Research On The Expansion Strategies Of Praxelis Clematidea Under The Stimulated Greenhouse,Nitrogen Deposition And Both Conditions

Global climate change,including climate warming and nitrogen deposition,has been changing the ecological environment that human beings survived on,which caused increasing attentions and researches.The change of environment may have influtence on the interspecific competition of plants,and affect the invasive process and results of exotic species into a new habitat.The interactions between plant invasion and global change factors have become a hot issue in Global Ecology.As two most important limiting factors on plant growth,temperature and nitrogen are closely related to the plasticity of the invasive plants.So the researches on the relationship between the climate change and exotic invasive plants growth are helpful to fulfill the climate change disturbance theory and provide reliable basis for analyzing the growth and invasiveness of invasive plants under the background of global warming and N deposition.This article chose Praxelis clematidea and Lagedium sibiricum as objectives and separately conducted three experiments by using simulated warming treatment,N addition treatment,and warming plus N addition treatment to discuss the impact of warming and N decomposition on Praxelis clematidea,the interspecific competition between the Praxelis clematidea and Lagedium sibiricum.The main results were as follows:1.The increasing of temperature had influence on the growth and morphological features of Praxelis clematidea.Different warming models had various influence on the growth of plant.The response of Praxelis clematidea to warming from strong to weak was day warming,night warming,daily warming.Such three warming models had promotion on the aboveground growth of Praxelis clematidea,but went against the growth of it's root.2.The increasing of N,even under low content,significantly increased the stem height and root length of Praxelis clematidea.More specifically,N addition let Praxelis clematidea had a greater leaf dry mass,leaf area,and number of blades.The ability of positive response to N can enhance the competitiveness of Praxelis clematidea against other original plants to some extent.3.Praxelis clematidea showed strong response of plasticity in the treatment of warming plus N addition treatment.Stem height and root length were significant higher in warming plus N addition treatment than those in warming treatment.On the contrary,leaf number and leaf area were lower in warming plus N treatment than those in warming or N addition treatment.Those characteristics demonstrated that the warming and N addition treatment of Praxelis clematidea showed different complementary and antagonistic action on different life history traits,thus affecting its morphological characteristics.4.The stem height of Praxelis clematidea become higher anlong with the higher density of Praxelis clematidea with Lagedium sibiricum plant.Because of different densities of mixture sowing and proportion of Praxelis clematidea and Lagedium sibiricum,the biomass,height,relative yield and total relative yield were significantly different.