bluuebunny/crossref_metadata_2025 huggingface dataset:
A Genetic Algorithm Approach to Tree Bucking Optimization
Authors: Kivinen Veli-Pekka
Published: April 2024

Tree bucking on modern cut-to-length harvesters is controlled by two types of matrices. The price matrix provides the bucking computer with information on how to prioritize various log grades and diameter-length combinations within the same grade, while the demand matrix specifies the desired proportion for each combination. The traditional approach has been to apply the samematrix set to all stands to be harvested within the same planning period, although the stand structure and the characteristics of trees may vary markedly from stand to stand. The purpose of this research was to test the hypothesis that controlling bucking matrices prior to harvesting would improve bucking results at the forest level. The search for stand-specific price matrices was based on a genetic algorithm (GA) that, given a desired overall log distribution and the stem profiles of all the trees in each stand, optimizes, in a parallel manner, the price matrix of a given log grade for each stand involved in the process. The mutation rate and the degree of elitism had the greatest effect on the performance of the developed GA system. In 10 test runs with the same parameter set, the fitness value of the poorest solution (price matrix string) was 98.2% of that of the best solution. The simulations with the bucking simulator, however, indicate that precontrol of price matrices does not improve the fit between the overall demand matrix and the global output matrix even if the log prices are adjusted according to stem data without estimation errors. FOR. SCI. 50(5):696–710.
Small-Mammal Relationships with Down Wood and Antelope Bitterbrush in Ponderosa Pine Forests of Central Oregon
Authors: Smith Troy G. , Maguire Chris C.
Published: April 2024

The influence of down wood on fire behavior in ponderosa pine (Pinus ponderosa) forests in central Oregon is much understood. However, little is known about down-wood affiliations with wildlife in this area. Antelope bitterbrush (Purshia tridentata) contributes to wildfires, nitrogen fixation, and the food web, yet its influence on small-mammal populations remains poorly defined. In this study, population density, survival, and reproductive status of yellow-pine chipmunks (Tamias amoenus), golden-mantled ground squirrels (Spermophilus lateralis), and deer mice (Peromyscus maniculatus) are estimated under three down-wood and shrub-cover conditions in ponderosa pine/antelope bitterbrush forests of Oregon. The odds for golden-mantled ground squirrel survival are 4.2 times greater on units with high (x¯ = 117.8 m3/ha) versus low down-wood volume (x¯ = 15.8 m3/ha), and each 35.1-m3/ha increase in down wood coincides with a 10% increase in ground squirrel density. Yellow-pine chipmunk densities are 57% higher on units with high (x¯ = 31.2%) versus low total shrub cover (x¯ = 9.2%), and 4.4 and 2.3% increases in total shrub and live bitterbrush cover, respectively, coincide with 10% increases in chipmunk density. Deer mouse populations are little affected by down-wood volume or shrub cover. Study results suggest that management activities influencing down wood or bitterbrush will likely affect the composition of small-mammal communities through population changes in one or more small-mammal species. FOR. SCI. 50(5):711–728.
Young Stand Growth Modeling for Intensively-Managed Loblolly Pine Plantations in Southeastern U.S
Authors: Westfall James A. , Burkhart Harold E. , Allen H. Lee
Published: April 2024

