bluuebunny/crossref_metadata_2025_split huggingface dataset:
Estimation of Temporal Variations in Historical Fire Frequency from Time-Since-Fire Map Data
Authors: Reed W. J. , Larsen C. P. S. , Johnson E. A. , MacDonald G. M. 
Published: April 2024

Abstract
This paper describes an improved statistical methodology for estimating historical forest fire frequencies from time-since-fire map data. Of particular interest is the question of estimating fire frequency in temporally distinct epochs. Unlike previous graphical and ad hoc methods, the new methodology is firmly grounded within the established statistical paradigm of likelihood inference. In addition, in contrast to earlier methods, it takes into account the fact that surviving stands which originated in earlier epochs, have been subject to different hazards of burning as they have lived through more recent epochs. Neglecting this fact leads to overestimates of the fire frequency in the more recent epochs. Procedures for obtaining maximum likelihood estimates and likelihood ratio confidence intervals for the fire frequency in each epoch are developed, along with a likelihood ratio test to assess whether the fire frequencies in distinct epochs were significantly different. This test is not strictly valid when the change points separating epochs are suggested from exploratory data analysis; rather it is developed assuming that change points are determined independently of the data. This distinction, which is necessary to avoid selection bias, has not been noted before. The fact that forest fire is a contagious process, with consequent spatial autocorrelation in time-since-fire observations, is taken into account through the use of an overdispersed model, with associated quasi-likelihood function. This aspect has been ignored, by and large, in previous analyses which have implicitly assumed independence of observations. An example is given in which the method is applied to published fire history data from the Kananaskis Valley. The results indicate that the previous analysis overestimated the fire frequency for the most recent epoch. The conclusions of other studies concerning temporal changes in fire frequency may need to be reconsidered. For. Sci. 44(3):465-475.
Comparative Susceptibility of Conifers to Larch Dwarf Mistletoe in the Pacific Northwest
Authors: Mathiasen Robert L. 
Published: April 2024

Abstract
A total of 62 mixed conifer sites in Idaho, Montana, Oregon, and Washington infested with larch dwarf mistletoe (Arceuthobium laricis) were sampled to compare host susceptibility to this parasitic flowering plant. Temporary circular plots (6 m radius) were established around dominant, severely infected, principal, and secondary hosts. Within plots, species, diameter at 1.37 m above the ground, and dwarf mistletoe rating (6 class system) were determined for each live tree over 1.37 m in height. A total of 11,270 trees were sampled in 620 plots. Based on the percentage of infection, species were assigned to host susceptibility classes: western larch is the only principal host of larch dwarf mistletoe; mountain hemlock and lodgepole pine are secondary hosts; subalpine fir and ponderosa pine are occasional hosts; and Engelmann spruce, grand fir, and western white pine are rare hosts. No infection was observed on Douglas-fir, western hemlock or western redcedar. However, based on a report of larch dwarf mistletoe parasitizing western hemlock in Washington, western hemlock must be designated as a rare host. Pacific silver fir and whitebark pine are tentatively classified as occasional hosts. For. Sci. 44(4):559-568.
Economic and Fragmentation Effects of Clearcut Restrictions
Authors: Barrett T.M. , Gilless J.K. , Davis L.S. 
Published: April 2024

Abstract
Clearcut restrictions limiting individual clearcut size affect economic outputs and alter the spatial distribution of wildlife habitat over the landscape. Simulations of different clearcutting restrictions were applied to a 47,500 ha mixed-ownership landscape in the Sierra Nevada of California. The private owner was assumed to pursue a goal of maximizing net present value (NPV), while the public owner was assumed to use a combination of low-intensity selection harvesting and long rotations to develop late-seral habitat. With a 10 yr exclusion period, maximum clearcut size limits of 4 and 32 ha reduced the private owner's NPV to 79% and 91% of the unconstrained maximum, respectively; with a 20 yr exclusion period, to 65% and 88% of the unconstrained maximum. Initially, smaller clearcut size limits resulted in more mature forest [average stand diameter (ASD) greater than 30 cm], but with greater fragmentation. Ultimately, late-seral habitat (ASD &gt; 61 cm) was insensitive to clearcut size limits because rotation lengths of 60 or 90 yr did not produce that habitat class for most forest types. For. Sci. 44(4):569-577.
Effects of Thinning and Nitrogen Fertilization on Sugars and Terpenes in Douglas-Fir Vascular Tissues: Implications for Black Bear Foraging
Authors: Kimball Bruce A. , Turnblom Eric C. , Nolte Dale L. , Griffin Doreen L. , Engeman Richard M. 
Published: April 2024

