bluuebunny/crossref_metadata_2025_split huggingface dataset:
Factors Influencing the Timber Harvest Intentions of Nonindustrial Private Forest Owners
Authors: Young Robert A. , Reichenbach Michael R. 
Published: April 2024

Abstract
Intentions of woodland owners to harvest timber were examined in an effort to increase understanding of the factors that influence wood production on nonindustrial private forests. Six-hundred-twenty-one randomly selected woodland owners were interviewed by telephone to determine their attitude and beliefs about harvesting timber, and the influence of "important others" in making harvest decisions. Responses were compared for those owners who intended to harvest timber within the next 10 years with those who had no intention to harvest. Attitudes and subjective norms accurately predicted intentions to harvest (R = .75). Standard regression coefficients indicate that intentions were more influenced by the owner's attitude than by the influence of social groups. Differences in beliefs and in the influence of social groups were observed between those who intended to harvest and those respondents who did not. Recommendations are made that would increase the number of owners who intend to produce wood products from their private woodlands. For. Sci. 33(2):381-393.
Production and Cost of Scenic Beauty: Examples for a Ponderosa Pine Forest
Authors: Brown Thomas C. 
Published: April 2024

Abstract
Psychophysical models of scenic b eauty for an all-aged ponderosa pine area were combined with estimates of management costs and physical output values to indicate more efficient input combinations for production of scenic beauty. Also, in combination with biophysical models, the scenic beauty models were used to examine tradeoffs between scenic beauty and net present worth from timber, forage, and water yields. These examples demonstrate the use, as well as important limitations, of scenic beauty models in a multiple use context. For. Sci. 33(2):394-410.
Efficient Unbiased Tree-Volume Estimation
Authors: Van Deusen Paul C. , Lynch Thomas B. 
Published: April 2024

Abstract
Two unbiased methods for estimating the volume of an individual tree are examined. One method is based on importance sampling and has been discussed by Gregoire et al. (1986). The other method is a logical extension of critical height sampling, which was first discussed by Kitamura (1962). The two methods are compared using a simple model for tree taper. When independent samples are drawn, the critical height method requires an inordinate sample size. However, when a negative correlation is induced in the sample observations using antithetic variates, both methods become much more efficient. The conclusion is that antithetic variates should be considered when taking multiple observations with either of these methods for unbiased tree volume estimation. For. Sci. 33(2):583-590.
A Stem Dissection Technique for Dating Branch Mortality and Reconstructing Past Crown Recession
Authors: MaGuire Douglas A. , Hann David W. 
Published: April 2024

Abstract
A stem dissection technique for dating branch mortality and estimating past crown recession was evaluated on 28 Douglas-fir trees from permanent plots in Oregon and Washington. Repeated height to live crown measurements over the past 15 years on each of the 28 trees provided a basis for comparison with the branch mortality dating technique. After each tree was felled in a scheduled thinning, heights to 10-15 consecutive branch whorls below crown base were measured. Sections containing the whorls were then removed and dissected on a band saw to expose longitudinal sections through the encased dead branches. Discontinuities between branch and bole growth rings, corresponding to the delineation between tight and loose knot zones, allowed estimation of years since branch mortality. Past heights to live crown were reconstructed from the branch mortality estimates and whorl heights. Backdated crown base positions corresponded closely with the 15-yr field remeasurements. For. Sci. 33(4):858-871.
Fixed and Equilibrium Endpoint Problems in Uneven-Aged Stand Management
Authors: Haight Robert G. , Getz Wayne M. 
Published: April 2024

