bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tree-Growth and Understory Responses to Low-Severity Prescribed Burning in Thinned Pinus ponderosa Forests of Central Oregon
Authors: Busse Matt D. , Simon Steven A. , Riegel Gregg M. 
Published: April 2024

Abstract
The growth of ponderosa pine and associated understory vegetation was evaluated for a 6 yr period following spring underburning of surface fuels. Underburn and control (unburned) plots were paired at 15 replicate sites in pole-sized ponderosa pine forests of central Oregon. The burns were generally low in severity, as noted by low 0 horizon mass reduction (24%) and tree mortality (6%). A small but significant decline in basal area and volume growth rates of surviving trees was found in the 6 yr following underburning. The reduction in tree growth was related to a combination of crown length reduction, 0 horizon reduction, and site productivity. More productive stands had the highest proportional reduction in growth due to burning. By comparison, site conditions including stand density, initial basal area, elevation, parent material, and soil fertility were not related to the observed growth reduction. Understory vegetation showed a mixed response to burning. Shrub cover, dominated by Purshia tridentata, declined significantly following burning and remained well below preburn levels for the length of the study, even though one-fourth of all burned Purshia plants successfully resprouted. Total herbaceous vegetation cover and production were unaffected by burning, while species diversity increased slightly. With the exception of the decline in Purshia cover, the results indicate that low-severity prescribed burning has a relatively minor impact on tree-growth and understory response in thinned ponderosa pine stands. For. Sci. 46(2):258-268.
Predicting Daily Mean Soil Temperature from Daily Mean Air Temperature in Four Northern Hardwood Forest Stands
Authors: Brown Shannon E. , Pregitzer Kurt S. , Reed David D. , Burton Andrew J. 
Published: April 2024

Abstract
Soil temperature is very important in regulating ecosystem processes, yet it is often difficult and costly to measure. Most models that have endeavored to predict soil temperature have either a long time step or several complicated independent variables. Daily mean air and soil temperatures were measured from 1989-1997 in four northern hardwood sites along a 500 km latitudinal gradient in Michigan. These data were used to derive a simple method to predict daily mean soil temperature (depth of 15 cm) using the daily mean air temperature from the previous day and a cosine function of Julian date (R² = 0.93-0.96; SEM = 0.98-1.40°C). Predicted values were compared with actual recorded soil temperatures from 1997 at each of the sites, and the average difference between the observed and predicted values ranged from 0.11 to 0.39°C. Different coefficients were estimated for each of the sites; however, this general method of predicting soil temperature appears applicable to any site. Once calibrated for a given site, soil temperature may be simply estimated, thus reducing the need for extended monitoring efforts. This method also allows the reconstruction of soil temperature records beyond the monitoring period. Projecting long-term trends in soil temperature may help to further elucidate several ecosystem processes and also may provide more information on how a changing global climate will impact forest ecosystems. For. Sci. 46(2):297-301.
Perceived Ecological Risks to Water Environments from Selected Forest Industry Activities
Authors: Cavanagh Nigel , McDaniels Timothy , Axelrod Lawrence , Slovic Paul 
Published: April 2024

Abstract
This article examines underlying factors shaping lay perceptions, and differences between lay and expert perceptions, of the ecological risks to water environments associated with six forest industry activities. A survey was administered to 183 lay subjects in four communities within the Lower Fraser Basin of western Canada. Parts of the survey were also administered to 16 aquatic science professionals. The results show that both lay and expert respondents generally perceive that clearcut logging and effluent from pulp mills pose a high degree of risk, while selective logging poses a lesser degree of risk. Both groups believe that fertilizer use poses a risk to water quality. However, the experts viewed the construction of logging roads as posing significantly more risk to water environments, and requiring greater regulation, than did the lay respondents. Conversely, the lay respondents viewed pesticide use as posing significantly more risk to water environments, and requiring greater regulation, than did the expert respondents. Discussion about the implications of these perceptions in terms of policy issues and communication efforts complete the article. FOR. SCI. 46(3): 344–355.
Predicting Future Forestland Area: A Comparison of Econometric Approaches
Authors: Ahn SoEun , Plantinga Andrew J. , Alig Ralph J. 
Published: April 2024

