Impacts of climatic warming on reproductive stages of forages growing in alpine grassland of the Three River Sources Areas

The meteorological record data from 1961 to 2010 and the reproductive data of Stipa sareptana var. krylovii from 1999 to 2010 were used to determine the impacts of climatic warming on reproductive stages of S. sareptana var. krylovii in the standard weather station of Xinghai County, Qinghai Province. This study showed that the average temperature and precipitation during growth period (from April to September) significantly increased, and hours of sunshine lightly increased in the Xinhai regions in the past 50 years; the regreening, heading, maturity and withering stage of S. sareptana var. krylovii were in advance year by year, and flowering stage was delayed. The multistepwise regression results showed the average temperature of March and the accumulative temperature during the date with temperature above 0℃ to the date of regreening stage greatly impacted on the regreening stage; the average temperature of May and accumulative precipitation from regreening stage to heading stage significantly impacted the heading stage; the average temperature of May had the greatest impacts on flowering stage; the average temperature of April and July showed the greatest impacts on maturity stage; and the day with average temperature above 5℃, average temperature of July, and accumulative sunshine hours during maturity stage had greatest impacts on withering date.