Abstract
Studies in uneven-aged management have concentrated on the determination of optimal steady-state diameter distribution harvest policies for single and mixed species stands. To find optimal transition harvests for irregular stands, either fixed endpoint or equilibrium endpoint constraints can be imposed after finite transition periods. Penalty function and gradient methods are presented to solve these problems. The methods are demonstrated with a stage-structured model for projecting stands that contain mixtures of California white fir (Abies concolor [Gord. & Glend.] Lindl. (Iowiana [Gord.])) and red fir (Abies magnifica A. Murr.). With present value as the efficiency criterion, optimal transition strategies are computed for three kinds of target steady states: the extremal steady state associated with an infinite time horizon dynamic optimization problem, an investment-efficient steady state, and a maximum sustainable rent steady state. Harvest regimes that convert to investment-efficient or maximum sustainable rent steady states are dominated by red fir and are suboptimal compared to transition regimes that convert to the extremal steady state, which includes only white fir. The fixed endpoint regimes are compared with transition strategies that are obtained with equilibrium endpoint constraints that do not require a particular steady-state stand structure. Transition regimes that convert to the extremal steady state are suboptimal compared to regimes that solve the more general equilibrium endpoint problem, and the present values of these two kinds of regimes converge as the transition period lengthens. The species composition and structure of the steady states found by solving the equilibrium endpoint problem depend on the transition period length. For. Sci. 33(4):908-931.
Effects of Aeriai Detection Schedules on the Age of Southern Pine Beetle Infestations
Authors: de Steiguer J. E. , Hedden Roy L. 
Published: April 2024

Abstract
A method for scheduling southern pine beetle detection flights was developed and implemented as a computer program entitled OVERFLIGHT. The program determines the seasonal arrangement of flights that minimizes spot age, and therefore, forest damage, at the time of detection. The only data input to the program are the percentage of annual spots initiated in each month. These data were obtained from state pest control officers and the methodology applied to two regions of the South. The results indicate the best seasonal positioning of flights. Also, incremental flights showed decreasing marginal gains in reducing spot age with little improvement beyond five flights per year. Assumptions of the model are discussed, as well as use of the model in economic analyses. For. Sci. 34(1):229-235.
Ontogenetic Patterns of CO2 Exchange of Quercus rubra L. Leaves During Three Flushes of Shoot Growth II. Insertion Gradients of Leaf Photosynthesis
Authors: Hanson P. J. , Isebrands J. G. , Dickson R. E. , Dixon R. K. 
Published: April 2024

Abstract
Carbon dioxide exchange rates (CERs) of all leaves along the stem of northern red oak (Quercus rubra L.) seedlings (a leaf insertion gradient or profile) were determined at several stages of ontogeny. Seedlings were grown and measured under growth chamber conditions favorable for the production of multiple flushes of shoot growth. The CERs were measured with a portable closed-circuit CO2 analyzer at ambient photosynthetic photon flux densities and were determined for every leaf of each seedling. Carbon dioxide exchange rates per unit projected area of individual leaves (CERA) increased along leaf-maturation gradients in expanding flushes. After flush growth was completed, all leaves of a flush has similar CERA. However, because median flush leaves were the largest, they accounted for the greatest proportion of an expanded-flush's CER. First-flush leaves were the major contributors to total seedling CER through the second flush of growth—encompassing half of the period required to produce a three-flush oak seedling. This study's data, based on short-term CER measurements, showed ontogenetic patterns of CO2 exchange similar to those reported for northern red oak under "steady state" laboratory conditions. For. Sci. 34(1):69-76.
Site Preparation Effects on Soil Moisture and Available Nutrients in a Pine Plantation in the Florida Flatwoods
Authors: Burger J. A. , Pritchett W. L. 
Published: April 2024

Abstract
Burning and mechanical preparation of cutover forest sites enhances pine plantation establishment, but soil and site changes in southeastern forests have not been well documented. Two site-preparation treatments (burned-chopped and burned-bladed-harrowed-bedded) were applied to plots on a Florida flatwoods site. Harvesting caused a rise in the water table, and during the drier times of the year, the more intensively prepared plots had a higher water table than the chopped plots. Despite lower total nitrogen reserves after two growing seasons on the more intensively prepared plots (770 versus 1020 kg ha-1), ammonium and nitrate levels in the soil solution were twice that of the chopped plots; as a result, foliar-N levels of two-year-old planted seedlings were 0.93 versus 0.85%, respectively. Soil solution phosphorus levels averaged ten times higher and potassium averaged five times higher on the intensively prepared plots compared to the chopped plots. Total biomass of the competing vegetation two years after harvest was 1489 kg ha-1 on the intensively prepared plots compared to 3548 kg ha-1 on the chopped plots. At the end of the second season there was no difference in survival between the two treatments, but stem volume of trees on the intensively prepared plots was 2.8 times greater. This superior growth response elicited by intensive preparation was attributed to better moisture conditions, higher levels of available nutrients, and less competition. For. Sci. 34(1):77-87.
A Discrete State, Continuous Parameter Markov Process Approach to Timber Harvesting Systems Analysis
Authors: Hassler Curt C. , Disney Ralph L. , Singlair Steven A. 
Published: April 2024

