东北草地异质生境芦苇种群根茎芽年龄结构及输出规律

为明确异质生境条件下芦苇种群根茎芽年龄结构及输出规律,揭示芦苇种群的营养繁殖特性,采用单位土体挖掘取样,分别计数各龄级根茎芽的调查与统计方法,对东北草甸草原草甸土和盐碱土两个生境单优群落芦苇种群根茎芽动态进行比较分析。结果表明,两个生境芦苇种群根茎芽库主要均由6个龄级组成;草甸土生境在6—10月均为增长型年龄结构;盐碱土生境6—7月份为衰退型年龄结构,8月份为稳定型年龄结构,9—10月份为增长型年龄结构。根茎芽数量1—4a普遍以草甸土生境高于盐碱土生境,5—6a普遍以盐碱土生境高于草甸土生境,各龄级根茎芽数量与月份之间均符合y=a+bx直线关系(P0.05)。随着龄级的增加,休眠芽比率呈逐渐下降趋势,而萌发芽比率则呈逐渐上升趋势,5个生育期的休眠芽比率和萌发芽比率与龄级之间均符合y=a+bx直线关系(P0.01)。各龄级根茎的休眠芽具有一个相对稳定的萌发输出过程,草甸土生境根茎休眠芽按每年11%的比率萌发输出,而盐碱土生境根茎休眠芽按每年7%的比率萌发输出。虽然芦苇种群根茎芽年龄结构及年龄谱在异质生境中存在显著差异,但却有着相同的季节变化规律,均以不断形成新根茎的芽来维持着种群的营养繁殖更新。

Age structure and output regularity of Phragmites australis rhizome buds from populations occurring in heterogeneous meadow habitats in Northeast China

Rhizome bud development was studied in two populations of Phragmites australis: one from an area with typical meadow soil and another from an area characterized by saline-alkali soil. Soil samples were taken from each site and the number of rhizome buds in different age classes was recorded. The aim of this research was to determine the age structure, output regularity and vegetative propagation characteristics of P. australis rhizome buds in heterogeneous habitats. Results showed that P. australis rhizome bud banks are composed of six age classes, the age structure was expansive from June to October in the meadow soil habitat. In contrast, in the saline-alkali soil habitat it declined from June to July, was stable in August and was expansive from September to October. The number of rhizome bud at the 1st to 4th is generally higher in meadow soil habitat than that in saline-alkali soil habitat, while the number of rhizome bud at the 5th to 6th is generally higher in saline-alkali soil habitat than that in meadow soil habitat. There was a significant linear correlation(P < 0.05)between the number of rhizome buds and month. As the age class increased, the proportion of dormant buds declined, and the proportion of germinating buds rose. There was also a significant linear correlation (P < 0.01) between the percentage of dormant buds and germinating buds in the growing periods and age classes. The rate of bud dormancy for each age class was relatively stable, the output rate of rhizome dormancy buds in the meadow soil habitats was about 11% per year,and the output rate of rhizome dormancy buds in saline-alkali soil habitats was about 7% per year. To conclude, there were significant differences in the age structure and age spectrum of P. australis population rhizome buds in heterogeneous habitats; however, they showed similar seasonal patterns ensuring new rhizome bud formation for vegetative propagation.