Buried charcoal layer and ectomycorrhizae cooperatively promote the growth of Larix gmelinii seedlings

Charcoal produced by fire on the soil surface mixes into the soil over time and is heterogeneously distributed within the soil profile in post-fire forests. To determine how different patterns of vertical distribution of charcoal and ectomycorrhizal formation affect the growth of Larix gmelinii (Gmelin larch) in post-fire forests, we conducted a model experiment in the pots. In this study, pots with a layer of charcoal in the middle of the soil profile promoted growth of the root system of the seedlings significantly more than did pots with no charcoal or with charcoal scattered throughout the soil. Along with the development of the root system, above-ground biomass and total biomass were also increased. Furthermore, in addition to the positive effects of charcoal in the soil, there were also strong positive effects on the growth of seedlings from ectomycorrhizal root formation. As a result, the largest above-ground biomass and total biomass were found for seedlings grown in layered charcoal with ectomycorrhizae. Furthermore, the highest phosphorus concentration in needles was also found for seedlings grown in layered charcoal with ectomycorrhizae. This is attributable to the frequent contact of roots with charcoal in the middle layer of the soil and the utilisation of phosphate by ectomycorrhizae. This suggests that buried and layered charcoal occurring in patches in post-fire stands may provide a suitable habitat for the growth of Gmelin larch seedlings.