bluuebunny/crossref_metadata_2025 huggingface dataset:
The Impact of Reserve Prices in Sealed Bid Federal Timber Sale Auctions
Authors: Carter Douglas R. , Newman David H.
Published: April 2024

In this article we examine the impact of reserve prices on timber revenues from federal timber sale auctions in North Carolina from a game-theoretic perspective by recognizing the effect of competition on optimal bid strategies. The empirical model endogenizes the number of bidders in a simultaneous-equations Tobit framework, and estimates the impacts of the reserve price on the probability that an offering will sell, as well as on the sale price given that the offering is sold, in the presence of strategic bidding behavior. Model results support the underlying game-theoretic structure. The number of bidders and the reserve price are both important in determining market value or high bid. Using a Wu-Hausman test, we reject exogeneity in the number of bidders. Importantly, a calculation of the change in market value given a change in the reserve price shows that increasing reserve prices will likely increase timber revenues on sales in North Carolina, thus providing evidence that reserve prices are not optimal. However, increasing the reserve price will decrease the proportion of sold sales which may not support nontimber objectives of the Forest Service. For. Sci. 44(4):485-495.
Risk Preferences and Adaptive Harvest Policies for Even-Aged Stand Management
Authors: Gong Peichen
Published: April 2024

Uncertainty in future states of nature affects the set of feasible management alternatives as well as a forest owner's preferences among different alternatives. To incorporate uncertainty into forestry decisions, both effects should be recognized simultaneously. This study concerns the final harvest decision in even-aged stand management with stochastic stumpage prices. An expected utility maximization model is developed for determining the optimal adaptive harvest policy. Instead of assuming risk-neutrality on the side of forest owners, the model explicitly incorporates risk preferences into the determination of reservation prices. A method for estimating the set of efficient adaptive harvest policies for risk-averse forest owners is developed based on the mean-variance rule and stochastic dominance analysis. The set of efficient adaptive harvest policies is estimated and compared with the set of efficient rotation ages for two example stands. Numerical results show that any risk-averse forest owner prefers the optimal adaptive harvest policy to the optimal rotation age. By using the rule of "harvest only when the observed stumpage price is equal to or higher than the reservation price," the expected net present value can be increased, and, meanwhile, the standard deviation of the net present value can be reduced significantly. Incorporation of risk-aversion leads to reservation prices that may be lower than those that maximize the expected net present value. It indicates that risk-averse forest owners typically should harvest earlier than risk-neutral forest owners. For. Sci. 44(4):496-506.
Using the Non-Parametric Classifier CART to Model Forest Tree Mortality
Authors: Dobbertin Matthias , Biging Gregory S.
Published: April 2024

A binary classification tree (CART) was used to predict forest tree mortality for two conifer species. CART models were fitted using binary recursive splitting of the data set into increasingly homogeneous subsets. Models were compared in terms of improvement of prediction accuracy, representativeness in average size of the predicted mortality trees, and interpretability of the results. For shade intolerant ponderosa pine, crown ratio, diameter increment prediction, or variables indicating the relative position of a tree in a stand were used for splitting. For shade tolerant white fir, height increment prediction and stand density were selected for splitting. The prediction accuracies for mortality trees of the best CART models were between 28-36% for ponderosa pine and between 11-17% for white fir. CART was also compared with logistic regression using a stochastic and a deterministic assignment of mortality. Efficiencies similar to those achieved with CART were reached with deterministic logistic models using thresholds probabilities. However, CART and the logistic model tended to utilize different predictor variables, especially for white fir. CART uncovered additional factors for white fir important for predicting mortality not identified by the logistic regression. For. Sci. 44(4):507-516.
The Economic Impact of a Subsidy on Mexican Grains and Forestry: A CGE Analysis
Authors: Boyd Roy , Doroodian Khosrow
Published: April 2024

This study first examines the economy-wide impacts of the "Pro-Campo" grains subsidy program. It then analyzes the effects of extending this program to forestry as a means of curbing further deforestation. To accomplish these objectives, we employ a computable general equilibrium (CGE) model of the Mexican economy. Our findings show that (1) the subsidies lead to a transfer of resources from the refining, natural gas, services, and financial services sectors into the various agricultural, manufacturing, and mining sectors; (2) All consumption sectors except the food and the alcohol and tobacco sectors decrease as a result of subsidies; (3) The lower income groups experience an increase in their income at the expense of the upper income groups when government revenue and expenditure are held constant. Such results suggest that extension of "Pro-Campo" benefits to the forestry sector should have the desired impact of keeping land and capital resources in forestry. Our results, however, only pertain to commercial species and do not include the off-side damages which may occur to useful noncommercial species. For. Sci. 44(4):578-586.
Analyzing Consistency of Experts' Judgments—Case of Assessing Forest Biodiversity
Authors: Kangas Jyrki , Alho Juha M. , Kolehmainen Osmo , Mononen Ari
Published: April 2024

