bluuebunny/crossref_metadata_2025 huggingface dataset:
Spruce Budworm Defoliation and Growth Loss in Young Balsam Fir: Cohort Models of Needlefall Schedules for Spaced Trees
Authors: Fleming Richard A. , Piene Harald
Published: April 2024

The relationship between the age-specific rates of needlefall, q(x), and needle age, x, for cohorts of needles from young, spaced balsam fir (Abies balsamea [L.] Mill.) was described by the discrete hazard function of the Weibull model, q(x) = 1 - exp{(xs - [x + 1]s)/us}. Here u = 6.32 yr (SE = 0.122 yr), s = 3.03 (SE = 0.109), and R² = 0.982. These age specific rates increased with needle age, demonstrating a type I pattern of needlefall. Three phases of needlefall were distinguished. An "early life" phase in which the mean rates of needlefall remained under 10% per year occurred during the first 2 years of existence. Later, up to about needle age 4, the rates climbed steadily upwards with age (at 5.5% per year per year). After age 4, the rate of increase in needlefall with age increased to over 8% per year per year. This may be due to the onset of old-age or wear-out effects in the progressive deterioration of the needles with age. Use of crown level and year of observation as independent variables in addition to needle age did little to extend the explanatory power of our models. These results are consistent with the period analysis performed by Fleming and Piene (1992) on the same stands.

Because of the large year-to-year variability in age-specific rates of needlefall, fits of the Weibull's discrete hazard function to individual cohorts usually left over half the variation in the rates unexplained. This contrasted with the period analysis in which the Weibull model explained over 80% of the variation each year. Hence, despite the success of the period analysis, the large year-to-year variability drastically restricts our ability to predict age-specific rates of needlefall. Although the Weibull model may describe future needle age distributions within a given year accurately, large fluctuations in parameter values, possibly reflecting weather-caused variations or long-term cycles and trends in needlefall, can be expected. For. Sci. 38(3):678-604.
The Variability of User-Based Social Impact Standards for Wilderness Management
Authors: Williams Daniel R. , Roggenbuck Joseph W. , Patterson Michael E. , Watson Alan E.
Published: April 2024

A key element of wilderness management planning is prescribing standards for acceptable levels of impact or change to wilderness conditions based on input from the public. Specifically, to obtain standards for social impacts, wilderness users are surveyed to determine acceptable levels of encounters with other parties. Using a variance components model and generalizability analysis, this study examines four sources of variation in user-based social impact standards: occasion (on-site vs. mailback surveys), wilderness area, encounter context (type and location of encounter), and respondent. Data come from a survey of visitors to four wilderness areas. Results indicate that social impact standards are generalizable across wilderness areas and to a lesser degree across measurement occasions. As expected, social impact standards vary depending on the context of contact. Contrary to normative theory in sociology, standards are also highly variable across respondents. These results suggest that respondents appear to share a high level of sensitivity to encounters, but that the task of assigning a numerical standard may be too abstract or hypothetical to be meaningful. Generalizability coefficients are reported to provide guidelines to future researchers and wilderness managers for obtaining user-based standards. For. Sci. 38(4):738-756.
Evaluating the Stability of Softwood Lumber Demand Elasticity by End-Use Sector: A Stochastic Parameter Approach
Authors: Adams Darius M. , Boyd Roy , Angle John
Published: April 2024

Estimates of the elasticity of demand for softwood lumber are obtained from a production theoretic model disaggregated by major end-using sector. Model parameters are treated as stochastic and estimated using the Kalman filter algorithm. The analysis supports Spelter's (1985) earlier findings of a highly inelastic aggregate U.S. demand for softwood lumber and that this elasticity has declined over the period since 1950. The extent of the decline was found to be only some 25%, however, and to have occurred in a relatively uniform fashion. Lumber demand elasticities in specific end-use sectors varied widely. Significant declining elasticity trends were found only in residential upkeep and alteration and materials handling. These trends arise from both a declining share of lumber in the costs of wood-based inputs and declining elasticities of demand for the wood-based inputs themselves. At the aggregate level, the significant declining trend in elasticity derives both from changing consumption shares across end uses and from the combined movements of the component elasticity series. For Sci. 38(4):825-841.
Allocating Resources to Large Wildland Fires: A Model with Stochastic Production Rates
Authors: Mees Romain , Strauss David
Published: April 2024

Wildland fires that grow out of the initial attack phase are responsible for most of the damage and burned area. We model the allocation of fire suppression resources (ground crews, engines, bulldozers, and airdrops) to these large fires. The fireline at a given future time is partitioned into homogeneous segments on the basis of fuel type, available resources, risk, and other factors. Each is assigned a utility value corresponding to the importance of holding the segment. For a given resource allocation, the probability of holding the segment is modeled in terms of the (random) width of fireline built. The task is then to find the allocation that maximizes the expected total utility. With certain restrictions, it proves possible to formulate the optimization as a linear programming problem. Use of the model is demonstrated with a case study of a large fire representative of conditions on the Los Padres National Forest in southern California. One feature is that different assumptions about the uncertainty in the predictions of constructed fireline widths can lead to differences in the optimal resource allocations. Thus, if one inappropriately took the uncertainty to be zero (the deterministic case), the resulting allocation may well not be the optimal one. This illustrates the potential advantage of probabilistic modeling over the previous deterministic approach. For. Sci. 38(4):842-853
No Relationship Between Fir Decline and Air Pollution in the Bavarian Forest
Authors: Kandler Otto
Published: April 2024

