高寒草原针茅牧草花期物候变化特征及其影响因子分析

利用三江源区兴海县气象局观测的1999—2021年高寒草原西北针茅牧草开花期物候资料及同期气象资料,对牧草开花期变化趋势进行分析,寻找出影响花期的主要气象因子,并构建花期预测模型。结果表明：（1）1999—2021年三江源区兴海县高寒草原西北针茅牧草开花期的平均气温较平稳,而降水量呈显著增多趋势。（2）1999—2021年三江源区兴海县高寒草原西北针茅开花期呈不显著推迟趋势。牧草开花期年际变化较大,最早与最晚相差26天。（3）相关分析表明,4月上旬和下旬的平均气温、平均最高气温与牧草开花期呈显著负相关;5月上旬平均最高气温、日照时数与牧草开花期呈显著正相关;4月下旬的平均最低气温与牧草开花期呈极显著负相关。（4）回归方程显示,4月下旬平均最低气温每升高（或降低）1.0℃,牧草开花期则相应提前（或推迟）2.1天。

Phenological Change Characteristics of Stipa Grass at Flowering Stage on Alpine Grassland and Their Influencing Factors

Based on the phenological data of Stip sareptana var. krylovii flowering stage on alpine grassland and contemporaneous meteorological data observed by Xinghai County Meteorological Bureau in Sanjiangyuan region from 1999 to 2021, this paper analyzed the change trend of the Stip sareptana var. krylovii flowering stage on alpine grassland, to find out the main meteorological factors influencing the flowering time and build the forecast model by using the regression analysis method. The results showed that: (1) the average temperature was stable during flowering stage of Stip sareptana var. krylovii on alpine grassland of Xinghai County from 1999 to 2021, but precipitation increased significantly; (2) the flowering stage of Stip sareptana var. krylovii showed no significant delay trend from 1999 to 2021, and the flowering time of herbage varied greatly from year to year, the difference between the earliest and the latest was 26 days; (3) correlation analysis showed that, the average temperature and average maximum temperature in the first ten days and the last ten days of April were significantly negatively correlated with the flowering time, the average maximum temperature and sunshine duration in the first ten days of May were significantly positively correlated with the flowering time, and the average minimum temperature in late April was very significantly negatively correlated with the flowering time of herbage; (4) the regression analysis showed that for every 1.0℃ increase (or decrease) of the average minimum temperature in late April, the flowering time of herbage was correspondingly earlier (or delayed) by 2.1 days.