小五台山天然青杨林雌雄群体的生长差异

Inter-sexual difference of growth characteristic for Populus cathayana natural forests in the Xiaowutai Mountains

关键词:  雌雄异株  青杨  生长特征  雌雄差异  性成熟  异速生长

Key words:  dioecy   Populus cathayana  growth characteristic  intersexual difference  reproductive maturation  allometry

摘要:

通过对小五台山天然青杨种群的野外调查,并使用胸径与株高的异速生长模型来分析其雌雄群体间的生长差异,以探究雌雄异株植物青杨在性成熟条件和形态特征中是否存在性间差异。结果表明:(1)在青杨生长过程中,胸径随年龄呈指数型增长,而株高随年龄呈对数型增长;(2)雌雄植株的性成熟条件不同。雌株进入性成熟阶段的最低年龄和胸径都小于雄株;(3)青杨高径生长过程存在性别差异。雌株的异速生长指数显著大于雄株(P=0.024)。表明天然青杨种群中雌株一般性成熟较早,成熟后营养生长偏重于胸径增粗; 而雄株性成熟较晚,营养生长偏重于植株增高。相对于雄株,雌株具有较高的树干机械强度。

Abstract:

It was investigated that whether the gender differences existed in sexual maturation conditions and morphological characteristics for this dioecious plant,by the field research for the natural population of Populus cathayana in the Xiaowutai Mountains,and using the allometric models for DBH(diameter at breast height)and plant height to analyze the growth characteristics between the male and female groups. The results were as follows:(1)In the growth process of Populus cathayana,the DBH increased exponentially with the growth of the age,while its plant height was logarithmic growth;(2)Sexual maturation conditions were different between male and female plants. The minimum age of sexual maturity stage and the DBH for female plants were both less than males;(3)The gender differences presented in the growth process. The allometric exponent for female plants was significantly higher than males(P=0.024). It was shown that female plants matured generally earlier in the Populus cathayana natural population,and the vegetative growth emphasized mainly thickening of DBH; while male plants matured later,and emphasized plant height. Compared with the male plants,the female ones had a higher trunk mechanical strength.