STAND MANAGEMENT COOPERATIVE

 Abstracts of Publications

Back to Newsletter

Susan D. Carson, Oscar Garcia, and Judy D. Hayes. Realized Gain and Prediction of Yield with Genetically Improved Pinus radiata in New Zealand. FOR. SCI. 45(2):186-200

Pinus radiata seedlots of varying genetic quality were compared in block-plot genetic-gain trials at 10 locations representing most of the site types in New Zealand. Permanent sample plots were measured annually for growth from age 6-8 yr. from planting to ages 15-17 year (midrotation). Seedlots from first-generation open-pollinated seed orchards and a mix of crosses that all involved the top-performing parent were, respectively, on average 4.5% and 5.3% taller and had 6% and 11% larger mean diameter, 12% and 30% more basal area, and 15% and 34% more stem volume than seedlots originating from mild mass selection in harvested stands (“climbing select”). The observed growth increases were quantified as changes in the rate of growth from that predicted by pre-existing growth models in order to account for tree size and stocking differences. Seedlots from first generation seed orchards and crosses of the top clone, respectively, grew 5.1% and 4.5% faster in height, and functions for basal area and stocking changed 13% and 26.4% faster, respectively, than the baseline growth models, which were based on climbing select. This implies that increased basal area growth must be taken into account in order to obtain accurate prediction of gain in stem volume. The incorporation of these observed increases in growth rates into stand growth models as “genetic-gain multipliers” in order to extrapolate predictions of growth of genetically improved seedlots beyond the sites, silvicultures, and seedlots represented in the genetic gain trials is discussed.

David W. Hann. An Adjustable Predictor of Crown Profile for Stand-Grown Douglas-Fir Trees. FOR. Sci. 45(2):217-225.

This study developed a method for predicting the crown profile of stand-grown trees that can be adjusted to other populations of the same species by using either measurements or predictions of the largest crown width (LCW) for trees in the alternative population. The method should be of particular interest for tree species such as Douglas-fir that have exhibited variation in crown attributes across both their geographic range and genotypes. To model crown profile, the crown was divided into two segments: the portion of the crown above the point where LCW occurs, and the portion below that point. The equation for the upper portion predicted a crown profile that ranged in shape from nearly conic to parabolic, depending on position within the crown and the social status of the tree, as indicated by the ratio of total height divided by diameter at breast height for the tree. The equation for the lower portion predicted a crown profile with a cylindrical shape. This method explained nearly 94% of the variation in crown width when used with the felled tree measurement of LCW, 87% with a measurement of LCW taken while the tree was standing, and 83% with the use of a value for LCW that was predicted from an equation developed from an independent data set.

R. Rose, J.C. Ketchum, and D.E. Hanson. Three-Year Survival and Growth of Douglas-Fir Seedlings Under Various Vegetation-Free Regimes. FOR. Sci. 45(l):117-126

Responses of Douglas-fir seedlings were studied for 3 years following eight vegetation-control treatments in three western Oregon clearcuts. The objectives were to determine seedling growth response to different areas of spot vegetation control and to determine the relative influence of early woody and herbaceous competition on seedling growth. Herbicide treatment areas varied in size from those receiving no control to full control (9.3 m2 ). Controlled areas were maintained free of herbaceous vegetation for 2 years and all woody vegetation was controlled for 3 yrs. Two additional treatments, complete control of woody vegetation only and complete control of herbaceous vegetation only, were also examined. On two sites (Summit and Marcola), seedling growth parameters were maximized at or near full vegetation control with a tree spacing of 3 m x 3 m. On the third site (Pedee), maximum growth response occurred between 5 and 6 m2 of control. Herbaceous vegetation control resulted in increased seedling growth at all sites while woody vegetation control yielded increased seedling growth only at the Pedee site. Cumulative 3 year herbaceous cover accounted for 68% and 41% of the variability in stem volume at Summit and Marcola, respectively. Adding cumulative 3 year woody cover to the model accounted for an additional 18% and 49% of the variability in stem volume at Summit and Marcola, respectively. At Pedee, neither herbaceous nor woody cover significantly influenced 3 year stem volume, suggesting that factors other than vegetation cover were responsible for differences measured.