Abstract
The chemical constituents of coniferous vascular tissues play a role in bear forage selection. In particular, bear foraging preferences are related to the concentrations of simple sugars (nonstructural carbohydrates) and terpenes in the forage. Analyses of vascular tissue samples from trees collected in test plots indicated that both thinning and fertilization caused the sugar concentration of vascular tissues in the lower bole to increase. However, these treatments had no effect on the concentrations of hydrocarbon monoterpenes, oxygenated monoterpenes, or sesquiterpenes. These results may explain the observations that black bears prefer to forage in thinned and fertilized stands. For. Sci. 44(4):599-602.
Measuring Environmental Quality in the Southern Appalachian Mountains
Authors: Pendleton Linwood , Sohngen Brent , Mendelsohn Robert , Holmes Thomas 
Published: April 2024

Abstract
This study presents a method for valuing recreational environmental quality in the forests of the southeastern United States. The paper offers a method for choosing, measuring, and valuing forest attributes. Surveys and popular recreation literature are used to identify forest attributes that contribute to recreational quality. Standard ecological techniques are employed to measure levels of these attributes along trails in Tennessee, North Carolina, and Georgia. Finally, the paper demonstrates how hedonic methods can be used to assign values to forest attributes. We show that values for recreational quality vary across users and sites. Furthermore, we demonstrate the existence of negative marginal values for certain forest attributes and provide evidence that suggests these negative values are not the result of mis-specification, but are consistent with oversatiation. For. Sci. 44(4):603-609.
A Methodology to Analyze Divergent Case Studies of Non-Timber Forest Products and Their Development Potential
Authors: Pérez Manuel Ruiz , Byron Neil 
Published: April 2024

Abstract
Debate currently rages over the development potential of Non-Timber Forest Products (NTFP) in tropical forests. Proponents of particular "solutions" can refer to evidence (case studies, data) which tend to support their interpretation of events and relationships. Recommendations thus frequently depend on how data are classified and interpreted. Inaccurate or incomplete classification leads to defective subsequent theories, models, and recommendations. We present a method for classifying very divergent case-study data, and some initial results as a basis for general understanding of key factors that influence a given result. Crucial issues determining outcomes of NTFP development include the nature of government involvement, distribution of property rights, the ability of local people to claim and enforce such rights, market transparency, and pressure on the resource. This paper concludes with suggestions for further testing and development of the methodology. For. Sci. 45(1):1-14.
Spatial Restrictions in Harvest Scheduling
Authors: Murray Alan T. 
Published: April 2024

Abstract
Forest resource use has traditionally been multifaceted. In order to ensure that these resources continue to be available for use by current and future generations, sustainable management practices are essential for striking a balance between the varied and often competing demands associated with forest use. This has meant that analysis incorporate specific objectives and considerations aimed at minimizing the impacts of forest activities. One such management planning approach has been the inclusion of spatial restrictions in harvest scheduling analysis. This article reviews two basic harvest scheduling models which may be used for imposing spatial restrictions. Distinctions between the alternative methods are highlighted and operational considerations are discussed. This article establishes and outlines priority areas for future harvest scheduling research. For. Sci. 45(1): 45-52.
Compatible Volume and Taper Models with Coefficients for Tropical Species on Hainan Island in Southern China
Authors: Fang Zixing , Bailey Robert L. 
Published: April 2024

