Effects Of Intraspecific Interaction On Morphological Plasticity In Karst-adaptable Plants

Plants growing in natural habitats are affected by both abiotic and biotic environmental factors.Resource conditions such as light,water and soil nutrients are the basic needs of plant growth and reproduction,and the presence of neighboring plants can also cause competition for limited resources.Therefore,abiotic environmental conditions and adjacent plants and their interactions often determine the survival and development of plants,but there is still a lack of research on how plants respond to the interaction between biotic and abiotic environmental factors.In this paper,a variety of karst-adaptable plants as the object,through 1)the response dynamics of Bidens pilosa to population density under different soil moisture conditions.2)Responses of Buddleja lindleyana and Bidens pilosa to the interaction of intraspecific interactions and abiotic environmental factors.3)The effects of early intraspecific interactions between Lindera communis and Rumex acetosa on morphological plasticity induced by abiotic environmental factors were studied.The strategies of plants to cope with complex environmental changes were discussed,and the relationship between intraspecific interactions and plasticity was revealed.The following important results were obtained:1)The response of most morphological and biomass allocation characteristics of B.pilosa to density and the way in which they change with growth stages are significantly affected by water content.Under two soil moisture conditions,high density will lead to the increase of plant stem biomass allocation and plant height,and the response of other morphological characteristics and component biomass allocation to density will change with the growth stage under different soil moisture conditions.In the early stage,better soil moisture conditions can cause a positive response of plant root biomass allocation to density.At the expense of leaf biomass allocation and leaf number reduction,the total biomass did not respond.Under drought conditions,plants promote root proliferation and reduce stem biomass allocation through medium-level underground interactions,so that plants can maintain growth under environmental stress,and the response of total biomass is not significant.In the middle stage,the interaction between plants was not strong and mainly promoted,and the ground diameter showed a positive response to density(drought condition).Leaf area,specific leaf area and total biomass showed a positive response to density under two soil moisture conditions.In the late stage,the better soil moisture conditions caused fierce competition in dense populations,resulting in a decrease in total biomass and root biomass allocation,leaf area and specific leaf area.Under drought conditions,most of the characteristics are not affected by density.2)The promoting effect of early intraspecific interaction on B.pilosa was transformed into competitive effect under the influence of late light conditions,and the interaction between intraspecific interaction and light seriously affected the performance of various morphological and biomass characteristics of Bidens pilosa.The response of root traits(root biomass and root shoot ratio)of B.lindleyana to intraspecific interactions under different light conditions is still negative,indicating that the underground competition effect still exists.Due to the asymmetry of aboveground competition,the growth of aboveground traits(plant height,ground diameter,leaf area)is promoted,and biomass accumulation(stem biomass)is improved.When water resources were sufficient,the promoting effect of early intraspecific interaction on B.pilosa gradually changed to competition,which reduced the number of leaves.The effect of early intraspecific interactions on B.lindleyana was dominated by competition.Under humid conditions,intraspecific competition intensified,which reduced leaf number,leaf area,root biomass,leaf biomass and total biomass.The intraspecific interaction of Bidens pilosa and B.lindleyana aggravated the plastic response of leaf number and other traits under drought stress.The reduction of leaf number was their growth strategy to cope with drought stress.With the continuation of drought stress,the intraspecific interaction of B.pilosa could promote the increase of leaf area and other characteristics to maintain its vegetative growth.Under normal nutrient conditions,the aboveground stem,leaf and underground root biomass of the two plants were greatly reduced,and the total biomass decreased sharply.Under oligotrophic conditions,intraspecific interactions significantly reduced the number of leaves,leaf area,root,stem,leaf,and total biomass of B.pilosa.The presence of the same neighbor only reduced the number of leaves of B.lindleyana,and the biomass characteristics of each component were not affected.3)Early intraspecific interactions can have a positive impact on the growth of L.communis in the later period.L.communis improves the adaptability of adverse habitats such as shading and drought and nutrient deficiency in the later period by increasing the main root length,plant height,leaf number and leaf biomass.Under better nutrient conditions,the negative effect of early intraspecific treatment had an adverse effect on the later growth of R.acetosa,resulting in a sharp decrease in the leaf morphology and stem and leaf biomass characteristics of the above-ground part.In addition,compared to plants growing alone,intraspecific interactions improved the negative response of L.communis under low nutrient conditions,indicating that nutrient variation induced plant plasticity,while early intraspecific interactions could affect the plasticity of plasticity induced by nutrient variation.