The alleged relationship between fir decline and air pollution in the Bavarian Forest, claimed by Visser and Molenaar (1992), is due to the use of an inadequate measure of the degree of air pollution and a biased set of tree ring data. For Sci. 38(4):866-869.
Multiple-Pass Harvesting and Spatial Constraints: An Old Technique Applied to a New Problem
Authors: Nelson J. D. , Errico D.
Published: April 2024

A methodology for approximating and incorporating spatial harvesting constraints into forest-level, aspatial models is presented. First, operational cut block scheduling methods based on map-coloring theory are used to sample the number of passes and the percentage of area-per-pass that can be harvested without violating adjacency and exclusion period constraints for a given set of harvesting guidelines. These results are defined as spatial approximation rules, and they are subsequently used to control harvest rates within a spatial approximation model. In test cases, the multiple-pass harvesting technique used in the spatial approximation model appears to closely estimate actual cut block schedules. Two major advantages of the spatial approximation technique are: (1) the onerous task of designing and scheduling cut blocks for an entire forest is not necessary, and (2) policy analysis is enhanced because the spatial approximation rules can be quickly altered to reflect different harvesting guidelines. Model calibration and optimization of harvest timings are identified as areas requiring further research. FOR. SCI. 39(1):137-151.
Southern Pine Beetle Infestation Development: Interaction Between Pine and Hardwood Basal Areas
Authors: Showalter T. D. , Turchin P.
Published: April 2024

We evaluated the interactive effects of pine and hardwood basal areas on stand susceptibility to southern pine beetle during 2 yr. Low and high pine basal areas (12 vs. 25 m²/ha, respectively) and presence and absence of hardwoods (11 rs. 2 m²/ha, respectively) were represented in a 2 x 2 factorial experiment replicated in four blocks of 30-40-year-old pine stands during 1989 and 1990. Infestations were initiated by introducing bolts containing southern pine beetle pupae and callow adults from two infested trees into each experimental plot. Bolts were placed around a baited tree that provided a focus for attack.

During both years the dense, pure pine treatment showed significantly greater infestation growth than the other treatments, killing an average of 9 trees during 1990 and 6 trees for the 2 yr combined. Infestations in the other treatments killed, on average, only the baited tree. These results demonstrated experimentally that thinned stands are less susceptible to southern pine beetle and that hardwoods apparently do not increase susceptibility but may interfere with infestation growth. Implications of these results for forest management are discussed. FOR. SCI. 39(2):201-210.
Turbulence Near the Forest Floor of an Old-Growth Douglas-Fir Stand on a South-Facing Slope
Authors: Lee Xuhui , Black T. Andrew
Published: April 2024

This paper reports the results of the analysis of measured turbulence regimes near the forest floor in an old-growth Douglas-fir stand on a south-facing slope in northern Vancouver Island, Canada. Primary instrumentation included one eddy correlation unit, which consisted of a three-dimensional sonic anemometer, a krypton hygrometer and a fine wire thermocouple, and four home-made hot wire anemometers.

The general features of the turbulence regimes near the forest floor within this stand were similar to those observed previously in other stands with an open trunk space. The high value of the ratio of the wind speed inside the stand to that outside (0.42) suggested the existence of a secondary maximum in the stand wind profile. The wind speed near the forest floor was approximately a logarithmic function of height with an effective roughness length of 0.012 m. The average turbulence intensity was 0.86. Power spectra for the streamwise and lateral velocity components exhibited a bimodal distribution in contrast with a unimodal distribution for the spectrum of the vertical component. Near the forest floor, latent heat and sensible heat generally flowed down humidity and temperature gradients, respectively. Some unique features were also observed, namely the suppression of the vertical velocity variance by the moderate to strong temperature inversion in the daytime and the occurrence of a very small eddy diffusivity for sensible heat flux. FOR. SCI. 39(2):211-230.
Prediction Equations for Centers of Gravity and Moments of Inertia of Loblolly Pine Stems
Authors: Lynth Thomas B. , Max Timothy A. , Burkhart Harold E. , Liu Jiping
Published: April 2024

Adequate design of tree harvesting equipment requires reliable estimates of centers of gravity and moments of inertia for full trees and tree-length stems. Several prediction models were developed for both centers of gravity and moments of inertia based on the theory of geometric solids. These models were fitted to center of gravity and moment of inertia estimates that were derived from stem dimension and weight measurements on loblolly pine (Pinus taeda L.) trees. The models were compared, and the best prediction equations for center of gravity and moment of inertia of tree-length stems were identified. Application of standard multiple regression methods resulted in a moment of inertia prediction model with a slope parameter estimate that had a sign opposite to that indicated by a theoretical model. Ridge regression and nonlinear regression were used to fit moment of inertia prediction models having coefficient signs consistent with those predicted by the theoretical model. The parameter estimates obtained by nonlinear regression were selected since they conformed more closely to properties of the theoretical moment of inertia model. FOR. SCI 39(2):260-274.
Soil Moisture Stress Induces Transplant Shock in Stored and Unstored 2 + 0 Douglas-Fir Seedlings of Varying Root Volumes
Authors: Haase Diane L. , Rose Robin
Published: April 2024

