Analysis of relationship between the withering date of Stipa sareptana var. krylovii and conditions in Sanjiangyuan alpine grassland |
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DOI:10.7606/j.issn.1000-7601.2012.01.42 |
Key Words: Sanjiangyuan alpine grassland Stipa sareptana var.krylovii withering date meteorological condition |
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Abstract: |
The observatory data of Stipa sareptana var. krylovii and the meteorological data of temperature, precipitation and sunshine hours in Xinghai 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 ≥0℃, and it got earlier with the remarkable 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 temperature 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℃. |
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