The effects of the climate change in the Qinghai Lake region on the growth and yield of Stipa krylovii

The data from Haibei livestock meteorological experiment station in the northern region of Qinghai Lake were used to determine the influence of the climate change on the grass growth and yield of Stipa krylovii by stepwise regression, wavelet analysis, logistic curve fitting and MK test. This study showed that the average annual temperature had the obviously increasing trend with the extent of 0.529 ℃ per 10 a, and the mutations occurred in 1986 and 1997. The rainfall also has the increasing trend with the extent of 4.955 mm per 10 a and the annual rainfall oscillated every 9 years. The annual evaporation and sunshine hours also increased. The S. krylovii growth was affected by both the highest temperature during February and April and rainfall of the August in the previous year, but the climate change made it become green earlier, and climate warming postponed the time of grass wilting. The grass height was influenced by both the average lowest temperature in June and the evaporation from March to June. Climate change made the height increase. The grass yield had the positive correlation with the lowest temperature from June to July, and had the negative correlation with sunshine hours from June to August, and the changeable trends of the two factors encouraged grassland yield to increase.