Incorporation of biodiversity considerations into forest planning requires methods for the operationalization of biodiversity and for the quantification of expert judgments concerning the future implications of alternative forest management plans. Applying expert knowledge in numerical decision support most probably involves much uncertainty. To reduce biases, the use of several independent experts seems advisable. However, the experts may disagree, and it is not always clear whether this is due to genuine disagreements, or because of misunderstandings or other errors that may occur in the elicitation process. In this study, an approach is presented for analyzing the uncertainties in expert judgments elicited by pairwise comparisons, and for improving the consistency of judgments. Ecological expertise is applied in the estimation of an evaluation model which can be used in assessing alternative forest plans with respect to biodiversity in optimization calculations. The approach is based on the combined use of HERO optimization method developed for tactical forest planning, Delphi technique, and variance components modeling. The Delphi technique may be helpful in understanding better the causes of the possible disagreements. Variance components modeling is used to estimate the changes in the views of 11 experts concerning the different components of biodiversity, in three Delphi rounds. It turned out that the views converged to some extent, but in one case an increase in shared inconsistency among judges was also detected. For. Sci. 44(4):610-617.
Nutritional and Sexual Responses of Jack Pine to Ammonium Nitrate and Gibberellins
Authors: Fogal W.H. , Larocque G.R. , Lopushanski S.M. , Schooley H.O. , Anderson M.L. , Edwards I.K. , Coleman S.J. , Wolynetz M.S.
Published: April 2024

The nutritional and sexual responses of jack pine (Pinus banksiana Lamb.) seed orchard trees to NH4NO3 fertilization and GA4/7 foliar sprays were examined in seedling and grafted orchards at an Ontario location where soils were low N acidic sandy loams and in a Saskatchewan grafted orchard on high N calcareous sandy clay loams. High seed strobilus abortion and low pollen strobilus production and seed yields characterized the Saskatchewan trees. NH4NO3 fertilizer increased soil NH4+ and NO3- at both locations, current-year needle N and Mg in Ontario, Fe in Saskatchewan, and Ca at both locations, seed strobilus initiation and seed yields in Ontario; it decreased K in Saskatchewan. GA4/7 increased needle senescence and current-year needle N and P at both locations, K at Saskatchewan, seed and pollen strobilus initiation in Ontario, seed strobilus initiation and abortion in Saskatchewan, and seed yields per tree in Ontario; it decreased Ca at both locations, Mg at Saskatchewan, and diameter increments the year following treatments in Ontario. NH4NO3 and GA4/7 treatments did not interact for strobilus counts. Sexual expression varied with clones in Saskatchewan but not with families in Ontario. Clones interacted with GA4/7 but not NH4NO3 for seed strobilus initiation. For. Sci. 45(1):136-153.
Basal Area Growth and Crown Closure in a Loblolly Pine Spacing Trial
Authors: Radtke Philip J. , Burkhart Harold E.
Published: April 2024

Data collected after each of the first 13 yr since planting of a loblolly pine spacing trial were used to study relationships between basal area growth and crown closure. Crown closure and crown competition factor at the inflection age of cumulative basal area growth were examined on 192 plots of varying initial density and rectangularity at four sites in the Piedmont and the Atlantic Coastal Plain. Inflection age increased with initial growing space, but at a decreasing rate, presumably approaching some maximum value that would be realized in the absence of all competition. The inflection generally occurred earlier on study sites with the highest site index values, but exceptions to this trend were observed. The degree of crown closure at the inflection age increased with planting density, but did not depend in a meaningful way on the site index of the study sites. Crown competition factor at the inflection age increased with planting density, but also increased with site index. Rectangularity did not significantly affect the inflection age, but it did reduce the level of crown closure at that age. A test for the effect of rectangularity on crown competition factor was inconclusive. For. Sci. 45(1):35-44.
Composite and Calibration Estimation Following 3P Sampling
Authors: Gregoire Timothy G. , Valentine Harry T.
Published: April 2024

Two alternatives to the generalized ratio estimator, i.e., Grosenbaugh's 3PSEVENTH, are studied. Both make more complete use of auxiliary information which is available at the conclusion of 3P sampling. Both appear to be more biased but more accurate than 3PSEVENTH. For. Sci. 45(2):179-185.
Forecasting Adoption and Substitution of Successive Generations of Structural Wood Panel Products in the United States
Authors: Shook Steven R.
Published: April 2024

