Study On Dynamics Of Bud Bank In Restoration Succession Series Of Degraded Grassland In The Songnen Plain Of China

Bud bank, formed by buds of a plant which are exploitable for vegetative regeneration, plays a fundamental role in local plant population even community structure and dynamics. Leymus chinensis + Puccinellia tenuiflora community and Leymus chinensis +Carex duriuscula community are the transitional types of the restoration succession process of degraded grassland in the Songnen Plain. Leymus chinensis, Puccinellia tenuiflora and Carex duriuscula, the dominant species in the communities, are the typical clonal plants, which can reproduce vegetative buds to renew and maintain the populations consistently. In this research, the ability of vegetative propagation, the composing, the quantitative characteristics, and the diversity of bud banks, and the structure of dormancy modules were calculated and analyzed quantitatively in the whole growth season so that the restoration succession theory and biodiversity theory would be enriched and these would offer a theoretical guidance to restoration practice of meadow ecological system. The results are showed as follows: ⑴ The earing rate of L. chinensis, P. tenuiflora and C. duriuscula were low in these communities. On the contrary, the ability of vegetative propagation of the three populations were strong. The ability of vegetative propagation of L. chinensis was stronger than that of P. tenuiflora and C. duriuscula obviously. In addition, the ability of vegetative propagation of L. chinensis in L. chinensis +C. duriuscula community was stronger than that in L. chinensis+P. tenuiflora community. The ability of vegetative propagation and the number of bud banks of populations were fluctuated during the different succession series that reflected there was differentia in the ability of vegetative propagation in the environmental space. ⑵ The bud banks of P. tenuiflora only consist of the tillering node buds, whereas the bud banks of L. chinensis and C. duriuscula consist of the tillering node buds and the rhizome buds. The bud banks of L. chinensis constituted the majority in the rhizome buds in L. chinensis + P. tenuiflora community except in June. The bud banks of L. chinensis constituted the majority in the rhizome buds in April, May, and August, and constituted the majority in the tillering node buds in June, July and September. While the bud banks of C. duriuscula constituted the majority in the tillering node buds in L. chinensis +C. duriuscula community except in May. The percentage of the rhizome buds of L. chinensis and C. duriuscula were the lowest in June and increased gradually in the end of growth season in two communities. Storage and collocation of the bud banks were significantly different among the different succession series in every month. ⑶ According to the different growing position, the rhizome buds are divided into the node buds and the topmost buds of the rhizomes. Storage of the rhizome buds of L. chinensis population and C. duriuscula population constituted the majority in the node buds of rhizomes and the topmost buds of rhizomes in the whole growth season in two communities respectively. The ability of expanding the space of the topmost buds of rhizomes of L. chinensis in L. chinensis+P. tenuiflora community was stronger than that in L.chinensis +C. duriuscula community. The change trend of the percentage of the topmost buds of L. chinensis population and C. duriuscula population were similar and the lowest in June and May respectively, then increased gradually in the end of growth season in two communities ⑷ Dormancy modules, which consisted of the bud banks and the seedling banks, are the potential population next year. The input of the bud banks of dominant species was bigger than the output in two communities in the end of growth season. Dormancy modules of L. chinensis and P.tenuiflora were respectively 1.67 and 1.75 times more than the parent tillers in L. chinensis + P. tenuiflora community, and trended to increase in the community next year. Dormancy modules of L. chinensis and C. duriuscula were respectively 1.32 and 0.64 times more th...