Variation in the morphology of fine roots in Cryptomeria japonica determined by branch order-based classification
2019
Wada, Ryusei | Tanikawa, Toko | Doi, Ryuusei | Hirano, Yasuhiro
AIMS: This study assessed intraspecific variation in morphological traits of the fine root branch orders of Cryptomeria japonica, and identified variation in the diameter of the first three-order roots among species types with mycorrhiza, and the diameter of first-order roots at the family level. METHODS: Diameter, length, and specific root length of branch order roots (up to the fourth-order) were measured in intact fine root systems collected in four C. japonica stands. Relationships between soil chemical properties and morphological traits of the first- to fourth-order roots were investigated. The diameter of roots of 52 tree species reported in previous studies was compared at species types with mycorrhiza and at family level. RESULTS: The diameter of first-order roots in C. japonica varied by 1.2 times among stands. Negative correlations between soil NH₄⁺ content and specific root length of the second- and third-order roots were observed in C. japonica. The diameter of first- and second-order roots forming arbuscular mycorrhiza in coniferous trees were significantly higher than those of roots forming ectomycorrhiza in coniferous and broadleaf trees. The diameter of first-order roots in Cupressaceae were significantly larger than those of Pinaceae, Sapindaceae, Betulaceae, and Fagaceae. CONCLUSIONS: Clarifying intraspecific variation in morphological traits of C. japonica lower-order roots may contribute to understanding their responses to different site conditions such as soil inorganic nitrogen contents.
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