Transplant shock was induced by applying a range of soil water contents to unstored and cold-stored 2-yr-old (2 + 0) bareroot Douglas-fir seedlings graded by root volume. Moisture stress had the greatest influence on morphological characteristics that express transplant shock. Seedling terminal growth, stem diameter growth, and needle length increased dramatically with increased soil moisture content. In addition, number of needles per centimeter on the terminal greatly increased with increasing moisture stress. Under high moisture stress, seedlings with relatively high root volumes tended to exhibit early reduced growth, but later showed significantly increased overall growth regardless of soil water content. In every case, seedlings grown in the driest soil had the lowest dry weights and those grown in the most moist soil had the highest weights for all seedling components. Similarly, seedlings with the smallest initial root volumes had the lowest dry weights, and those with the largest root volumes had the highest weights. The results indicate that moisture stress is a cause of transplant shock, and that increased seedling root volume may enable seedlings to avoid shock following outplanting to a specific site. FOR. SCI. 39(2):275-294.
More on Forest Regulation: An LP Perspective
Authors: Hoganson Howard M. , McDill Marc E.
Published: April 2024

Optimal solutions to some 2500 linear programming formulations were compared to examine the impact of forest regulation constraints. The solutions demonstrate that regulation can be expensive, with no simple rules available to describe how a regulated forest can best be achieved or what rotation age should be used for the regulated forest. The optimal rotation age can be longer or shorter than the Faustmann rotation, but results strongly suggest that the optimal rotation will be close to the Faustmann rotation if long conversion periods are used. The cost of regulation can be sensitive to the length of the conversion period, the initial age distribution of the forest, stability constraints on harvests during the conversion period, and the range of management options and rotation ages possible. Large cost savings are sometimes possible with relatively small increases in the length of the conversion period. The need to hold land idle during the conversion period can substantially increase the cost of regulation. FOR. SCI. 39(2):321-347.
Interactive Role of Elevated CO2, Nutrient Limitations, and Water Stress in the Growth Responses of Red Spruce Seedlings
Authors: Samuelson Lisa J. , Seiler John R.
Published: April 2024

Red spruce (Picea rubens Sarg.) seedlings were grown from seed for 5 mo in ambient (362 ppm) or elevated (711 ppm) CO2 to determine the potential effect of an increase in global CO2 concentration on seedling growth and establishment. CO2 exposure treatments were crossed with two levels of soil fertility and water stress treatments to determine if seedling dry weight, size, and fixed growth responses to elevated CO2 depended on nutrient and water supply. Seedling dry weight and size responses to elevated CO2 at 5 mo did not depend on nutrient and water supply. Seedlings grown in both soil fertility treatments and water stress treatments responded similarly to CO2 treatment. Water stress and CO2 treatments did have an interactive influence on the fixed growth potential of the terminal leader. Leaf weight, leaf area, and height of the terminal leader of water-stressed seedlings were greater in seedlings exposed to elevated CO2 during budset than seedlings exposed to ambient CO2. Total new fixed growth (lateral plus terminal) and total terminal fixed growth (leaf plus stem) were greater in seedlings that formed shoot primordia in elevated CO2 than in ambient CO2. Red spruce seedlings grown in elevated CO2 for 5 mo had greater stem diameter, height, branching density, leaf weight, root weight, stem weight, total weight, and mean relative growth rate (RGR) from 3 to 5 mo than seedlings grown in ambient CO2. Red spruce seedling responses to elevated CO2 suggest that seedling establishment in natural environments may be enhanced when ambient CO2 concentrations rise even if water and nutrient availabilities are limited. FOR. SCI. 39(2):348-358.
Interference Interactions in Simulated Pine-Hardwood Seedling Stands
Authors: Fredericksen Todd S. , Sedaker Shepard M. , Seiler John R.
Published: April 2024

A multiresource factor approach, using biomass allocation patterns and resource-use efficiencies, was employed to investigate interference mechanisms in mixed species tree seedling stands. Seedling mixtures of loblolly pine (Pinus taeda L.) with one of two hardwood tree species, black locust (Robinia pseudoacacia L.) or red maple (Acer rubrum L.), were grown together at close spacing under well-watered and water-stressed conditions in a greenhouse. Pure stands of each species were included as controls. Greatest biomass growth increment was observed in pure hardwood stands, while pure pine stands had the lowest increments. Interference in mixed stands was highly one-sided, with hardwoods suppressing pine growth. Mechanisms or attributes accounting for interference outcomes included higher relative growth rates, increased below-ground allocation of photosynthate, effective display of foliage, and higher resource-use efficiencies of hardwood species. Interference strategies differed for hardwood species. Black locust could be classified as an uptake specialist with a high relative growth rate and a low root:shoot ratio. Red maple was a resource-use specialist, exhibiting high internal resource-use efficiencies for light, soil moisture, and nitrogen. FOR. SCI. 39(2):383-395.
Influence of Dwarf Mistletoe and Western Spruce Budworm on Growth and Mortality of Douglas-Fir in Unmanaged Stands
Authors: Filip Gregory M. , Colbert J. J. , Shaw III C. G. , Hessburg Paul F. , Hosman Kevin P.
Published: April 2024

