基于1999—2010年SPOT VEGETATION旬值NDVI数据,结合谐波分析法与偏相关分析等方法,对三江源地区年植被物候特征值进行了确定,并分析了年际物候对不同时段水热变化的响应。结果表明:① 三江源地区响应时段累积降水量和气温的增加都会使植物生长季始期推迟。② 三江源地区植物生长季末期与累积降水和气温的最值偏相关系数分别为0.180 6和-0.067 8,说明响应时段累积降水量的增加会使植物生长季末期推迟,而累积气温的升高会使植物生长季末期提前,但累积气温影响相对较小。而响应时段累积降水量的增加,会使植物生长季长度延长;累积气温的升高,会使植物生长季长度缩短。③ 三江源地区植物生长季长度的年际变化,受生长季末期的影响较大。④ 三江源地区植物生长季始期主要受前一年累积气候要素影响强烈;生长季末期主要受生长季内累积降水影响强烈。生长季长度受生长季之前的累积气温的作用强烈。
Using methods of harmonic analysis and partial correlation analysis,based on the SPOT-VEGETATION NDVI of 10 days during the period from 1999 to 2010,we identified the beginning and end time of vegetation growing season for each year in the Three-River source region, and analyzed the temporal and spatial relation between vegetation phenology and cumulative hydrothermal at different times. Results are shown as follows:① The increase of cumulative precipitation and temperature of response time makes start of growing season delayed.② The extremum of partial correlation coefficient between end of growing season and cumulative precipitation and temperature is 0.180 6 and -0.067 8,respectively.It shows that the increase of cumulative precipitation of response time make end of growing season delayed,but end of growing season shift to an earlier date with less impact due to the rise of cumulative temperature.Length of growing season extends and shortens because of the increase of cumulative precipitation and temperature of response time,separately.③ The end of growing season change greatly impacts the annual variation of growing season length. ④ The start of growing season mainly reflect cumulative hydrothermal of the previous year, but the cumulative precipitation of growing season worked powerfully upon the end of growing season.For the growing season length,cumulative temperature before the growing season is the most influential factor.
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