LAUSR

AimsA dominant species of steppe in northern China, Stipa grandis, is gradually being replaced by S. krylovii due to climate change events. The aim of this study was to explore how conditioned soil, nitrogen (N) resource, and competitor influenced the responses of S. grandis and S. krylovii.MethodWe planted S. grandis and S. krylovii monoculture and mixture in each of four conditioned soils with two N treatments and analyzed which factor(s) significantly influenced the plant–soil feedbacks (PSFs), competitiveness, and N-addition effects of each species by general linear model univariate analysis.ResultsCompetitor but not nitrogen significantly influenced PSFs of both S. grandis and S. krylovii. Compared with PSFs in monoculture, the negative PSFs of S. grandis were suppressed and PSFs of S. krylovii shifted from positive to negative in mixture. Competitor only significantly influenced the N-addition effects on S. krylovii; nitrogen only significantly influenced the competitiveness of S. krylovii. The highest competitiveness of S. krylovii was obtained in S. grandis conditioning soil with high N treatment.ConclusionCompared with any of the other growth conditions, soil conditioned by S. grandis with high N treatment could increase S. krylovii’s competition superiority by increasing its competitiveness and N-addition effect.