bluuebunny/crossref_metadata_2025 huggingface dataset:
Simultaneous Infestation by Dwarf Mistletoe and Western Spruce Budworm Decreases Growth of Douglas-fir in the Blue Mountains of Oregon
Authors: Filip Gregory M. , Parks Catherine A.
Published: April 2024

One-hundred paired branches, half with dwarf mistletoe plants and half without, were sampled from 100 Douglas-fir in five stands defoliated by the western spruce budworm. The budworm completely defoliated new shoots and buds of all branches sampled including those infected by dwarf mistletoe. Radial growth of host trees (Douglas-fir) was significantly less during the budworm outbreak compared with a similar period before the outbreak. Nonhost trees (ponderosa pine) showed significantly more radial growth during the outbreak than before it. Regression analyses showed that decreases in radial growth were associated primarily with increases in dwarf mistletoe severity (R² = 16.2-18.1). Trees within all dwarf mistletoe infection classes were defoliated by the budworm, and the additional growth reduction caused by defoliation was not significantly different among dwarf mistletoe severity classes. For. Sci. 33(3):767-773.
Decay and Dynamics of Snags in the Sierra Nevada, California
Authors: Raphael Martin G. , Morrison Micheal L.
Published: April 2024

A study on the rates of decay, falling, and recruitment in a population of snags (standing dead trees) in the Sierra Nevada, California, during 1975-83 showed that large-diameter (>38 cm dbh) snags fell slower than small-diameter snags. Firs (Abies spp.) fell at a lower rate than pines (Pinus spp.). Snags lost all needles and twigs within five years; 75% of pines and 66% of firs had lost most larger limbs within five years. Compared with the numbers of live trees in the parent stand, rates of new mortality were highest among Jeffrey pine (Pinus jeffreyi Grev. and Balf.) <15 cm dbh. Live-tree morality exceeded the rate that snags fell during our study, causing an increase in the snag population from 1978 to 1983. A Leslie matrix model of this snag population was developed that accounted for falling rates, transitions among decay stages, and recruitment of snags. Use of the model was illustrated using field data from five unburned study plots. For. Sci. 33(3):774-783.
Fusiform Rust Incidence and Severity in Loblolly Pine Plantations Following Herbaceous Weed Control
Authors: Zutter Bruce R. , Gjerstad Dean H. , Glover Glenn R.
Published: April 2024

Seven studies established to examine the effects of herbaceous weed control on loblolly pine (Pinus taeda L.) growth were assessed for fusiform rust incidence and severity after the fifth growing season. On four sites, greater loblolly pine growth on weed control treatments was accompanied by greater rust incidence and severity. Increases in incidence of branch galls were significant on four sites, while increases in incidence of stem galls were significant on only two sites. Trees with and without stem infections at age five were found not to differ in height at age one or two within any treatment. At age five, trees with stem infections were generally smaller in dbh and height than those without infections. For. Sci. 33(3):790-800.
Dominance in a Metric Trait of Pinus Patula Schiede and Deppe
Authors: Barnes R. D. , Matheson A. C. , Mullin L. J. , Birks J.
Published: April 2024

In an early Pinus patula Schiede & Deppe progeny test in Zimbabwe, three out of six full-sib families produced by controlled pollinations between ten plus tree parents showed statisitically significant 3:1 segregation ratios of large: small trees; a proportion of unusually large trees also occurred in the same families. It is suggested that variation in diameter was largely controlled by a single locus with slow growth recessive to fast growth; but the hypothesis that overdominance was exhibited in the heterozygote would explain the selection of an unexpectedly high proportion of heterozygotes among the plus trees. The presence of this gene could jeopardize advance with breeding strategies based on recurrent selection for general combining ability. Nevertheless, if there is overdominance, the gene has potential value; heterozygotes could be most effectively passed on to operational forestry through vegetative propagation or through seed production from a two-clone orchard containing homozygotes for the fast and slow growth alleles. The identification of this gene highlights the importance of progeny testing and of paying close attention to the occurrence, distribution, and fate of "runts." For. Sci. 33(3):809-815.
Predicting Girdling Probability for Pine and Hardwood Saplings in Low-Intensity Backfires
Authors: Greene Thomas A. , Shilling Charles L.
Published: April 2024

Six hundred saplings of Pinus taeda, Quercus nigra, and Liquidambar styraciflua in four ground-line diameter (dgl) classes ranging from 3-10 cm were treated at five fire intensity levels, 0, 36, 64, 80, and 98 kJ/s/m, with a propane-fueled backfire simulator during February-April 1985. Of 200 trees of each species, 10 loblolly pines were girdled (out of 35 scarred), 98 water oaks were girdled (143 scarred), and 5 sweetgums were girdled (142 scarred).

