Effects Of Habitat Heterogeneity On Growth And Competition Of Aquatic Clonal Plants

The essential resources for plant growth(such as nutrition and water)and the environmental conditions(such as terrain)are usually heterogeneously distributed.Plants often have strategies with adaptive growth and reproduction to cope with resource heterogeneity.Resource heterogeneity can affect the competition relationship among plants,and then affect the structure of populations and communities.Most of aquatic plants are clonal plants.Currently,the adaptive growth strategies of emergent clonal plants to the resources heterogeneity are not clear.Habitat heterogeneity may affect the growth and intraspecific competition of the invasive clonal plants with different propagule.Therefore,this study focused on the effects of heterogeneous habitat conditions on growth traits and competition among species of aquatic clonal plants(including exotic species).Our results will further analyze the mechanism of habitat heterogeneity effect on the clonal growth of native aquatic plants and invasive aquatic plants,and provide a theoretical basis for the ecological restoration of native species and the control of invasive species.1.The first part of this paper focused on the effects of habitat heterogeneity(resource heterogeneity and environmental heterogeneity)on the reproduction,growth,competitive relationship and invasive ability of different alien aquatic plants.Results of the third chapter showed that soil heterogeneity neither enhanced the growth performance of Alternanthera philoxeroides,nor increase the intraspecific competition intensity of A.philoxeroides.Results of the fourth chapter revealed that soil heterogeneity increased the number and length of branch in Myriophyllum aquaticum.Results of the fifth chapter showed that clonal integration could help Eichhornia crassipes to relieve stress from stressful habitats and enhance the growth performance of E.crassipes,which promote its colonization from aquatic habitats to terrestrial habitats and improve its invasion ability.2.The second part of this paper focused on the effects of resource heterogeneity(soil nutrition heterogeneity and water heterogeneity)on the growth,reproduction and competition relationship of native clonal plants.Results of the sixth chapter found that there was no significant difference in growth traits of Acorus calamus and Phragmites australis between two soil substrates.The biomass of Typha angustifolia(discrete-type clonal plant)significantly increased in heterogeneous soil substrate,whereas more biomass of Schoenoplectus tabernaemontani(polyaxial-type clonal plant)was accumulated in homogeneous soil substrate.The four plants showed different plasticity responses to soil heterogeneity,which may be related to their characteristics and clonal structure.Results of the seventh chapter showed that with the rise of water level,A.calamus and S.tabernaemontani increased their investment on the aboveground part(such as aboveground biomass and plant height),and reduced the traits of clonal growth(such as ramet number and the length of rhizomes).Their interspecific competition also decreased with the rise of water level.Results of the eighth chapter revealed that the soil substrate treatment significantly influenced the biomass and intraspecific competition of Bolboschoenus yagara.However,water heterogeneity had little impact on intraspecific competition,suggesting that B.yagara was more sensitive to soil heterogeneity than water heterogeneity.Plants respond differently to environmental heterogeneity with respect to the supply of two co variable resources at different plant densities.The results of this part suggested that differences in species characteristics and clone structure affected their plastic responses of different clones to soil nutrient heterogeneity.A trade-off strategy between vertical growth and horizontal clonal growth was presented in phalanx-type clonal plants under high water level.The temporal and spatial heterogeneity of soil nutrition and water supply was closely related to the growth and competition relationship of B.yagara and its population density.In summary,the reproductive mode,species characteristics,clonal growth structure and population density determine the growth performance and competitive relationship of aquatic clonal plants in heterogeneous habitats.