1981－2005年中国东北榆树物候变化特征及模拟研究

探讨了1980－2005年中国东北榆树物候的时空变化与气候因子的关系。结果表明：近26 a，东北地区13个站点榆树的展叶期和枯黄期变化趋势较大，13个物候时间系列，展叶初期显著提前趋势占54%，枯黄初期显著推后趋势占38%；榆树物候与气温呈显著相关关系：展叶期与3－4月平均气温呈显著的负相关关系，与平均展叶期的积温呈显著的负相关关系；各站点枯黄期与8－9月平均气温关系不显著，整个东北地区呈显著的正相关关系。研究表明，榆树物候与降水、日照关系不显著。以日平均气温最高日为界，枯黄期积温值可分为呈线性关系的两段，从日平均气温最高日开始，连续10 d积温值低于固定值时，植物开始枯黄。

Phenology characteristics of ulmus pumila and its simulation from 1981 to 2005 in Northeast China

The temporal and spatial changes of ulmus pumila phenology and the relationship with climate factors in Northeast China from 1981 to 2005 were discussed.The results show that the change trends of leave unfolding phase and leave coloring phase of ulmus pumila are obvious during recent 25 years based on the data from 13 observation stations in Northeast China.Time sequence numbers that leave unfolding phase is significantly advanced account for 54% of the total leave unfolding time sequence numbers,and those that leave coloring phase is significantly delayed account for 38%.The relationship between ulmus pumila phenology phases and air temperature is significant.The leave unfolding phase has negative relationships with mean air temperature of March and April and its cumulative temperature.The relationship between leave coloring phase in each station and mean air temperature of August and September is not significant,while it is a positive relation in the whole study areas.The results also indicate that the phenology phases of ulmus pumila are not significantly related to precipitation and sunshine duration.In terms of the day of maximum daily mean air temperature,the cumulative temperature of leave coloring phase can be divided into two stages.Plant species start to become yellow when the cumulative temperature value of continuous 10 days from the highest daily mean air temperature day is lower than the fixed value.