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Species identities impact the responses of intensity and importance of competition to the change of soil nutrition condition
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  • Nianxi Zhao,
  • Yujuan Xu,
  • Liping Chen,
  • Man Jiang,
  • Ke Dong,
  • Jinlong Wang,
  • Yubao Gao
Nianxi Zhao
Nankai University College of Life Sciences
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Yujuan Xu
Nankai University College of Life Sciences
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Liping Chen
Nankai University College of Life Sciences
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Man Jiang
Nankai University College of Life Sciences
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Ke Dong
Nankai University College of Life Sciences
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Jinlong Wang
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Yubao Gao
Nankai University College of Life Sciences
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Abstract

Aims How plant-plant interactions vary with the changes of biotic and abiotic factors has debated for a long time among ecologists. The aim of this study was to explore how different neighbors influenced the responses of the intensity and importance of competition on Stipa grandis and S. krylovii to the change of soil nutrition condition. Methods The seedlings of the target species, S. grandis and S. krylovii, were grow alone and in two-species mixtures with different neighbors under two soil nutrition treatments. For each target species, we measured the biomass, root: shoot ratio, intensity and importance of competition and nutrition-addition effect. Important Findings We founded that the competition responses were mediated by the identities of neighbors and target species. (1) When in mixture with Leymus chinensis, both intensity and importance of competition negatively increased with the increase of soil nutrition. The competition importance was significantly negative on S. grandis under both soil nutrition treatments and on S. krylovii under the high soil nutrition treatment, supporting Grime’s theory. (2) When in S. grandisS. krylovii mixture system, the competition inhibition decreased while competition importance showed no significant effects on both target species with the increase of soil nutrition, indicating competitive reduction. (3) When in mixture with Agropyron cristatum, the competition intensity significantly influenced by the interaction between target species and soil nutrition, suggesting competitive change along the soil nutrition gradient. The competition importance was significantly negative on S. grandis under the low soil nutrition treatment and on S. krylovii under the high soil nutrition treatment. Ultimately, our results demonstrate that the identities of both target and neighbor species influenced the responses of intensity and importance of competition to the change of soil nutrition condition. Several mechanisms potentially contributed to these different competition effects on different target species.