Effects Of Heavy Metal Stress On Growth Adaptation Among Different Functional Types Of Invasive And Native Plants

In recent years,with the intensification of human activities and the development of industrial,the problem of heavy metal pollution has become increasingly serious worldwide.Once heavy metal contaminated soil then absorbed into plants through their roots,it will interfere with the physiological activities and growth of plants.There are some serious harmful effects about invasive alien plants,such as inhibiting the growth of native species,reducing the diversity of native species,changing soil nutrient status,and destroying ecological balance.Invasive alien plants and global heavy metal pollution have become an ecological issue of increasing concern.In addition,clonal integration is a very important trait of invasive alien plants.There are some studies on the response of plants to heavy metal stress and the role of clonal integration of plants in heterogeneous heavy metal environments.However,studies on the response of different functional types of invasive and native plants which under heavy metal stress and the clonal integration of invasive and native clones under heavy metal stress are scarce.In this experiment,we based on 6 pairs of invasive and native species that are same family or genus and can coexist in their habitat,heavy metals Cd were applied in the first part of the experiment to investigate the response of invasive and native plants of different functional types(Forb,Grass,Legume)under heavy metal stress.In the second part of the experiment,heavy metal Cd and Pb were added in 2 pairs of invasive and native clonal plants to investigate the contribution of clonal integration in the response of invasive and native plants to heavy metal stress.The results of the study showed that:1.Heavy metal stress causes different degrees of biomass reduction in invasive and native plants,but invasive alien plants can accumulate higher biomass than native plants.2.For different functional types of plants,legumes had the highest tolerance to heavy metals,and there was no significant difference in total biomass of legumes under heavy metal stress,followed by forb,and grass were subjected to the greatest negative effect of heavy metal stress,Heavy metal stress led to significant reduction in biomass of both above and below ground parts of grass.3.When plant under the heterogeneous heavy metal stress,clonal plants can divide labor through clonal integration.The recipient plant under heavy metal stress will reduce root biomass and root to shoot ratio to alleviate heavy metal stress,then increase aboveground biomass to maintain all physiological functions,while the connected donor plant will increase below-ground root biomass and root to shoot ratio to absorb soil nutrients for the whole clonal fragment.4.Under heterogeneous heavy metal stress,invasive alien plants can benefit more from clonal integration than native plants.Compared to native plants,alien invasive recipient plants under heavy metal stress increased more biomass through clonal integration,while the negative effect on biomass of donor alien invasive plants was lower than that of native plants.5.The plant biomass was significantly inhibited under the separate treatments of Cd and Pb and the plant growth was further synergistically inhibited under the combined heavy metal stress.