近50年北京树木物候对气候变化的响应

Response of tree phenology to climate change for recent 50 years in Beijing

采用统计学方法探讨了北京地区1963～1988年间20种树木芽萌动期及1950～2000年间4种树木开花期的变化及其对气温变化的响应情况.结果表明,北京树木芽萌动的早晚主要受冬季气温的影响,冬季及秋末气温的升高使春芽萌动有提前的效应.萌芽早的树木萌动期长,萌芽晚的树木萌动期短,前者对温度的变化反应更敏感,且前者的萌动期长度随着萌动期间(主要在早春)气温的升高而缩短,后者的萌动期长度随着初冬、秋末平均最低气温的升高而延长.始花前2～9旬,特别是前5旬(主要是3～4两个月),气温对始花期影响最显著,该时段内始花期对气温的变化反应最敏感.北京春温升高开花期提前,春温每升高1℃,开花期平均提前3.6天.春季树木开花物候与春季气温的年际、年代间的波动基本对应,但波动幅度不一致.

Statistic methods are applied to investigate the response of phenology to recent climatic changes in Beijing. This study focuses on the correlation between budding dates of 20 species and air temperature for the period 1963~1988 and between flowering dates of 4 species and air temperature for the period 1950~2000. It shows that the germination is mostly influenced by winter air temperature but not by spring air temperature, the warmer winter and late autumn temperature leads to an earlier beginning of sprouting. The earlier species which spend longer time in budding are more sensitive to air temperature changes than the later ones which need shorter time to sprout, at the same time, a higher temperature in early spring leads to fewer days for the former to complete sprouting and a higher temperature in late autumn and early winter leads to more days for the latter to complete sprouting. Air temperature of 20-90 days before flowering influences flowering dates very much, and especially that of 50 days before flowering,mainly from March to April, does the most. And during this period, flowering events are most sensitive to air temperature changes . Warmer temperature in spring causes earlier flowering, and an increase of air temperature by 1℃ leads to an advance of flowering by 3.6 days. On the other hand, the observed trends in annual and ten-year fluctuation in flowering phenology correspond well with air temperature in spring, that is, a higher temperature in spring leads to an advance of flowering dates and a lower temperature in spring means a delay of flowering events, while the extent isn't the same. In general, a deviation in air temperature is bigger than that in tree phenology.