三江源区草地植被返青及其与气候因子的关系

为厘清三江源地区草地植被返青及其与气候因子的关系。以三江源地区为研究对象,选取该区2003—2012年日照时数、平均气温和降水以及草地植被返青资料,采用线性倾向率和Pearson相关分析法,较为系统地分析探讨了近10年三江源地区气候变化趋势及其与草地植被返青的相关关系。结果表明:(1)近10年来,三江源地区草地植被返青呈"提前—推迟—再提前—再推迟"的变化趋势。(2)海拔4000 m以上的地区草地植被返青期极差较大,相差约40 d;且高寒草原和高寒荒漠草地植被返青时间突变最为显著。(3)三江源地区草地植被返青日期与返青期前30 d光、温、水的相关性较好。除局部地区草地植被返青与光、温、水呈显著负相关外,其余地区均显著正相关。以上研究结果表明,三江源地区草地植被返青期不是由单一因素决定,而是光照、气温和降水等因素综合作用的结果。

Relationships between grassland vegetation turngreen and climate factors in the Three-river Resource region

The aim of this study was to specify the grassland vegetation turngreen date and its relationships with climate factors over the Three-river Resource region, which was used as the research area in this study. The sunshine hours, average temperature and precipitation, grassland vegetation turngreen information data from 2003 to 2012, linear trend rate, and Pearson''s correlation analysis were used to systematically analyze and explore the climate change trend and its correlation relationships with grassland vegetation turngreen date over the Three-river Resource region. The results showed that the trend for grassland vegetation turngreen date was "ahead- postpone- ahead- postpone" across the region over the past 10 years. The maximum difference for vegetation turngreen date at over 4000 m above sea level and the climate factors was about 40 days. Furthermore, the most significant change trends were for grassland vegetation in alpine steppe and alpine desert areas. There was generally a good correlation between grassland vegetation turngreen date and sunshine, temperature, and precipitation 30 days before the turngreen date. However, there was a significant negative correlation between grassland vegetation turngreen date and sunshine, temperature, and precipitation in some parts of the Three-river Resource region, but there was a significant positive correlation across the rest of the region. The results showed that the grassland vegetation turngreen date was not determined by a single factor in the Three-river Resource region but was affected by a combination of sunshine, temperature, and precipitation.