Effects Of Resource Heterogeneity On The Growth And Competition Between Alien Invasive And Alien Non-invasive Or Native Clonal Plants

From the global perspective,except for the direct rupture of habitat,the invasive plants have relatively great impacts on local communities.At present,a lot of hypotheses explain the mechanism of biological invasion,but due to the differences of invasive species,habitats and ecological systems,a single hypothesis cannot fully explain the entire biological invasions.However,domesticly and internationally are mainly validations of a single hypothesis.This paper tried to combine propagule pressure hypothesis and fluctuating resource hypothesis together into two experiments,to study how the nitrogen deposition and competition influence the invasive plants as well as the native plants.The first experiment mainly investigated the differences between exotic invasive species and native species in the condition of nitrogen deposition.The second experiment focused on the effects of nutrient variability and propagule pressure on exotic invasive and non-invasive clones on local communities.We researched the effects of resource heterogeneity on the growth and competition of foreign invasions with exotic invasive and non-invasive clones,through a multispecies greenhouse experiment.The main results are as follows:(1)In the case of nitrogen subsidence,foreign species and native species have different responses to the type of competition at the individual level.In individual experiments,exotic invasive species showed better growth performances than local ones.The subsidence of nitrogen can promote the growth of plants,and the increase in nitrogen deposition is more conducive to the growth of exotic invasive species.Under the conditions of increased nitrogen deposition,the exotic invasions have better growth ability than the local species,regardless of the type of competition.The main effects of inter-species competition and intra-species competition are the growth of the plant's stem.In the case of stem biomass,exotic invasive species are more competitive,and the local varieties are more competitive.(2)In group level experiments,exotic invasive species showed better growth performance than non-invasive species and native species.Exotic invasive species has better growth ability than exotic non-invasion under high propagule pressure due to the growth of the exotic invasive species of performance is better than exotic non-invasive species.Therefore,with the lower survival rate,the exotic invasive species growth still relatively large.Nutrients heterogeneity can affect the growth of the underground part of plant,the underground part of the invasive species in multimodal keep environment than its in homogeneous environment to grow better.(3)Nutrient changes may not lead exotic invasive species have better growth performance compared to native species,but they can reduce the uniformity of local communities.Under the global changes,due to the invasive species can better adapt to the heterogeneity of resources,the invasion of alien invasive species can success rather than non-invasive species.(4)The heterogeneity of nutrients under the background of global changes can promote biological invasions as well as have a positive effect of reproductive pressure on biological invasions.The greater the pressures are,the greater the influences on exotic invasions in the nutrient heterogeneity environment.Therefore,it is possible to infer that the environment of high propagule pressure under global nutrient changes is more conducive to invasive plant invasion.