. Author manuscript; available in PMC: 2011 Oct 24.

Published in final edited form as: Tree Physiol. 2011 Jan;31(1):59–67. doi: 10.1093/treephys/tpq099

Table 1.

Anatomical and UE characteristics of wood splits.

	Category I	Category II	Category III	Category IV
Lumen area (μm²)	547.2 ± 2 7 .0^c	386.5 ± 38.3^b	213.5 ± 1 7 .7^a	213.4 ± 7. 9^a
Lumen diameter radial (μm)	29.3 ± 0.7^c	22.4 ± 1.8^b	15.4 ± 0.5^a	17.8 ± 0.4^a
Lumen diameter tangential (μm)	23.6 ± 0.7^c	20.5 ± 0.9^b	15.7 ± 0.7^a	15.3 ± 0.4^a
Tracheids per cross-sectional area (number/mm²)	1011.4 ± 35.2^a	1295.1 ± 83.8^b	1626.1 ± 85.8^c	2016.0 ± 51.4^d
Wood density (g/cm³)	0.31 ± 0.01^a	0.39 ± 0.03^a	0.51 ± 0.03^b	0.35 ± 0.01^a
UE Energy (aJ)	138.0 ± 16.4^b	111.8 ± 14.6^b	25.4 ± 3.9^a	30.0 ± 3.2^a
Cumulative number of UE (10⁻³)	12.4 ± 1.6^a	16.6 ± 1.3^a	24.9 ± 1.7^b	31.6 ± 1.7^b
N	10	10	8	10

Split samples consisted of mature wood with quite uniform lumen diameters (Category I), of wood from the earlywood–latewood transition zone or of mature earlywood with 30–50% latewood from the previous annual ring (Category II), of mature wood with >50% latewood from the previous or the same annual ring (Category III) and of juvenile earlywood with quite uniform tracheid diameters (Category IV). Different letters indicate signifcant differences in the mean values.