Abstract
Compatibility of a volume-taper equation system is generally defined to mean that volumes determined by integrating the taper curve from groundline to total tree height are algebraically identical to those obtained from the total volume or appropriate volume ratio equations. This constraint was applied to a previously published model as a boundary condition using the constant of integration resulting from the solution of the differential equation. Four cases are discussed that apply to different solutions of the differential equation. This set of models, all based on the same geometric assumption, makes a very flexible system for modeling stem taper. We fitted the resulting taper models and corresponding tip volume equations simultaneously to stem-measurement data for 23 tropical species growing on Hainan Island in southern China. The simplest case among the four (case I-a) was acceptable for some species, but for some others, a more general case (case II-b) was needed. We compared the results for the simplest and the most general cases of this system with a published geometric model having only a point constraint at dbh and with a published variable exponent taper equation. We examined how well each one predicted upper-stem diameters, merchantable height for a given upper-stem diameter, and total stem volume. Our taper models always had the smallest bias and standard error of estimates for total volume estimation. The variable exponent taper equation was the best for predicting upper-stem diameter and merchantable height. The advantages of a taper system with a geometric rationale are discussed, and two examples of easy extensions of our taper model are shown in the appendix. For. Sci. 45(1):85-100.
Afforestation as a Real Option: Some Policy Implications
Authors: Thorsen Bo Jellesmark 
Published: April 2024

Abstract
The theory of real options is applied to the decision of establishing a new forest stand. Assuming that afforestation costs are known and constant and that future net prices of roundwood follow a Geometric Brownian Motion, a simple model of the decision problem is formulated. Using this model, a real option analysis of the afforestation opportunity is performed. Next, the implications of the real option approach for afforestation subsidy schemes are analyzed. It is found that the subsidies needed to induce a desired investment behavior will in general increase, and that the actual increment will depend on the way subsidies are offered to the landowners and affect their expectations. An empirical example is used to illustrate the potential significance of the findings. For. Sci. 45(2):171-178.
Combining a Decomposition Strategy with Dynamic Programming to Solve Spatially Constrained Forest Management Scheduling Problems
Authors: Borges José G. , Hoganson Howard M. , Rose Dietmar W. 
Published: April 2024

Abstract
A decomposition approach to solve the forest management scheduling adjacency problem is developed for application to large forests. Overlapping subproblems amenable to exact dynamic programming solution are solved sequentially. A heuristic is used to define and link subproblems such that near-optimal solutions to the master problem are obtained. Both the contrasting size and the irregular shape of stands complicate the problem of formulating the dynamic programming network. Subproblem size and the sequencing of stands for each corresponding dynamic programming network are defined simultaneously, as model size is especially sensitive to stand sequencing. Emphasis is on efficient dynamic programming formulations to allow for large subproblems. Results from over 100 test computer runs are discussed for applications to 3 large problems. Results suggest that the strategy can consistently produce near-optimal solutions at reasonable computational cost. A procedure is developed to derive three slightly different adjacency problems so that the optimal solution can be found. Results for applications to the modified problems show that the proposed heuristic's solutions were within 0.01, 0.04, and 0.01% of the optimal solution, respectively. The proposed solution method consistently outperformed two other heuristics that were applied. For. Sci. 45(1):201-212.
An Adjustable Predictor of Crown Profile for Stand-Grown Douglas-Fir Trees
Authors: Hann David W. 
Published: April 2024

Abstract
This study developed a method for predicting the crown profile of stand-grown trees that can be adjusted to other populations of the same species by using either measurements or predictions of the largest crown width (LCW) for trees in the alternative population. The method should be of particular interest for tree species such as Douglas-fir that have exhibited variation in crown attributes across both their geographic range and genotypes. To model crown profile, the crown was divided into two segments: the portion of the crown above the point where LCW occurs, and the portion below that point. The equation for the upper portion predicted a crown profile that ranged in shape from nearly conic to parabolic, depending on position within the crown and the social status of the tree, as indicated by the ratio of total height divided by diameter at breast height for the tree. The equation for the lower portion predicted a crown profile with a cylindrical shape. This method explained nearly 94% of the variation in crown width when used with the felled tree measurement of LCW, 87% with a measurement of LCW taken while the tree was standing, and 83% with the use of a value for LCW that was predicted from an equation developed from an independent data set. For. Sci. 45(2):217-225.
Considering Intergenerational Equity in Linear Programming-Based Forest Planning Models with MAXMIN Objective Functions
Authors: Church Roger , Daugherty P. J. 
Published: April 2024

