The Experimental Study Of The Relationship Between The Trait Plasticity Of Peatland Plants And Interspecific Competition

Phenotypic plasticity is an adaptive capacity expressed by plants as a result of interaction with environment.The phenotypic plasticity is one of responses of plants to many ecological and environmental factors.Competition is an important factor influencing the phenotypic plasticity of plants.The plant plasticity may occur with morphological,partition,and physiological traits in different competitive environments,which may affect the competitive ability of plants or the intensity of competition among plants,and thereafter influence the outcome of competition and inter-specific relationships.In recent years,researches on relationship between plant phenotypic plasticity and competition gradually increased,among them more and more studies have been focused on the field that understanding the competition mechanism based on phenotypic plasticity of functional traits.This study creatively explored the relationship between plant phenotypic plasticity and competitive ability with aboveground and belowground competition separately,and the competitive effect ability(the ability to reduce the fitness of competitors)and response ability(the ability to resist the competitive pressure from competitors)were also detected separately.Results from this study could help to discover the phenotypic plasticity strategies of functional traits when plants under aboveground and belowground competition,to detect the effects of phenotypic plasticity to two different competitive abilities of plants are consistent or inconsistent,and to further understand the growth strategies of plants with competition,mechanism of functional traits-interspecific interaction.This study was conducted with six peatland plants: Carex angustior,Eleocharis valleculosa,Geranium erianthum,Comarum palustre,Lysimachia davurica and Saussurea amurensis.Plants grew under four competition treatments(no,full,aboveground and belowground competition,C.angustior as the phytometer),two light treatments(full sunshine,shade),and two nutrient treatments(high and low soil nutrients).The phenotypic plasticity of 7 functional traits,competitive effect and response abilities were measured.The plasticity response of plants to inter-specific competition,relationships of phenotypic plasticity and competitive ability were analyzed,and the effect of soil nutrient and light to phenotypic plasticity of functional traits and their relationships with competitive ability were also explored.The main results of this study as blow :(1)The phenotypic plasticity of 6 functional traits from 6 species were significantly responded to the competition,which reduced the root shoot ratio,specific leaf area,maximum root length,total root length,specific root length and root diameter,increased the plant height.(2)The effects of belowground and aboveground on the phenotypic plasticity of 6 functional traits were significantly different,and this effects were influenced by soil nutrients and light.Furthermore,competitive pressure from belowground and aboveground simultaneously affected the phenotypic plasticity of belowground and aboveground traits.(3)The phenotypic plasticity of functional trait closely related with the competitive response ability.The positive plasticity of root shoot ratio,height,maximum root length,total root length and root diameter,and the negative plasticity of specific leaf area and specific root length could improve the ability of plant to resist the competition.(4)The relationship between phenotypic plasticity of functional traits and competitive affect ability was weak in this study,indicating the phenotypic plasticity of morphological traits may not affect the ability of plant to press others.Therefore,the phenotypic plasticity of plant morphological traits may only help plants to resist or endure competitive pressure rather than reduce the fitness of others.It is necessary to distinguish the competitive effect and response ability when exploring the inter-specific relationship,competition process and competition mechanism based on functional traits.(5)The different completion treatment less affected the relationship between phenotypic plasticity and competitive ability,only significant under high soil nutrient environments.