The blooming and production of reproductive modules in relation to tree age and their position within crowns in Betula platyphylla
白桦的开花时间及生殖构件的数量与树龄和树冠层次的关系

The time of first blooming and fruiting of birch varied greatly in different habitats and origins.On the same habitat,seed\|origin plant bloomed over 6 years later than that from sprouts.The first flowers in mesic site appeaired earlier than those in wet site.Blossom date within a year also varied among different stands.Catkin module number,reproductive branch number,and the number of catkins per reproductive branch were directly related to the age of tree.The number of catkin modules in middle\|aged trees>...