Intensively managed loblolly pine stands are often subjected to a variety of silvicultural treatments at time of planting or shortly thereafter. However, most loblolly pine growth-and-yield models predict growth after crown closure has occurred. In this article, we describe the development and implementation of a system of equations designed to simulate growth of loblolly pine before the onset of intraspecific competition. Treatment response functions were also developed for various site preparation, herbaceous weed control, and fertilization practices. These functions modify the baseline model predictions to simulate the effects of treatments on tree growth and stand development. This system was incorporated into the PTAEDA2 growth-and-yield simulator to make growth projections from time of planting through rotation age for intensively managed stands of loblolly pine in the southeastern United States. Growth simulations specifying either bedding or disking showed increases in volume growth for both treatments. The shear-and-pile site-preparation method reduced growth rates slightly. Volume growth responses to herbaceous weed control were positive, with magnitude of increase largely depending on duration of treatment. Increases in volume attributable to fertilization at planting were related to types of element applied. The largest predicted response was for phosphorus fertilization, whereas application of potassium was the least effective fertilization treatment. Site preparation, weed control, and fertilization treatment combinations produced additional volume gains when compared to single treatments, while maintaining predicted values that are within biological limits for loblolly pine growth. Levels of response to treatments are consistent with results from published studies on intensive management practices. The addition of the precompetitive growth system did not significantly affect the predictive behavior of the PTAEDA2 model for untreated stands. FOR. SCI. 50(6):823–835.
Are Self-Thinning Constraints Needed in a Tree-Specific Mortality Model?
Authors: Monserud Robert A. , Ledermann Thomas , Sterba Hubert
Published: April 2024

Can a tree-specific mortality model elicit expected forest stand density dynamics without imposing stand-level constraints such as Reineke's maximum stand density index (SDImax) or the −3/2 power law of self-thinning? We examine this emergent properties question using the Austrian stand simulator PROGNAUS. This simulator was chosen specifically because it does not use stand density constraints to determine individual tree mortality rates. In addition, it is based on a probability sample of the population that includes the span of the data being used to test the hypothesis. Initial conditions were obtained from 27 permanent research plots that were established in young pure stands of Norway spruce (Picea abies L. Karst.) and Scots pine (Pinus sylvestris L.) in Austria. A growth period of 250 years was simulated. We conduct our test in two parts. First, we compare our simulated results to Reineke's theory of maximum density and stand density index by examining the self-thinning relationship between stem number per hectare and quadratic mean diameter (log-log scale). Second, we compare our results to Sterba's full competition density rule, which incorporates dominant height along with stem number and quadratic mean diameter. From the results for Norway spruce, we conclude that stand-level density constraints are not necessary to obtain Reineke's maximum size-density relations. Norway spruce results confirm that the maximum size-density relationship reflects reasonable and stable stand dynamics and conforms to that expected by Reineke's theory. Results from simulation of Scots pine also display reasonable and stable stand dynamics, except that they greatly exceed Reineke's maximum stand density index determined empirically from the literature. This Scots pine result argues for stand-level constraints (such as specifying SDImax) to ensure that the appropriate intercept for the maximum density line is used. Our second test revealed that the estimated maximum stand density index according to Sterba's theory was too high for both species, but that the relative rankings across plots were correct. Thus, we are left with ambiguous results. First, that a density-dependent individual-tree mortality model, developed on an adequate data set, is sufficient for the desired stand-level behavior of Reineke to emerge. Second, that stand-level constraints on SDImax need to be imposed if the underlying mortality modeling database is not adequate. FOR. SCI. 50(6):848–858.
Improved Estimation for Multiple Means with Heterogeneous Variances
Authors: Green Edwin J. , Strawderman William E. , Amateis Ralph L. , Reams Gregory A.
Published: April 2024

Two new estimators are presented for use in situations where simultaneous estimation of more than two sample means is required and alternative, possibly biased information is available. The new estimators are modifications to an older estimator by Green and Strawderman. The latter estimator assumed homogeneous variances, whereas the new ones are designed for the more usual case of heterogeneous variances among the sample means. In simulation experiments, the new estimators yielded superior performance to that of the ordinary sample mean vector (X). Surprisingly, the estimator designed to dominate X under precision-weighted loss was apparently the best estimator, even under nonprecision-weighted loss. Use of the new estimators should allow foresters to achieve considerable savings in estimation precision. FOR. SCI. 51(1):1–6.
Genotype by Environment Interactions in an Australia-Wide Radiata Pine Diallel Mating Experiment: Implications for Regionalized Breeding
Authors: Wu Harry X. , Matheson A. Colin
Published: April 2024

