Sapwood, heartwood and bark thickness of silviculturally treated Eucalyptus grandis

Summary

The effects of a number of silvicultural treatments on the quantity of heartwood, sapwood and bark of 9.5 year old plantation grown Eucalyptus grandis were examined at three heights (butt 10–25 cm, 25% and 50% of total tree height). Treatments were: control (C); pre-ploughing & thinning (P); insecticide & P (I); weeding & P (W); fertilizer & P (F); and fertilizer, weeding, insecticide & P (A). Compared to controls, all silvicultural treatments produced wider sapwood (up to 134% in W at the 25% height), a greater area of sapwood (up to 160% in A at all heights), a greater area of heartwood (up to 315% in A at the butt height) a greater area of bark (up to 171% in W at the 25% height), a higher proportion of heartwood (up to 131% in A at the butt height) and increased rates of growth (up to 237% in A at the butt height). The percentage of bark was lower in treatment A. Increases in heartwood area in treatments I, F, W and A were proportionally greater at the butt height. Sapwood width and area decreased above butt height. Overall, the percentage of sapwood was correlated negatively with rate of growth and positively with height in the stem.