A sizable body of literature concerned with technological substitution modeling exists within the domain of forest products. These models have generally been used to develop market share forecasts for various forest products and their substitutes based on relative product prices. Substitution models usually assume that the potential market size is known and that products can freely substitute for one another. A small but growing literature concerned with the diffusion of innovations also exists within the domain of forest products. This diffusion literature typically focuses on factors affecting consumer acceptance for product innovations and forecasting the level of demand growth without constraining the potential market size. In this paper, we examine the dynamic sales behavior of three and four successive generations of structural wood panel products using varying forms of a multigeneration diffusion model. The multigeneration diffusion model introduced here, which encompasses the elements of diffusion and substitution modeling, assumes that a new structural wood panel product will diffuse through a population of potential consumers over time and that market share competition will be introduced with successive generations of structural wood panels. It is important to note that our results are contingent upon the use of domestic production data, which is used as a proxy for domestic consumption. In other words, our results do not factor in net imports. Estimation results indicate that market share competition between various structural wood panel products are differentially impacted by substitution and diffusion effects. We explore the managerial implications of the model results and suggest alternative multigeneration diffusion models that could be developed for structural wood panel products. For. Sci. 45(2):232-248.
Spatially Optimizing Wildlife Habitat Edge Effects in Forest Management Linear and Mixed-Integer Programs
Authors: Bevers Michael , Hof John
Published: April 2024

We present a spatial optimization model that accounts for wildlife edge effects through multiple habitat needs in a multistand forest management problem. Wildlife population dynamics are based on discrete reaction-diffusion processes combined with multiple limiting-factor constraint sets, one for nest site capacity and another for effective forage capacity. The model is shown to reasonably represent both negative and positive effects of forest edges on wildlife by varying the amount of forage production from harvested and unharvested forest areas in a static formulation. A dynamic model is also demonstrated, and scale effects are examined using mixed-integer programming. For. Sci. 45(2):249-258.
Occurrence of Moths among Habitats in a Mixed Mesophytic Forest: Implications for Management of Forest Bats
Authors: Burford Laura S. , Lacki Michael J. , Covell Charles V.
Published: April 2024

We used blacklight traps during summer 1992 to index the frequency of occurrence and species composition of moths in five habitats on an actively managed, mixed mesophytic forest in eastern Kentucky. The habitats sampled were clearings, poletimber (< 30 yr old), moderate-aged sawtimber (30-50 yr old), and mature timber (70-80 yr old); the latter habitat was only available at the base of cliffs and on top of cliffs, where no harvest restrictions were in effect. We identified 4,107 moths representing 158 species and 17 families in the catches. Moths in the family Arctiidae were captured most frequently (n = 1,389), whereas moths in the family Noctuidae comprised the largest number of species (n = 53). We captured the most species (n = 83) and families (n = 17) of moths in stands of mature timber at the base of cliffs, and the fewest species (n = 57) of moths in clearings. Moths in the families Yponomeutidae, Limacodidae, Pyralidae, Geometridae, and Notodontidae were captured most frequently in stands of moderate-aged sawtimber, whereas moths in the family Arctiidae were most common in stands of moderate-aged sawtimber and poletimber. We captured moths in the family Noctuidae most frequently in stands of mature timber on top of cliffs. Moths in the families Limacodidae, Geometridae, Notodontidae, and Arctiidae were captured less frequently in clearings than other habitats, suggesting less use of clearings by moths than the other habitats sampled. These data indicate that the frequency of occurrence and species composition of moths varied among habitats in a mixed mesophytic forest in eastern Kentucky, suggesting that forest management practices can influence the diversity and abundance of moth species. These results have implications for sustaining forest biodiversity, particularly vertebrate predators that feed on moths including forest-dwelling insectivorous bats. For. Sci. 45(3):323-332.
Distributive Impacts of Forest Resource Policies in Alberta
Authors: Alavalapati Janaki R. R. , Adamowicz Wiktor L. , White William A.
Published: April 2024

Economy-wide and distributive impacts of: (1) an $80 million increase in pulp and paper exports; (2) a $10 million decrease in lumber exports; (3) a 25% increase in the costs of timber production; and (4) a 25% increase in the costs of pulp and paper production in Alberta's forest sector are examined. A social accounting matrix (SAM)-based quantity model is used to examine the first two shocks, while a SAM-based price model is used to analyze the last two shocks. The results of the quantity model suggest that higher income households get a larger share of the benefits than lower income households in response to an expansion in the pulp and paper industry. A contraction in the lumber sector will hurt higher income households more than lower income households. Larger shares of medium and higher income households in total labor income and capital rents are identified as reasons for this asymmetric response. The results of the price model suggest that additional costs associated with sustainable forest management and environmental regulations will hurt lower income households more than higher income households. The higher share of consumer expenditure in total income for lower income households when compared to that of high income households may be responsible for this result. For. Sci. 45(3):342-348.
Effects of Douglas-Fir Dwarf Mistletoe on Trees in Thinned Stands in the Pacific Northwest
Authors: Tinnin Robert O. , Parks Catherine G. , Knutson Donald M.
Published: April 2024