Abstract
. Predictions of future forestland area are an important component of forest policy analyses. In this article, we test the ability of econometric land use models to accurately forecast forest area. We construct a panel data set for Alabama consisting of county and time-series observation for the period 1964 to 1992. We estimate models using restricted data sets—namely, data from early periods—and use out-of-sample values of dependent and independent variables to construct precise tests of the model's forecasting accuracy. Three model specifications are examined: ordinary least squares, dummy variables (fixed effects), and error components (random effects). We find that the dummy variables model produces more accurate forecasts at the county and state level than the other model specifications. This result is related to the ability of the dummy variables model to more completely control for cross-sectional variation in the dependent variables. This suggests that the estimated model parameters better capture the temporal relationship between forest area and economic variables. FOR. SCI. 46(3): 363–376.
Calibrating Predicted Diameter Distribution with Additional Information
Authors: Kangas Annika , Maltamo Matti 
Published: April 2024

Abstract
The diameter distribution of the growing stock is an essential starting point in many forest management planning problems. There are several methods for predicting the diameter distribution of a stand, varying from methods which utilize theoretical distribution functions to nonparametric methods. Usually the predicted diameter distribution is scaled so that the stem number corresponds to the measured value. However, if stem number and basal area are both known, it may be difficult to predict a distribution that gives correct estimates for both these characteristics. Such diameter distributions can be obtained using an approach adopted from sampling theory—calibration estimation. In this study, the diameter distributions of Scots pine were predicted with two different methods, the Weibull and percentile based methods, and then calibrated with additional information. The calibration reduced the RMSE of stand variables computed from the predicted distribution. FOR. SCI. 46(3): 390–396.
Centroid Method: Comparison of Simple and Complex Proxy Tree Taper Functions
Authors: Coble Dean W. , Wiant Harry V. 
Published: April 2024

Abstract
Cubic-meter volumes estimated from simple and complex proxy taper functions were compared to observed volumes of loblolly pine (Pinus taeda, L.) and ponderosa pine (Pinus ponderosa, Dougl. ex Laws.) trees to evaluate accuracy (bias and precision) in the centroid method. The results of this investigation showed no clear evidence that a more complex proxy taper function is more accurate than a simple function. The results also support previous studies that show accurate volumes of standing trees may be obtained using the centroid method, which requires only one upper-stem diameter measurement. FOR. SCI. 46(4):473–477.
Determination of Stand Properties in Boreal and Temperate Forests Using High-Resolution Imagery
Authors: Shugart H.H. , Bourgeau-Chavez Laura , Kasischke E.S. 
Published: April 2024

Abstract
The existence of a relatively long (ca. 40 yr) satellite imagery archive for examination of potential worldwide forest change motivated an inspection of the relation between forest features observable from higher resolution airborne and satellite imagery and measures of forest biomass, height, and age. Using these data, we inspected the relation between stand age, mean diameter, height, and standing aboveground biomass for forest stands located in boreal forest (near Fairbanks, Alaska) and temperate forest (near Durham, North Carolina). The features of a spatial statistic, semivariance, prove to be related to the structure, age, and biomass patterns of these forests. These initial results indicate the feasibility of using appropriately calibrated high-resolution satellite imagery to estimate and monitor aboveground carbon reserves of forests. FOR. SCI. 46(4):478–486.
An Econometric Analysis of Norwegian Sawmilling 1974–1991 Based on Mill-Level Data
Authors: Baardsen Sjur 
Published: April 2024

