Molinia caerulea alters forest Quercus petraea seedling growth through reduced mycorrhization

Marine Fernandez (1) , Philippe Malagoli (1) , Lucie Vincenot (2) , Antoine Vernay (3) , Thierry Ameglio (1) , Philippe Balandier (1)

1 PIAF - Laboratoire de Physique et Physiologie Intégratives de l’Arbre en environnement Fluctuant
2 ECODIV - Etude et Compréhension de la biodiversité
3 EVZH - Équipe 2 - Écologie Végétale et Zones Humides

Oak regeneration is jeopardized by purple moor grass, a well-known competitive perennial grass in the temperate forests of Western Europe. Below-ground interactions regarding resource acquisition and interference have been demonstrated and have led to new questions about the negative impact of purple moor grass on ectomycorrhizal colonization. The objective was to examine the effects of moor grass on root system size and ectomycorrhization rate of oak seedlings as well as consequences on nitrogen (N) content in oak and soil. Oak seedlings and moor grass tufts were planted together or separately in pots under semi-controlled conditions (irrigated and natural light) and harvested 1 year after planting. Biomass, N content in shoot and root in oak and moor grass as well as number of lateral roots and ectomycorrhizal rate in oak were measured. Biomass in both oak shoot and root was reduced when planting with moor grass. Concurrently, oak lateral roots number and ectomycorrhization rate decreased, along with a reduction in N content in mixed-grown oak. An interference mechanism of moor grass is affecting oak seedlings performance through reduction in oak lateral roots number and its ectomycorrhization, observed in conjunction with a lower growth and N content in oak. By altering both oak roots and mycorrhizas, moor grass appears to be a species with a high allelopathic potential. More broadly, these results show the complexity of interspecific interactions that involve various ecological processes involving the soil microbial community and need to be explored in situ.

Mots clés: Ectomycorrhization rate; Fungal symbionts; Interaction; Lateral root; Pot experiment

Domaines: Botanique; Interactions entre organismes; Sylviculture, foresterie

Marine Fernandez, Philippe Malagoli, Lucie Vincenot, Antoine Vernay, Thierry Ameglio, et al.. Molinia caerulea alters forest Quercus petraea seedling growth through reduced mycorrhization. AoB Plants, 2023, 15 (2), plac043. ⟨10.1093/aobpla/plac043⟩. ⟨hal-03977500⟩