Permanent inventory plots in 94 unmanaged stands of primarily Douglas-fir (Pseudotsuga menziesii) on three national forests in Oregon and Washington were examined for growth suppression caused by dwarf mistletoe (Arceuthobium douglasii) and western spruce budworm (Choristoneura occidentalis). Ten-year increments of diameter and basal area were calculated from measurements in 1977-1987. Severity of dwarf mistletoe was scored using the six-class system. Severity and duration of defoliation were determined from aerial maps drawn over a 20-yr period.

Dwarf mistletoe significantly decreased 10-yr diameter increment. Western spruce budworm significantly reduced diameter increment and basal area increment. No significant interactions between defoliation and dwarf mistletoe were found.

Ten-year mortality of Douglas-fir due to dwarf mistletoe averaged 5% and 2% of the infected trees and basal area, respectively, for stands with moderate dwarf mistletoe severity and 4% and 3% of the infected trees and basal area, respectively, for stands with severe dwarf mistletoe infestation. Mortality was highest in stands with the most dwarf mistletoe and in stands with the most severe defoliation. There were no significant differences in diameters of dead trees among severity classes for dwarf mistletoe. Dead-tree diameters were significantly smaller in stands with the most severe defoliation during the measurement period. For. Sci. 39(3):465-477.
Ecotypic Specificity of Spruce Emergence-Stimulating Pseudomonas putida
Authors: Chanway C. P. , Holl F. B.
Published: April 2024

Hybrid spruce (Picea glauca X engelmannii) seed and seedlings were collected from two sites in British Columbia, near Mackenzie and near Salmon Arm. One strain of Pseudomonas putida was isolated from the rhizosphere of seedlings collected from each site. These strains were deduced to be distinct from each other based on analysis of bacterial fatty acids. Experiments were conducted to determine if P. putida affected spruce seedling emergence, and if the nature or magnitude of these effects were related to the geographic origin of bacteria and seed. Inoculation of spruce with P. putida that did not originate from the same site as the seed caused an increase in the number of seedlings that emerged, but this effect was not statistically significant. However, when the origin of the spruce seed was matched to that of the P. putida strain, a significant (P < 0.05) increase in the amount and rate of seedling emergence was detected. These results are discussed in relation to the regeneration strategy of spruce in natural forests. For. Sci. 39(3):520-527.
Colonization Patterns of the Mountain Pine Beetle in Thinned and Unthinned Lodgepole Pine Stands
Authors: Preisler Haiganoush K. , Mitchell Russel G.
Published: April 2024

Outbreak populations of the mountain pine beetle, Dendroctonus ponderosae Hopkins, in central Oregon, were analyzed with an autologistic regression model to evaluate colonization patterns in thinned and unthinned plots of lodgepole pine, Pinus contorta Dougl. Results confirmed previous observations that beetle attacks in unmanaged stands were related to tree diameter and spacing among trees. Beetles showed a decided preference for colonizing trees with large diameters. Trees with small diameters were rarely attacked unless they were close to other trees under attack. Thinned plots were initially unattractive to beetles, but when attacks occurred, colonization was not very different from the pattern in unthinned plots. Conditional probabilities of attack for trees near other attacked trees were actually greater in thinned plots, indicating that the wide spacing between trees in these plots did not seem to interfere with the switching of attacks between trees. Vigor was not a significant covariate for estimating probability of attack in the unthinned plots. It was significant for one of the thinned plots, however, and marginally significant for another. Only one tree was colonized in a third thinned plot that had the widest spacing and the greatest vigor. A surprise was that some of the oldest trees on thinned plots appeared resistant to attack; their resistance was unrelated to diameter, vigor, or position relative to other attacked trees. For. Sci. 39(3):528-545.
Photosynthetic Apparatus in Cold-Stored Conifer Seedlings Is Affected by Nursery and Storage Photoperiod
Authors: Camm Edith L. , Lavender Denis P.
Published: April 2024

