Abstract: The changes of minimum temperature periodical biological phenomena and frost in yound Tilia amurensis and Fraxinus mandshurica plantation stands were systematically analyzed based on the vertical gradient observation and plot investigation.Meanwhile,the resistance of Tilia amurensis to late frost was also studied.The results showed that the phenophase of T.amurensis was later than that of F.mandshurica.Influenced by significant temperature inversions in this area,the phenophase of T.amurensis and F.mandshurica changed regularly in different aspects and slope positions.The sprouts on west slope started earlier than that on east slope.The higher they grew on the slope,the earlier they sprouted,with the earliest sprout at the top of slope.Late frost in this area only took place when the trees were sprouting, but air temperature decreased significantly at the same time.The degree of injury from the late frost could be controlled effectively by selecting suitable site.Sites down the slope,especially the east slope,were not suitable for T.amurensis and F.mandshurica plantation in this research area.Chemical treatment and biological shading could prevent late frost injury through putting off sprout.Mixed plantations could prevent F.mandshurica and T.anurensis from late frost injury significantly,and the frost injury index and the proportion of the tree number of different injury grades were lower than those in pure stands.

Key words: Tilia amurensis, Fraxinus mandshurica, Plantation, Pehenophase, Late frost control, monsoon broad-leaved evergreen forest, non-structural carbohydrate, seasonal dynamic, forest layer