三江源高寒草地针茅牧草黄枯期与气象条件的关系

Analysis of relationship between the withering date of Stipa sareptana var. krylovii and conditions in Sanjiangyuan alpine grassland

利用1999—2010年青海省三江源兴海县牧业气象观测站西北针茅牧草(Stipa sareptana var.krylovii)观测资料及同期的气温、降水、日照时数等气象资料,分析了气象因子对兴海高寒草地西北针茅牧草黄枯期的影响。结果表明:高寒草地西北针茅牧草黄枯期12年来表现为显著提前的趋势,平均每年提前1.4 d;牧草黄枯期与日平均气温≥0℃的终日呈显著正相关,并且随着9月中旬平均温度的显著升高牧草黄枯期提前;兴海9月上中旬降水量的减少以及日照时数的增加使牧草提前黄枯。多元线性回归分析表明,8月下旬和9月上旬的温度对西北针茅牧草黄枯影响最大,温度每上升1℃,黄枯期分别提前5.0 d和1.0 d。

The observatory data tation and sunshine hours in Xingbai of Stipa sareptana var. krylovii and the meteorological data of temperature, precipi- of Sanjiangyuan area were used to analyse the effects of these factors on the withering date of Stipa sareptana var. krylovii. The results showed that the withering date of Stipa sareptana var. krylovii had a trend of getting increasingly earlier in the last 12 years, with an advancing speed of 1.4 d per year. The withering date of the grass had significantly positive correlation with the final day of temperature 1〉 0 ~C, and it got earlier with the re- markable increase of mean tempeature in mid September. The derease of precipitation and increase of sunshine hours in early and mid September advanced the withering of the grass. The results of regression analysis indicated that the temper- ature in late August and early September had the greatest effect on the withering date of the grass, and the withering date got 5.0 d and 1.0 d earlier respectively when the temperature rose by 1℃.