The effects of changing sedimentation disturbance on the invasiveness of alternanthera philoxeroides are trait dependent

Abstract

Tolerance and resistance to environmental stresses determine the invasion success of alien plants under disturbed conditions. Colonization time and environmental heterogeneity have been thought to contribute to the invasiveness of alien plants. However, few previous studies have synthesized disturbance, environmental heterogeneity and colonization time in the exploration of the invasion mechanisms of invasive clonal plants. In the present study, the performance of the invasive clonal wetland plant Alternanthera philoxeroides was compared under undisturbed (UD), homogeneous burial (HoD) and temporal heterogeneous burial (HeD) conditions at the early and late phases of colonization. Using functional traits including biomass allocation and plant physiology as indicators of invasive performance, we found that in the early phase A. philoxeroides showed phenotypic maintenance in stolon mass ratio (SMR), root mass ratio (RMR), root-shoot ratio and non-structural carbohydrate content of stolon (NSCCstolon) after either HoD or HeD; leaf mass ratio (LMR), specific leaf area (SLA), the maximal fluorescence (Fv/Fm), nitrogen content per leaf mass (Nmass) and leaf carbon/nitrogen (C/N) ratio after HoD; chlorophyll content (Cht) and leaf construction cost per leaf area (CCarea) after HeD. We found that CCarea varied HoD while LMR, SLA, Fv/Fm, Nmass and C/N ratio varied after HeD in the early phase. In the late phase, A. philoxeroides showed phenotypic maintenance in LMR, SMR, RMR, root-shoot ratio and Fv/Fm after either HoD or HeD; Cht and NSSCstolon after HoD. Moreover, we found that SLA, Nmass, C/N ratio and CCarea varied after either HoD or HeD while Cht and NSSCstolon after HeD in the late phase. Both tolerance (phenotypic maintenance) and resistance (phenotypic variation) to the burial disturbance are trait dependent and facilitate the invasion of A. philoxeroides. In addition, the heterogeneity of the disturbance exerted facilitative or insignificant impacts on its invasive performance. These mechanisms may explain the broad invasion of A. philoxeroides into diverse habitats.