放牧对大针茅草原优势植物叶片生态化学计量特征的影响OA

Understanding how grazing affects leaf carbon(C),nitrogen(N),and phosphorus(P)concen-trations and their stoichiometric relationships is important for elucidating nutrient cycling in grassland eco-systems.This study examined two dominant species,Stipa grandis and Cleistogenes squarrosa,in a S.grandis steppe under free grazing at 1.66 sheep/(hm2·a),with enclosure as the control,to evaluate grazing effects on leaf ecological stoichiometry and identify the main drivers.Compared with enclosure,free graz-ing significantly increased leaf N and P concentrations in S.grandis from 0.93％and 0.05％to 1.20％and 0.06％,respectively,decreased C/N from 43.31 to 36.53,and increased N/P from 19.72 to 21.87(P<0.05).In C.squarrosa,free grazing significantly increased leaf C,N,and P concentrations from 38.72％,0.99％,and 0.05％to 42.00％,1.19％,and 0.06％,respectively,and decreased C/N from 39.90 to 35.99(P<0.05),while N/P did not differ significantly between treatments.Redundancy analy-sis(RDA)showed that leaf ecological stoichiometry of S.grandis was mainly associated with soil nitrate nitrogen under free grazing,whereas that of C.squarrosa was mainly associated with plant community rich-ness under enclosure.Overall,free grazing significantly altered the leaf ecological stoichiometry of domi-nant species in the S.grandis steppe by changing soil nutrient conditions and community characteristics.