Abstract
This paper describes alternative approaches to formulating linear-programming-based forest planning models. These approaches consider a form of equity between current and future generations, as represented by the periods in a planning horizon. Both nominal net revenue in each period and each period's present net worth with values discounted relative to each period, are used as criteria for welfare. The minimum present net worth or net revenue outcome obtained for the set of periods is maximized. The approaches are different. Using present net worth relative to each period as a criterion allows for a concern for economic efficiency and allows variation in net revenue. Using net revenue focuses on a more even distribution of net revenue between periods. The approaches are tested in a case study, and the results are compared to those from a standard approach of maximizing present net worth relative to the first period. The results suggest that the approaches could be useful in a forest planning context, either as an alternative to standard approaches or as a means of generating relevant information. For. Sci. 45(3):366-373.
Effects of an Intense Wildfire in a Mexican Oak-Pine Forest
Authors: Fulé Peter Z. , García-Arévalo Abel , Covington W. Wallace 
Published: April 2024

Abstract
An oak-pine forest burned by intense wildfire in April, 1996, and a companion unburned area were sampled 1 month and 1 yr postfire in La Michilía Biosphere Reserve, Durango, Mexico. Up to 90% of the trees were killed or top-killed in the burned area, but larger trees tended to survive, so basal area was only reduced by 66%. Top-killing was relatively higher among fire-susceptible oaks and lower among fire-resistant pines. However, oaks were strong resprouters both in the canopy and at the base of top-killed trees. Damage codes based on crown scorch and bole char were highly accurate when predicting that a tree would die but substantially overestimated survivors. Most tree regeneration was top-killed in the fire, but oak sprout density was 700% that of the unburned area by 1 yr postfire. Manzanita shrubs also resprouted vigorously. Herbaceous production and cover were lower after the first postfire growing season in the burned area than the unburned area. Woody fuels and forest floor depth were also reduced. Although short-term fire effects indicate that the forest ecosystem has moved closer toward a savanna condition, remnant seed trees and sprouting trees are expected to maintain forest cover. Future herbaceous production is likely to increase in response to overstory mortality. Quantification of fire effects is helpful for supporting short-term management decisions since oak-pine forests cover millions of hectares in northern Mexico. As a long-term management strategy, however, we suggest that restoring the frequent, low-intensity fire regime may be desirable for ecological and economic reasons. For. Sci. 46(1):52-61.
Optimizing Forest Stand Management with Natural Regeneration and Single-Tree Choice Variables
Authors: Hof John , Bevers Michael 
Published: April 2024

Abstract
This article addresses the any-aged forest management problem with individual trees as the choice variables in integer programming models. In order to sustain the forest using natural regeneration, spatial proximity of seed trees is required for harvesting to take place in these models. This problem requires integer variables to avoid harvesting part of a tree, but it is remarkably integer-friendly. Solvability of large models is thus explored, along with the patterns of solution that can be recognized in smaller models. Results from these exploratory models are sensitive to initial forest conditions and do not display the steady state conditions typically assumed for uneven-aged management in the literature. For. Sci. 46(2):168-175.
Effects of Correlation among Parameters on Prediction Quality of a Process-Based Forest Growth Model
Authors: Guan Biing T. 
Published: April 2024