The growth of 450 Douglas-fir (Pseudotsuga menziesii) in thinned stands was assessed over 20 yr. Trees infected with Douglas-fir dwarf mistletoe (Arceuthobium douglasii) were compared with uninfected trees. A significant reduction in radial and height growth was observed when infection progressed beyond half to two-thirds of the volume of a tree crown being composed of witches' broom. Growth rates varied over time, depending on environmental conditions, but heavily infected trees showed significantly reduced growth under all observed conditions. The effect of dwarf mistletoe on diameter growth in heavily infected trees was greater when the trees grew under more rigorous conditions. Tree vigor, as estimated by the ratio of basal area increment to sapwood area, was significantly reduced among trees with more than two-thirds of the crown broomed. The level of infection was measured using broom volume rating, a seven-class system based on a ratio of the volume of broomed to unbroomed branches. Over a 10-yr period, tree infection class increased at the rate of approximately one infection class every 15 yr on average. At high levels of infection, crown decline and dieback contributed to an accelerated rate of change in infection class in this study. For. Sci. 45(3):359-365.
An Optimization Approach to Selecting Research Natural Areas in National Forests
Authors: Snyder Stephanie A. , Tyrrell Lucy E. , Haight Robert G.
Published: April 2024

The USDA Forest Service has a long-established program to identify areas in national forests for designation as protected Research Natural Areas (RNAs). One of the goals is to protect high quality examples of regional ecosystems for the purposes of maintaining biological diversity, conducting nonmanipulative research and monitoring, and fostering education. When RNA designation conflicts with other land uses, difficult choices must be made about the best number and location of sites. We addressed this problem by adapting a classic optimization formulation from the location science literature. The formulation was an integer optimization model for selecting the set of RNAs that maximized the number of regional ecosystems and natural communities represented subject to an upper bound on the total area covered by the sites in the selected set. We applied the formulation using 33 potential RNAs in the Superior National Forest in northeastern Minnesota. The 33 potential RNAs were chosen for our case study because they had been mapped and field-surveyed for the presence of natural communities. The use of those sites does not imply that other areas in the Superior National Forest do not merit further study as RNA candidates. The model quickly generated information about the trade-offs between different protection goals. We found multiple sets of potential RNAs, ranging from all 33 sites to a much smaller set of 21 sites, that attained the specified goals for natural community representation. Thus, the decision-maker can choose among sets of sites with a wide range of total areas without compromising the representation goal. We also found that requirements to choose a set of sites that represents a range of locally defined ecosystems or priority natural communities can limit the total number of natural communities that can be represented within a set of sites of a given area. Average solution times for different problems were less than 5 seconds on a personal computer, suggesting that integer optimization can readily facilitate investigation of the impacts of RNA selection goals. For. Sci. 45(3):458-469.
A Framework for Forest Accounting
Authors: Vincent Jeffrey R.
Published: April 2024

Many recent empirical studies have proposed a variety of forest-related adjustments to the national income accounts. The complexity of forest-economy interactions makes such adjustments prone to double-counting and other problems if they are not guided by economic theory. This paper presents a framework for making internally consistent, theoretically sound adjustments. The framework offers two broad guidelines for applied work. First, one should adjust the overall level of gross domestic product (GDP), and thus net domestic product (NDP), for household consumption of nonmarket forest amenities and nontimber products, but not for production externalities. Accounting for production externalities involves reallocating value added among different production sectors included in GDP. Second, one should adjust NDP for the net accumulation (not just depreciation) of forest-related assets, including the timber stock, the carbon stock, and land converted from forest to other uses. The framework also offers some guidance for methods to quantify values associated with these adjustments. For. Sci. 45(4):552-571.
Estimating Type B Genetic Correlations with Unbalanced Data and Heterogeneous Variances for Half-Sib Experiments
Authors: Lu Peng-xin , White Timothy L. , Huber Dudley A.
Published: April 2024

A statistical approach is proposed for estimating type B genetic correlations with unbalanced data and heterogeneous variances across environments. First, parental GCA (one-half of the parental breeding value) effects are predicted separately for each environment using best linear unbiased prediction (BLUP). Second, predicted parental GCAs are weighted by their prediction accuracies and Pearson correlation between weighted GCAs in two environments is obtained. Third, type B genetic correlation is calculated by dividing the Pearson correlation with the mean products of prediction accuracies. Advantages of this approach include: (1) fixed effects are removed using best linear unbiased estimation (BLUE) so that they less seriously confound genetic effects when data are unbalanced; (2) heterogeneous variances associated with genetic group means are adjusted for during the process of parental GCA prediction; and (3) it is applicable when experimental designs are different in two environments. Numeric comparisons of estimation methods using simulated data of known true genetic parameters indicated that the new approach produces less bias and higher precision when data are highly unbalanced or have high level heterogeneity of variances across environments. For slightly or moderately unbalanced data, the method of Yamada (1962), however, is simpler and yields satisfactory estimates using standardized data. For. Sci. 45(4):562-572.
Compatible Volume-Taper Models for Loblolly and Slash Pine Based on a System with Segmented-Stem Form Factors
Authors: Fang Zixing , Borders Bruce E. , Bailey Robert L.
Published: April 2024