Abstract
The introduction of simulation into timber harvesting systems analysis has spawned a proliferation of such models. As a result, the potential for applying stochastic process theory has been largely overlooked. This paper develops the theoretical aspects of a discrete state, continuous parameter Markov process model for application to timber harvesting systems analysis. Erlang and mixed Erlang probability distributions are introduced as models for time-based timber harvesting activities. These families of distributions are used because they offer flexibility in modeling the variety of distributions encountered in the field, yet maintain the integrity of the Markov assumptions. General formulation and solution of the Markov process model is discussed. An application of the theory to the analysis of timber harvesting system interaction is presented. The interaction between a grapple skidder and a mechanical slasher is formulated and solved as a discrete state, continuous parameter Markov process. The analytic solution showed that the system was severely unbalanced, with the skidder delayed 84.5% of the time, the slasher never idle, and both simultaneously performing productive work 15.5% of the time. For. Sci. 34(2):276-291.
A Framework for Stand Structure Projection of Uneven-Aged Loblolly-Shortleaf Pine Stands
Authors: Murphy Paul A. , Farrar Robert M. 
Published: April 2024

Abstract
A growth and yield model for uneven-aged loblolly-shortleaf pine (Pinus taeda L.-Pinus echinata Mill.) was developed. Stand-level equations for merchantable basal area, sawtimber basal area, quadratic mean diameter, and maximum tree diameter were derived first. Parameters for the doubly truncated Weibull distribution were obtained by the "parameter recovery" technique by using estimates of maximum diameter, quadratic mean diameter, and the sawtimber-merchantable basal area ratio. Compatibility for basal area estimates is thus maintained between the stand-level estimates and those produced from the Weibull distribution. Because inventory data were used to develop the model, potential users should be cautious in applying the model on an operational basis. For. Sci. 34(2):321-332.
Timber Harvesting with Fluctuating Prices
Authors: Brazee Richard , Mendelsohn Robert 
Published: April 2024

Abstract
Because of volatility in demand, timber prices tend to fluctuate from year to year. Timber owners know today's price but are uncertain about tomorrow's prices. Traditional Faustmann harvesting ignores these random annual price fluctuations and prescribes harvests on the basis of expected prices. In this paper, we adapt an asset sale model to forestry and solve for the optimal schedule of reservation prices. When current price is above the reservation price, owners should cut that age class, otherwise they should wait another year. This flexible price harvest policy significantly increases the present value of expected returns over the more rigid Faustmann model. For. Sci. 34(2):359-372.
Multiple Use vs. Organizational Commitment
Authors: Twight Ben W. , Lyden Fremont J. 
Published: April 2024

Abstract
Q factor analysis and cluster analysis data demonstrate a high level of homogeneity among USDA Forest Service district rangers resembling that found by Kaufman in the 1950s, suggesting a current organizational culture committed primarily to one constituency group rather than the multiple constituencies implied by the Multiple Use-Sustained Yield Act. Such strong commitment to a single-constituency perspective may preclude agency sensitivity to other public perspectives obtained through citizen participation. Organization theory and social institutions theory are used to explain the findings. For. Sci. 34(2):474-486.
Leaf Area, Stemwood Growth, and Nutrition Relationships in Loblolly Pine
Authors: Vose James M. , Allen H. Lee 
Published: April 2024

