The grey correlative degree analysis on the relationship between grassland productivity and climate factors in temperate steppe of Gonghe Basin

Based on the application of the gray correlative analysis, the gray correlative degree between grassland productivity and climate factors in temperate steppe of Gonghe Basin was studied, using yield at each growth stages as control series, monthly mean temperature, precipitation, sunlight time as parallel series. The results showed that the relationship between forage yield at heading stage and temperature, precipitation in May, and sunlight time in March to May was the greatest. While the greatest relationship was obtained between seed yield at maturity and temperature, sunlight time in June to August. In conclusion, the forage yield at early growth stages depended on the temperature, precipitation May and sunlight from March to May; the forage yield at maturity depended on the temperature and sunlight from June to August, especially the temperature.