Logistic regression models based on dgl and mean temperature exposure were developed from these data and can be used to predict probability of girdling in 3-10 cm dgl stands of loblolly pine, water oak, and sweetgum by backfires with intensities from 0-98 kJ/s/m. For. Sci. 33(4):1010-1021.
On the Possibility of Using Joint Cost Allocation in Forest Management Decision Making
Authors: Hof John G. , Field Richard C.
Published: April 2024

A refutable hypothesis is developed theoretically that joint cost allocation schemes are not likely to lead to correct output level decisions. This hypothesis is supported in a test case experiment involving a managed forest in Alabama. Seven allocation schemes are tested: Separable Cost-Remaining Benefits, Nucleolus, Proportional Nucleolus, Weak Nucleolus, Benefit-Included Nucleolus, Shapley Value, and a Generalized Shapley Value. None of these schemes indicate, in the test case, correct timber output levels based on timber benefits and allocated costs alone. For. Sci. 33(4):1035-1046.
Stein-Rule Estimation of Timber Removals by County
Authors: Green Edwin J. , Thomas Charles E. , Strawderman William E.
Published: April 2024

The Stein-rule estimator for multivariate, unequal variance problems proposed by Morris in 1983 is applied to timber volume removal data from 11 counties in Louisiana. The estimator compared favorably to the standard sample mean in simulation trials with two sampling rules. The county means were closer to each other and had larger variances for hardwood removals than for softwood removals. Thus the gains were larger (up to 50% reductions in squared error) for hardwood removals, but there were substantial gains (10-30%) for softwood removals also. For. Sci. 33(4):1054-1061.
Comparison of Volume Growth Calculation Methods for Remeasured Horizontal Line Sampling
Authors: Yang Yong-Chi , Chao Shi-Ling
Published: April 2024

In remeasured horizontal line sampling, there is only one commonly used method for estimating yield. However, there are several methods for estimating growth. Five different methods of growth estimation, based on how a given classification of tree could be treated in the growth estimation, were tested on four species groups (true fir and spruce, cypress, pine, mixed softwood and hardwood) in Taiwan.

The classical method (also called the Strand method, or the compatible method), where tree status was ignored, had significantly larger mean squared error of the estimators than the others. There was no interaction between species group and method. The other four methods were very similar in the precision of estimate. Based on the ease of gathering data, the revised Purdue method is recommended. If volume and growth need to be compatible, the variable diameter factor method should be used for remeasured horizontal line sampling. For. Sci. 33(4):1062-1067.
Variation in Yield of Blue Spruce Monoterpenes Associated with Crown Position and Frequency of Resin Canals
Authors: Moore P. P. , Hanover J. W.
Published: April 2024

Large differences were found in the yield of monoterpenes from xylem, bark, and needles of blue spruce (Picea pungens Engelm.). Yields were greatest from bark samples and least from xylem. There were significant differences among trees in yield for all tissues. Yield of xylem and needle but not bark monoterpenes varied with position in the crown. Yields of total monoterpenes in xylem and needle samples were highly correlated with the proportion of resin canals in these tissues. Needle and bark extracts showed significant among-tree differences in the relative concentrations of most monoterpenes. Concentrations of most monoterpenes in needle and xylem extracts varied significantly with position in the crown, while few bark monoterpenes varied significantly. For. Sci. 33(4):1081-1088.
Constraints on Tree Breeding: Growth Tradeoffs, Growth Strategies, and Defensive Investments
Authors: Loehle Craig , Namkoong Gene
Published: April 2024

Analysis of basic growth processes and between-species trait correlations suggests that because of growth tradeoffs, breeding for growth rate (volume increment) may adversely affect defensive and other properties of trees. This can lead to negative impacts on sawtimber quality and tree lifespan. Selection for yield and for pathogen resistance may conflict, separate breeding programs may be needed for pulp and saw-timber purposes, and older ages may be more appropriate for selection of plus trees. In order for breeders to consider consequences of selection on tree performance, a means is required of assessing potential adult pathogen resistance and lifespan. Four methods are proposed for accomplishing this using properties of young trees. The properties of young trees that may correlate with adult performance are (1) wood properties related to defense, (2) wound healing ability, (3) the allometric growth coefficient, and (4) age of sexual maturity. For. Sci. 33(4):1089-1097.
Marginal Productivity of Public Research in the Softwood Plywood Industry: A Dual Approach
Authors: Seldon Barry J. , Newman David H.
Published: April 2024

The production function approach commonly used in agricultural studies is modified to estimate returns from publicly funded forestry research. The method indirectly estimates production function coefficients using a simultaneous, constrained supply and demand system. From these estimates the value of the marginal product (VMP) of public research involving softwood plywood is used to calculate a marginal internal rate of return (MIRR) on publicly funded research. Whereas similar studies in the agricultural literature use a short-run VMP based solely on the initial impact of R&D, we develop a long-run VMP, which incorporates research impacts over time. A short-run VMP is also defined, however, and compared to the results reported in the agricultural literature. Estimates of the short-run VMP for softwood plywood are similar to other aggregate research cases, such as corn and poultry. The estimated long-run VMP, however, is large; the most conservative assumptions yield an estimated VMP of public research in softwood plywood of $33.11 in 1967 dollars. The MIRR is also large with a lower estimate of 236%. For. Sci. 33(4):872-888.
An Econometric Analysis of the Southern Softwood Stumpage Market: 1950-1980
Authors: Newman David H.
Published: April 2024

