The Energy-related Characteristics Of Common Aquatic Macrophytes In Liangzi Lake And The Influence Of The Environmental Factors

The characters related to the energy of aquatic plants mainly include caloric value,ash content,construction cost,carbon and nitrogen concentration.Studying on the differences of these traits between different organs,different species(especially between invasive species and native species)and the influence of environmental factors on these traits,which contribute to understand the energy allocation of aquatic plants and its resource allocation strategies,and to explore whether invasive and alien species have special advantages in energy accumulation and utilization.However,there is a lack of research about the energetic characteristics of aquatic plants in LiangZi Lake.Thus we made a comparison study on the energetic characteristics of common aquatic plants in LiangZi Lake,and we studied on the effect of nitrogen addition on the energetic characteristics of Alternanthera philoxeroides,Myriophyllum aquaticum and Jussiaea repens;moreover,we explored the effect of water salty on the energetic characteristics of Myriophyllum spicatum and Potamogeton crispus.The main results are as follows:(1)The ash-free caloric value of the leaves was significantly higher than that of the stems and roots among the common aquatic plants in Liangzi Lake.There were no significant differences in ash-free caloric value of leaves between life-forms,but there was a trend of the emergent>the floating>the submerged.The construction cost of the leaves was significantly greater than that of the stems and roots among all species we collected.There were no significant differences in construction cost of leaves between life-forms,and it showed the same pattern as the ash-free caloric value,the emergent>the floating>the submerged.The ash content of roots was significantly higher than that of stems and leaves,and the result of ash content of leaves when compared different life-forms was the submerged>the floating>the emergent.The mean ash content of the aquatic plants was higher than that of terrestrial plants.The carbon concentration of leaves was significantly greater than that of stems and roots and in the high degree of lignification of plants,such as Zizania caduciAora,its carbon concentration of stems was greatest.The carbon concentration of the submerged was lower than other life-forms except Potamogeton maackianus A.Benn,showing the pattern that the emergent>the floating>the submerged.The nitrogen concentration of leaves was significantly higher than that of stems and roots.The construction cost was positively correlated with the ash-free caloric value,carbon concentration and nitrogen concentration,and it was negatively correlated with the ash content.The ash-free caloric value was positively correlated with carbon concentration and nitrogen concentration,was negatively correlated with ash content.(2)Nitrogen addition significantly enhanced the mass-based construction cost of Alternanthera philoxeroides,which was significantly higher than that of Jussiaea repens L.and Myriophyllum elatinoides Gaudich under nitrogen addition treatment.Moreover,nitrogen addition significantly increased the leaves nitrogen concentration,relative growth rate and reduced the C/N ratio of Alternanthera philoxeroides.which means that Alternanthera philoxeroides showed pretty phenotypic plasticity,this may be the mechanism for its invasion.Alternanthera philoxeroides has higher construction cost and photosynthetic capacity.The specific leaf area,nitrogen concentration and photosynthesis related traits of the leaves of Myriophyllum elatinoides Gaudich were the lowest in the three plants,and the weak photosynthetic gain might limit its invasion in non-origin.There was no significant difference in maximum net photosynthetic rate and maximum electron transport rate between Alternanthera philoxeroides and Jussiaea repens L.The mass-based construction cost and the relative electron transport rate was positively correlated with nitrogen concentration respectively.The relative electron transport rate was positively correlated with the specific leaves area.The area-based construction cost was negatively correlated with the specific leaves area.(3)There were no significant differences in the main energy-related traits,such as ash-free calorific value,ash content,and construction cost of Potamogeton crwaspus and Myriophyllum spicatum L.in our experimental setting salinity range(0.15-3.4 ‰).