Genotype by site interactions were studied in an Australia-wide diallel experiment covering 10 testing sites for stem dbh, stem straightness, branch angle and size, and number of branch clusters on the stem at age 10.5 to 11.5 years. The size and practical importance of genotype by site interactions were examined by four approaches: (1) the ratio of interaction variance to general combining ability (GCA) variance; (2) additive genetic correlations among sites; (3) testing whether the interaction was a result of a few families reacting more than others; and (4) by the size of genetic gains through a proposed regionalization. The genotype by site interaction for dbh observed in this experiment was larger than reported earlier for radiata pine because two high-elevation sites were included. There were more interactions between the two high-elevation sites and other lower elevation sites than interactions between lower elevation sites. The large genotype by region interaction was attributed to the extensive snow loading at the two higher elevation sites. Gain predictions from five regionalization schemes in this experiment favor regionalization of radiata pine breeding into two main regions: higher elevation and lower elevation sites. FOR. SCI. 51(1):29–40.
Forest Fragmentation Estimated from Remotely Sensed Data: Is Comparison Across Scales Possible?
Authors: García-Gigorro Soledad , Saura Santiago
Published: April 2024

Remotely sensed data with different spatial resolutions are being used as the primary information source for the analysis of forest fragmentation. However, there is currently a lack of appropriate methods that allow for the comparison of forest fragmentation estimates across various spatial scales. To provide insights into this problem we analyzed a forested study area in central Spain and a set of 10 widely used fragmentation indices. Forests were mapped from two simultaneously gathered satellite images with different spatial resolutions, 30 m (Landsat-TM) and 188 m (IRS-WiFS). TM forest data were transferred to WiFS resolution through different aggregation rules and compared with actual WiFS data. We found that incorporating sensor point spread function (which replicates the real way in which remote sensors acquire radiation from the ground) greatly improved comparability of forest fragmentation indices. We found a poor performance of power scaling laws for estimating forest fragmentation at finer spatial resolutions, and suggest that the true accuracy and practical utility of these scaling functions may have been overestimated in previous literature. Finally, we report an unstable behavior of three cell-based fragmentation indices (clumpiness, aggregation, and patch cohesion indices), for which spuriously high values can be obtained by resampling forest data to finer spatial resolutions. We believe that the results and guidelines provided may significantly contribute to an adequate analysis and comparison across scales of forest fragmentation estimations. FOR. SCI. 51(1):51–63.
Motivations and Behaviors of New Forest Owners in Virginia
Authors: Kendra Angelina , Hull R. Bruce
Published: April 2024

Forestry must find ways to remain relevant to its changing constituency and client base. Market segmentation techniques can help. This study assessed the motivations and forest practices of 661 people who recently purchased forested lands ranging in size between 0.8 and 20 ha in rapidly growing counties in Virginia. Cluster analysis techniques were used to identify six market segments: absentee investors (4%), professionals (13%), preservationists (16%), young families (19%), forest planners (21%), and farmers (21%). (The remaining 6% demonstrated no variance in their responses and were not clustered.) The results suggest that lifestyle and amenity concerns are much more important motivations for landownership than are timber production and economic concerns. We discuss communication strategies, management services, and landowner assistance programs that might appeal to people in each of the six market segments. FOR. SCI. 51(2):142–154.
Nitrogen Management in a Fraser Fir (Abies fraseri [Pursh] Poir.) Christmas Tree Plantation: Effects of Fertilization on Tree Performance and Nitrogen Leaching
Authors: Rothstein David E.
Published: April 2024