This paper presents an aggregate regional model of the southern softwood solidwood (combined lumber and plywood) and pulpwood stumpage markets. The derivation of stumpage supply includes direct substitution possibilities by stumpage producers. The derivation of stumpage demand follows a profit maximization framework and includes the effects of input substitution as well as production capacity. Three-stage least squares regression techniques provide simultaneous parameter estimation of the market system. Solidwood stumpage is a complement in production with pulpwood; however, in solidwood production, an asymmetrical relationship exists as pulpwood is a substitute good. With respect to demand, solidwood stumpage responds to a greater extent to changes in final good price than does pulpwood. For. Sci. 33(4):932-945.
Optimizing Species Composition in Uneven-Aged Forest Stands
Authors: Bare B. Bruce , Opalach Daniel
Published: April 2024

This article describes an approach for determining the optimal sustainable equilibrium diameter distribution and species composition for a mixed-species forest stand. Using the Prognosis Model-a single tree distance independent growth model and its attendant regeneration subsystem—the maximization objective is formulated in terms of three decision variables per species: (1) the scale and shape parameters of a Weibull distribution function, and (2) the total number of trees per acre. A direct search, derivative-free, constrained nonlinear programming algorithm is used to optimize the growth model under a sustainable equilibrium constraint. To facilitate optimization, the stochastic features of the Prognosis Model are transformed to their deterministic counterparts. Results are presented for the Abies lasiocarpa/Clintonia uniflora habitat type found in northern Idaho. For. Sci. 33(4):958-970.
Height Growth Rate of Douglas-Fir: A Comparison of Model Forms
Authors: Hann David W. , Ritchie Martin W.
Published: April 2024

Five model forms were evaluated for their ability to predict height growth rate of individual Douglas-firs (Pseudotsuga menziesii [Mirb.] Franco) growing in even or uneven-aged stands of southwest Oregon. Three models had been previously used for Douglas-fir; the fourth was a simple modification of one of these, and the fifth was developed in this study by means of multidimensional graphing and modeling. Two forms were age-dependent, in that they used transformations of stand age, and three were age-independent. The model developed by multidimensional techniques provided the lowest mean squared error for both an even-aged data set (1,763 observations) and a combined even- and uneven-aged data set (2,242 observations). The five models were verified on a randomly drawn subset of the data consisting of 241 observations. Again the model developed with multidimensional techniques had the lowest mean residual and the lowest mean squared error. Independent variables in this model are stand crown closure at the top of the tree, crown ratio, and potential height growth rate as predicted by an existing dominant height equation. The resulting model is age-independent and can be applied to trees in both even- and uneven-aged stands. Multidimensional techniques were most useful in modeling this complex nonlinear surface. For. Sci. 34(1):165-175.
Trends in Wood Quality for the British Columbia Coast and the United States, Pacific Northwest, Westside
Authors: Constantino Luis F. , Haley David
Published: April 2024

Two alternative methods of measuring wood quality are described—the index number approach and the hedonic approach.

Indices of wood quality are constructed for the Vancouver Forest Region (VFR), 1925-80, the Vancouver Log Market (VLM), 1925-82 and the Pacific Northwest, West-side (PNW) log market, 1957-82.

The general hypothesis that the quality of the wood supply on the British Columbia (BC) Coast has declined over time is confirmed. However, this decline proceeded at a decreasing rate between 1925 and 1970, and during the 1970s an increase in wood quality was measured. This increase was more pronounced for the VLM than for the VFR. Wood quality declined at a faster rate in the PNW than in B.C. from 1957 to 1982.

On the VLM, most of the decline in wood quality, prior to 1957, was due to deterioration in the grade mix while between 1957 and 1970 changes in the species mix was the dominant factor. On the PNW log market, quality decline between 1957 and 1982 was entirely due to deterioration in the grade mix, the species mix showing some improvement during this period. For. Sci. 34(1):176-189.
Modeling Long-Term Fire-Caused Mortality of Douglas-Fir
Authors: Ryan Kevin C. , Peterson David L. , Reinhardt Elizabeth D.
Published: April 2024

Mortality was determined in a stand of Douglas-fir 8 years after 20 plots were treated with light surface fires. Logistic regression was used to model long-term mortality as functions of morphological variables measured shortly after burning. Independent variables were diameter at breast height, height of needle scorch, percentage of the prefire crown volume scorched, season of burn, and the number of quadrants with dead cambium at 1.4 m bole height. Mortality increased with increasing scorch height, percent crown scorch, and dead cambium. It decreased with larger diameter. The best predictor of mortality was the number of quadrants with dead cambium. Percentage of crown volume scorched was a better predictor than lethal scorch height. For a given level of damage, mortality following fall season fires was slightly higher than following spring fires. Models may be used in planning prescribed fires and for salvaging fire-damaged Douglas-fir. For. Sci. 34(1):190-199.
Use and Characteristics of Snags in Young and Old Forest Stands in Southwest Virginia
Authors: Rosenberg Daniel K. , Fraser James D. , Stauffer Dean F.
Published: April 2024

