Traits of an invasive grass conferring an early growth advantage over native grasses  

作　　者：Lara G.Reichmann Susanne Schwinning H.Wayne Polley Philip A.Fay 

机构地区：[1]Department of Integrative Biology,University of Texas at Austin,Austin,TX 78712,USA [2]USDA-ARS Grassland,Soil and Water Research Laboratory,808 E Blackland Road,Temple,TX 76502,USA [3]Department of Biology,Texas State University,San Marcos,TX 78666,USA

出　　处：《Journal of Plant Ecology》2016年第6期672-681,共10页植物生态学报（英文版）

基　　金：funded by USDA-NIFA(2010-65615-20632).

摘　　要：Aims Invasive species often have higher relative growth rates(RGR)than their native counterparts.Nutrient use efficiency,total leaf area and specific leaf area(SLA)are traits that may confer RGR differences between natives and invasives,but trait differences are less prominent when the invasive species belongs to the same plant functional type as the dominant native species.Here,we test if traits displayed soon after germination confer an early size advantage.Specifically,we predicted that invasive species seedlings grow faster than the natives because they lack trade-offs that more strongly constrain the growth of native species.Methods We quantified plant morphological and physiological traits and RGR during early seedling growth at high and low nutrient levels in three dominant perennial native C_(4) grasses:Panicum virgatum L.(switchgrass),Schizachyrium scoparium(Michx.)Nash(little bluestem)and Andropogon gerardii Vitman(big bluestem);and a perennial C_(4) exotic invasive grass,Sorghum halepense(L.)Pers.(Johnsongrass).Important Findings After 2 weeks of growth,Johnsongrass seedlings had greater biomass,SLA and photosynthetic nitrogen use efficiency,but lower leaf N concentrations(%leaf N)and root:shoot ratio than natives.As growth continued,Johnsongrass more quickly produced larger and thicker leaves than the natives,which dampened the growth advantage past the first 2 to 3 weeks of growth.Investment in carbon gain appears to be the best explanation for the early growth advantage of Johnsongrass.In natives,growth was constrained by an apparent trade-off between allocation to root biomass,which reduced SLA,and production of leaves with high N content,which increased carbon gain.In Johnsongrass,root:shoot ratio did not interact with other traits,and%leaf N was decoupled from RGR as a result of a trade-off between the positive indirect association of%leaf N with RGR and the negative direct association of%leaf N with RGR.

关 键 词：biomass allocation invasive plants RGR Sorghum halepense trade-offs trait development 

分 类 号：Q94[生物学—植物学]