Abstract:

To explore the characteristics of forage mature period and their influencing factors in alpine grassland, and provide a scientific basis for the determination of local forage maturity, based on the phenological period data of the mature period of alpine grassland and the corresponding meteorological data observed by Xinghai County Meteorological Bureau in Sanjiangyuan region from 1999 to 2021, this paper analyzed the change trend of the mature period of alpine grassland and its main influencing meteorological factors, and built the forecast model of the mature period of herbage. (1) The average temperature in the mature period of Stipa herbage showed a weak trend of decrease, while the precipitation showed a very significant trend of increase in Xinghai County of Sanjiangyuan region from 1999 to 2021. (2) From 1999 to 2021, the mature period of herbage in Xinghai County showed a non-significant early-trend. The mature period of herbage varied greatly from year to year, and the difference between the earliest and the latest was 36 d. (3) The correlation analysis showed that sunshine duration in the middle of April, mean temperature and mean maximum temperature in the middle of May, mean maximum temperature in early June, mean temperature and mean maximum temperature in late July had significantly negative correlations with the mature period of herbage. (4) The regression analysis showed that, when the mean maximum temperature in early June and late July increased (decreased) by 1.0℃, and the sunshine duration increased (decreased) by 10 hours in the middle of April, the maturity of herbage was earlier (or delayed) by 1.6, 2.0 and 1.7 days, respectively. The established forecast model can provide a theoretical basis for the timely and accurate forecast of the mature period of natural pasture forage in the Sanjiangyuan region.

Key words: alpine grassland, phenological period, variation characteristics, correlation analysis, forecast model, Sanjiangyuan region