Objective The effects of planting methods and the mycorrhizal types on absorptive root traits of tree species were analyzed to reveal the adaptive conditions for species coexistence.

MethodsIn this study, monoculture and mixture of 8 species (5 AM and 3 EM) were selected. The main morphological traits (root diameter, specific root length, root tissue density, individual root length) and architectural traits (root branching intensity, root branching ratio strength) and mycorrhizal colonization of absorptive roots (first two order roots) of two types of mycorrhizal tree species (AM vs EM) under two planting patterns (monoculture vs mixture) were analyzed.

ResultsMycorrhiza significantly affected morphological and architectural traits of absorptive roots (p<0.001), and significantly affected mycorrhizal colonization(p<0.05); while planting patterns only significantly affected root tissue density and root architectural traits (p<0.05); mycorrhizal types and planting patterns had no interaction on all root traits (p>0.05). The correlation between root traits of AM species was higher than that of EM species, and the mixture greatly reduced correlations between root traits of AM tree species. For AM species, the mixture reduced the plasticity of root morphological traits (except for specific root length) and increased the plasticity of architectural traits. For EM species, the mixture reduced the plasticity of root tissue density, and increased the plasticity of root diameter, architectural traits and mycorrhizal colonization.

Conclusion There are significant differences in root morphological and architectural traits between AM and EM species. Mixed forests mode has varying degrees of effects on the plasticity of root traits of AM and EM species, mainly increasing the branching intensity of AM species and decreasing the root tissue density of EM species. Therefore, different mycorrhizal species can achieve species coexistence by regulating different root trait changes.