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Background: Resin pockets and blemishes in pruned logs of radiata pine (Pinus radiata D.Don) can reduce the value of clear and moulding grades of lumber. External resin features (ERF) on the bark of the logs have proved an effective method of predicting the incidence of resin pockets in the lumber. Resin canals have been associated with resin blemishes in radiata pine, and could prove useful in improving the prediction of the grade recovery of lumber. Methods: Pruned butt logs of radiata pine trees from two forests in the North Island, New Zealand, were selected for low, moderate, and severe levels of external resin features (ERF) on the bark, and for low, average, and high resin canal diameter, frequency and brightness from breast height increment cores. The relationships were evaluated between these properties, and the lumber resin features and grade recovery of the logs. Results: The number of resin pockets, the blemish rating, and the percentage of boards with resin streaks and resinous heartwood increased, and the recovery of clears and moulding grade boards and the lumber value declined, with the severity of the ERF class of the logs. Multiple regression models gave good predictions of the grade recovery and loss of lumber value, using the log ERF class, volume, heartwood content, and number of Type 1 resin pockets on the ends of the logs, as independent variables. The resin canal properties did not improve the regression models. Resin blemishes were associated with Type 2 resin pockets, and were more frequent in the forest where false growth rings were present. This suggests the constitutive resin flow from resin canals, rather than the resin canal size and frequency, is more important in determining the incidence of resin blemishes. Conclusions: The prediction of the grade recovery of lumber using the ERFs of radiata pine logs, was supplemented by the log volume, heartwood content and number of Type 1 resin pockets on the ends of the logs. The environmental factors that drive the constitutive resin enrichment of resin canals, such as drought conditions that give rise to false growth rings, could be useful in improving the prediction of grade recovery for forest stands.

Biosolids have been applied to a 1000 ha Pinus radiata D. Don plantation in Nelson, New Zealand, since 1996. A research trial was established in a 6-year-old stand in 1997 with three stocking rates (300, 450, and 600 stems·ha–1), and biosolids were applied at ages 6, 9, and 12 years at three application rates based on total nitrogen loading at each application of 0 (control), 300 (standard), and 600 kg N·ha–1 (high). The aim of this study was to evaluate the responses of tree growth rate and wood properties to biosolids application at midrotation. Since the trial was established, tree diameter and volume increment in the biosolids-treated plots have increased markedly. This increase in growth is being maintained at midrotation, with the year 13–14 volume increment being 40% greater in the standard treatment than the control, and 46% greater in the high treatment than the control. The response in growth has occurred across all stockings in the trial, although there has been a tendency for the difference in growth between the standard and high rates to be greater at higher stockings. A small but significant reduction of basic wood density and standing-tree sonic velocity in P. radiata was found in the biosolids treatments. Although the reductions in wood density and stiffness may slightly decrease the average log value in biosolids treated trees, this will be greatly outweighed by the large increase in wood volume.