There is increasing concern over the effects of nitrogen (N) pollution resulting from fertilizer inputs to food and fiber production systems. Christmas tree production is one segment of the forestry sector that uses substantial fertilizer inputs. However, we know very little about the environmental costs and production benefits of N fertilization in Christmas tree plantations. I studied the costs and benefits of 2 years of N applications (as ammonium sulfate) at 0, 47, 95, and 140 kg N ha−1 year−1 to 4-year-old Fraser fir (Abies fraseri) Christmas trees. These rates correspond to 0, 50, 100, and 150% of the amount recommended for 4-year-old trees, and 33, 67, and 100% of recommendations for 5-year-old trees. There were no significant effects of fertilization rate on tree growth or morphology. In contrast, foliar N concentrations increased with increasing rates of N application, and there was a trend toward improved foliage health (indicated by chlorophyll fluorescence) at the lowest application rate. Mineral N (NH+4 + NO−3) concentrations in water leaching below the rooting zone increased markedly with increasing N application rates. Lysimeter NO−3 concentrations in the highest application treatment were consistently 20–30 times greater than the safe drinking water standard of 10 mg NO−3-N/l. Together, these results suggest that conventional guidelines for fertilization of Michigan Fraser fir plantations greatly exceed the capacity of trees and surface soils to store N, provide no benefit to tree growth, and create the potential for significant N pollution of ground and surface waters. Furthermore, these results indicate that applying N at a lower rate of 47 kg N ha−1 year−1 substantially reduced NO−3 leaching with no decline in growth rates or tree quality. FOR. SCI. 51(2):175–184.
Hypogeous Ectomycorrhizal Fungal Species on Roots and in Small Mammal Diet in a Mixed-Conifer Forest
Authors: Izzo Antonio D. , Meyer Marc , Trappe James M. , North Malcolm , Bruns Thomas D.
Published: April 2024

The purpose of this study was to estimate the portion of an ectomycorrhizal (ECM) fungi root community with a hypogeous fruiting habit. We used molecular methods (DNA sequence analysis of the internally transcribed spacer [ITS] region of rDNA) to compare three viewpoints: ECM fungi on the roots in a southern Sierra Nevada Abies-dominated old-growth forest, fungi in scat samples collected from small mammals in the same forest, and hypogeous sporocarps found throughout the Sierra Nevada. We found that hypogeous taxa accounted for a minimum of 21% of the species and 25–40% of the dry root biomass of all samples. This estimate is two to three times greater than estimates from previous studies. This difference may be due to methodological advantages of this study, but may also be related to conditions in dry forests typical of western North America where prolonged drought may favor this form of fruiting. Although molecular analysis of scat samples did not add to our view of the ECM roots, we readily isolated sequences from Rhizopogon species. From these results we inferred that two species, R. occidentalis and R. olivaceotinctus, are represented primarily in the spore bank and may be dependent on substantial disturbance to become abundant on roots. FOR. SCI. 51(3):243–254.
Comparing and Combining Stem Analysis and Permanent Sample Plot Data in Site Index Models
Authors: García Oscar
Published: April 2024

Most site index models are built either from repeated measurements on permanent sample plots or by using data obtained by stem analysis. Sometimes both types of data are available. It is then of interest to test them for consistent height-age trends, and to estimate model parameters using all the data. Efficient procedures should take into account the difference in error patterns between the two data sources. A stochastic differential equation model is proposed in which trend and error parameters can take either different or common values for various data groups. All parameters are simultaneously estimated by maximum-likelihood, and computed likelihoods and likelihood-ratio tests can be used for comparing model variants and for hypothesis testing. The methods are applied to Pinus pinaster plantations in northern Spain. FOR. SCI. 51(4):277–283.
Localizing a Predicted Diameter Distribution Using Sample Information
Authors: Mehtätalo Lauri
Published: April 2024

