三江源区人工草地建植对土壤-微生物化学计量特征的影响OA

Soil-microbial biomass stoichiometric characteristics serve as a robust indicator of ecosystem nutrient cycling efficiency,yet the mechanisms by which different artificial grassland restoration modes influence these traits remain unclear.This study investigated 3-year-old artificial grasslands dominated by tall-grass species(SF),short-grass species(XF),and a mixed planting of tall-and short-grass species(SFXF)in the Three-River-Source Region,with severely degraded alpine grassland(CK)as the control.Soil organic carbon(SOC),total nitrogen(TN),total phosphorus(TP),microbial biomass carbon(MBC),nitrogen(MBN),and phosphorus(MBP)in the 0-10 cm layer were measured to analyze their stoichiometric ratios and microbial quotients.The impacts of different restoration modes on soil-microbial stoichiometric balance were further eluci-dated.The results demonstrated that all three artificial grassland establishment modes significantly enhanced SOC,MBN,and MBP contents.Specifically,the SF treatment increased soil TN,whereas the XF treatment reduced TN and decreased TP by 50.42%.MBN incresed by 24.36%and 35.59%under SF and XF treat-ments,respectively.The SFXF treatment decreased the microbial C-quotient by 78.40%,while the XF treat-ment elevated the microbial N-quotient by 49.61%,and the SFXF treatment reduced it by 11.33%.After res-toration,the stoichiometric imbalances in soil-microbial biomass(Cimb:Nimb,Cimb:Pimb,and Nimb:Pimb)increased across all treatments,with the most pronounced escalation observed in the SFXF treatment.Redun-dancy analysis(RDA)revealed that soil N:P and C:P ratios were key drivers of microbial quotient variations.In conclusion,the SFXF mixed planting exerted the most substantial influence on soil-microbial C-N-P cycling.For practical management,supplemental nitrogen fertilization is recommended to optimize plant growth and improve soil quality.