Comparative Study On Functional Traits And Their Responses To Environments Of Common Native And Exotic Plants In China

To clarify the mechanism of invasive alien species is the basis of controlling invasive organisms,and it is also an important scientific problem to be solved in the field of plant protection.Plant functional traits(such as seed germination rate and insect resistance)are a series of core attributes that are closely related to plant colonization,survival,growth and death.Compared with native plants,some exotic plants have higher resource utilization efficiency and growth rate,it has higher resistance to biological(such as insect feeding,inter-species competition)and abiotic(such as drought)stresses.The differences of these functional traits may promote the invasion of exotic plants,which provides a new way to explore the mechanism of plant invasion.However,previous studies have tended to focus on a few invasive species,focusing on the functional traits of a plant at a particular stage of growth,such as seed or adult plant.Therefore,whether there are universal differences in functional traits between native and exotic plants is still controversial.In view of this,this research selects our country common 150 kinds of native plants and 89 kinds of exotic plants as the research object.The functional traits of seeds,seedlings and adult plants of these native and exotic plants,and the responses of adult plant growth to insect feeding and interspecific competition were compared by indoor and outdoor control experiments.We obtained following main findings:1)In general,only some seed functional traits(seed mass,length to width ratio and area)had significant phylogenetic signals;while only a few other functional traits(such as total mass at seedling stage)had phylogenetic signals when native species were analyzed separately.The results indicated that most functional traits of these species were not phylogenetically conserved,that is,the values of functional traits were not related to the phylogenetic relationships.2)The seed area,germination rate,seedling survival rate and seeding shoot length of exotic plants were significantly higher than those of native plants.There was no significant difference in seed mass and length to width ratio,root,shoot and leaf mass,root and leaf length,growth rate and root to shoot ratio between native and exotic plants.3)Based on pgls analysis,it was found that some functional traits of seeds and seedlings were significantly correlated(such as seed mass is negatively correlated with germination rate),but the traits of seeds and seedlings were not correlated with adult traits.These findings suggest that some seed traits could predict the fitness of plants at seedling stage,but not for adult growth.In addition,the correlation of functional traits between native and exotic plants was different.For example,some seed and seedling traits(such as seed area and seedling shoot weight)are negatively correlated with relative growth rate and total mass for native plants,but there is no correlation in exotic plants.4)In the complex field environment,the total mass and root to shoot ratio of exotic plants were significantly lower than that of native plants.Insecticide treatment had no impacts on the relative growth rate and biomass of all plants,while interspecific competition significantly reduced the growth rate and the root mass of these species,regardless of the origin(exotic vs.native)of the species.In conclusion,the survival rate of exotic plants was significantly higher than that of native plants,which may be helpful to establish populations of exotic plants in new regions.Under field conditions,the biomass of adult plants of native plants was significantly higher than that of exotic plants,which had the potential to inhibit the population expansion of exotic plants Spraying insecticides(feeding by leaf-eating insects)has limited effect on the invasion of alien plants.These findings contribute to a deeper understanding of the mechanisms of plant invasion and provide scientific guidance for the development of ecological control techniques of invasive plants,such as biological substitution techniques.