Fig. 5

Relationships between root functional traits (average root system diameter, RS Diameter, specific root length, SRL, root tissue density, RTD, and root branching intensity, RBI) ) and soil variables (base saturation, soil BS, and total phosphorus, soil total P). Points show average individual trait values for 3–5 root systems (y-axis) and soil percent base saturation and phosphorus content of 1 kg of soil collected from where root systems were excavated (x-axis) for 300 individuals of 50 species (see Table 6 in the Appendix). Lines represent ordinary least-squares regression, with 95% confidence intervals (shading) in the form of trait ~ soil variable. Models were fit separately by forest type (see Table 3). Asterisks show statistically significant regression slopes (α = 0.05)