Abstract
An eight-input translog total cost function was estimated, and the estimates were used to calculate Allen and Morishima substitution elasticities, price elasticities of conditional input demands, elasticity of size, and technical change for Norwegian sawmilling at a five-digit disaggregate industry level, based on an unbalanced panel of 3,090 individual observations of sawmills over the period 1974–1991. The unusually rich source of data made it possible to analyze the production economics of sawmilling in more detail than has ever been possible before. As far as comparisons with other studies could be made, many of the Allen substitution elasticities and price elasticities of conditional input demand were in accordance with previous findings. The inputs were found to be inseparable. Therefore, frequently used overall aggregates like “materials” and “energy” are not to be recommended. Since the average sawmill had economies of size yet to be exploited, it would have been better off by increasing its size. The most effective way of doing this is to use relatively more sawlogs, electricity, capital, and the aggregate other inputs, and relatively less labor, lumber input (for planing), and the aggregate input other materials. The rate of technical change was negative for the average sawmill. FOR. SCI. 46(4):537–547.
Ideotype Development in Southern Pines: Rationale and Strategies for Overcoming Scale-Related Obstacles
Authors: Martin Timothy A. , Johnsen Kurt H. , White Timothy L. 
Published: April 2024

Abstract
Indirect genetic selection for early growth and disease resistance of southern pines has proven remarkably successful over the past several decades. However, several benefits could be derived for southern pine breeding programs by incorporating ideotypes, conceptual models which explicitly describe plant phenotypic characteristics that are hypothesized to produce greater yield. The potential benefits of using ideotypes include improvement in trait heritabilities and genetic correlations, higher genetic gain in diverse silvicultural environments, guidance for developing mating designs, and provision of a framework for synthesis of tree production physiology knowledge. There are numerous obstacles to the development of ideotypes for southern pines, most of them related to the difficulty of linking traits and processes that operate at small spatial and temporal scales (e.g., tree crown morphological traits or leaf net photosynthesis) with outputs that occur at large spatial and temporal scales (e.g., stand-level, rotation-age stem biomass yield). Fortunately, as we enter the 21st century, several relevant advances are converging that bode well for overcoming these obstacles. These advances relate to improvements and developments of process modeling, advances in technologies that permit measures of component processes at relevant scales, the likely future importance of intensive clonal forestry, and the movement toward large-scale genetic block plot experiments. FOR. Sci. 47(1):21–28.
Applying 3-PG, a Simple Process-Based Model Designed to Produce Practical Results, to Data from Loblolly Pine Experiments
Authors: Landsberg Joe J. , Johnsen Kurt H. , Albaugh Timothy J. , Allen H. Lee , McKeand Steven E. 
Published: April 2024

Abstract
3-PG is a simple process-based model that requires few parameter values and only readily available input data. We tested the structure of the model by calibrating it against loblolly pine data from the Control treatment of the SETRES experiment in Scotland County, NC, then altered the Fertility Rating to simulate the effects of fertilization. There was excellent correspondence between simulated values of stem mass and the values obtained from field measurements, and good correspondence between simulated and measured stem diameters and Leaf Area Index values. Growth efficiency values derived from the model were similar to those obtained from field data. We used the model, without further calibration, to predict tree growth in terms of stem diameter at SETRES 2, a genotype × environment interaction trial in the same locality. Simulated mean stem diameters of two provenances did not differ significantly, over 3 yr, from those observed in the Control (unfertilized) treatments, but rates of change were lower than those of fertilized provenances. We then used 3-PG to simulate fertilized stand growth for an entire rotation length, and these results corresponded to those obtained with a traditional growth and yield model. This study showed that the model can simulate accurately the behavior and responses to environmental factors of loblolly pine and that it has considerable potential value as a management tool, for scenario analysis and as a research tool. FOR. Sci. 47(1):43–51.
Analysis of Longitudinal Data from Progeny Tests: Some Multivariate Approaches
Authors: Apiolaza Luis A. , Garrick Dorian J. 
Published: April 2024