This study presents a new method for predicting the diameter distribution of a stand, utilizing the percentile-based diameter distribution. The expected diameter percentiles are first predicted using stand measurements. Subsequently, the distribution is calibrated (localized) for the stand using sample order statistics, which consist of one or more diameters of sample trees and their ranks on the sample plot(s). These measurements can be quickly carried out in the field, because the rank can be assessed visually. The sample order statistics can be interpreted as measured sample percentiles. The expectations, variances, and covariances of the measured sample order statistics are derived using the theory of order statistics. Regression models are used to predict the conditional expectations of predefined percentiles, which are then combined with the measured percentiles using the best linear unbiased predictor. The method was tested in a real data set using simulated sample plots. The test showed that, even with a small number of sample measurements, the relative root mean square error and bias of volume per hectare could be decreased remarkably. Furthermore, increasing the number of measurements steadily improved the prediction. The proposed method seems to be a promising tool in the prediction of diameter distributions of various forms, including those found in complex stands. FOR. SCI. 51(4):292–303.
Spatial Assessment of Model Errors from Four Regression Techniques
Authors: Zhang Lianjun , Gove Jeffrey H.
Published: April 2024

Forest modelers have attempted to account for the spatial autocorrelations among trees in growth and yield models by applying alternative regression techniques such as linear mixed models (LMM), generalized additive models (GAM), and geographically weighted regression (GWR). However, the model errors are commonly assessed using average errors across the entire study area and across tree size classes. Little attention has been paid to the spatial heterogeneity of model performance. In this study, we used local Moran coefficients to investigate the spatial distributions of the model errors from the four regression models. The results indicated that GAM improved model-fitting to the data and provided better predictions for the response variable. However, it is nonspatial in nature and, consequently, generated spatial distributions for the model errors similar to the ones from ordinary least-squares (OLS). Furthermore, OLS and GAM yielded more clusters of similar (either positive or negative) model errors, indicating that trees in some subareas were either all underestimated or all overestimated for the response variable. In contrast, LMM was able to model the spatial covariance structures in the data and obtain more accurate predictions by accounting for the effects of spatial autocorrelations through the empirical best linear unbiased predictors. GWR is a varying-coefficient modeling technique. It estimated the model coefficients locally at each tree in the example plot and resulted in more accurate predictions for the response variable. Moreover, the spatial distributions of the model errors from LMM and GWR were more desirable, with fewer clusters of dissimilar model errors than the ones derived from OLS and GAM. FOR. SCI. 51(4):334–346.
Confirmation of Oak Recruitment Failure in Indiana Old-Growth Forest: 75 Years of Data
Authors: Aldrich Preston R. , Parker George R. , Romero-Severson Jeanne , Michler Charles H.
Published: April 2024

We report on a long-term study of changes in the diameter distribution of red and white oaks in old-growth forest of Indiana. We expand the scope of a prior 50-year demographic study of a 20.6-ha stand by (1) extending the census period, (2) comparing diameter distributions in the large stand with those of a smaller (2.3-ha) stand, and (3) examining small-diameter ingrowth of red oaks into both stands. Oaks displayed bell-shaped or even-aged diameter distributions in 1926, suggesting a history of disturbance from timber removal, grazing, and fire. These exogenous disturbances were suppressed starting in 1917 with acquisition of the property by Purdue University. Subsequent censuses indicated considerable ingrowth of nonoak stems into both stands. Oaks that were mid-sized in 1926 gradually moved through the size classes and were replaced by younger individuals in the small stand but not in the center of the large stand. The survey of red oak saplings confirmed this pattern, revealing numerous recruits in the small stand but virtually none in the large stand. These data support the view that oaks are failing to regenerate in part due to shade-intolerance and a waning disturbance regime in the large stand interior. FOR. SCI. 51(5):406–416.
Forecasting Germany's Printing and Writing Paper Imports
Authors: Hetemäki Lauri , Mikkola Jarmo
Published: April 2024