The photosynthetic apparatus of outdoor grown seedlings of white spruce (Picea glauca [Moench] Voss) and lodgepole pine (Pinus contorta Dougl. var. latifolia Englem.) responded in different ways to similar nursery and storage photoperiod treatments. Seedlings of both species were (1) exposed to natural or short days (SD: 8-hr photoperiod for 4 or 8 wk) during late summer, (2) returned to natural conditions, and (3) subsequently put in indoor storage at 2°C in the dark or with a low intensity photoperiod (≤15 μmol m-2-s-1, 8 hr daylength) for a 6 mo storage period starting October, December, or January. Poststorage measurements of chlorophyll (chl) a fluorescence in light-stored white spruce showed, relative to dark controls, increased variable fluorescence and decreased photochemical quenching (qP), with little increase in nonphotochemical quenching (qN). In contrast, qP was relatively unaffected in lodgepole pine seedlings, although the combination of SD treatment followed weeks later by light in storage induced an increase in qN. The sequentially applied SD treatment plus light during storage also led to the accumulation of a foliar 23kD protein in pine seedlings. The above foliar responses to the treatments were only weakly related to effects of treatments on diameter and height increase assessed 3 mo after spring planting. The interaction of the treatments shows that the pine foliage was able to integrate environmental signals received months apart. For. Sci. 39(3):546-560.
Influence of Water Relations on the Limited Expansion of Pinus Monophylla into Adjacent Cercocarpus Ledifolius Communities in the Central Great Basin
Authors: Jaindl R. G. , Doescher P. S. , Eddleman L. E.
Published: April 2024

We investigated the influence of plant water relations on the limited expansion and dominance of Pinus monophylla (an arid land coniferous tree) into adjacent Cercocarpus ledifolius (an evergreen nonconiferous shrub or small tree) communities. Water relations and growth of both species were monitored during 2 growing seasons on a P. monophylla dominated, alluvial fan (2070 m) and a C. ledifolius dominated, exposed ridge (2745 m). In 1990, the influence of supplemental water at the lower site was investigated. Carbon isotope composition was determined from material collected in August 1990. Predawn and midday xylem pressure potentials and transpiration rates suggested that P. monophylla was more water-use efficient than C. ledifolius. Cercocarpus ledifolius had higher transpiration rates throughout the growing season and reached lower xylem pressure potentials late in the season. This suggests C. ledifolius is better able to take advantage of available water for recharging plant moisture and rapid water use. Supplemental water's only effect was a significant increase in C. ledifolius transpiration. Carbon isotope ratios (∂13C) were more negative for C. ledifolius than P. monophylla and with increasing soil water availability. Lower rates of growth and water-use patterns by P. monophylla are not an advantage in the C. ledifolius zone and contribute to its limited expansion into this zone. For. Sci. 39(4): 629-643.
A Generalized Methodology for Estimating Forest Ingrowth at Multiple Threshold Diameters
Authors: Shifley Stephen R. , Ek Alan R. , Burk Thomas E.
Published: April 2024

Ingrowth is defined as the number or volume of trees that periodically grow into the smallest measured size class of a forest stand. We present a model to predict the number of ingrowth trees at a variable threshold diameter for 6 forest vegetation types common to the central United States. The model is based on observations on 2,373 remeasured inventory plots from 8 sources in Missouri, Illinois, Indiana, and Ohio. The number of ingrowth trees decreases significantly with increasing threshold diameter. The concept of crown competition factor was used to set a biologically realistic upper limit on the number of ingrowth trees for any given threshold diameter. Number of ingrowth trees · acre-1 · decade-1 was predicted as a function of the maximum possible number of ingrowth trees and the threshold diameter. Fitted models were highly significant for all forest types, and the general shape of the response surface was biologically realistic. Precision of the estimates was low because ingrowth is a highly variable process. For. Sci. 39(4):776-798.
Biotechnical Progress in Forestry: An Optimal Control Analysis
Authors: Bhattacharyya Anjana , Lyon Kenneth S.
Published: April 2024

A discrete time optimal control model is constructed in this paper to measure the gains from biological research expenditures in forestry. This is an extension of the timber supply model of Sedjo and Lyon (1990). We posit a production function for biotechnological improvements, which take the form of improved varieties of seeds and improved silvicultural practices. The model takes into account all the dynamic benefits from a dollar of research spending in terms of its effect on the current and future levels of technology, and of the future timber supplies resulting from the improved seeds and management practices. These separate effects are tracked in the model using state variables for the "index of technology" and for the "embodied yield index." The results of implementing the model on data for the U.S. South are reported. The empirical results indicate that biotechnical productivity gains in the range of 8 to 16% over a 25-yr period are sufficient to justify investment in biotechnology at historic levels. For. Sci. 40(1):120-141.
A Column Generation Algorithm for Solving General Forest Planning Problems with Adjacency Constraints
Authors: Weintraub Andrés , Barahona Francisco , Epstein Rafael
Published: April 2024

An algorithm is presented for solving general forest planning models when spatial relationships, in particular adjacent constraints, are considered. We solve a master linear program with a column generation approach. The generation of columns is done by solving a stable set problem. To preserve the adjacency properties, fractional solutions in the master problem are rounded off to integrality through a heuristic procedure. Computational experience on medium-sized problems showed that solutions with small deviations from the optimal could be obtained with moderate computational effort. For. Sci. 40(1):142-161.
Variation in Potential Volume Yield of Loblolly Pine Plantations
Authors: Hasenauer Hubert , Burkhart Harold E. , Sterba Hubert
Published: April 2024

Variation in the potential volume at a given site index, which is a result of differences in the maximum basal area, was investigated using data from permanent plots in loblolly pine plantations across the southern United States. The data were stratified into three physiographic regions--Atlantic Coastal Plain, Piedmont, and Gulf Coastal Plain--and the maximum stand density index (SDImax) value (Reineke 1933) was estimated for each stand by applying Sterba's (1975) extension of the competition density rule of Kira et al. (1953).

