Variation in the functional traits of fine roots is linked to phylogenetics in the common tree species of Chinese subtropical forests
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The phylogenetic variations of fine root traits, which are related to plant growth and development as well as to physiological and ecological processes, are not fully understood. This study aimed to: (1) examine how tree species and sampling methodology affect the anatomical, morphological and nutrient traits of fine roots; and (2) determine whether phylogenetic signals affect fine root trait relationships and influence comparison of root traits between the branch order-based and diameter-based cut-off sampling categories.
Fine root samples of 16 subtropical forest tree species were obtained and their anatomical, morphological and nutrient traits were studied. The phylogenetic signals of trait variations were calculated to determine trait relationships.
Tree species and sampling methodology significantly affected fine root traits (p < 0.05). Mean root diameters, root tissue density (RTD) and carbon-to-nitrogen ratio were the lowest in the first-order category and highest in the ≤2 mm category. The reverse pattern was found for specific root length, specific root area and nitrogen concentration. Morphological traits showed significant phylogenetic signals; however, nutrient traits did not reflect phylogenetic conservatism. Phylogenetic factors influenced correlations between traits for the first-order root economics spectrum. Root traits were multidimensional and RTD was loaded on a novel phylogenetic principal component analysis.
Functional traits of fine roots are multidimensional for subtropical tree species and closely linked to phylogeny. Morphological traits of first order roots showed a much stronger phylogenetic signal than those of roots ≤2 mm (traditionally defined fine roots). The findings improve understanding of root trait strategies in response to environmental changes.
KeywordsFine root order Morphology Anatomy Root nitrogen C/N ratio Phylogeny
This study was funded by the National Natural Science Foundation of China (31570447 and 31870431) and the Huitong Forest Ecological Station funded by the State Forestry Administration of the People’s Republic of China. Cong Liu would like to acknowledge the China Scholarship Council for supporting her joint Ph.D. program grant (201708430137).
Idea and study design: WX; data collection and analysis: CL, LZ, PL, YZ and ZL, with support from SO, XD, and XF; manuscript writing: CL, WX and CP.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
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