Abstract
Longitudinal data arise when trees are repeatedly assessed over time. The degree of genetic control of tree performance typically changes over time, creating relationships between breeding values at different ages. Longitudinal data allow modeling the changes of heritability and genetic correlation with age. This article presents a tree model (i.e., a model that explicitly includes a term for additive genetic effects of individual trees) for the analysis of longitudinal data from a multivariate perspective. The additive genetic covariance matrix for several ages can be expressed in terms of a correlation matrix pre- and post-multiplied by a diagonal matrix of standard deviations. Several models to represent this correlation matrix (unstructured, banded correlations, autoregressive, full-fit and reduced-fit random regression, repeatability, and uncorrelated) are presented, and the relationships among them explained. Kirkpatrick's alternative approach for the analysis of longitudinal data using covariance functions is described, and its similarities with the other models discussed in this article are detailed. The use of Akaike's information criterion for model selection considering likelihood and number of parameters is detailed. All models are illustrated through the analysis of weighed basic wood density (in kg/m3) at four ages (5,10,15, and 20 yr) from radiata pine increment cores. FOR. SCI. 47(2):129–140.
Species-Independent Height-Age Models for British Columbia
Authors: Nigh Gordon D. 
Published: April 2024

Abstract
Species-specific height-age models abound in the scientific literature. Some researchers have used Zeide's two-point system to reduce the number of models in service. However, this system requires two height-age pairs which are not always available. The purpose of this research is to develop a height-age model for British Columbia, Canada, that is independent of species. From a large database of stem analysis data, 15 plots from three coastal and seven interior species were chosen to uniformly cover the range of site index for each species. After converting the stem analysis data into height-age data, a model based on the logistic function was fit to each plot. A preliminary analysis showed that site index, geographic region (coast, interior), and shade tolerance (tolerant, intolerant) are potentially good predictors of height. These variables, along with breast height age, were incorporated into a species-independent height-age model based on the log-logistic function. An additional ten plots per species were chosen to test the model. The testing showed that the species-independent model had approximately the same accuracy as the species-specific models. Future endeavors can be directed at improving the model by incorporating more species into the analysis and including other important climatic and ecological variables. FOR. SCI. 47(2):150–157.
Relationships Between National Forest System Employee Diversity and Beliefs Regarding External Interest Groups
Authors: Halvorsen Kathleen E. 
Published: April 2024

Abstract
This article examines the relationship between USDA Forest Service National Forest System (NFS) employee beliefs about external interest groups and the employees' race, gender, and career path. These interest groups include environmentalists, citizen activists, the timber and mining industries, range users, tribal representatives, and recreationists. Gender, race, and career path are demonstrated to be significant factors related to NFS employee beliefs about a number of these interest groups. These results suggest that NFS employee diversification policies may have introduced into the workforce a set of employees who are less positive in their expectations of the timber industry, but more positive about environmentalists and some other key interest groups. This shift is predicted to aid the NFS in working more successfully with a wider diversity of external constituencies than in the past. For. Sci. 47(2):258–269.
Nonlinear Mixed Effects Modeling for Slash Pine Dominant Height Growth Following Intensive Silvicultural Treatments
Authors: Fang Zixing , Bailey Robert L. 
Published: April 2024

Abstract
A modified Richard's growth model with nonlinear mixed effects is developed for modeling slash pine (Pinus elliottii Engelm.) dominant height growth in conjunction with different silvicultural treatments. All three parameters in the model turn out to have both fixed and random individual plot or silvicultural treatments effects. Moving average correlation with 2° was identified as within-plot error structure. The advantages of the mixed effects model in prediction for new responses are demonstrated in detail by formulations and examples. The modified Richards model has a form that combines dominant height growth and site index into one model form, so the incompatibility between height growth and site index model can be avoided. The general methodologies of nonlinear mixed effects model building, such as which parameters in the model should be considered to be random and which should be purely fixed, how to determine appropriate within-plot variance covariance structure, and how to specify between-plot variation via appropriate covariate modeling, are addressed in detail. Likelihood ratio test and Akaike information criterion (AIC) are used in model performance evaluation. Some useful graphical model diagnosis tools are also presented. FOR. SCI. 47(3):287–300.
Imputation and Model-Based Updating Techniques for Annual Forest Inventories
Authors: McRoberts Ronald E. 
Published: April 2024

