Table II. Root diameter, SRA, and RTD of the species A. platanoides, C. betulus, Q. robur, and T. cordata arranged by root order classes ≥3, 1 + 2 brown, and 1 + 2 white.

Different small letters indicate significant differences of parameters between root order classes and within species, and different capital letters indicate significant difference of parameters between species within the same root order class (mean ± se, n = 5–18; Tukey-Kramer test, P < 0.05).

Root Order Class	Root Diameter				SRA				RTD
	Acer sp.	Carpinus sp.	Quercus sp.	Tilia sp.	Acer sp.	Carpinus sp.	Quercus sp.	Tilia sp.	Acer sp.	Carpinus sp.	Quercus sp.	Tilia sp.
	mm				cm2 g−1				g cm−3
Root order ≥ 3	2.60 ± 0.16 aA	2.36 ± 0.20 aA	2.40 ± 0.13 aA	2.66 ± 0.10 aA	44 ± 4 cA	38 ± 4 bA	40 ± 2 bA	45 ± 2 bA	0.40 ± 0.02 aBC	0.47 ± 0.02 aA	0.44 ± 0.02 aAB	0.35 ± 0.02 aC
Root order 1 + 2, brown	0.42 ± 0.02 bA	0.38 ± 0.02 bAB	0.39 ± 0.02 cAB	0.32 ± 0.01 cB	712 ± 114 bA	665 ± 45 aA	441 ± 29 aB	667 ± 60 aA	0.13 ± 0.01 bB	0.18 ± 0.01 bAB	0.25 ± 0.01 bA	0.25 ± 0.04 bA
Root order 1 + 2, white	0.59 ± 0.02 bC	0.67 ± 0.04 bBC	1.30 ± 0.16 bA	0.81 ± 0.06 bB	877 ± 61 aA	654 ± 46 aA	540 ± 162 aA	750 ± 122 aA	0.08 ± 0.00 cA	0.09 ± 0.00 cA	0.08 ± 0.01 cA	0.08 ± 0.01 cA