摘要
白桦的初始开花结实年龄在不同生境、不同起源情况下是有很大差别的。在相同的生境下 ,实生苗比萌生苗的始花年龄晚 6a以上 ,中生生境的林分始花期要早于湿生生境的林分 ,在同一年中花期的早晚因林龄而异。花序构件种群、生殖枝构件种群以及生殖枝花序数量都与树龄直接相关。花序构件数量壮年期 >老龄期 >结实初期。在同一生殖个体上 ,构件数量雄花序为中层 >上层 >下层 ,雌花序数量为上层 >中层 >下层。每个生殖枝平均的花序构件数量在 50～ 60 a后一直维持在很高的水平。老龄树生殖构件的减少是生殖枝的减少 ,而不是每枝生殖构件的减少造成的 。
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>that of old trees>that of trees in initial fruiting phase.The number of male catkins in the middle crown layer>that in top layer>that in bottom layer,while the number of female catkins in the top crown layer>that in middle layer>that in bottom layer.The number of catkins per reproductive branch remained constant after a birch tree reaching 50～60 years old.Decrease in the total number of reproductive modules in old trees was due to the decrease in the total number of reproductive branches,instead of the decrease in the number of reproductive modules per reproductive branch.In addition,the number of catkin modules decreased when canopy density increased.Female catkin modules occued mostly in top or middle canopy layer.This might be resulted from distributive adoption of birch reproduction to light sources.
出处
《生态学报》
CAS
CSCD
北大核心
2000年第4期673-677,共5页
Acta Ecologica Sinica
基金
黑龙江省杰出青年科学基金资助项目
