Ecological Analysis On Clonal Reproduction And Dispersal Of Exotic Species, Rhus Typhina

At present, the researches about clonal plants are mainly about herbaceous plants, but few about woody plants home and abroad. This paper studied and analyzed the physiology plasticity of woody clonal plant, Rhus. typhina. In this paper, the mother ramet and its clonal ramets of Rhus typhina were taken as a whole,a system of the mother ramet and its clonal ramets for the first time, which was selected as research material. The experiments of cutting rhizomes and of finding characteristics of Rhus typhina in response to different water and nutrient conditions, and the investigation about male and female of Rhus. typhina were carried out from March,2008 to September,2008 in urban and suburb of TaiAn in ShanDong province. The diurnal variation of photosynthetic parameters and chlorophyll fluorescence parameters were determined by using the portable photosynthetic measurement CIRAS-2 and the portable chlorophyll fluorescence measurement Pam-2100, and the variation of photosynthetic characteristics, growth characteristics and relative chlorophyll content of the ortet and clonal ramets of Rhus typhina were contrasted and analyzed. The results are as follows:â‘ The materials were under different degrees of water stress in a short time after being cutting rhizomes in three different ways, which could also be considered that the ortet and clonal ramets of Rhus typhina were in different water conditions. The decrease amplitudes of physiological transpiration and chlorophyll fluorescence parameters showed as: the first grade ramets (or the first grade ramets losing the ramets of the same level)>the Rhus typhina ortet>the second grade ramets which were out the system (or the first grade ramets which were out the system). The conclusion is that the influence to the first grade ramets (it was the first grade ramets which were still in the system if there were many) were greatest and the decrease amplitudes of physiological parameters were the most evident.â‘¡The differences between male and female Rhus typhina plants at the physiological characteristic plasticity, morphological characteristic plasticity and growth characteristics plasticity were found after the research. The male Rhus typhina plant had bigger crown and better ability in physiological transpiration than the female, but the female Rhus typhina plant paid more attention to height growth and DBH growth. So the female Rhus typhina plant occupied more upper space and the male Rhus typhina plant occupied more ground space. As to the reproduction, both male and female Rhus typhina plants could accomplish clonal reproduction, and the female Rhus typhina plant could accomplish sexual reproduction as well. The male Rhus typhina plant could produce more generations and amounts of clonal ramets, so it had better clonal reproduction ability and played a more important role in the establishment process of the monodominant communities.â‘¢The physiological parameters of Rhus typhina ortet under"low nitrogen & low water level"or"nitrogen (both low and high level) & high water level"conditions were the best and those conditions were most beneficial to the life activities and reproductions of Rhus typhina ortet among the different levels of water and nitrogen in the research. The best conditions for the morphological growth of Rhus typhina plant could be concluded as:"high water level & low or none nitrogen level were favorable to the height growth, high water& nitrogen level or low water& nitrogen level was good for the DBH growth, and low nitrogen & water level or none nitrogen & high water level was beneficial for crown growth. The"low nitrogen & high water level"condition was beneficial to clonal reproduction, in which all physiological parameters of the Rhus typhina ramets were the biggest. The situation which was good for raising the relative chlorophyll content of Rhus typhina plant could be concluded as: the relative chlorophyll content of Rhus typhina plant under low nitrogen level conditions, both low and high water levels were higher than none water level, however, under high water level conditions, both low and high nitrogen levels were good for raising the relative chlorophyll content of Rhus typhina plants.