The Gulf Coastal Plain exhibited the lowest density potential and differs significantly from each of the other two regions. Between the Atlantic Coastal Plain and the Piedmont, no significant differences in the density potential exist. Significant differences mean different maximum basal areas and therefore differences in the total yield within the same site index; these differences in yield cannot be detected using the site index method only.

Data from the control plots, which represent the stand development without any thinning influences, showed that the variation between the regions was mainly due to differences in the potential of supporting trees/ha. This result was confirmed by calculating the mean relative space (Hart 1928) for each region. The relationship between top height and volume/ha for the unthinned control plots showed different volume production potential under comparable conditions at a given top height among the regions. The volume development figures follow the same order by region as the SDImax values. The highest potential (volume/ha at a given top height) is represented by the Atlantic Coastal Plain, followed by the Piedmont, followed by the Gulf Coastal Plain. For. Sci. 40(1):162-176.
Landscape Characterization of Forest Susceptibility to Gypsy Moth Defoliation
Authors: Liebhold Andrew M. , Elmes Gregory A. , Halverson Joel A. , Quimby John
Published: April 2024

This paper seeks to relate defoliation by the gypsy moth, Lymantria dispar (L.), to components of the landscape in order to elucidate processes operating at the regional scale. Aerial sketch maps of gypsy moth-caused defoliation in Pennsylvania from 1969-1989 were assembled in a raster-based geographical information system (GIS). These images were manipulated using Boolean algebra to determine the total defoliation frequency for each 2 X 2 km grid cell over the 21-yr study period. Because the gypsy moth became established in different parts of Pennsylvania at different times, the defoliation frequency for each cell was corrected by dividing the raw frequency by the total number of years at risk to defoliation. The number of years at risk to defoliation was calculated as the number of years each area was considered within the generally infested area minus a constant lag term, to correct for the period in years between first designation of quarantine until first defoliation. For Pennsylvania the lag was estimated as 5 yr. Average defoliation frequencies were calculated for each of six major forest type groups occurring in Pennsylvania. Pine, oak-pine, and oak-hickory type groups were the most susceptible to defoliation; maple-birch-beech, aspen-birch, and nonforest-type groups were the least susceptible. The high defoliation frequency in pine types reflects heavy feeding on oaks in these areas since gypsy moth larvae rarely feed on most pine species. Forest type group areas were further cross-tabulated by elevation classes. The three most susceptible forest type groups exhibited decreased susceptibility at elevations lower than 200 m. For. Sci. 40(1):18-29.
Sampling with Partial Replacement and Stratification
Authors: Scott Charles T. , Köhl Michael
Published: April 2024

Sampling with Partial Replacement (SPR) is extended to double sampling for stratification on three occasions based on the two-occasion case presented by Bickford et al. (1963). Ware and Cunia's (1962) unbiased estimator of net change is extended to double sampling for stratification on two and three occasions. A closed form solution is presented for the two-occasion case. However, the net change estimator in the second-occasion case requires solving a system of seven equations. The estimators presented make it possible to use Sampling with Partial Replacement on two or three occasions, with simple random sampling, stratified random sampling, or double sampling for stratification; and, for estimation of current attributes, their net change between occasions, and components of growth. For. Sci. 40(1):30-46.
Crown Class Transition Rates of Maturing Northern Red Oak (Quercus rubra L.)
Authors: Ward Jeffrey S. , Stephens George R.
Published: April 2024

Crown classes and diameters of 704 northern red oaks on medium quality sites were measured at 10-yr intervals between 1927-1987. Nominal age of northern red oaks at the beginning of the study was 25 yr. Mortality rates between ages 25-55 and between ages 55-85 decreased with each increase in crown class (i.e., mortality of dominant is < codominant is < intermediate is < suppressed). Ascension rates into higher crown classes increased with each increase in crown class between ages 25-55 and between ages 55-85. Mortality rates of dominant, codominant, and intermediate trees were higher between ages 55-85 than between ages 25-55. The cause of the increased mortality was likely periodic episodes of defoliation which began after age 55. Within several diameter classes at age 25, survival through age 55 and the proportion found in upper canopy at age 55 increased with crown class. Mortality rates between ages 25-55 were lower for the largest northern red oak in a sprout clump than for lesser sprouts and for those trees which were not part of a sprout clump. There was no significant difference in canopy position transition rates between ages 55-85 for the largest red oaks in a sprout clump and those trees which were not part of a sprout clump. However, mortality rates between ages 55-85 of lesser trees in a sprout clump were significantly higher than for either the largest sprout in a clump or for those trees which were not part of a sprout clump. Survival of suppressed and intermediate 25-yr-old red oak was negatively related to the number of oaks in dominant and codominant crown classes. Crown class can be a powerful tool for determining the future status of maturing northern red oaks in southern New England. For. Sci. 40(2): 221-237.
Modeling Responses of Ponderosa Pine to Interacting Stresses of Ozone and Drought
Authors: Chen Carl W. , Tsai W. T. , Gomez Luis E.
Published: April 2024