By integrating a variable-form differential equation for taper, a segmented-stem system of models involving a taper equation, merchantable volume equation, and total stem volume equation results. Through the constraints imposed on the coefficients of integration, the taper model is continuous at the inflection points, and all components in the system are compatible with each other. Models are derived for a bole with two inflection points, but the constant form factor model (no inflection point) and one inflection point segmented model can be obtained as special cases by substituting appropriate parameters directly into this more general model. All parameters are shared by the components in this compatible system. Simultaneous parameter estimation techniques are used so that all appropriate information is obtained from the data. Based on stem analysis data for 1,280 loblolly pine (Pinus taeda L.) trees and 871 slash pine (Pinus elliottii Engelm.) trees, improved predictions result with respect to predicting a stem profile when compared to a constant form factor model. For. Sci. 46(1):1-12.
Generalized Algebraic Difference Approach: Theory Based Derivation of Dynamic Site Equations with Polymorphism and Variable Asymptotes
Authors: Cieszewski C.J. , Bailey R.L.
Published: April 2024

Biologically realistic site models require the ability to concurrently express variable asymptotes and polymorphism in curve shapes. Moreover, it is only logical and rational to require that these models be invariant to changes in the index or base age. This manuscript explains the Generalized Algebraic Difference Approach that can be used effectively to derive truly base-age invariant difference equations capable of describing concurrent polymorphism and variable asymptotes. This new generic methodology for derivation of even the most complex dynamic equations is mathematically sound. The equations derived with it can be extremely flexible and may generate intricate patterns of concurrent polymorphism and variable asymptotes. This methodology is relevant to all situations in which the dependent variable is a function of an unobservable variable, and the models can be implicitly defined by their initial conditions. It is equally useful for derivation of new equations and for improvement of existing base-age specific equations. For. Sci. 46(1):116-126.
Optimal Harvesting and Thinning with Stochastic Prices
Authors: Brazee Richard J. , Bulte Erwin
Published: April 2024

This article rigorously incorporates optimal thinning decisions for an even-age stand into an optimal harvesting model with fluctuating stumpage prices. The theoretical model optimally determines how often and at what ages to thin when stumpage prices are independently drawn from a stationary distribution. New theoretical results include increases in the net present value of both land and stumpage, and an increase in some harvest reservation prices from introducing thinning. A simplified model is numerically simulated using parameters estimated from Dutch data for Pinus sylvestris to determine when to thin. The simulation results suggest that the gains from incorporating thinning are significant when compared to the Faustmann approach and at least modestly important when compared to optimal harvesting models without thinning. The simulation results also indicate that expected thinning age may decrease significantly while the expected harvest age increases, when compared to the Faustmann approach. For. Sci. 46(1):23-31.
Analytical Group Decision Making in Natural Resources: Methodology and Application
Authors: Schmoldt Daniel L. , Peterson David L.
Published: April 2024

Group decision making is becoming increasingly important in natural resource management and associated scientific applications, because multiple values are treated coincidentally in time and space, multiple resource specialists are needed, and multiple stakeholders must be included in the decision process. Decades of social science research on decision making in groups have provided insights into the impediments to effective group processes and on techniques that can be applied in a group context. Nevertheless, little integration and few applications of these results have occurred in resource management decision processes, where formal groups are integral, either directly or indirectly. A group decision-making methodology is introduced as an effective approach for temporary, formal groups (e.g., workshops). It combines the following three components: (1) brainstorming to generate ideas; (2) the analytic hierarchy process to produce judgments, manage conflict, enable consensus, and plan for implementation; and (3) a discussion template (straw document). Resulting numerical assessments of alternative decision priorities can be analyzed statistically to indicate where group member agreement occurs and where priority values are significantly different. An application of this group process to fire research program development in a workshop setting indicates that the process helps focus group deliberations; mitigates groupthink, nondecision, and social loafing pitfalls; encourages individual interaction; identifies irrational judgments; and provides a large amount of useful quantitative information about group preferences. This approach can help facilitate scientific assessments and other decision-making processes in resource management. For. Sci. 46(1):62-75.
Influence of Vertical Foliage Structure on the Distribution of Stem Cross-Sectional Area Increment in Western Hemlock and Balsam Fir
Authors: Kershaw John A. , Maguire Douglas A.
Published: April 2024

