Testing the differentiation of relative root distributions among
species
To increase statistical power, the comparisons of relative root
distributions were focused on the 53 most common species with
occurrences ≥ 15 cubes. For a given species, we calculated the averaged
value of relative root abundance in each soil zone of that species and
tested whether soil zone significantly influenced the means of relative
root abundance using a one-way Welch’s ANOVA. Pairwise comparisons of
the means of relative root abundance among soil zones was performed
using the Games-Howell Post-Hoc Test. Finally, we categorized the 53
species into different groups based on their relative root distributions
using clustering analysis.