bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
Four small (&lt; 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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.