Afonso Figueiredo Filho and Luciano Budant Schaaf. Comparison Between Predicted Volumes Estimated by Taper Equations and True Volumes Obtained by the Water Displacement Technique (Xylometer). Can. J. For. Res. 29: 451-461 (1999)

The objective of this paper was to compare volumes estimated by taper equations to true volumes obtained by the water displacement technique (xylometer). Four previously published models and a fifth-degree polynomial were analyzed. Three sets of diameters measured on 52 fallen trees from Southern pine were used to fit the models. Clark et al.’s (1991; USDA Forest Service Southeast Forest Experiment Station Research Paper Number. SE-282) model was the best to predict diameters along the stem, merchantable volume, and total volumes. Max and Burkhart’s (1976; For. Sci 22(33): 283-289) model also had an excellent performance. The results still showed that the normal comparison between volumes estimated by integration of taper equations to those estimated by Smalian or Huber’s formula (usual procedure) underestimates the true error which is achieved by comparison with true volumes (xylometer).

R. L. Parfitt, D. J. Ross, and G. J. Salt. Nitrogen and Phosphorus Mineralizations in Pinus Radiata Harvest Residue Samples from a Coastal Sand. New Zealand Journal of Forestry Science 28(3): 347-360 (1998)

Although nitrogen mineralization after harvest of Pinus radiata plantation forests has been studied previously, little work has addressed nitrogen and phosphorus mineralizations in stockpiles of harvest residues on coastal sands. We examined, in the laboratory, the mineralization of nitrogen and phosphorus in dead needles, L/FH materials, and mineral soil (0-10 cm depth) from windrows, and in raked soil, and compared results with those from an adjacent standing forest. Microbial carbon, nitrogen, and phosphorus were also determined. Samples were taken 12 and 32 months after harvest. Mineralization of nitrogen was greatest in the dead needles, and was greater in windrow L and FH materials than in corresponding forest samples. The proportion in the nitrate-nitrogen form increased with time after harvest, and became susceptible to leaching loss. Microbial carbon, nitrogen, and phosphorus values were initially highest in the windrow dead needles and L material. These data were consistent with previous results suggesting that net nitrification is likely in P. radiata needles with carbon/ nitrogen ratios <40, whereas net immobilization of nitrogen is likely if the ratio is >55. Extractable phosphorus was comparatively high, and carbon/phosphorus ratios comparatively low, in the windrow L and FH materials, which suggests that net mineralization of phosphorus would readily occur in these materials. Net mineralization of phosphorus in mineral soil was higher in the windrow and raked soil than in the standing forest. These data are also consistent with previous data suggesting that net mineralization of phosphorus occurs when the carbon/phosphorus ratio for the FH horizon is <550. Since the nitrogen in the windrows is readily mineralized, and some losses by leaching occur, management practices could be initiated to allow for greater retention of nutrients after harvest on coastal sands.

Gordon Hosking and John Hutcheson. Wind-Caused Disturbance of a Red/Silver Beech Forest: Ten Years On. New Zealand Journal of Forestry Science 28(3): 325-334 (1998)

A 10-year study of the effect of wind damage on the health of residual beech forest showed tree mortality continued throughout the period in severely damaged forest. Forest with less than 30% canopy loss was much less affected by continued deterioration and showed little difference from undamaged forest at the end of the period. The two species showed different trends in mortality over time; the mortality rate of red beech leveled off after 7 years while that of silver beech was still increasing after 10 years. Pinhole borers were not a primary cause of tree mortality, attack being largely confined to trees that were already unhealthy. Blowdown debris harbored only a single generation of pinhole borers, decay being too advanced to support further broods.

Back to Newsletter

The Stand Management Cooperative Home Page is provided by the College of Forest Resources. To find the contact you need, please check the Members or contact David Briggs, SMC Director, or Megan O'Shea, SMC Program Manager, SMC Cooperative, University of Washington Box 352100 Seattle, WA 98195, 206-206.543.1581. © 2000-2001, University of Washington, Stand Management Cooperative, including all photographs and images unless otherwise noted