Snags were sampled in chestnut oak (Quercus prinus) and oak-hickory (Quercus spp.—Carya spp.) stands in southwest Virginia. More large (≥17 cm dbh) snags were found in stands ≥100 years of age and more small (≤10 cm dbh) snags were found in stands <80 years of age, than expected under the model of equal distribution among age classes (χ2 = 25.3, df = 6, P = 0.0003). Log-linear models suggested that large diameter snags are more likely to be used by foraging birds than smaller snags. Tall snags were also used more than short ones, but 4-way log-linear models suggested that this was a result of a positive dbh-height relationship, rather than a reflection of bird selection of tall snags. Similarly, cavities were found more often than expected in large dbh trees. For. Sci. 34(1):224-228.
Determining Investment-Efficient Diameter Distributions for Uneven-Aged Northern Hardwoods
Authors: Bare B. Bruce , Opalach Daniel
Published: April 2024

The constant "q" of de Liocourt is often used to model the diameter distribution of uneven-aged forest stands and produces "balanced" size class distributions. Claims that such distributions are the most efficient for uneven-aged management or necessary to achieve sustention of production have led to the use of the concept in a variety of management models. Using a northern hardwood mixed-species growth model and a Weibull distribution function, we demonstrate that "balanced" diameter distributions are not investment-efficient and are not necessary to achieve sustention of production over a fixed cutting cycle. Results are very sensitive to per tree price and maximum tree size assumptions. For. Sci. 34(1):243-249.
Short-Run Actual and Least-Cost Productivities of Variable Inputs for the British Columbia Interior Softwood Lumber Industry
Authors: Meil J. K. , Singh B. K. , Nautiyal J. C.
Published: April 2024

A dynamic empirical cost structure analysis of the British Columbia interior softwood lumber industry was conducted using a variable cost approach. The analysis proceeds from the implicit assumption that the industry minimizes the variable cost of production in the short run, conditional on the quantity (level) of the quasifixed capital factor, rather than the usual assumption of total cost minimization. The introduction of interrelated factor demand via a simple partial adjustment model affords the measurement of productivity decline and higher costs due to incomplete implicit adjustment to least-cost levels when factor demand changes. The analysis also employs a somewhat restrictive method for accounting for the three major outputs of the industry in a single output model; however, this refinement does represent one prevelant production behaviour observed in the Canadian sawmilling industry as a whole. The resuls indicate that: (1) demand for variable inputs in the regional industry are interrelated; (2) the assumption of full and instantaneous adjustment in variable factor demands, as maintained in short-run static models, proved to be implausible; (3) small, but significant economies of scale and technology progress were present in the industry; (4) the technology was largely materials (wood) using and labor saving; (5) all input substitution possibilities were found to be substitutes on the least-cost expansion path except for materials and energy relationship, which were found to be weak complements; (6) labor productivity was positive on both the observed and least-cost productivity expansion paths, but the observed labor productivity was only 80% of the least-cost productivity; and (7), wood and energy productivities were declining on both the observed and least-cost paths, but at a slower rate on the least-cost productivity path. For. Sci. 34(1):88-101.
Classification of Airborne Multispectral Scanner Data for Mapping Current Defoliation Caused by the Spruce Budworm
Authors: Leckie Donald G. , Ostaff Donald P.
Published: April 2024

Airborne multispectral scanner data were acquired over a mixed fir and spruce forest affected by both current defoliation (red discoloration) and cumulative defoliation (loss of needles) caused by feeding of the spruce budworm (Choristoneura fumiferana [Clem]). The spectral bands, ratios and differences of bands, and principal components derived from the bands were examined for their usefulness for discriminating defoliation condition. Classifications were conducted using the best combinations of two through nine bands or features derived from the bands. Three levels of current defoliation could be classified (heavy, light, and healthy). Cumulative defoliation and mixed-wood areas caused confusions in the classifications. There was little advantage to including more than four bands or derived features in the classifications. For. Sci. 34(2):259-275.
Goodness-of-Fit Tests and Model Selection Procedures for Diameter Distribution Models
Authors: Reynolds Morion R. , Burk Thomas E. , Huang Won-Chin
Published: April 2024

The process of developing diameter distribution yield models based on probability distributions involves selecting a family of probability distributions, developing a methodology for estimating the distribution parameters, and validating the final selected model. Standard goodness-of-fit tests have been widely used at various stages of this process, often in an ad hoc manner. Goodness-of-fit tests are reviewed and formalized and problems associated with applications to diameter distribution models are discussed. The effect of correlations between tree diameters on a plot and the effect of using multistage techniques to estimate the parameters of the probability distribution are investigated. Results from a simulation of the entire fitting process suggest that, in many situations, use of goodness-of-fit tests may be inappropriate. Other testing and selection procedures that may be more appropriate than goodness-of-fit tests are reviewed. As an alternative to goodness-of-fit tests, an error index is proposed for use in selecting and validating models. The error index is used in conjunction with the fitting process simulation to investigate the effect of the fitting technique and the characteristics of the fitting data on final model selection. For. Sci. 34(2):373-399.
Effects of Whole-Tree and Stem-Only Clearcutting on Postharvest Hydrologic Losses, Nutrient Capital, and Regrowth
Authors: Mann L. K. , Johnson D. W. , West D. C. , Cole D. W. , Hornbeck J. W. , Martin C. W. , Riekerk H. , Smith C. T. , Swank W. T. , Tritton L. M. , Van Lear D. H.
Published: April 2024

