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Table 1 Testing interspecific vertical root segregation either based on root-placement patterns (MPDplacements) throughout the 0-30 cm soil zone or relative root abundance (MPDabundance) in the 0-10 (P1), 10-20 (P2) and 20-30 cm (P3) soil zones using three different parameters. The similarity in relative root abundance of co-occurring species was evaluated with mean pairwise distances (MPD), standard deviation (SD) and variance (Variance) of species relative root abundance. Values indicate the proportions of root neighbourhoods with root segregation (Sepa.), significant segregation (Sig-S.), aggregation (Aggr.) and significant aggregation (Sig-A.). The mean of the standardized effect size of the corresponding parameter was compared with the null expectation of zero to examine whether it was significantly differed from zero across the entire study site.