Abstract
The relationships among loblolly pine (Pinus taeda L.) stand leaf area index (LAD, stemwood volume growth (m3/ha/yr), and growth efficiency (m3stemwood/ha/yr/LAI) were examined in three nitrogen (N) by phosphorus (P) fertilization field trials. Prior to fertilization, stockinglevels and nitrogen limitations varied for the three stands. LAI increased significantly (up to 60%) following N fertilization on the two N deficient stands. Phosphorus additions did not affect LAI. Stemwood growth was positively and linearly related to LAI across treatments and stands. Variationsin LAI across stands reflected the differences in stocking and N availability. On average, a unit of LAI produced 7.3 m3stemwood/ha/yr. Growth efficiency was not affected by fertilization on two of the three stands. A decrease in growth efficiency at a projected LAI above 3.5 resultedfrom an asymptotic relationship between stemwood growth and LAI on a stand that was fully stocked and highly responsive to N fertilization. The use of LAI as an index of stocking is proposed because LAI integrates tree size, stand density, and site resource supply. In addition, it is proposedthat the deviation of a stand's current LAI from the maximum supportable LAI based on fixed site factors (e.g., water, temperature) may provide a good measure of a stand's potential responsiveness to fertilization. For. Sci. 34(3):547-563.
The Effect of Eccentricity on the Estimation of Basal Area and Basal Area Increment of Coniferous Trees
Authors: Biging Greg S. , Wensel Lee C. 
Published: April 2024

Abstract
A sample of noncircular tree cross-sections was examined to determine basal area and basal area increment. Basal area estimates were calculated with a circular model from single measurements of diameter and from averages of two diameter measurements. Basal area increment estimates were made with several geometric models from single measurements of radial increment and averages of two measurements of radial increment. Commonly used tree cross-sectional area estimates investigated were biased, usually overestimating basal area. Several generalized geometric models of area increment were investigated, but none tested were uniformly supported by the data with accuracy related to the specific increment measurements selected. However, results indicated that either a single increment measurement taken on the minor axis or the shortest increment from the major axis yielded accurate estimates of basal area increment for several of the models tested. For. Sci. 34(3):621-633.
A Forestry Application of Schnute's Generalized Growth Function
Authors: Bredenkamp Brian V. , Gregoire Timothy G. 
Published: April 2024

Abstract
A case is presented where the Chapman-Richards growth function is suitable to describe growth for a certain period during the life of a stand of Eucalyptus grandis in South Africa. Toward the end of that period, diameter growth exhibited strong asymptotic properties. After marked competition mortality, the stand resumed growth beyond what had appeared to be an asymptotic level and the Chapman-Richards function could no longer be satisfactorily fitted. A generalized growth function developed by Schnute successfully tracked this renewed growth. The parametric relationships between the two models are established. For. Sci. 34(3):790-797.
Stand Structure in Subalpine Forests of Yosemite National Park, California
Authors: Parker Albert J. 
Published: April 2024

Abstract
Variation of seedling densities and diameter-class distributions with site condition is examined for 5 coniferous tree species sampled in 30 stands between 2400 and 3300 m elevation in Yosemite Park, California. There is an apparent tolerance ranking from mountain hemlock and red fir (high tolerance) through lodgepole pine (intermediate) to whitebark and western white pine (low tolerance). Diameter curves for each species vary in form across environmental gradients, from stable, persistent forms (reverse-J and multimodal) on optimal sites to random forms on marginal sites. Multimodal diameter structure is common among populations in Sierran subalpine forests. In this climatically rigorous setting, interannual variability of conditions affecting seedling survival and growth rates may combine with canopy gap dynamics to yield stable diameter curves punctuated by discrete episodes of establishment, release and growth. For. Sci. 34(4):1047-1058.
The Ratio of Shoot Silhouette Area to Total Needle Area in Scots Pine
Authors: Oker-Blom Pauline , Smolander Heikki 
Published: April 2024

