bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Method to Distribute Mortality in Diameter Distribution Models
Authors: Cao Quang V. 
Published: April 2024

Abstract
Bailey (1980) derived tree diameter growth models by transforming variables which preserved the functional form of the probability density function that approximated diameter distributions. The necessary assumption was either no mortality, or that mortality was proportionally distributed among diameter classes. The latter assumption might not be realistic since smaller trees should suffer more from competition than large trees and are more likely to die. This paper deals with the case when mortality is not proportionally distributed. If diameters in a stand originally follow a Weibull distribution and mortality for a growing period can be assumed to occur at the beginning of that period, then a Weibull was found to successfully approximate the diameter distribution immediately after mortality. The stand then grows without further mortality and reaches the end of the period with its diameters remaining Weibull. A similar method to derive a diameter distribution after mortality was developed for the beta distribution. The Weibull technique was applied to data from loblolly plantations. Results showed that the new approach worked reasonably well and was comparable with a diameter distribution model in approximating diameter distribution of a stand at the end of the growth period. For. Sci. 43(3):435-442.
A Distribution-Independent Approach to Predicting Stand Diameter Distribution
Authors: Tang Shouzheng , Wang Yonghe , Zhang Lianjun , Meng Cho-Ho 
Published: April 2024

Abstract
A new approach to projecting future stand diameter distribution was proposed without assuming a predefined probability density function. The Lebesque-Stieltjes integral was applied to derive a group of equations for the relationships between current and future stand diameter distributions and stand-level attributes. The parameters in the tree survival function and diameter growth function were recovered using these equations based on independent estimates of future stand mean diameter, quadratic mean diameter, and survival from a whole stand model. This disaggregation approach ensured that the resolutions at size-class distribution and/or individual tree levels were compatible with the stand-level aggregates. A stochastic error component was incorporated into the tree diameter growth function. This allowed us to mimic the tree diameter differentiation process over time, and it improved prediction accuracy for future stand diameter distributions. The proposed approach can also be used to allocate stand growth and yield to a list of individual trees. The fluctuation of tree growth and survival for each tree can be implemented by simulating the variance of tree diameter growth and survival probability using Monte Carlo or error propagation methods. For. Sci. 43(4):491-500.
Managerial and Institutional Factors Affect Prescribed Burning Costs
Authors: González-Cabán Armando 
Published: April 2024

Abstract
Prescribed burning costs are extremely variable, even if conditions are similar. This variability complicates planning and evaluation of prescribed burning programs and budgets, resulting in imprecise projections of their economic benefits. Evaluating the worth of prescribed burning efforts in objective terms is difficult, but the continual shrinkage of USDA Forest Service budgets requires an increase in program efficiency and understanding the causes of variability for prescribed burning costs. An analysis of variance model was used to describe and quantify the relative effect of managerial and institutional factors, such as smoke emission limitations or the constraint to control all types of fires, on prescribed burning costs. Data were collected by using a questionnaire to fire and fuel managers in the USDA Forest Service's Northern, Intermountain, and Pacific Northwest Regions. Estimated prescribed burning costs were significantly affected by changes in the managerial and institutional factors, such as minimizing escape potential or complying with smoke emission standards presented to these fire managers. Contrary to our expectations, burn objective (the main reason for conducting the burn) was not a significant cost factor. Unit size of the burned area affected prescribed burning costs more than either change in slope or unit shape, both of which increase the amount of burn perimeter relative to the area burned. Costs per acre demonstrated economies of scale: the larger the unit burned, the lower its per-acre cost. For. Sci. 43(4):535-543.
Forest Harvesting and Minimum Cuts: A New Approach to Handling Spatial Constraints
Authors: Hochbaum Dorit S. , Pathria Anu 
Published: April 2024

