Plant Population Ecological Study On Dominant Rhizome Plant In Songnen Plain Wetland In China

Songnen plains wetland affected by seasonal rainfall and river feedwater has the dry-wet alternant progress seasonally, which strongly affect plants with natural selective plasticity, and adapt to the evolutionary research on wetland plants. Wetland plants responsive to the dry-wet alternant progress have the vicarism between wet and dry predominant population mutually, and the progress are propitious to the observation and research about dynamics of wetland predominant population. Based on the observation about the ramets characters of predominant clonal rhizome plants from wetland, their modular structure, reproductive allocation and population dynamics were measured and results indicate that:(1) There are 2 or 3 age classes of ramets and 3 types of tubers of Scirpus planiculmis population in terms of four times observation in three years. The seasonal dynamic of the quantity, biomass and height structure of ramets and the quantity, biomass and size structure of tubers were all different. There are 3 age classes of ramets and 4 age classes of rhizomes of Carex kirganica which quantity and biomass were different between age classes. The same life form, vegetative reproduction strategy and similar age structure of Scirpus planiculmis or Carex kirganica were due to the long time convergent adaptation.(2) There was significant allomatric growth of Phalaris arundinacea and Phalaris arundinacea between ramets height and biomass or constituent biomass, between ramets biomass and constituent biomass in wet and drought environments. And the relationship between ramets biomass or height and ramets quantitative characteristics also followed allomatric growth for Phragmites australis and Phragmites Jeholensis in wet and drought environments. The allomatric scaling for the wet clonal plants including Phalaris arundinacea Scirpus planiculmis Phragmites australis and Phragmites Jeholensis did not show "1/4-power Rule". The variation of the allometric exponents between vegetative and reproductive ramets was mainly due to the different regulation mechanisms in different development stages. Moreover, the variation of the allometric exponents between plantsin wet or drought environments was the result of the long-time divergent response for ramets to moisture environments.(3) The reproductive allocation (RA I and RA II ) of three age classes Carex kirganica from aquatic habitat were 20.2%-26.75% and 16.36%-22.14%, and that of two age class Scirpus planiculmis were 0.10%-24.99% andl5.23%~19.36%?There were generally reproductive growth in each age class ramets of Carex kirganica as well as that in Scirpus planiculmis. Furthermore, the more or less of the reproductive allocation was certain and that is the result of reproductive trade-off and the adaptation to their habitats. The reproductive allocation of Phragmites australis was 5.82%- 16.31% in 12 grads of moisture and its reproductive growth ratio(Rrg) was 10.68%- 16.35%. RA I of Phragmites hirsuta was 9.09% and 13.98% from two habitat, which Rrg was 22.07% and 18.06%. RA I and Rrg of Phragmites australis and Phragmites hirsuta from different habitats showed nonconforming rules because they are affected by the action of environmental factors and the changes of modular characteristics during their growing process together.(4) Zhalong, Xianghai and Momoge wetland have the seasonal dry-wet alternative progress in the Songnen plains. Dry-wet interface distribute different vegetation space succession serials. The dynamics of a diversities and 3 diversities of communities, numbers of predominant population and population relative dominance were different in growing season. Phragmites australis was the predominant population when the surrounding tended to wet, and that was Leymus chinesis when dry occurred on Zhalong and Xianghai wetland. Deyeuxia angustifolia population and Carex tato population coexisted in growing season and their dominance alternated during three-observation period on the typical dry-wet interface of Momoge wetland.