Abstract
The USDA Forest Service is developing an annual inventory system to establish the capability of producing annual estimates of timber volume and related variables. The inventory system features measurement of an annual sample of field plots with options for updating data for plots measured in previous years. One imputation and two model-based updating techniques are described and evaluated with respect to the bias and precision of their annual estimates of basal area per unit area. The evaluations indicate that simple plot-level imputation and model-based updating techniques produce adequately unbiased and precise estimates of annual mean basal area per unit area for large areas. FOR. SCI. 47(3):322–330.
Herbivory and Fire Influence White Oak (Quercus alba L.) Seedling Vigor
Authors: Adams A.S. , Rieske L.K. 
Published: April 2024

Abstract
We manipulated arthropod and mammalian herbivory levels on white oak seedlings using a combination of insecticide applications and fencing and employed a split-split-plot design to assess the impact of single- and multiple-year burns on seedling growth over a 2 yr period. Herbivory levels increased over time on all sites, but there was no significant difference in herbivore pressure on seedlings in single-year burned, multiple-year burned, and nonburned plots. Insecticide-treated seedlings suffered less herbivore pressure than did noninsecticide treated seedlings, and mammalian herbivory was significantly reduced by the presence of a fence. Seedling height growth, shoot elongation, diameter growth, and specific leaf mass were greatest on once-burned sites, intermediate on twice-burned sites, and least on nonburned sites. Bud expansion was the only seedling performance parameter unaffected by burn treatment. Arthropod feeding was the greater component of overall herbivory, but this herbivory did not impede seedling growth. Seedling height growth and shoot elongation were more closely linked to mammalian herbivory. These results suggest that the observed herbivory may play a negligible role, and prescribed fire may be a beneficial component of a management program designed to enhance oak regeneration. FOR. SCI. 47(3):331–337.
Phosphorus and Potassium Uptake Kinetics in Red Maple Seedlings
Authors: Kelly J.M. , Kelly J.K. 
Published: April 2024

Abstract
Acquisition of nutrients by tree roots generally is viewed as a complex process. Models that make use of Michaelis-Menten kinetics concepts provide a means to mechanistically simulate nutrient uptake. The objectives of this study were to provide: (1) estimates of the Michaelis-Menten parameters Imax, Km, and Cmin for P and K uptake by red maple (Acer rubrum L.) seedlings, and (2) to test the efficacy of these values in the modeling context by using the Barber-Cushman nutrient uptake model as a test vehicle. A nutrient depletion approach that used intact seedlings and transient conditions was used to define the kinetics values. These estimates were combined with literature values to provide a full parameter set for the model. Uptake of P proceeded rapidly and yielded an average Imax of 5.5E-6 μmol cm-2 s-1. Mean Km and Cmin values for P were 15.0 and 0.001 μmol mL-1, respectively. Potassium uptake was slower with a mean Imax of 3.8E-6 μmol cm-2 s-1, and the Km and Cmin values were 10.5 and 0.003 μmol mL-1, respectively. Simulated P uptake compared poorly with observed uptake (0.8 vs. 830 μmols). However, additional model runs indicated that the lack of agreement was more the result of a low estimate of soil solution P concentration than a problem with the P kinetics values. Simulated K uptake was in much better agreement with the observed value (891 vs. 1890 μmols). The Cmin values for P and K reflect an ability to continue root uptake at extremely low solution concentrations. This may contribute to the “supergeneralist” status accorded red maple. This study indicates these Imax, Km, and Cmin values can be used in the Barber-Cushman model to simulate P and K uptake by red maple. However, use of these Imax, Km, and Cmin values needs to be tempered with the understanding that several interacting factors influence uptake. This caveat is important when generic literature values provide some or all of the numbers used to initialize the model. FOR. SCI. 47(3):397–402.