Abstract
In this paper we discuss two forest harvesting optimization problems that arise in forest management. We consider one-stage decision problems in which the forest to be managed is partitioned into cells and the decision is to be made as to which cells to harvest. There are competing concerns to consider in assessing the value of a particular harvesting decision: the first has to do with the value of the timber harvested, and the second has to do with assessing the relative values of the resulting spatial layout from a wildlife habitat point of view. The two problems that we consider are similar, but they assess the relative merits of resulting spatial layouts somewhat differently and therefore have different objective functions to be optimized. The first problem we consider assigns benefits for harvesting cells and penalties for harvesting adjacent cells; the second problem considered assigns benefits for harvesting cells as well as benefits for creating borders that separate harvested and unharvested cells. We show that both forest harvesting problems can be interpreted as instances of the Generalized Independent Set graph optimization problem, which we introduce in this article. Generalized Independent Set is a generalization of the well-known Independent Set graph optimization problem (a set of nodes in a graph is said to be independent if no two nodes in the set are adjacent). When the underlying graph is bipartite, we derive an efficient solution method for Generalized Independent Set via network flow methods. If the cell structure is grid-like in the forest harvesting problems, then an instance of either forestry problem can be reduced to an instance of Generalized Independent Set on a bipartite graph. For such instances we developed efficient algorithms for determining an optimal harvesting strategy. The running time is O(n² log n), where n is the number of cells in the land area to be spatially managed. For. Sci. 43(4):544-554.
A Comparison of Timber Market Models: Static Simulation and Optimal Control Approaches
Authors: Sohngen Brent , Sedjo Roger 
Published: April 2024

Abstract
In this paper, we compare and contrast two types of timber models that have been used to analyze the market impacts of policy proposals or exogenous forces that affect timber markets. The framework and theory for static simulation and optimal control models are presented and discussed. We then compare single region, empirical versions of the models across six scenarios of exogenous economic shocks. The models are found to predict different outcomes for timber market behavior when demand changes, or when young timber is affected by a supply shock. Similar outcomes between the models are obtained when older timber stocks are affected by shocks, or when the exogenous forces impact timber markets gradually over time. For. Sci. 44(1):24-36.
Transect Relascope Sampling--A Method for the Quantification of Coarse Woody Debris
Authors: Ståhl Göran 
Published: April 2024

Abstract
A method for the quantification of coarse woody debris in terms of the total length of downed material is presented. The method combines relascope and line intersect sampling theory. Estimation is based on a count of downed logs using a relascope instrument along survey lines. In cost-efficiency comparisons with line intersect and circular plot sampling, the proposed method was found to be a competitive alternative. For. Sci. 44(1):58-63.
Use of Individual Tree Mixed Models to Account for Mortality and Selective Thinning When Estimating Base Population Genetic Parameters
Authors: Wei Xianming , Borralho Nuno M. G. 
Published: April 2024

Abstract
The ability of individual tree mixed models to estimate unbiased genetic parameters was investigated for growth, Pilodyn penetration, and bark thickness, in an Eucalyptus urophylla progeny trial where the smaller trees have been previously thinned. A multivariate Restricted Maximum Likelihood (REML) analysis including the growth measurements of all trees prior to thinning, and later measurements of only those that remained, resulted in almost unbiased estimates of heritabilities and age-age genetic correlations for growth traits at all ages. Analysis based only on trees remaining after thinning resulted in considerably lower estimates of heritabilities and age-age genetic correlations. On the other hand, genetic parameters for Pilodyn penetration or bark thickness were not affected by the thinning. This was due to the low correlations between the thinning criteria (tree size) and the wood and bark traits. For. Sci. 44(2):246-253.
Determining the Optimal Planting Density and Land Expectation Value--A Numerical Evaluation of Decision Model
Authors: Gong Peichen 
Published: April 2024