Short-term forecasting of forest products demand is one of the key inputs for successful market planning in the forest sector. Currently, this field is dominated by consultants' and industry analysts' forecasts, which are often based on methods and procedures that are not well documented, or are ad hoc. This article seeks to contribute to the scarce literature on this topic by presenting results for short-term forecasts for the import demand for coated printing and writing paper in Germany. A number of univariate time series models, single equation econometric models, and multivariate systems models are estimated using quarterly data from 1991:Q1–2001:Q2, and observations from 2001:Q3–2002:Q4 are used for the out-of-sample forecast performance evaluation. Forecasts are also computed using various weighted combinations of the individual forecasting models. The results indicate that forecast accuracy increases when one moves from univariate time series models to econometric models. The best single forecasting model in terms of the root-mean-squared error criterion is a VARX model in differences. However, by optimally combining individual model forecasts, one is able to produce even more accurate forecasts. FOR. SCI. 51(5):483–497.
Soil Compaction and Forest Floor Removal Affect Early Growth and Physiology of Lodgepole Pine and Douglas-Fir in British Columbia
Authors: Kamaluddin Mohammed , Chang Scott X. , Curran Michael P. , Zwiazek Janusz J.
Published: April 2024

We investigated the effects of soil compaction and forest floor removal on growth and physiology of lodgepole pine (Pinus contorta ex Loud. var. latifolia Engelm.) and Douglas-fir (Pseudotsuga menziesii var. glauca [Baissn.] Franco) seedlings on a calcareous long-term soil productivity (LTSP) study site near Invermere, British Columbia. Treatments consisted of factorial combinations of soil compaction (noncompacted versus compacted) and forest floor removal (forest floor intact versus forest floor removed) as well as a remedial (rehabilitation) treatment of deep ripping following soil compaction. The experiment was not replicated at the treatment plot level, therefore no statistically based mean comparisons were made. After two growing seasons, we found that the two tree species responded differently to those treatments. Lodgepole pine height and diameter growth and unit needle-weight (dry mass per unit needle) averaged 25, 51, and 30% greater, respectively, in the rehabilitation than in the other treatments, whereas Douglas-fir responded to the rehabilitation treatment by increasing stem diameter growth by 27%, but not height growth (a change of 9%). Forest floor removal decreased height growth in lodgepole pine by 11%, but increased diameter growth in Douglas-fir by 15%. The decreases in growth for lodgepole pine in the forest floor removal treatments were accompanied by lower foliar N concentrations. Foliar N concentrations were positively correlated with rates of net photosynthesis (r = 0.69, P = 0.004) and height growth (r = 0.76, P = 0.004) in lodgepole pine, but not in Douglas-fir. Low N supply (as observed for lodgepole pine) and depletion of soil moisture as a result of forest floor removal likely played a role in shaping the growth and physiological responses of the trees in this study. FOR. SCI. 51(6):513–521.
Mismatch between Herbivore Behavior and Demographics Contributes to Scale-Dependence of Host Susceptibility in Two Pine Species
Authors: Ylioja Tiina , Slone Daniel H. , Ayres Matthew P.
Published: April 2024

The impacts on forests of tree-killing bark beetles can depend on the species composition of potential host trees. Host susceptibility might be an intrinsic property of tree species, or it might depend on spatial patterning of alternative host species. We compared the susceptibility of loblolly pine (Pinus taeda) and Virginia pine (P. virginiana) to southern pine beetle (Dendroctonus frontalis) at two hierarchical levels of geographic scale: within beetle infestations in heterospecific stands (extent ranging from 0.28 to 0.65 ha), and across a forest landscape (extent 72,500 ha) that was dominated by monospecific stands. In the former, beetles preferentially attacked Virginia pine (tree mortality = 65–100% in Virginia pine versus 0–66% in loblolly pine), but in the latter, loblolly stands were more susceptible than Virginia stands. This hierarchical transition in host susceptibility was predicted from knowledge of (1) a behavioral preference of beetles for attacking loblolly versus Virginia pine, (2) a negative correlation between preference and performance, and (3) a mismatch in the domain of scale between demographics and host selection by individuals. There is value for forest management in understanding the processes that can produce hierarchical transitions in ecological patterns. FOR. SCI. 51(6):522–531.
Simulating Landscape-Level Effects of Constraints to Public Forest Regeneration Harvests due to Adjacent Residential Development in Northern Wisconsin
Authors: Ward Brendan C. , Mladenoff David J. , Scheller Robert M.
Published: April 2024