Abstract
A nonparametric method was introduced as a technique for evaluating the effects of parameter correlation on prediction quality of process-based forest growth models. The method was based on a rank correlation and Cholesky decomposition. For a given data matrix, by reordering the observations, the method would produce a rearranged matrix with the desired correlation structure. The method was computationally simple and efficient. Using a process-based model calibrated for red pine (Pinus resinosa Ait.) as an example, small-scale Monte Carlo simulations revealed that parameter correlation had different effects on the model's prediction means and variances, depending on the importance of the parameters involved. In general, given the same level of correlation, correlation between two important parameters would have greater influences on prediction quality than correlation between two less important parameters. Parameter correlation slightly affected the prediction means but could significantly change prediction variances. The relationship between prediction quality and the degrees of correlation, however, was not necessarily a linear one. The same parameter correlation might also have different effects on different state variables. For. Sci. 46(2):269-276.
Analytical Site Index Solution for the Generalized Log-Logistic Height Equation
Authors: Cieszewski C.J. 
Published: April 2024

Abstract
The generalized log-logistic height equation computes height as a function of age and a fixed base-age site index. This equation and its modifications have been used for many applications in various regions. It is seemingly apparent that this equation is analytically insolvable for the site index; no general analytical solution to this equation is readily available. This article presents such a solution that has proven to be valid and useful with all tested parameters. This solution is based on an adaptation of the Ramanujan's (1887-1920) solution for a trinomial with real-number exponents. Ramanujan's solution is a series that in many cases can be expressed as a closed-form equation. In the present context, this series may be used for derivations of various special cases of closed-form solutions, initial-condition difference and differential equations, and for various analytical sensitivity and trend analysis, as well as for efficient site index computations. For. Sci. 46(2):291-296
The Engines of Change in Rsource-Dependent Communities
Authors: Force Jo Ellen , Machlis Gary E. , Zhang Lianjun 
Published: April 2024

Abstract
Social scientists have long attempted to understand change in natural resource-dependent communities. This article examines the relationship of three alternative “engines of change”: local resource production, local historical events, and broad societal trends. Regression models were used to examine the relationships between four dimensions of community social change (size, structure, cohesion, and anomie) and the alternative “engines of change” in seven resource-dependent communities in the Pacific Northwest for over 50 year time periods. Included in the group were four timber towns, as well as communities dependent upon fishing, tourism, and mining. The data suggest that broad societal trends followed by local historical events explain the largest proportion of the variation in community social change dimensions of size and structure. Local resource production has modest explanatory power when combined with the other “engines of change.” FOR. SCI. 46(3): 344–355.
Differential Effects of Rhizobacterial Strain and Dose on the Ectomycorrhizal Colonization of Loblolly Pine Seedlings
Authors: Vonderwell J.D. , Enebak S.A. 
Published: April 2024

Abstract
Loblolly pine seed were inoculated at sowing with one of four plant growth-promoting rhizobacteria (PGPR) strains at four different rates both in the nursery and in the greenhouse. Seedlings were harvested at 4, 8, and 12 wk after sowing in the greenhouse and at 5, 10, and 15 wk after sowing in the nursery. Ectomycorrhizae colonization, estimated as the total number ectomycorrhizal roots per seedling and averaging by gram root biomass, were not evident on any treatment at either 5 wk in the nursery or 4 wk in the greenhouse. However, by 8 wk after sowing, many treatments significantly (P &lt; 0.0001) inhibited ectomycorrhizal root formation. Generally, increasing the rate of all bacteria applied in the greenhouse decreased ectomycorrhizal root formation. Conversely, strain LS212 at 1011 cfu resulted in an increase in ectomycorrhizal roots in the nursery. Increases in seedling root growth were also dependent on bacterial strain and rate, whereas shoot biomass was not effected. Decreases in ectomycorrhizae colonization accounted for 61% of the variation in increases in root biomass, suggesting high metabolic costs of mycorrhizal maintenance in the presence of some rhizobacteria. However, differences in shoot height and survival after outplanting could not be attributed to the mycorrhizae colonization effect. These studies demonstrate that mycorrhizae may serve as a carbon sink early in seedling development and indicate a complex interaction between soil microflora and bacterium in nursery and greenhouse settings. FOR. SCI. 46(3): 437–441.