Abstract
Different decision models can be constructed and used to analyze a regeneration decision in even-aged stand management. However, the optimal decision and management outcomes determined in an analysis may depend on the decision model used in the analysis. This paper examines the proper choice of decision model for determining the optimal planting density and land expectation value (LEV) for a Scots pine (Pinus sylvestris L.) plantation in northern Sweden. First, a general adaptive decision model for determining the regeneration alternative that maximizes the LEV is presented. This model recognizes future stand state and timber price uncertainties by including multiple stand state and timber price scenarios, and assumes that the harvest decision in each future period will be made conditional on the observed stand state and timber prices. Alternative assumptions about future stand states, timber prices, and harvest decisions can be incorporated into this general decision model, resulting in several different decision models that can be used to analyze a specific regeneration problem. Next, the consequences of choosing different modeling assumptions are determined using the example Scots pine plantation problem. Numerical results show that the most important sources of uncertainty that affect the optimal planting density and LEV are variations of the optimal clearcut time due to short-term fluctuations of timber prices. It is appropriate to determine the optimal planting density and harvest policy using an adaptive decision model that recognizes uncertainty only in future timber prices. After the optimal decisions have been found, however, the LEV should be re-estimated by incorporating both future stand state and timber price uncertainties. For. Sci. 44(3):356-364.
Survival of Hemlock Woolly Adelgid (Homoptera: Adelgidae) at Low Temperatures
Authors: Parker Bruce L. , Skinner Margaret , Gouli Svetlana , Ashikaga Takamaru , Teillon H. Brenton 
Published: April 2024

Abstract
The hemlock woolly adelgid (Adelges tsugae Annand [Homoptera: Adelgidae]) (HWA), a nonnative insect, is a major threat to New England forest and suburban environments, where one of its hosts, eastern hemlock, Tsuga canadensis (L.) Carrière, is a dominant native tree species. To determine the potential spread of HWA into northern New England, we studied the winter coldhardiness of a northerly population. Sistens were collected at three times during the winter and subjected to temperatures typical of those during winter in the next coldest USDA plant coldhardiness zone. Samples collected in January and February 1996 were subjected to -20, -25, and -30°C; those collected in March to -15, -20, and -25°C; all date-temperature treatments were tested at exposure times of 1, 2, 4, 8, and 24 hr. When all exposure times were combined, the percentage of live adelgids after subzero treatment (adjusted for control mortality at 0°C) declined significantly as temperature decreased. In most cases, fewer HWA were alive after treatment as exposure time increased. Significantly more HWA collected in January were alive after treatment than those collected in February and March. This suggests that HWA coldhardiness declines over this time period. When comparing the percentage of live HWA from February and March for -20 and -25°C, a noticeable decline occurred between the February and March sample dates. Although mortality was as high as 95% in one of the most severe treatments (February collection exposed to -30°C for 24 hr), the fact that complete mortality did not occur suggests that HWA may be able to continue to expand its range into areas with colder winters. For. Sci. 44(3):414-420.
Development and Evaluation of Habitat Models for Herpetofauna and Small Mammals
Authors: Block William M. , Morrison Michael L. , Scott Peter E. 
Published: April 2024

Abstract
We evaluated the ability of discriminant analysis (DA), logistic regression (LR), and multiple regression (MR) to describe habitat use by amphibians, reptiles, and small mammals found in California oak woodlands. We also compared models derived from pitfall and live trapping data for several species. Habitat relations modeled by DA and LR produced similar results, averaging about 70% classification success of the trapping stations to the correct group (capture or noncapture habitat). Although more variables were included in DA (4-5) than in LR (2-3), those included in LR were typically a subset of those in DA. On average, MR habitat models accounted for 56% of the variation in the index of relative species' abundance. The variables included in the MR models were seldom the same as those for DA and LR. Most differences between MR and the other two methods were related to differences in spatial scale: MR modeled habitat among grids, whereas DA and LR modeled habitat within grids. Habitat models for the same species differed between the trapping methods used. Live traps are most useful for describing general habitat relations of some small mammal species across large geographic areas, whereas pitfall traps are useful for intensive sampling of a larger portion of the vertebrate community within smaller geographic areas. Thus, the choice of trapping methods must be based on the study goals, biology of the species, and the spatial scale of study. For. Sci. 44(3):430-437.
Using Dynamic Programming and Overlapping Subproblems to Address Adjacency in Large Harvest Scheduling Problems
Authors: Hoganson Howard M. , Borges Jose G. 
Published: April 2024

