作者：Jiqiong Zhou, Jinchao Gong, Shan Liu, Adam B. Cobb, Gaowen Yang, Xiangjun Li, Feida Sun, Yan Peng, Yanhong Yan, Lin Liu*,
Aims: Mixed communities of plant species with different functional traits or microbial associations canmore fully utilize soil nutrient pools. However, thereis a gap in our understanding of the synergistic influences of arbuscular mycorrhizal (AM) fungi in nutrient capture and resource partitioning across differentsoil depths in mixed plant communities, as well astheir possible effects on plant coexistence. To addressthese knowledge gaps, we assessed the effect of AMfungi on nutrient uptake and competition betweenshallow- and deep-rooted pairs of grass and legumespecies.
Methods: To quantify the mycorrhizal mediationof N uptake at different soil depths,15N tracer wasinjected into soil at 3- and 25-cm depths of microcosms planted with monoculture or bi-species mixtures, with or without AM fungi.
Results: AM symbioses reduced plant competitionby equalizing access to N and subsequently increasing shoot N and P concentrations of plant species onmixed communities. Niche differentiation had minimal effects on grass and legume competitive interactions. Both deep-rooted plant species, i.e., Medicagosativa and Dactylis glomerata, and shallow-rootedspecies, i.e., Lolium perenne and Trifolium repens,primarily acquired nutrients from shallow soil layers.However, AM fungi significantly enhanced nutrientuptake and facilitated N2fixation in legumes at 3 and25 cm soil depths.
Conclusion: Our results suggest AM fungi stronglyinfluence host-plant competitiveness and verticalnutrient capture in mixed plant communities, underscoring that microbial mutualist-mediated nutrient acquisition is a key driver of gains in productivity ofgrass–legume mixtures.
Arbuscular mycorrhizal (AM) fungi, Competitive balance, Grass–legume mixtures,15Ntracer, Vertical nutrient capture