松嫩平原野古草种群构件结构动态

野古草是根茎型无性系禾草,在松嫩平原草甸经常形成单优种群落。采用单位面积挖掘取样、分株按营养繁殖世代划分龄级、根茎按实际生活年限划分龄级的方法,对松嫩平原单优群落和混生群落的野古草种群构件结构进行了调查与分析。结果表明,在生长季初期两群落野古草种群均以春性分株和根茎芽占优势,且分株及芽构件结构相对稳定,芽库的输出率单优群落为80.4%,混生群落为62.5%;整个生长季分株由2—3个龄级组成,1a分株数量是2a的2.9—10.2倍,其生物量各月份所占比例平均为93%,随着龄级的增加依次明显减少,呈增长型年龄结构;根茎由3—4个龄级组成,根茎累积长度及生物量均以2a占绝对优势,为稳定型年龄结构;分株生产力1a明显高于2a,对种群贡献最大;根茎贮藏力除个别月份以3a、4a最高外,两群落大部分以2a最高,在生长季后期,1a根茎物质积累的速率最快。

Dynamics of module structures on Arundinella hirta populations in Songnen Plains of China

Arundinella hirta is a typical clonal plant with rhizome. It always forms monodominant community in the meadow of the Songnen Plains, China. By using the method of excavating samples in unit area, ramet were classified according to the generation of vegetative propagation and rhizomes age classes were did according to the actual living years. To reveal the number and biomass dynamics of A. hirta populations during restoration succession, a survey and analysis was conducted on the module structures of A. hirta populations. The monodominant community and mixed community were in different stages from A. hirta to Leymus chinensis restoration succession series. Research results showed that spring ramets and rhizome buds were dominant in two communities in the early growing season. Spring ramets were 3 times that of winter ramets, and rhizome buds accounted for more than 90% of total buds which was predominant. Age structures of ramets and buds were stable at the same time. Mixed community was lower than that of monodominant community in the output rate of bud banks, 62.5% and 80.4%, respectively. Throughout the growing season, ramets consisted of two to three age classes and biomass of the 1st age ramets accounted for an average of 93% in each month, and the number of ramets of 1st age class was 2.9-10.2 times more than 2nd age class. The number and biomass of ramets reduced significantly in turn with age class increase and appeared expanding age structures. Dynamics of ramet biomass corresponded to the ramet number. But the differences were not significant among 2nd age class in each month. Rhizomes consisted of three or four age classes. Accumulation length and biomass of 2nd age rhizomes were predominant, which accounted for more than 50% of total rhizomes. Age structures of rhizomes presented stable. It is worth mentioning that the contribution of 4th age rhizome biomass was very small, and these old rhizomes all died before winter. Productivity of ramets represents plant vegetative production and storage, which can be reflected by biomass of unit ramets number. Productivity of 1st age was significantly higher than 2nd age ramets, and it had the greatest contribution to the populations. The minimum of average productivity appeared in June of different plots. Rhizome is an important organ for vegetative propagation and matter storage. Storage capacity can be reflected by the biomass per unit rhizome length, and storage capacity of 1st age rhizomes increased with season in two communities. The 2nd age class rhizome had the highest storage capacity in communities in every month except for June and July. Matter accumulation of 1st age rhizome had the fastest growth rate in the late growing season.