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Abstracts of Publications

Ulf Hallonborg. Wobbling in Pneumatic Systems for Transporting Seedlings. Journal of Forest Engineering July Vol. 9 No. 2: 7-13 (1998)

When a containerized seedling is pneumatically transported through a pipe or hose it occasionally undergoes oscillating movements, referred to as “wobbling”, with the container being flung from one side of the hose to the other. Data on this phenomenon obtained in a previous feed-time study were further analyzed. In addition, a laboratory study was carried out in which the behaviors of seedling-container dummies of different sizes and shapes were studied at different air velocities in Plexiglas pipes of various diameters. Both the analyses of the frequencies of wobbling from the previous feed-time study and the results from the laboratory test confirmed that there is covariation between the wobbling tendency of a seedling and the shape of its container. Containers with a large butt-end area tend to wobble more. This leads to differentiation of the seedlings into two groups, seedlings with butt-ended and less butt-ended containers. This differentiation was the same whether it was based on feed times from the previous study, frequencies of wobbling from the previous study, or the wobbling behavior in the recent laboratory test with dummies.

Runsheng Yin, Leon V. Pienaar, and Mary Ellen Aronow. The Production and Profitability of Fiber Farming. Journal of Forestry November Vol. 96, No.11 13-18. (1998)

Standard site preparation for pine plantations in south Georgia was combined with fertilization, bedding, and herbicide treatments. These intensified silvicultural practices can boost volume by 128 percent and the rate of return by 12 percent. Combining the growth-and-yield data with a forest level analytic framework shows the cost structure of timber production and its intra- and inter-regime changes. The high yields possible from fiber farming could allow changes in land use, from timber production to other uses, while maintaining supplies of low-cost fiber.

John M. King, C. Cartwright, J. Hafton, and A.D. Yanchuk. The potential of improving western hemlock pulp and paper quality. I. Genetic control and interrelationships of wood and fibre traits. Can J. For. Res. 28: 863-870 (1998)

This paper reports relationships between wood and fibre traits and investigates the potential for using genetic selection to improve traits that will increase both the yield and the value of the western hemlock pulpwood resource. Strong family effects were present in the internal wood and fibre properties of relative wood density, average fibre length, and fibre coarseness. Heritability estimates for these traits ranged from 0.5 to 0.9. Heritability estimates for growth variables of height and diameter ranged from 0.15 to 0.2. Besides the moderate to high heritabilities for internal wood variables, coefficients of variation at the individual and family mean level ranged from 7.5 to 13% and from 4 to 6.5%, respectively. Correlations at an individual phenotypic and genetic level showed adverse correlations between growth rate and both relative wood density (negative correlation) and fibre coarseness (positive correlation). A significant negative phenotypic correlation between relative wood density and coarseness would appear to be due to the fact that both traits were strongly correlated to growth rate. The partial correlation controlling for diameter between coarseness and diameter was nonsignificant. Power analysis demonstrated that pulp and fibre traits could be assessed effectively using as few as six individuals per family.

Kevin R. Gehringer. Dynamic Forest Growth and Yield Modeling with Temperature and Precipitation using S-systems: An Application to Douglas-fir Plantations in the Pacific Northwest. Ph.D. Thesis, University of Washington, College of Forest Resources 1998

The S-system modeling framework is presented as a simple and robust unifying framework for forest growth and yield modeling. A two variable S-system model for the size-density self-thinning relationship in even-aged monoculture plant stands is developed, demonstrating the ease with which S-system based models may be constructed. The ability of the S-system size-density self-thinning model to capture the observed behavior of even-aged monoculture plant stands is also demonstrated. An extension of this simple two variable model to include temperature and precipitation effects in a forest growth and yield model is then proposed. A method for estimating the parameters of an S-system model is presented and applied to simulated data from the two variable size-density self-thinning model to test its effectiveness. The estimated S-system model is shown to be consistent with the original model, both in terms of the estimated parameter values and the behavior of the estimated model. Finally, the parameter estimation method is applied to a three variable S-system model with the state variables diameter at breast height, height, and planting density for even-aged monoculture stands of Douglas-fir in the Pacific Northwest. The estimated three variable S-system model demonstrates the applicability of the S-system modeling framework to forest growth and development phenomena by capturing the observed growth behavior.

P. Crossland, G. Murphy, G. Martin, and M. Dean. Energy and Force Requirements for Six Pruning Shear Designs. New Zealand Forestry November Vol. 42 No. 3: 22-23 (1997)

Six pruning shear designs were compared under laboratory conditions. Total energy and peak force required for cutting radiata pine and Douglas-fir branches were measured. Branch sizes ranged from 9 to 65 mm. Under one set of standard conditions, some shears required over 50% more energy and peak force than others. Douglas-fir required more energy and force than radiata pine. Two brands tested on both species differed in terms of the magnitude of the additional requirement. Total energy and force requirements tended to increase with cutting edge angle and with blade thickness.

Bruce A. Kimball, Dale L. Nolte, Doreen L. Griffin, Steve M. Dutton, and Steve Ferguson. Impacts of Live Canopy Pruning on the Chemical Constituents of Douglas-fir vascular Tissues: Implications for Black Bear Tree Selection. Forest Ecology and Management 4387 1-6 (1998)

The impact of live canopy pruning on the carbohydrate and terpene content of vascular tissues was investigated in the lower bole of Douglas-fir. Cambial zone vascular tissue samples were collected from pruned and unpruned trees in the lower bolel and within the live canopy. Current year’s radial growth was estimated from the mass of vascular tissue removed from 800 cm2 sample area. Chemical analyses were conducted to determine the concentration of carbohydrates and terpenes in the samples. Results indicated that two years following treatment, pruning resulted in reduced growth and decreased carbohydrate content of the vascular tissue. Pruning had no effect on the terpene concentration of the vascular tissues. The impact of pruning on the foraging selection of black bears was evaluated by surveying bear damaged trees in a 50 acre stand of pruned and unpruned timber. Odds ratios indicate that black bears were four times more likely to forage unpruned Douglas-fir than pruned Douglas-Fir. Tree selection may be explained in part to the higher availability of carbohydrates in the unpruned tree with respect to the pruned tree.

