模拟氮沉降下少花蒺藜草生物量分配及其异速生长的变化OA

Cenchrus pauciflorus is an invasive alien plant that severely threatens both ecological security and economic development in the agro-pastoral ecotone of northern China.In recent years,increasing atmospheric nitrogen(N)deposition has exerted increasingly pronounced effects on the growth and spread of invasive plants.In this study,N deposition was simulated using a 1∶1 mixture of KNO3 and NH4Cl(M/M)at five levels:0,5,20,40,and 120 kg/(hm2·a).The effects of N deposition on phenotypic traits,biomass allocation,and allometric growth of C.pauciflorus were analyzed.The results demonstrate that with increasing N deposition,plant height,leaf width,basal stem diameter,node number,root biomass,and leaf biomass tended to increase.Leaf length,leaf number,stem biomass,and fruit biomass initially increased and then decreased,peaking at 40 kg/(hm2·a),while leaf thickness and spike number peaked at 20 kg N/(hm2·a).The allocation of fruit biomass decreased with increasing deposition,whereas the bio-mass allocation patterns of roots,stems,and leaves differed.Except for the 40 kg/(hm2·a)treatment,where fruit biomass and total biomass exhibited isometric growth,all other treatments showed allometric growth with an exponent greater than 1.In conclusion,with increasing N deposition,C.pauciflorus shifts its resource allocation from reproduction to vegetative growth,and dynamically adjusts the allocation pat-terns of roots,stems,and leaves according to N levels,thereby enhancing its resource acquisition and com-petitive capacity and promoting population expansion.Moreover,the allometric relationship between fruit and total biomass(a>1)indicates that larger individuals contribute disproportionately to reproduction,thus achieving efficient reproductive resource allocation during rapid population expansion.Therefore,these resource allocation strategies form an important ecological basis for the successful invasion of C.pauciflo-rus under N deposition,and the findings provide scientific support for ecological risk assessment and tar-geted prevention and control of this species under regional N deposition levels.