Nutrient removal by sawlog or pulpwood harvest (SAW), and whole-tree harvesting (WTH) was determined for 11 forest stands located throughout the United States. Data from this study combined with previously published nutrient budgets indicated potential net losses of Ca and K at most sites without harvest, and net losses of N, P, K, and Ca with either SAW or WTH. Total stem biomass and nutrients were significantly correlated with total above-stump biomass, providing a means for estimating nutrient removals with WTH and SAW in commercial forests. Limited data from harvested stands indicated greater regrowth biomass with SAW than with WTH on some sites. In the 11 harvested stands, hydrologic losses of N, K, and Ca generally increased immediately after harvest, but returned to levels comparable to control areas within 3 years. Because of the short duration of elevated nutrient losses, the hydrologic losses are considered minor relative to harvest removals. Ca and K are possible exceptions. The large difference in amounts of nutrients left on site in logging slash after SAW compared with WTH did not result in major differences in leaching or runoff at sites where comparisons were made. For. Sci. 34(2):412-428.
Growth and Survival Modeling for Planted Conifers in the Great Lakes Region
Authors: Belli Keith L. , Ek Alan R.
Published: April 2024

In the steady advance of techniques to model forest systems, the development of models to represent the brief, but crucial, establishment phase of planted conifers has been largely ignored. A framework of prediction equations was developed for the growth and survial of red pine and white spruce during the first 5 years after planting. The model development process incorporated data synthesized from published reports of planting experiments in the Great Lakes region. Two compatible growth estimation functions were derived to accomodate observations of plantation averages in the form of either annual stem height increment or total cumulative stem height. A single function was hypothesized for total percent survival. The overall modeling effort is a "first step" in characterizing the regeneration system. For. Sci. 34(2):458-473.
Physiological and Morphological Responses of Three Half-Sib Families of Loblolly Pine to Water-Stress Conditioning
Authors: Seiler John R. , Johnson Jon D.
Published: April 2024

The effect of water-stress conditioning on drought tolerance of three open-pollinated families of loblolly pine (Pinus taeda L.) during water stress was investigated. Seedlings were subjected to one of two levels of prolonged, sublethal drought or were kept well watered. After the conditioning period, photosynthesis, transpiration, and growth were evaluated. Photosynthesis was decreased greatly with reduced needle water potential. Conditioned seedlings generally maintained positive net photosynthesis to water potentials 0.15 (moderate water-stress conditioning) and 0.40 (severe water-stress conditioning) MPa lower than those of control seedlings. This response was likely the result of an acclimation of the photosynthetic process resulting in less nonstomatal inhibition of photosynthesis at low needle water potentials. Under well-watered conditions, transpiration, but not photosynthesis, was reduced greatly by the conditioning treatments and resulted in improved water-use efficiency. Root growth was affected more by water stress than shoot growth, causing a decrease in root/shoot ratio. Genetic differences in photosynthetic acclimation were not apparent. However, compared to seedlings representing two Virginia seed sources, a family from Texas, known for its superior drought tolerance, had the lowest root/shoot ratio and the least change in transpiration in response to water-stress conditioning. For. Sci. 34(2):487-495.
Merchantable Height in Lieu of Total Height in Stem Profile Equations
Authors: Fowler John H. , Rennie John C.
Published: April 2024

A procedure that uses merchantable height in lieu of total height in an existing stem profile equation was devised and tested using data from natural hardwood stands in Tennessee. Diameter at merchantable height was subtracted from each measured stem diameter. Consequently the transformed diameter at merchantable height becomes zero and provides compatibility with existing stem profile equations while maintaining tree stem profile. A stem profile model was fitted to the transformed data and evaluated for its ability to predict upper stem diameters. Standard errors of the estimate and biases indicate a good fit based on comparison with published results using total height. Equations to predict height at a specific diameter and volume between two heights derived from the stem profile equation modified for merchantable height are presented in an appendix. For. Sci. 34(2):505-511.
Conditioning a Segmented Stem Profile Model for Two Diameter Measurements
Authors: Czaplewski Raymond L. , McClure Joe P.
Published: April 2024

The stem profile model of Max and Burkhart (1976) is conditioned for dbh and a second upper stem measurement. This model was applied to a loblolly pine data set using diameter outside bark at 5.3m (i.e., height of 17.3 foot Girard form class) as the second upper stem measurement, and then compared to the original, unconditioned model. Variance of residuals was reduced; however, bias was approximately the same for both the conditioned and unconditioned models. Benchmark prediction problems, which reflect common multiproduct utilization criteria for southern pines, were used to judge the practical importance of these reductions. Square root of the average squared residuals from the conditioned model were 10 to 25% less than those from the unconditioned model for most benchmark evaluations. These reductions might be of practical importance, depending on the particular objectives and the relative cost of an upper stem measurement compared to the cost of measuring more trees. For. Sci. 34(2):512-522.
Patterns of Leaf Area Distribution Within Crowns of Nitrogen- and Phosphorus-Fertilized Loblolly Pine Trees
Authors: Vose James M.
Published: April 2024