Plant-Growth-Stress Model (PGSM) is a physiologically based process model that integrates the effects of ozone, acid deposition, elevated carbon dioxide, temperature, drought, and nutrient deficiency. The model uses an hourly time step for photosynthesis and a daily time step for all other plant and soil processes. It can be set up to run for as many years as needed. The model was applied to simulate the growth pattern of ponderosa pine seedlings under the experimental conditions of ozone and drought stresses. The simulated diameter and biomass of canopy, roots, and stem were comparable to the measured. Major effect of drought stress was root mortality; however, its sublethal effect on stomata opening caused significant reductions of photosynthesis, canopy, roots, and stem. Ozone stress increased litterfall and decreased canopy. Trees compensated by growing more new needles. The canopy photosynthesis was not reduced to the extent of an across-the-board decrease of roots and stem. Ozone and drought stresses had an antagonistic effect, in which the biomass reductions due to the combined stresses were less than the sum of reductions from individual stresses. However, the observed data indicate a protective effect, not simulated by the model. For. Sci. 40(2): 267-288.
Height Estimation in Stem Analysis Using Second Differences
Authors: Fabbio Gianfranco , Frattegiani Mauro , Manetti Maria Chiara
Published: April 2024

Issa, a new method for estimating heights at different ages from crosscut ring count, is discussed in this paper. Heights corresponding to the location of nodal diaphragms for 27 black pine trees were used as control values to test the precision of the Issa method in comparison with Lenhart's (1972) and Carmean's (1972) methods and with branch whorl method. The algorithms were applied at three different crosscut sampling frequencies (50-100-200 cm). The precision of the methods was tested both in height growth and in annual height increment estimation and the predicted values were analyzed for each sampling frequency. The Issa method was the most precise at a frequency of 50 cm, and the Carmean method was the most precise at a frequency of 200 cm. Lenhart's algorithm produced the least satisfactory estimations independently of crosscut sampling frequency. For. Sci. 40(2):329-340.
Relative Accuracy of a New Base-Age Invariant Site Index Model
Authors: Payandeh Bijan , Wang Yonghe
Published: April 2024

A new base-age invariant site index model was developed based on the constrained version of the Chapman-Richards function. It was compared with that of Goelz and Burk's (1992) in terms of relative accuracy and average bias across a range of potential base ages. The data format for fitting the above models was also simplified. Comparing the models on a set of white spruce (Picea glauca [Moench] Voss) stem analysis data indicated that the choice of predictor age influences the models' accuracy and bias. Except for very young ages, the new model performed as well as that Goelz and Burk's (1992) model in relative accuracy. For. Sci. 40(2):341-348.
Evidence of Reduced Photosynthetic Rates in Old Trees
Authors: Yoder B. J. , Ryan M. G. , Waring R. H. , Schoettle A. W. , Kaufmann M. R.
Published: April 2024

Wood production generally declines as forests age. The decrease in production has been attributed to higher respiration associated with increasing biomass, but direct measurements fail to support this assumption. An alternate hypothesis is that the growth decline is caused by reduced net photosynthesis. To test this hypothesis, we compared the net photosynthetic rates of foliage from trees that had ceased height growth with foliage from actively growing, mature trees. Results showed that net photosynthesis per unit area of 1-yr-old foliage from old Pinus contorta and P. ponderosa averaged 14-30% lower than the same-aged foliage from younger trees. Computer simulations from a previous study indicated that differences of this magnitude are sufficient to explain the lower wood production in old trees. The cause of the photosynthetic decline is not clear, but it did not appear to be due to a reduction in the maximum capacity for photosynthesis. Ratios of stable carbon isotopes from leaves and wood indicated a greater stomatal limitation of photosynthesis in older trees. A possible relationship between lower hydraulic conductance in the vascular systems of older trees leading to greater stomatal closure is discussed. For. Sci. 40(3):513-527.
Basal Area Growth of Individual Trees: A Model Derived from a Regional Longleaf Pine Growth Study
Authors: Quicke Harold E. , Meldahl Ralph S. , Kush John S.
Published: April 2024

An individual tree basal area increment (BAI) model for thinned, even-aged stands of naturally regenerated longleaf pine (Pinus palustris Mill.) is presented. The model is an intrinsically nonlinear equation, which is constrained so that it performs within the bounds of biologically reasonable outputs for any combination of values for the independent variables. All parameters in the equation were estimated simultaneously. This is a departure from the more traditional potential-times-modifier approach in which parameters for a potential growth function are estimated from a sample of trees exhibiting the fastest growth. Independent variables used to describe BAI are stand basal area, the competitive position of an individual tree within the stand calculated as the sum of the basal areas of all trees larger than the subject tree, mean age of dominant and codominant trees, and individual tree diameter outside-bark at breast height. Noticeably absent from the model is an independent variable that explicitly characterizes site differences. For. Sci. 40(3): 528-542.
Surrogates for Foliar Dry Matter in Loblolly Pine
Authors: Valentine Harry T. , Baldwin V. C. , Gregoire Timothy G. , Burkhart Harold E.
Published: April 2024