A set of western hemlock (Tsuga heterophylla Raf. [Sarg.]) and balsam fir (Abies balsamea [L.] Mill.) from western Washington, USA and western Newfoundland, Canada, respectively, were destructively sampled to examine relationships between vertical foliage structure and distribution of stem cross-sectional area increment. A series of stem growth distribution models describing the relationship between amount of foliage area above a given height and stem cross-sectional area increment at that height was derived from the pipe model theory. These models were derived with increasing generality so that two commonly held assumptions could be explicitly tested: (1) linear increase in cross-sectional area increment with increasing foliage area; and (2) constant cross-sectional area increment below base of the live crown. Overall, the models performed very well, accounting for over 80% of the observed variation in cross-sectional area increment for both species. The results show that, while cross-sectional area increment increases with increasing current foliage, the increase is not proportional (i.e., linear). Furthermore, the rate of cross-sectional area increment below base of the live crown was found to increase in the smaller balsam fir trees and decrease in the larger western hemlock trees. These results suggest that cross-sectional area increment per unit foliage below the live crown may change as trees grow. For. Sci. 46(1):86-94.
Understanding the Tradeoffs Between Site Quality and Species Presence in Reserve Site Selection
Authors: Church Richard , Gerrard Ross , Hollander Allan , Stoms David
Published: April 2024

A number of optimization models have been developed for natural reserve design and reserve site selection. The most common approach seeks to maximize the number of individual species that occur among chosen sites. A number of heuristics and mathematical programming algorithms have been applied to solve this problem. Although attaining maximum overall species representation is important, the relative quality of representation [which could be affected by site attributes such as habitat value, adequate population size, presence of critical resources, existence (or lack thereof) of exotic competitors, etc.] has been absent from most representation models. Yet issues of site quality should be considered in order to have any assurance of long-term species persistence in a reserve system. Here we present a multiobjective optimization model that addresses the issue of balancing species presence with habitat quality. One type of interesting alternative yields more high quality representation at the price of some reduction in overall representation. We present an application using a large dataset from California Gap Analysis to demonstrate this and other tradeoffs. Optimal solutions are attained using commercial integer programming software with very reasonable computational effort. For. Sci. 46(2):157-167.
A Model and Tabu Search Method to Optimize Stand Harvest and Road Construction Schedules
Authors: Richards Evelyn W. , Gunn Eldon A.
Published: April 2024

An important function of tactical planning in forest management is to choose spatially and temporally explicit schedules for both harvesting and road construction activities. In addition to maintaining consistency with goals of the strategic planning process, harvesting decisions are subjected to spatial, environmental constraints. At the same time, planning and cost of road access over the medium-term planning horizon must be considered.This article presents a model and heuristic solution methodology to address stand level harvest scheduling and the associated road construction scheduling problem. The model is formulated to determine minimal cost schedules, for stand harvests and road construction, that achieve recommended timber harvest volume targets and that comply with environmental regulations. The harvest decisions are made at the stand level of resolution. Graph structures are used to formulate the spatial restrictions on clearcut opening size and location. Road construction projects are scheduled to create a feasible road network at minimum net present capital cost.The optimization problem is solved using a Tabu search heuristic, which includes special constructs to cope with the complexity of this problem. An efficient frontier of solutions is produced, which may be utilized to analyze tradeoffs between lost forest productivity, due to timing of harvests, and the capital cost of road construction. Forest Science 46(2):188-203.
Water and Nutrient Movement in Small, Forested Watersheds in the Boston Mountains of Arkansas
Authors: Wheeler Garland L. , Steele Kenneth F. , Lawson Edwin R.
Published: April 2024

Four small (< 13.5 ha), upland, hardwood watersheds were selected for a study of the changes in water dynamics and associated chemical changes as water moves through various components of the ecosystem. These watersheds were also used to determine what changes in water movement and chemistry are related to silvicultural treatments of conversion to pine, a shelterwood cut or a clearcut applied 6 yr earlier. A fourth watershed served as a control. It was estimated that 29% of the rainfall left the watersheds. The ratio of Na+ and Cl- indicated a marine source of these elements. Enrichment from terrestrial sources was indicated for Mg+2, Ca+2, K+, and SO42-.The major changes in water movement and in water chemistry occurred between the surface of the litter layer and the bottom of the A horizon where 55% of the water and most of the nutrients that entered the watersheds were absorbed by a root network that develops at the litter A horizon interface. The degree of absorption varied from 30% for Na+ to 86% for H+. In general, nutrients that passed the A horizon also passed the E horizon and were transported out of the watersheds. SO42- was the major nutrient deposited (21.5 kg ha-1) and accumulated (15.6 kg ha-1) in the watershed followed by NO3- (9.8 and 8.2 kg ha-1) and Ca+2 (9.6 and 5.6 kg ha-1). Cl- behaved differently than other nutrients because it was stored in the canopy and surface soil layers but lost from deeper zones in the watershed. Mg+2 also differed in that it was the only nutrient to have a net loss from the watersheds.Magnesium, K+, H+, and NO3- had differences related to silvicultural treatments. Magnesium was leached from the canopy in the control and shelterwood. K+ was enriched in the throughfall of the control and possibly shelterwood. Hydrogen was absorbed in the control canopy and leached from the clearcut canopy. FOR. SCI. 46(3):335–343.
A Method of Estimating Direct and Indirect Effects of Armillaria Root Disease and Other Small-Scale Forest Disturbances on Canopy Gap Size
Authors: Lundquist John E.
Published: April 2024