Field trials of nitrogen (N) and phosphorus (P) fertilization in loblolly pine plantations (Pinus taeda L.) were used to determine the effects of fertilization on within-crown leaf area distribution in a fully stocked stand, and two less than fully stocked stands. A second objective was to examine the utility of the Weibull distribution for modeling leaf area distribution in loblolly pine crowns. Results showed that leaf area increases were most evident in the mid- and lower-crown positions (2-4 m and 4-6 m crown depths), regardless of stocking level. Response patterns suggested that the Westvaco Stocking Chart, which is based on empirical relationships between stand basal area, stand density, and canopy closure, did not adequately reflect light interception in these stands because stands were ranked differently when stocking was expressed by stand leaf area index. The fully stocked stand was 50% below the theoretical optimum leaf area index value of 5. Thus, it is hypothesized that leaf area increases occurred in the mid- and lower-crown because shading in the mid- and lower-crown positions was insufficient to inhibit foliage production and survival. Fertilization-induced changes in leaf physiology may have also played an important role in leaf production and branch retention in the mid- and lower-crown. The Weibull distribution provided a good fit of within-crown leaf area distribution. For. Sci. 34(3):564-573.
Allelopathic Effects of Shrubs of the Sand Pine Scrub on Pines and Grasses of the Sandhills
Authors: Richardson D. R. , Williamson G. B.
Published: April 2024

Aqueous leachates prepared monthly from foliage of eight species and from litter of two of them from Florida's sand pine scrub community were tested for potential inhibitory activity on four receiver species: three grasses native to Florida's sandhill community (Andropogon gyrans, Schizachyrium scoparium, and Leptochloa dubia) and commercial lettuce (Lactuca sativa). Seed germination of the grasses was inhibited significantly by all ten leachates. Inhibition varied with month of preparation of the samples and was highly correlated with monthly precipitation. However, only two of ten leachates significantly inhibited radicle growth of the grasses, with a seasonal peak in late spring before the rainy season. Leachates from species dominant on open scrub sites were much more inhibitory than those from mature scrub. Lettuce seed germination was inhibited significantly, whereas radicle length was stimulated; neither effect exhibited significant seasonal variation. Andropogon gyrans watered with runoff from leaf misting of potted Ceratiola ericoides and Conradina canescens had significantly lower dry weights than control seedlings receiving distilled water. In a field transplant experiment designed to control resource competition, seedling pines (P. palustris, P. elliottii, P. clausa) and plugs of wiregrass (Aristida stricta) grew more slowly at scrub sites than at sandhill sites. Chemicals released from the shrubs may deter pines and grasses that otherwise provide fuel for surface fires which cause shrub mortality. For. Sci. 34(3):592-605.
Optimization with Expected Values of Random Yield Coefficients in Renewable Resource Linear Programs
Authors: Hof John G. , Robinson Kent S. , Betters David R.
Published: April 2024

This paper analyzes the problem of optimization when the yield coefficients are random variables with known (or acceptably approximated) means. An important distinction is demonstrated between the case where only land area constraints are included and where both area and yield constraints are included. The latter case is shown to be substantially more difficult both in problem formulation and solution. A test case that addresses the latter case empirically is presented. A bootstrap technique and Monte Carlo repetitions are used to simulate the expected value of the optimum. The test case indicates that current practice may closely emulate finding the expected value of the maximum objective function, but with uncertain feasibility. For. Sci. 34(3):634-646.
A Markov Chain Model for Evaluating Seasonal Forest Fire Fighter Requirements
Authors: Boychuk Dennis , Martell David L.
Published: April 2024

A model was developed to help resolve the decision of how many fire fighters a large forest fire management agency should hire for a fire season to minimize expected cost plus fire loss. It addresses the use of fire fighters for both initial and extended attack, the temporary hiring of extra fire fighters to satisfy peak demands, and the movement of fire fighters between regions within the agency's jurisdiction. It also recognizes the increase in subsequent fire fighter demand caused by fire fighter shortages. The fire management system is modeled as a Markov chain where the system state is related to the fuel moisture conditions throughout the protected area, and the total number of extended attack fires burning. Tests using representative hypothetical data demonstrated that it is a tractable approach for roughly evaluating fire fighter requirements. The model was used to evaluate the benefits of the centralized control of fire fighters, and indicated that it could reduce expected cost plus loss as much as 30% in the hypothetical example. For. Sci. 34(3):647-661.
Three-Dimensional Representation of Douglas-Fir Volume Growth: Comparison of Growth and Yield Models with Stand Data
Authors: O'Hara Kevin L. , Oliver Chadwick D.
Published: April 2024