Lee C. Wensel and Eric C. Turnblom. Adjustment of Estimated Tree Growth Rates in Northern California Conifers for Changes in Precipitation levels. Can J. For. Res. 28: 1241-1248 (1998)

Even with similar initial conditions, observed forest growth rates on permanent sample plots in the conifer region of northern California differ for different periods. Thus, individual-tree growth models built with growth parameters estimated from data from one period may not produce accurate estimates for another period unless some allowance is made for this variation in growth rates. Variation in growth rates of northern California conifers through time has been shown to be correlated with precipitation changes. A method is presented that adjusts periodic growth estimates for variation in precipitation between periods. This provides a basis for adjusting short-term growth data for making long-term growth projections. Perhaps more importantly, short term inventory updates might be made more accurately.

G. Murphy, J.G. Firth, M.F. Skinner. Soil Disturbance Effect on Pinus Radiata Growth During the First 11 Years. New Zealand Forestry November: 27-30 (1997)

The effects of soil disturbance (forest litter removal, topsoil removal and compaction) on the productivity of second-rotation Pinus radiata growing on a clay loam soil was assessed in a long-term trial. Relative to the controls, tree volumes at age 11 years were reduced by about 20% where litter had been removed by machine, about 55% where the topsoil had been removed and subsoil compacted with two passes of a loader, and about 65% where the top-soil had been removed and the sub-soil compacted with eight passes of a loader. Long-term indications are that although relative growth differences between trees in treated and untreated plots are decreasing with time, negative effects of top-soil removal combined with compaction of subsoil, are likely to be apparent when the trees are due to be harvested.

A.M. Quoreshi and V.R. Timmer. Exponential Fertilization Increases Nutrient Uptake and Ectomycorrhizal Development of Black Spruce Seedlings. Can. J. For. Res. 28: 674-682 (1998)

Intense fertilization may inhibit adequate mycorrhizal development for forest nursery stock production. Containerized black spruce seedlings exposed to four fertilization regimes (one conventional and three exponential at 12.5, 25, and 50 mg N/seedling, respectively) and two ectomycorrhizal inoculation (Hebeloma crustuliniforme and Quel. and Laccaria bicolor Orton) were grown from seed to assess mycorrhizal formation and nutrition of young trees under intensive greenhouse culture. Exponentially increasing fertilizer additions stimulated ectomycorrhizal development (49-85%) compared with conventional constant-rate fertilization (22-26%). Exponential fertilization also increased seedling N (13-34%) and P (5-18%) uptake, although dry matter production was reduced (17-25%) at the lowest exponential addition rate. Ectomycorrhizal inoculation did not affect seedling biomass but increased uptake of N (6-17%), P (5-20%), and K (4-18%), demonstrating a potential for nutrient loading by fungi. Higher ectomycorrhizal formation found under exponential fertilization regimes was attributed to lower initial nutrient levels maintained in the growing media. Results indicate that high exponential fertilization combined with fungal inoculation may be effective for producing both nutrient-loaded and ectomycorrhizally infected planting stock.

Bruce A. Kimball, Eric C. Turnblom, Dale L. Nolte, Doreen L. Griffin, and Richard M. Engeman. Effects of Thinning and Nitrogen Fertilization on Sugars and Terpenes in Douglas-fir Vascular Tissues: Implications for Black Bear Foraging. Forest Science 44(4): (599-602) 1998

The chemical constituents of coniferous vascular tissues play a role in bear forage selection, in particular bear foraging preferences are related to the concentrations of simple sugars (nonstructural carbohydrates) and terpenes in the forage. Analyses of vascular tissue samples from trees collected in test plots indicated that both thinning and fertilization caused the sugar concentration of vascular tissues in the lower bole to increase. However, these treatments had no effect on the concentrations of hydrocarbon monoterpenes, oxygenated monoterpenes, or sesquiterpenes. These results may explain the observations that black bears prefer to forage in thinned and fertilized stands.

F.D. Caccia and C.L. Ballare. Effects of Tree Cover, Understory Vegetation, and Litter on Regenerated Douglas-fir in Southwest Argentina. Can. J. For. Res. 28: 683-692 (1998)

The factors and processes that regulate Douglas-fir natural regeneration in southwest Argentina are unknown. We investigated (l) the germination response of Douglas-fir seeds to variations in the radiation and thermal environments imposed by canopy cover and litter, (II) the effects of litter on seedling emergence, and (III) the effects of understory vegetation on seedling performance and seed and seedling predation. Seed germination was high in darkness and under canopies. Under a combination of canopy types and litter covers, germination showed a negative correlation with temperature between 23 and 40°C. Germination was not altered by changes in red/far-red ratio. These results suggest that the presence of an overstory canopy promotes Douglas-fir seed germination compared with a no-canopy situation (e.g. a clearcut). Litter inhibited seedling emergence by reducing water availability and by acting as a mechanical barrier. Understory vegetation (established saplings) reduced seedling growth and survival. However, our results suggest that direct competition between seedlings and understory vegetation is not the principal force regulating regeneration; indirect effects appear to be of paramount importance because Douglas-fir seed and seedling consumption (presumably by rodents) is greatly encouraged by the presence of dense vegetation patches in the understory.

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