| Biological invasion, which was a focus of ecological research, threatened the biodiversity security severely and had brought huge economic costs to the world. In this paper, we worked in two different directions to identify traits associated with invasiveness. In one direction, we studied the allelopathic ability of 5 herbaceous species from Compositae family. Though all of these are common species in Xishuangbanna, China, they show different invasiveness: Eupatorium adenophorum and Chromoleana. odorata are alien plant with remarkable invasiveness, Ageratum conyzoides and Biden pilosa are non-invasive alien plant, Gynura sp. is a new-coming alien species with weak invasiveness. In another direction, we compared some growth-related and physiological trails of E. adenophorum, C. odorata and Gynura sp. which grown in 5 light regimes (relative irradiance 100%, 50%, 36%, 12.5% and 4.5%).After 4-month-growing in mixed community with E. adenophorum, C. odorata, A. conyzoides, B. pilosa and Gynura sp. had not showed any significant morphologic or physiological changes caused by allelopathy of E. adenophorum. But C. odorata, B. pilosa and Gynura sp. could reduce the collar diameter, leaf number and APX activity of E. adenophorum respectively through allelopathy. Many parameters of E. adenophorum could respond only to the light environment in the community.Some strategies involved in high-light (100% relative irradiance) acclimation were common for E. adenophorum. C. odorata and Gynura sp. Their specific leaf area (SLA), mean leaf size, leaf area ratio and leaf area root mass ratio were lower in high light regime, which resulted in a smaller but thicker leaves which led to enhanced heat-losing and water holding capacities. The maximum photosynthesis rates (Pmax), diurnal thermal dissipation (NPQ) and day respiration (Rj) of the three species were higher in RI 100%, which meant more light energy could be used in assimilation process and more excess energy could be dissipated. In addition, in RI 100% their chlorophyll concentration per unit leaf area were lower, while the nitrogen investmentsin carboxylation were higher, which could reduce the inactivation pressure of photosynthesis apparatus through reducing light capture and increasing the use of excited electons by CO2 assimilation.In another aspect, E. adenophorum, C. odorata and Gynura sp. had unique tactics to acclimate to high light condition. Both E. adenophorum and Gynura sp. had large number of branches in RI 100%, but with the change of irradiance, their changes of leaf mass ratio. leaf mass fraction and leaf area index and support biomass ratio (SBR) were totally different. These characteristics made E. adenophorum and Gynura sp. distinct in self-shading, with which both of the two species fit the high light regimes well. The minimum fluorescence of C. odorata and Gynura sp. in RI 100% were lower, while chlorophyll a, b ratio were higher than those in other light regimes. These phenomena indicated that C. odorata and Gynura sp. changed the light harvesting complex content of photosystem I and photosystem II (PS II) to regulate the light distribution between the two photosystems. In RI 100%, the Pmax and nitrogen use efficiency of Gynura sp. were higher than those of E. adenophorum and C. odorata, which indicated Gynura sp. was better fit for high light.With the decrease of light intensity, E. adenophorum and Gynura sp. increased plant height and decreased branch number, which could make plant intercept more light energy. But their biornass allocation strategies were different. In E. adenophorum, the root mass ratio (RMR) decreased and SBR increased with the decrease of light intensity, while in Gynura sp.. RMR increased and SBR decreased. The biomass allocation strategy of E. adenophorum was more successful than Gynura sp. The plasticity of biomass allocation-related parameters to light in C. odorata was smaller than that in E. adenophorum and Gynura sp. In low light regimes (RI 36%, 12.5%), E. adenophorum, C. odorata and Gynura sp. exhibited high light abs...
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