Growth and yield estimates for unthinned stands from the Douglas-fir Stand Simulator (DFSIM; Curtis et al. 1981) and the Tree and Stand Simulator (TASS; Mitchell and Cameron 1985) were used to construct graphical three-dimensional representations of Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) stand growth on site index 44 meters (50 year). The three-dimensional models used three variables: trees per hectare, breast height age, and either mean tree volume or stand volume. The TASS and DFSIM models were in agreement over most of their common range of age and number of trees. At wider spacings and older ages, however, the volumes predicted by the DFSIM model exceeded those predicted by the TASS model by as much as 25%. Comparisons of these three-dimensional models to unthinned and thinned stand data from a similar site quality found the models to be reasonably accurate representations of unthinned stand growth. The thinned stands, however, had greater mean tree and stand volumes than those indicated by the TASS model for unthinned stands at similar spacings. Complete comparisons were not possible with the DFSIM model because of its limited range of number of trees. These results suggest the TASS model, and to a lesser extent, the DFSIM model may be underestimating the growth of widely spaced stands, or thinning may actually increase the growth of thinned trees over that of trees which had always grown at the post-thinning spacing. For. Sci. 34(3):724-743.
Root Decomposition and Nutrient Flux Following Whole-Tree Harvest of Northern Hardwood Forest
Authors: Fahey Timothy J. , Hughes Jeffrey W. , Pu Mou , Arthur Mary A.
Published: April 2024

Decomposition of roots of four dominant species (Acer saccharum, Betula alleghaniensis, Fagus grandifolia, Picea rubens) in a northern hardwood ecosystem was measured following whole-tree harvest of watershed 5 at Hubbard Brook Experimental Forest, New Hampshire. To quantify the importance of element release from tree root systems after forest harvest, measurements of macronutrient (N, K, P, Ca, Mg) release from roots of seven diameter (mm) classes (< 0.6, 0.6-1.0, 1.0-2.5, 2.5-5.0, 5-10, 10-20, 20-100) were combined with information on root system nutrient content. Decay of fine roots (all species) was initially rapid but declined abruptly after the first summer. Ash-free weight loss from small woody roots decreased with increasing root diameter and was much slower than decay rates for corresponding aboveground tissues (twigs and branches). Weight loss rates among species generally were not significantly different; however, large woody roots (10-100 mm diameter) of sugar maple decayed much more rapidly than the other species.

Rapid release of K and Mg was observed for all roots. Initially high rates of N and P release were observed for fine roots, whereas these nutrients were effectively retained in decaying woody roots. Retention of Ca was observed for all roots, and significant accumulation of Ca was observed in the larger size classes of woody roots. Particularly for N and K, release from decaying roots was an important nutrient flux pathway supplying stream outflow and vegetation regrowth in the first two years following forest harvest. For Sci. 34(3):744-768.
Analysis of Forest Fertilizer Experiments: Obtaining Better Precision and Extracting More Information
Authors: Woollons R. C. , Whyte A. G. D.
Published: April 2024

Later-age forest fertilizer experiments can be quite difficult to analyze appropriately and in ways that extract all the information inherent in the collected data. Observed responses are likely to be partially confounded with variations in pretreatment stand development, most of which can be removed through analyses of covariance using quanta of initial growing stock as a covariate. Pretreatment growth rate may represent an even more discerning covariate. Rather than use covariance some authors have chosen, instead, to use arithmetical procedures to adjust treatment responses. Reanalysis of a Canadian experiment of this latter kind suggests that such methodology may be less than ideal, and should not be preferred to covariance analysis. A general and systematic procedure for examining forest nutrition experiments is proposed for those involving t treatments, and also those where the t treatments represent n factors at p levels in factorial combination. An example of adopting the recommendation methodology for the first type is given using a completely randomized experiment in naturally regenerated radiata pine in New Zealand with five replications of four treatments. Adoption of the suggested procedures in conjunction with two covariates provides a useful insight into the data, and appreciably increases precision. The system is sequential in structure, necessarily inducing some risk of erroneous hypothesis testing. Such a danger is usually minimal, however, and the suggested system, it is claimed, represents a useful method for isolating treatment and growth effects in forest fertilizer trials. For. Sci. 34(3):769-780.
Cross-Dating Cores as a Nondestructive Method for Dating Living, Scarred Trees
Authors: Sheppard P. R. , Means J. E. , Lassoie J. P.
Published: April 2024

The objective of this study was to validate the use of increment cores for dating scarred trees as part of fire-history studies. Thirty-seven scarred conifers from four sites in the western United States were sampled both by coring and wedging (removing a partial cross section from the scar). For each tree the cores and wedge were analyzed using dendrochronological techniques to determine absolute fire dates, and the core and wedge dates were compared. Twenty-one of the 37 sampled trees were successfully dated and had identical core and wedge dates. Given certain constraints, researchers can effectively cross-date prescar growth from cores in fire- or other disturbance-history studies, and can accurately date scars with cores when wedge sampling is inappropriate or prohibited. For. Sci. 34(3):781-789.
Specific Gravity Variation in a Loblolly Pine Seed Source Study in the Western Gulf Region
Authors: Byram T. D. , Lowe W. J.
Published: April 2024

Specific gravity in 28 plantings of the Western Gulf Forest Tree Improvement Program seed source study varied by provenance, family within provenance, and test location. Trees from south Arkansas had the highest specific gravity (0.424) while those from south Louisiana had the lowest (0.398). Southeast Texas and north Louisiana trees were intermediate with an average specific gravity of 0.405. Trees from a North Carolina coastal source had the lowest specific gravity in the five plantings in Arkansas and Oklahoma in which they were included.

