both sites from 1981 to 2005, and that the increase in yields was higher at the high-altitude site. During 1981–1998 the yields at the high-altitude site were lower than at the low altitude site, whereas after 1998 the yields at the high-altitude site were higher than at the low altitude site. In the face of climate change, winter wheat production in this region during 1981–2005 was higher at the higher altitude site than at the lower altitude site. It is expected that, by 2030, the interaction of warming temperature and changed rainfall will have led to a further increase of 3.1% in wheat yields at a low altitude and of 4.0% at a high altitude in the semiarid northwest of China.