The ecological and economic impacts of individual forest pathogens on forest stands are often difficult to measure because of indirect impacts arising from their interactions with other agents. Root diseases especially interact with many elements of the forest. This study uses a method called path analysis to estimate direct and indirect effects of Armillaria root disease and other small-scale disturbances on a pristine Pinus ponderosa stand in the Black Hills of South Dakota. Indirect effect was defined as an outcome where one small-scale disturbance alters the effect that another has on canopy gap size. Results indicate that key factors affecting gap size include Armillaria root disease, bark beetles, weak pathogens, ice/snow damage, lightning, and wildfires, presented in order of relative importance. Interactions occur between Armillaria and lightning, beetles, wind, and fire; between bark beetles and wind, fire, and weak pathogens; and between wind and fire. Armillaria and beetles both tend to occur where damage by wind is absent. Armillaria root disease was predicted to have the largest overall effect on gap size, which is mostly due to its direct effects, and not resulting from its interactions with other disturbances. Path analysis generates a predictive model based on covariation among disturbances and offers a way of quantifying the effects of these associations. FOR. SCI. 46(3): 356–362.
Linking Harvest Choices to Timber Supply
Authors: Prestemon Jeffrey P. , Wear David N.
Published: April 2024

Aggregate timber supply by ownership was investigated for a small region by applying stand-level harvest choice models to a representative sample of stands and then aggregating to regional totals using the area-frame of the forest survey. Timber harvest choices were estimated as probit models for three ownership categories in coastal plain southern pine stands of North Carolina using individual permanent and remeasured stand-level data from last two available USDA Forest Service Forest Inventory and Analysis (FIA) surveys. The timber harvest decision was modeled as a function of timber values, a cost factor, and stand volume as a proxy for nontimber values. Probit models were statistically significant at 1% for all ownerships. Area expansion factors (the portion of forest area in the region represented by the sampled stand) were then combined with harvest probabilities to model the aggregate effects of price changes on timber supply, given a fixed forest area. Implied price elasticities were estimated using this modeling of aggregate effects, and a bootstrapping procedure was applied to estimate confidence limits for supply elasticities with respect to price. Our results showed that NIPF and industry were elastically responsive in the aggregate when price increases are perceived as temporary but much less elastically and usually negatively responsive when increases are perceived as permanent. Results are consistent with theory of optimal rotations and highlight the critical influence of both existing inventory structure and expectations on aggregate timber supply. FOR. SCI. 46(3): 377–389.
Comparing Adjacency Constraint Formulations for Randomly Generated Forest Planning Problems with Four Age-Class Distributions
Authors: McDill Marc E. , Braze Janis
Published: April 2024

Three types of adjacency constraint formulations—pairwise, Type I ND (nondominated), and NOAM (new ordinary adjacency matrix)—were compared on 900 hypothetical, randomly generated, spatially explicit forest management problems with between 50 and 350 stands. Forests were generated using four age-class distributions, nominally called immature, regulated, overmature, and old-growth. Management planning problems with adjacency constraints were formulated for these forests in Model 1 format based on a planning horizon consisting of three 20 yr periods. The problems also included flow constraints and minimum average age requirements for the ending forest. For all age-class distributions, the Type I ND constraint type resulted in significantly lower solution times than either the Pairwise or the NOAM constraint types. NOAM constraints performed better than Pairwise constraints for immature forest problems, but Pairwise constraints performed better than NOAM constraints for overmature and old-growth forest problems. There was no difference between these two constraint types for regulated forest problems. Results also show that the age-class distribution of the forest is one of the most important factors determining the time needed to solve forest management problems with adjacency constraints. In general, the more mature the forest, the harder the problem is to solve. In particular, problems based on the old-growth age-class distribution typically took much longer to solve than comparable problems based on the other age-class distributions. FOR. SCI. 46(3): 423–536.
A Timing-Oriented Approach to Spatial Allocation of Fire Management Effort
Authors: Hof John , Omi Philip N. , Bevers Michael , Laven Richard D.
Published: April 2024