Residential development in rural forests is currently one of the most prominent land use changes in the United States. Such development can have important effects on ecosystem processes and landscape patterns. It can also constrain forest management on public lands, influencing tree species composition and age structure at the landscape scale. We used the forest landscape simulation model LANDIS-II to analyze changes to the landscape patterns of tree species composition, age structure, windthrow disturbance, and aboveground live biomass across a range of constraints to public forest timber harvests on a northern Wisconsin landscape. Our results demonstrate that decreasing harvest area through the use of buffers reduces the dominance of early-successional species, increases the dominance of mid to later-successional species, and shifts the stand age distribution within the landscape toward older forests. These buffers increase the spatial heterogeneity of dominant species and age structure at the landscape scale, and lead to more windthrow disturbance. We believe that our study can inform policymakers, forest managers, and scientists about potential long-term landscape-level effects of interaction between residential development and forest management. FOR. SCI. 51(6):616–632.
Substitutability between US Domestic and Imported Forest Products: The Armington Approach
Authors: Gan Jianbang
Published: April 2024

This article estimates the Armington elasticities of substitution between US domestic and imported forest products. The results indicate that US domestic and foreign forest products are far from perfect substitutes for each other. The low substitutability calls into question the effectiveness of import restrictions that alter the relative price between domestic output and imports and the trade impact assessments that impose the law of one price. The degree of substitutability is higher in the long run than in the short run and varies across product aggregation levels. The elasticity estimates, though remaining relatively stable for most forest products, show an increase since the late 1980s for the overall forest product, implying that US domestic and imported forest products have, in general, become more substitutable over time.
Optimal Regeneration Planning for Old-Growth Forest: Addressing Scientific Uncertainty in Endangered Species Recovery through Adaptive Management
Authors: Moore Clinton T. , Conroy Michael J.
Published: April 2024

Stochastic and structural uncertainties about forest dynamics present challenges in the management of ephemeral habitat conditions for endangered forest species. Maintaining critical foraging and breeding habitat for the endangered red-cockaded woodpecker (Picoides borealis) requires an uninterrupted supply of old-growth forest. We constructed and optimized a dynamic forest growth model for the Piedmont National Wildlife Refuge (Georgia, USA) with the objective of perpetuating a maximum stream of old-growth forest habitat. Our model accommodates stochastic disturbances and hardwood succession rates, and uncertainty about model structure. We produced a regeneration policy that was indexed by current forest state and by current weight of evidence among alternative model forms. We used adaptive stochastic dynamic programming, which anticipates that model probabilities, as well as forest states, may change through time, with consequent evolution of the optimal decision for any given forest state. In light of considerable uncertainty about forest dynamics, we analyzed a set of competing models incorporating extreme, but plausible, parameter values. Under any of these models, forest silviculture practices currently recommended for the creation of woodpecker habitat are suboptimal. We endorse fully adaptive approaches to the management of endangered species habitats in which predictive modeling, monitoring, and assessment are tightly linked.
The Effectiveness of Different Buffer Widths for Protecting Headwater Stream Temperature in Maine
Authors: Wilkerson Ethel , Hagan John M. , Siegel Darlene , Whitman Andrew A.
Published: April 2024

