关键词: 中国东北, 榆树物候, 生长期, 降水, 气温

Abstract: The temporal and spatial changes of ulmus pumila phenology and the relationship with climate factors in Northeast China from 1980 to 2005 were discussed. The results show that the change trends of leave unfolding phase and leave coloring phase of ulmus pumila are obvious in recent 26 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 with mean air temperature of March and April is a negative relation, so is with 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. Otherwise, the phenology phases of ulmus pumila are not significantly related to precipitation and sunshine duration. Using the day of maximum daily mean air temperature as the boundary, the cumulative temperature of leave coloring phase can 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.