This article explores spatial optimization approaches to fire (and possibly fuel) management problems, with a timing-oriented model formulation. The relevant land area is divided into cells, and the ignition time of “protection areas” (such as towns, homes, and campgrounds) is delayed as much as possible through spatial application of treatments that have the effect of slowing the fire front movement through each cell. Model variables track the entry and exit times of the fire front and account for the earliest ignition source for each cell. A stylized case example is used to demonstrate the model's application and spatial sensitivity with easily interpretable results. The results show that a spatial concentration of fire management effort may not be optimal, at least for the simple example analyzed. Extension of the model formulation to long-term fuels management is also discussed. FOR. SCI. 46(3): 442–451.
A Travel Cost Analysis of Nonconsumptive Wildlife-Associated Recreation in the United States
Authors: Zawacki William T. , Marsinko Allan , Bowker J.M.
Published: April 2024

Increased emphasis on sustainable resource management in forestry has effectuated a demand for various nontimber values. Nonconsumptive wildlife recreation is an important nontimber service produced on forest and rangeland. Travel cost models and data from the 1991 National Survey of Fishing, Hunting and Wildlife-Associated Recreation are used to estimate the demand and value for nonconsumptive wildlife-associated recreation in the United States. Resulting welfare measures are shown to be sensitive to assumptions about the cost of travel time, pecuniary costs, and functional form. Consumer surplus estimates range from 18.7 to 327.5 dollars per trip, while aggregate estimates of consumer surplus resulting from access to nonconsumptive wildlife recreation range from 5.8 to 66.4 billion dollars annually. Availability of information about nonparticipants allows comparison of truncated and untruncated demand models. Contrary to previous findings, consumer surplus estimates from truncated models are smaller than for untruncated counterparts. Trip demand is found to be adversely affected by per capita decreases in forest and rangeland. Models include interaction variables to avoid forcing hunting or fishing as potential substitutes for the large number of people who do not hunt or fish. Hunting and nonconsumptive wildlife recreation are complementary activities, while the results for fishing are mixed. FOR. SCI. 46(4):496–506.
Estimating Metrics of Forest Spatial Pattern from Large Area Forest Inventory Cluster Samples
Authors: Kleinn Christoph
Published: April 2024

The interest in ecologically meaningful information from forest inventories is increasing. Forest area and its characteristics of spatial distribution are among this information. This paper describes a technique for deriving some metrics of forest spatial pattern from nonmapped forest inventory samples. The technique is developed for clusters of subplots, though applicable also for other plot types. It evaluates the area of the three categories: forest, nonforest, and buffer, estimated by the percentage of cluster plots where all, none, or some subplot centers fall into forest. Of particular interest is the buffer area, which is an imagined strip along the forest boundary: the larger this area, the more forest boundaries there are, and the more fragmented the forest pattern is. The estimates of forest and buffer area percentage are used to derive metrics that are related to perimeter length and mean patch size. Variance estimators for these metrics are given. Two examples are presented to illustrate the characteristics of the method, one with a schematic map, one with real inventory data. The most meaningful results are obtained when the size of the cluster plots used is smaller than the forest patches and smaller than the distance between them. The examples suggest that, in order to obtain reasonably precise estimates, sample size should be n = 500 or more. These conditions commonly hold in large area forest inventories. The technique processes information that is readily available from the field measurements of large area forest inventories. It does not require extra measurements and adds an ecologically meaningful aspect to the data analysis. It is independent of the availability of complete maps of the inventory region or of mapped plots, and therefore also allows the retrospective analysis of old forest inventory sample data. FOR. SCI. 46(4):548–557.
Hydrologic Modeling of a Drained Pine Plantation on Poorly Drained Soils
Authors: Amatya Devendra Man , Skaggs Richard Wayne
Published: April 2024

Three experimental watersheds in eastern North Carolina have been continuously monitored since 1988 to study long-term hydrology of loblolly pine (Pinus taeda L.) forests on poorly drained soils. This study was conducted to test the forestry version of an agricultural hydrology model DRAINMOD with 10 yr (1988–1997) of data collected at one of these watersheds under conventional (open ditch) drainage. The model, which is based on hourly water balance for the land between parallel drainage ditches, simulates interception, evapotranspiration (ET) as the sum of canopy transpiration and soil evaporation, drainage, and surface runoff. Results showed that model predictions of daily water table elevations and flow rates on an average annual basis were within 0.15 m and 0.61 mm, respectively, compared to the measured data. Relative errors on drainage outflow varied from -18% to 23%, with an average of 0.4%. Errors in measured flow rates during weir submergence, missing rainfall and weather data, and uncertainty in estimates of stomatal conductance contributed to the differences between model predictions and field observations. It was concluded that the model is a reliable tool for assessing hydrologic impacts of silvicultural and water management treatments, as well as climate changes, on these pine stands. FOR. Sci. 47(1):103–114.