Effects Of Interspecific Interaction On Morphological Plasticity In Karst Suitable Plants

Plants can respond to various biotic and abiotic environmental factors through phenotypic plasticity.Plant interactions are important biotic environmental factors that can affect or even determine plant survival,growth,and reproduction.The influence of interspecific interactions may explain species competition or coexistence,as well as the composition and structure of the community.However,few studies have focused on the effects of interspecific interactions on plant plasticity,and studies on plant plasticity often consider only the effects of a single environmental factor,ignoring the effects of multiple environmental factors interacting with plants.In this study,invasive species Bidens pilosa and local species Buddleja lindleyana in karst areas were selected as research objects.Interspecific interactions and non-biotic environmental treatments were divided into two stages: 40 days of interspecific interactions treatment followed by 50 days of light,water,and nutrient treatments.The effects of interspecific interactions on the plasticity of morphological and biomass characteristics of the two plant species in response to variations in light,water,and nutrients were studied.The results of this study demonstrate significant differences in the plasticity of responses to light,water,and nutrient availability between the two species as a result of interspecific interactions.(1)Specifically,under interspecific interactions,B.pilosa responds positively to shading with increased leaf area,fractal dimension,and root biomass,while B.lindleyana responds negatively with decreased average specific leaf area(SLA)and root-shoot ratio,but positively with increased root diameter,fractal dimension,and leaf biomass.Both species tend to increase leaf growth to obtain more light when light resources are limited.(2)Under interspecific interaction,B.pilosa exhibits reduced SLA,average SLA,and average specific leaf weight(SLW)in response to drought,while B.lindleyana shows increased total biomass and root growth in response to moist conditions.(3)For B.pilosa,interspecific interaction mainly reduces the growth of specific leaf area and average specific leaf area under nutrient supplementation,while promoting main stem growth under high nutrient conditions.For B.lindleyana,interspecific interaction significantly increases the root-shoot ratio,root length,and root tip number under low nutrient conditions,while nutrient supplementation decreases leaf morphological characteristics under interspecific interaction.In conclusion,the two species have markedly different strategies in response to the interactive effects of interspecific neighboring plants and non-biotic environmental factors:(1)B.pilosa is less shade-tolerant than B.lindleyana,but it can respond to the double impact of interspecific interaction and shade by significantly increasing root and leaf growth,while B.lindleyana can promote its overall biomass under full sunlight;under shade conditions,B.lindleyana maintains its total biomass stability by reducing root and leaf growth.The invasive species B.pilosa tends to increase aboveground growth under full sunlight,while the native species B.lindleyana tends to increase belowground growth.(2)Under interspecific interaction,both species are more likely to respond to drought conditions by reducing their morphological characteristics.The biomass of B.pilosa is somewhat promoted by interspecific facilitation under drought conditions,while the root biomass of B.lindleyana is promoted under mesic conditions.Interspecific interaction promotes the growth of root system morphology of both species under both drought and moist conditions.(3)Interspecific interaction increases the root growth and total biomass of B.pilosa under low nutrient conditions,increases the aboveground competition of B.lindleyana under high nutrient conditions,and reduces stem growth.This suggests that B.lindleyana is better at utilizing resource-rich environmental conditions for rapid growth under interspecific interaction,while B.pilosa has a stronger ability to tolerate environmental stress.Interspecific interaction can reduce the growth of other plant features,increase or promote the growth of features that are most limited by environmental resources,and the specific feature response depends on the type of restricted environmental resource and the effects of plant morphology and biomass promotion or inhibition are different.