Abstract
The dependence of light interception efficiency on shoot structure was studied. The silhouette areas of 258 Scots pine (Pinus sylvestris L.) shoots inclined at different angles were measured, and the corresponding silhouette area to total needle area ratios (STAR) were determined. For each shoot, a mean silhouette to total needle area ratio (STAR) with respect to a spherical shoot orientation was calculated. STAR varied between 0.09 and 0.21 and averaged 0.14. For spherically oriented individual needles or leaves, the corresponding mean projection of unit foliage area is 0.25. Thus, the light interception efficiency of the shoots as indicated by STAR-values was on average reduced by 43% because of mutual shading of needles on the shoots. The silhouette areas and STAR-values were also calculated theoretically using a previous model of shoot geometry, and these values were compared to the empirical measurements. For. Sci. 34(4):894-906.
Minimum Age-To-Age Correlations in Early Selections
Authors: Magnussen Steen 
Published: April 2024

Abstract
The concepts and computational procedures of minimum age-to-age selection efficiency and correlations are introduced to assist the tree breeder in deciding selection age. When observed age-to-age correlations in a field test exceed the required minimum, selection at the current age will yield a higher rate of improvement than selection at an older age. For. Sci. 34(4):928-938.
Model Fitting Under Patterned Heterogeneity of Variance
Authors: Gregoire Timothy G. , Dyer Michael E. 
Published: April 2024

Abstract
Two approaches toward fitting regression models with multiplicative error heteroscedasticity recur in the forestry, ecology, and statistical literature. One includes the estimation of the heterogeneity in the fitting process. The alternative approach entails the use of variance estimators that are robust to the error variance heterogeneity. Under suitable conditions, the former method offers nonnegligible gains in efficiency, whereas the robust alternatives provide accurate assessment of ordinary least squares estimators even in the presence of heteroscedasticity. The performance of both approaches are examined and contrasted, and suggestions for future applications and research are made on the basis of these results. For. Sci. 35(1):105-125.
Application of Growth Models For Simulating Genetic Gain of Loblolly Pine
Authors: Knowe Steven A. , Foster G. Sam 
Published: April 2024

Abstract
A technique for predicting genetic gain in progeny tests using height-age models and stand simulations is presented for loblolly pine (Pinus taeda L.). Periodic remeasurements for a block-plot open-pollinated progeny test are used to examine trends in height growth, selection differential, and percent gain in height and volume. Using the Chapman-Richards model and approximate F tests, significant differences among families were detected in asymptote and rate parameters but not for the shape parameter. Separate base-age invariant height-age equations were developed for each family to account for polymorphism associated with the rate parameter.
Selection differential calculated from either observed or predicted heights exhibited similar trends although estimates from the height-age equations are consistently higher than obtained with observed height after age 5. Family rankings using the height-age models are consistent with those obtained using observed heights. Also, percent gain calculated from predicted heights is within 2% of the estimates obtained with observed heights at ages greater than 3 years.
Differences in survival, height, and diameter were combined to examine trends in volume production associated with families. Predicted volume for each family was simulated using a bivariate distribution of height and diameter accounting for differences in height-growth patterns among families. Family rankings for volume are also closely correlated, resulting in two or three of the same families being selected using observed and predicted data. Selection differential obtained from simulated and observed volume fluctuates in rank producing a satisfactory trend based on predicted volume after age 5. Gain based on simulated volume tends to be slightly greater than gain based on observed volume. Estimates of percent gain obtained by reinitializing the simulations with quadratic mean dbh and residual trees per acre after thinning differed more from the observed trends than the unthinned simulations. For. Sci. 35(1):211-228.
Projections with Ingrowth by Markov Chains
Authors: Valentine Harry T. , Furnival George M. 
Published: April 2024

Abstract
A Markov chain that accounts for ingrowth as well as growth, death, and harvest of trees is formulated for projecting a size-class distribution. Live trees of minimal or greater size reside in size classes 1 through n. A special size class 0 serves as a reservoir of potential ingrowth trees and as a repository for dead or harvested trees. Ingrowth is the movement of a tree out of size class 0 and into a larger size class. Conversely, death or harvest is represented by the movement of a tree out of a larger size class and into size class 0. Application of the Markov chain, including the calculation of a stationary size-class distribution, is demonstrated. For. Sci 35(1):pp. 245-250.