科研之友
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摘要
Based on indexes of NDVI and meteorological data in alpine meadow, the main climatic driving fac-tors and mechanism of desertification in alpine meadow were studied. Results indicated as follows: (1) the value of NDVI presents a trend of increasing and then decreasing during 2000 2016, northern and middle of study ar-ea is first to decrease and gradually expended to northwest of Sichuan. (2) The air temperature is sustained war-ming since 1990s, and the upward trend is obvious after 2000. The general tendency of precipitation is decrease and chiefly concentrated in summer with no significant change, sunshine duration showed a downward trend. An-nual average wind velocity showed an upward trend since 2000. (3) Air temperature and precipitation are the crucially influencing factors of NDVI, along with time-lapse, the explanatory power of sunshine duration and wind velocity are gradually increased. The interactive q values between two factors are higher than any q value of separated factors, and most of the interactive results belongs to bivariate enhancement or nonlinear enhancement, the interactive effect between each factor has great influence on the desertification process. (4) The gale and sandstorm occurred frequently in Zoige and Maqu, resultant sand transporting direction (RDD) was SSE with low wind energy environment and medium wind direction variability in Maqu during 2014 2016, the proportion of DP at high wind velocity level has increased, and the intensity of sand activity is enhanced from northwest to southeast. Consequently, rising temperature and decreasing precipitation are the dominant factors for meadow de-sertification, the growth of vegetation is affected by sunshine duration, and the desertification rate and spreading direction are determined by sand activity.
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