Abstract:

To better understand the characteristics of natural forage growth in the source of the Heihe and the impact of climate change on natural forage, this paper used natural forage data and climatic data from 2003 to 2021 from the ecological monitoring sites of Yanglong and Arou in the hinterland of the source of the Heihe, and employed the linear trend method, correlation analysis and temperature rebound coefficient calculation to study the height, cover, yield, re-greening and yellowing periods of natural forage in the source of the Heihe and the meteorological factors affecting them. The results showed that both the height and cover of natural forage grasses showed increasing trends at different rates, and the yield of natural forage grasses showed increasing trend at different rates. The greening period was advanced at a rate of -1.65 d/10 a, the wilting period was delayed at a rate of 1.70 d/10 a, and the growth period of natural forage was extended. From the analysis of the influence of meteorological factors on the growth of natural forage, it was concluded that water and heat conditions were the main factors affecting the growth of natural forage, and there was a significant correlation between the re-greening period of natural forage and the first day of ≥0℃ and the first day of ≥3℃, and there was a significant correspondence between the trend of increasing precipitation and the trend of increasing the height and cover of natural forage, more rain in the previous autumn might delay the re-greening period of natural forage, and less rain might make the re-greening period earlier. In addition to water and heat conditions, sunshine, ground temperature, frozen soil and wind speed had certain effects on the growth of natural grass, but the effects were minimal.

Key words: source of Heihe, natural herbage, growth characteristics, climate change, impact, linear trend