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Tree diversity effect on fine root biomass: overyielding via density dependence rather than spatial root partitioning
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  • Weixian Zeng,
  • Wenhua Xiang,
  • Bo Zhou,
  • Shuai Ouyang,
  • Yelin Zeng,
  • Liang Chen,
  • Grégoire Freschet,
  • Oscar J Valverde-Barrantes,
  • Alexandru Milcu
Weixian Zeng
Central South University of Forestry and Technology
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Wenhua Xiang
Central South University of Forestry and Technology
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Bo Zhou
Central South University of Forestry and Technology
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Shuai Ouyang
Faculty of Life Science and Technology, Central South University of Forestry and Technology
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Yelin Zeng
Central South University of Forestry and Technology
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Liang Chen
Central South University of Forestry and Technology
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Grégoire Freschet
CNRS, Centre d’Ecologie Fonctionnelle et Evolutive
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Oscar J Valverde-Barrantes
Florida International University
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Alexandru Milcu
CNRS
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Abstract

Complementarity in resource use leading to increased resource partitioning is the most commonly proposed mechanism for explaining the positive relationship between plant diversity and productivity. However, we still have a poor understanding of the relationship between plant diversity and root biomass. We test whether the hypotheses of spatial resource partitioning and symmetric proliferation are responsible for the phenomena that aboveground tree species richness (SRA) increases fine root (≤ 2 mm in diameter) biomass. We found that increasing SRA led to higher belowground biomass and a support for symmetric root proliferation strategies, but this pattern only appeared in the more nutrient-rich upper soil layer. Fine root biomass depended on the SRA × tree density interaction, with lower biomass at lower density and low richness, and this effect disappeared in mixtures with high density. The results indicate that density-dependent biotic interactions affecting tree recruitment are an important driver to influence productivity.