Abstract
The adjacency problem for forest management scheduling is formulated as a dynamic programming problem. To overcome typical model-size problems, a solution strategy is proposed which links dynamic programming formulations for overlapping subproblems. Subproblems are solved sequentially in a moving-windows fashion. Solutions are near-optimal for three large but simplified test cases. Model size is sensitive to the size of the moving window. Using relatively small windows produced solutions that are closer to optimal than those found using two other modeling approaches. Solutions are also insensitive to the side of the forest used to start the moving-windows process, and microcomputer solution times are not a major consideration. The strategy offers potential to treat adjacency measures as valued management outputs. It will likely fit well into broader forestwide models which decompose the forestwide problem into parts to help address other forestwide constraints. For. Sci. 44(4):526-538.
Survival and Growth of Seedlings of Four Bottomland Oak Species in Response to Increases in Flooding and Salinity
Authors: Conner William H. , McLeod Kenneth W. , McCarron James K. 
Published: April 2024

Abstract
Four oak species representing a range of flood tolerance were chronically (simulating sea level rise) and acutely (simulating hurricane storm surge) exposed to increased flooding and salinity in a complete factorial experiment. Survival, growth, and final biomass were measured to assess differential species' responses. No Nuttall or overcup oak seedlings died when flooded with fresh water, but 10% of the swamp chestnut and 35% of the water oaks died. Floodwater salinities of 2 and 6 g L-1 resulted in mortality of all seedlings of all four species. Watering with 2 g L-1 saline water did not cause any mortality although leaf browning was evident in all species. Overcup oak seedlings were the most tolerant to watering with 6 g L-1 saline water (100% survival), while the other three species had high mortality. Increased salinity, both in watered and flooded conditions, generally resulted in decreased diameter growth and decreased root and shoot biomass. Short-term increases in salinity (simulated storm surge) resulted in total mortality of flooded seedlings, while drained seedlings recovered and leafed out the following spring. Results indicate that these bottomland oak species would be seriously affected by increased flooding and salinity from either hurricane storm surges or sea level rise. For. Sci. 44(4):618-624.
A Linear Programming, Tabu Search Method for Solving Forest-Level Bucking Optimization Problems
Authors: Laroze Andre 
Published: April 2024

Abstract
The forest-level bucking optimization problem consists of determining the bucking program that maximizes the global profit subject to demand constraints, merchandising restrictions, and forest-estate. A Linear Programming-Tabu Search (LP/TS) method was developed for obtaining near-optimal, rule-based solutions to this problem. TS is used for generating an efficient bucking rule for every stand and merchandising restrictions considered. The LP model is used for determining the area of each stand that should be allocated to each merchandising alternative (and by doing so selecting the bucking rule defined for the corresponding specifications). The goal is to capture the synergy that can be obtained by combining logs from different sources that are produced applying different production guidelines. The results obtained for several estate, price, and demand conditions indicate that the LP/TS method consistently achieves an efficiency level of approximately 97% compared to the optimal solution for the same scenarios. Considering that the simplicity of the bucking rules offers an important operational advantage (Laroze and Greber 1997), the method developed for this study represents an interesting approach for solving forest-level bucking problems. For. Sci. 45(1):108-116.
Optimal Public Harvesting Under the Interdependence of Public and Private Forests
Authors: Koskela Erkki , Ollikainen Markku 
Published: April 2024