Families generally ranked the same in all tests. This implied that specific gravity was under strong genetic control and genotype by environment interaction was not operationally meaningful. However, specific gravity was environmentally sensitive as it varied significantly among locations. Environmental and genetic patterns of variation did not agree; therefore, in situ studies of regional specific gravities should not be used for making seed movement decisions. For. Sci. 34(3):798-803.
Forest Inventory and Management-Based Visual Preference Models of Southern Pine Stands
Authors: Rudis Victor A. , Gramann James H. , Ruddell Edward J. , Westphal Joanne M.
Published: April 2024

Statistical models explaining students' ratings of photographs of within-stand forest scenes were constructed for 99 forest inventory plots in east Texas pine and oak-pine forest types. Models with parameters that are sensitive to visual preference yet compatible with forest management and timber inventories are presented. The models suggest that the density of sawtimber-sized trees and the proportion of visual penetration are positively associated with scenic beauty. Foliage, twig, and small stem screening, and the density of small-diameter trees are negatively associated with scenic beauty. Results generally concur with other visual preference studies of within-stand forest scenes. Such models and associated parameter estimates can be used to objectively assess within-stand forest scenes and to routinely monitor scenic beauty of southern pine forest resources. Unlike similar scenic beauty studies, the limited amount of downed wood encountered was positively associated with scenic beauty. Also suggested is a decline in perceived scenic beauty during the summer season (May-October) coincident with sampling from northeast to southwest sections of east Texas. For. Sci. 34(4):846-863.
A Method to Estimate Input-Output Multipliers for the Forestry Sector Without an I-O Table
Authors: Zheng Chinlong , Harou Patrice A.
Published: April 2024

An input-output (I-O) multiplier can help quantify the relationship between an initial investment and the subsequent increase in the total production of an economy. A method for quickly estimating I-O multipliers without an I-O table is presented. It requires only two variables, which can be obtained at a low cost. Five I-O models with significant forestry sectors are used to validate the analysis empirically by comparing the actual and estimated multipliers. The applicability of the method is then discussed. For. Sci. 34(4):882-893.
A Height Prediction Model with Random Stand and Tree Parameters: An Alternative to Traditional Site Index Methods
Authors: Lappi Juha , Bailey Robert L.
Published: April 2024

A new method for predicting the height development of dominant trees is presented and illustrated with slash pine plantation data. The prediction procedure is based on a statistical model that explicitly describes the major random components in the variation of height curves. The average height of dominant and codominant trees in the population is expressed as a function of age. Then a model is developed for the variance-covariance structure of deviations from this average height curve due to stands and trees within stands. The model takes into account the fact that, within a given stand, heights of trees at a specific age are correlated, and tree heights and average stand height are correlated over time. The ability to specify and estimate this special covariance structure is obtained by including random stand and tree parameters in the height growth model. With the estimates of variances and covariances, and of the parameters of the function for average height, the height development of a given stand or single tree can be predicted using statistical prediction methods that utilize all available height measurements. With an example that includes two trees on one plot, one measured at one age only and the other measured at two ages, calculation of the variances of prediction errors is illustrated, and confidence limits on predicted values are calculated. For. Sci. 34(4):907-927.
Relationship Between Volume and Biomass of Early Successional Vegetation and the Prediction of Loblolly Pine Seedling Growth
Authors: Byrne Stephen V. , Wentworth Thomas R.
Published: April 2024

A simple and nondestructive method of measuring plant volume was developed to test the following two hypotheses: (1) plant volume is an effective substitute for plant biomass in the prediction of competitive potential; and (2) the plant biomass-volume relationship is affected by plant growth form. In 1983, above-ground volume and biomass were determined for all plants in 40 1-m² plots in an experimental loblolly pine (Pinus taeda L.) plantation having varying degrees of successional regrowth. After natural log transformations of plant biomass and volume, separate regression equations were developed for grass, forb, shrub, and tree growth forms. A test of homogeneity indicated that the slopes and intercepts for the four regression equations were not all identical. Specific contrasts among the regression equations were also tested for common slopes and intercepts to determine the source of overall significance. Results of the contrasts were explained by differences in plant allocation patterns. The variation in plant biomass accounted for by the volume models ranged from 78% for grasses to 94% for trees. As an application of this approach, volume was measured and biomass was estimated from the regression equations for successional plants within a 2m radius (the "neighborhood") of each of 69 loblolly pine seedlings. Total plant volume and total estimated biomass each accounted for approximately 40% of the variation in pine growth. For. Sci. 34(4):939-947.