Characterizing fine-root traits by species phylogeny and microbial symbiosis in 11 co-existing woody species
Understanding the differences in fine-root traits among different species is essential to gain a detailed understanding of resource conservation and acquisition strategies of plants. We aimed to explore whether certain root traits are consistent among subsets of species and characterize species together into meaningful community groups. We selected 11 woody species from different microbial symbiotic groups (ectomycorrhiza, arbuscular mycorrhiza, and rhizobia) and phylogenetic groups (broad-leaved angiosperms and coniferous gymnosperms) from the cool temperate forests of Nagano, Japan. We measured root architectural (branching intensity), morphological (root tissue density and specific root length), chemical (N and K concentrations), and anatomical (total stele and total cortex) traits. Significant differences were observed in all root traits, although many species did not differ from one another. Branching intensity was found to be the greatest variation in the measured root traits across the 11 woody species. The results of a principal component analysis of root traits showed a distinct separation between angiosperms and gymnosperms. We identified clusters of species based on their multidimensional root traits that were consistent with the different phylogenetic microbial association groups. Gymnosperm roots may be more resource conservative, while angiosperm roots may be more acquisitive for water and nutrients. We consider that the advances in root traits combination will make a breakthrough in our ability to differentiate the community groups rather than individual root trait.
KeywordsMycorrhiza Root anatomy Economic spectrum Root morphology Taxonomy
The authors acknowledged Ms. H Umezu, Ms. K Nakazawa, Ms. J Wang, Dr. H Kobayashi, Dr. T Kunito and Dr. H Park of Shinshu University for helpful support in field and laboratory experiments. We also thank two reviewers for their constructive comments and suggestions for the manuscript.
Author contribution statement
HY and NM conceived and designed the experiments. HY, NT, MO and NM performed the experiments and analyzed the data. HY and NM wrote the manuscript and other authors provided editorial advice.
This study was partially funded by Grant-in Aid for Japan Society for the Promotion of Science fellows (15K18719, 18K14488) and by the Fujiwara Natural History Foundation.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
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