Abstract
This article studies the design of optimal public harvesting in an economy with multiple-use forestry and private timber supply, where amenity services of public forests are public goods but, depending on access restrictions, those of private forests may or may not be. Public and private forest stands are assumed to be either substitutes, independents, or complements in the valuation of amenity services, and public and private forests are perfect substitutes as factors of production in forest industry. Under exogenous timber prices and free access, public harvesting should be used only if the marginal willingness to pay to forego public harvesting is sufficiently less than that of private harvesting. Public harvesting with no access reduces to a situation where private and public forests are independents under free access. Allowing for endogenous timber prices with free access increases the desirability of public harvesting, while having no impact under no access. Public harvesting should be set to equate the marginal costs of public harvesting corrected for the change in private timber supply and its marginal benefits due to price changes. For. Sci. 45(2):259-271.
Silvicultural Contracting in British Columbia: A Transaction Cost Economics Analysis
Authors: Wang Sen , Van Kooten G. C. 
Published: April 2024

Abstract
In the light of institutional reforms to British Columbia's forestry sector, this study investigates forest companies' decisions to contract out silvicultural activities or to perform them in-house. A model is developed to test the relationship between a firm's choice of contractual forms and (a) the attributes of the activity (e.g., specificity of technical skills and physical assets, frequency of operations, and uncertainty in controlling performance quality) and (b) characteristics of the firm (e.g., company size). Data from a survey of forest companies in the Province are used to test several hypotheses. The empirical results confirm the transaction cost logic that silvicultural activities performed in-house are likely those that are complex to manage, have a low degree of seasonality, require high levels of human skills, and involve highly specialized physical assets. For. Sci. 45(2):272-279.
Vertical Overstory Canopy Architecture of Temperate Deciduous Hardwood Forests in the Eastern United States
Authors: Yang Xiusheng , Witcosky Jeffrey J. , Miller David R. 
Published: April 2024

Abstract
The stand attributes and vertical overstory profiles of plant area (the total projected surface area of all canopy elements including leaves, twigs, and stems) for 15 temperate deciduous hardwood forest types were studied and reported. The study was conducted across the eastern United States within forest type-groups of boreal hardwood, northern hardwood, and upland oak. Vertical distributions of plant area were measured with gap-fraction-based optical sensors mounted on a mobile sampling tower. In general, the stand attributes of the surveyed forest types exhibited distinct characteristics among the three type-groups. The vertical profile of the overstory plant area demonstrated significant differences among forest types and therefore represented an important architectural feature of a forest type. The vertical profile data were well described by a modified Weibull cumulative distribution function. The two model parameters, one indicating a depth for 63% foliage inclusion and the other representing skewness, were presented for each of the 15 forest types. These two model parameters can be used to depict the vertical distribution of overstory plant area in other stands of the same types. The vertical profiles of overstory plant area were related to the successional characteristics and understory tolerance. For. Sci. 45(3):349-358.
Developing Resource-Based Social Conflict Models for Assessing the Utility of Negotiation in Conflict Resolution
Authors: Germain René H. , Floyd Donald W. 
Published: April 2024

Abstract
Social conflicts over the management of natural resources are increasing. An informative example of these conflicts is the debate over the management of our national forests. Despite sincere efforts by the USDA Forest Service to improve modes of public involvement, as well as the institutionalization of dispute resolution procedures, the contentiousness and frequency of conflict continues to escalate. This is manifest in the high number of administrative appeals on forest plans and projects. The study used a nation-wide survey of 238 appellants (response rate of 75%) of Forest Service management decisions to test the predictive utility of social conflict models for determining the feasibility of negotiation in resolving environmental conflict. This paper addresses the question of whether the utility of negotiation can be predicted based on (1) the resources involved in the dispute, (2) how those resources are being utilized, and (3) the perceived impact on social, economic, and health issues. The social conflict models proved to have some utility in predicting the types of conflict that may be predisposed to resolution through negotiation. For. Sci. 45(3):394-406.