Surrogates of foliar dry matter of trees commonly are used in applications of modeling and sampling. Some surrogates are linearly related to foliar dry matter. In this study, the linear relation between foliar dry matter (F) and cross-sectional area of the bole at the base of the live crown (A) was examined in loblolly pine (Pinus taeda L.). In addition, a linear relation was established between F and BR, where B is the cross-sectional area of the bole at breast height, and R is the ratio: (length of the live crown)/(tree height minus breast height). Slopes (c1 and c2) of linear models (F = c1 A and F = c2 BR) were estimated with maximum likelihood procedures with data gathered in: (1) June through mid-August 1984, in central Louisiana, (2) August and September 1991, in Virginia and North Carolina, and (3) August and September 1992, in central Louisiana. The estimates of both c1 and c2 obtained from data gathered in June through mid-August were greater than the estimates obtained from the two sets of data gathered in August and September. The estimate of c2 was as precise as the estimate of c1 obtained from each of the three sets of data. BR appears to be as good a surrogate for F as A. Linear relations between foliar dry matter and cross-sectional area of first-order branches in lower, middle, and upper crown strata also were examined. Branches in the lower stratum had less foliar dry matter per unit of cross-sectional area than branches in the other two strata. For. Sci: 40(3):576-585.
A Method to Determine Optimal Stand Data Acquisition Policies
Authors: Ståhl Göran , Carlsson Dick , Bondesson Lennart
Published: April 2024

A method to determine optimal forest stand data acquisition policies is presented. The method is based on a proposal about how timber management planning could be performed, recognizing that stand data cannot be exactly known. It is suggested that decisions be made using probability distributions of values in the calculations instead of point estimates. Within this planning framework, using Bayesian theory, a posterior distribution can be calculated if an inventory is carried out. The probabilities for different posterior distributions can also be calculated. As different distributions may imply different optimal harvest actions, the expected inoptimality losses from erroneous harvest decisions will decrease after an inventory. However, if an inventory is to be an adequate decision, the inventory cost must not be higher than the expected decrease in losses. The numerical results showed that the profitability of inventories depends to a large extent on factors such as the interest rate, stumpage value, compartment size, stand age, and prior distribution of true stand volume. We found inventories to be most profitable if they were undertaken well ahead of calculated optimal harvests. Moreover, we also found that a series of moderately precise but cheap inventories was superior to one single very precise but expensive inventory. For. Sci. 40(4):630-649.
Characterization of Hybrid Poplar Clones for Resistance to the Forest Tent Caterpillar
Authors: Robison Daniel J. , Raffa Kenneth F.
Published: April 2024

Forest tent caterpillar, Malacosoma disstria Hbn., behavioral and developmental interactions with 15 hybrid Populus spp. clones were studied in laboratory and glasshouse trials. Significant differences in larval preference and performance among the clones were found. Larval development time ranged from 30 to 52 days. Second-instar preference and larval development were significantly correlated, but 4th-instar preference and larval development were not. Second- and fourth-instar preferences were not correlated. Clonal productivity and tolerance of defoliation varied significantly, but were not correlated. The relationships between productivity, defoliation tolerance, and insect resistance were examined in regard to plant defense theory, host plant resistance, clonal selections for tree improvement, and assay utility. For. Sci. 40(4):686-714.
Buyer and Seller Behavior in Single-Buyer Stumpage Sales
Authors: Hardie Ian W. , Larson Douglas M.
Published: April 2024

While stumpage sales involving a single buyer are commonly observed, we have no evidence that lack of buyer competition will, in and of itself, result in different stumpage prices. Nor do we have an explanation why such sales continue to be made in markets where stumpage owners can instigate buyer rivalry. Finally we have no theory explaining how buyers decide what to bid when direct competition from other buyers is not present. This paper addresses these three issues. We offer evidence that price differences can exist between single-buyer and multiple-buyer sales. We show why it can be economically rational for nonindustrial private forest owners to conduct single-buyer sales. And we offer a theoretical explanation of buyer bid and owner bid-acceptance decisions in single-buyer sales that is consistent with some previously observed relationships between stumpage prices and owner characteristics. For. Sci. 40(4):759-773.
Observer Variation as a Source of Error in Assessments of Crown Condition Through Time
Authors: Ghosh Sucharita , Innes John L. , Hoffmann Christian
Published: April 2024

Data from the annual assessments of forest condition in Switzerland indicate that there are a number of problems with the collection of even the most basic information relating to forest condition. Of the 13 indices examined, 3 are assessed as continuous variables and 10 as categorical variables. In all cases, significant (P < 0.05) differences were found in 1 or more years between the field teams and the control team(s). For two measures of defoliation, these differences were present in all years. The assessment of the categorical variables was more reliable, but the differences indicate that the data must be treated with caution, even when only two or three relatively simple options are available to the surveyors. The surveyors involved in the work were all experienced foresters who had received a high level of training. The results suggest that many data related to forest measurement and assessment that have been reported in the literature cannot be reliably compared. The results also indicate an urgent need for the intensification of quality assurance work (training and subsequent checking) within the context of forest assessment. For. Sci. 41(2):235-254.