We evaluated the effect of timber harvesting on summer water temperature in first-order headwater streams in western Maine. Fifteen streams were assigned to one of five treatments: (1) clearcutting with no stream buffer; (2) clearcutting with 11-m, partially harvested buffers, both sides; (3) clearcutting with 23-m, partially harvested buffers; (4) partial cuts with no designated buffer; and (5) unharvested controls. Over a 3-year period we measured summer water temperature hourly before and after harvesting, above and below the harvest zone. Streams without a buffer showed the greatest increase in mean weekly maximum temperatures following harvesting (1.4–4.4°C). Streams with an 11-m buffer showed minor, but not significant, increases (1.0–1.4°C). Streams with a 23-m buffer, partial-harvest treatment, and control streams showed no changes following harvest. The mean weekly maximum temperatures never exceeded the thermal stress limit for brook trout (25°C) in any treatment group. The mean daily temperature fluctuations for streams without buffers increased from 1.5°C/day to 3.8°C/day, while with 11-m buffers fluctuations increased nonsignificantly by 0.5–0.7°C/day. Water temperatures 100 m below the harvest zone in the no-buffer treatment were elevated above preharvest levels. We concluded that water temperature in small headwater streams is protected from the effects of clearcutting by an 11-m buffer (with >60% canopy retention).
Fuzzy Multicriteria Approval Method and its Application to Two Forest Planning Problems
Authors: Kangas Annika , Kangas Jyrki , Laukkanen Sanna
Published: April 2024

Many different multicriteria decision aid methods have been used in forestry decision support. When opinions of the general public are considered, methods that are simple to understand and easy to use are required. One such method is multicriteria approval (MA). It is based on approval voting, where the voters have been replaced by criteria. In MA, alternatives are approved or rejected with respect to each voter, i.e., each criterion. In the basic version, the approval threshold is crisp and defined by the system. The varying importance of the criteria is considered using the concept of ordinal dominance. Thus, the importance order of the criteria is needed to make a recommendation. The basic MA approach favors solutions that may be mediocre with respect to all criteria. A crisp approval threshold used in MA may also lead to awkward recommendations. We propose a new method using a concept of fuzzy approval for solving these problems. The fuzzy approval also easily extends to group decision-making problems. Two forestry applications are presented, where the fuzzy version of MA is tested and compared to the results of original MA. The possibilities of using fuzzy approval in forestry decision support are discussed.
A Functional Comparison of Productivity in Even-Aged and Multiaged Stands: A Synthesis for Pinus ponderosa
Authors: O’Hara Kevin L. , Nagel Linda M.
Published: April 2024

The relative productivity of even-aged and uneven-aged or multiaged stands is a frequently debated topic in silviculture and forestry. Nearly all previous comparisons have been empirical growth studies, simulations of stand growth, or economic analyses based on differences in stem volume production. Both even-aged and multiaged systems are highly variable and the large number of variables and assumptions makes any comparisons difficult. In this review, a series of studies in ponderosa pine are synthesized to develop a more functional understanding of the relative stemwood productivity of these variable stand structures. Multiaged ponderosa pine stands were either as efficient or slightly more efficient at converting light energy to volume growth than even-aged stands. Even-aged stands appear to experience a higher level of mid-summer water stress than multiaged stands. This finding suggests reduced photosynthesis in even-aged stands and a possible cause for a slightly lower level of productivity in even-aged stands. However, differences in productivity are likely insignificant in comparison to the wide variations in even-aged and multiaged structures and differences caused by the operations necessary to maintain these structures. As ponderosa pine systems are primarily water-limited, these results may not apply to more light-limited systems.
Transpiration and Canopy Stomatal Conductance of 5-Year-Old Loblolly Pine in Response to Intensive Management
Authors: Samuelson Lisa J. , Stokes Thomas A.
Published: April 2024

The influence of weed control only (W) versus weed control plus irrigation (WI) and weed control plus irrigation and fertigation (WIF) on canopy stomatal conductance (G S) and transpiration expressed on a ground (E) and leaf area (E L) basis was examined over 1 year in 5-year-old loblolly pine (Pinus taeda L.) to determine whether increased leaf area index (L) in response to intensive silviculture resulted in regulation of G S, whole-tree hydraulic conductance per unit sapwood area (G), or the ratio of transpiring leaf area to conducting sapwood area (A L:A S) to minimize the gradient in water potential from soil to leaf (ΔΨ). Values of E were as high as 3.9 mm d−1 and increased from a total of 357 mm in the W treatment to 529 and 565 mm in the WI and WIF treatments, respectively. Values of E L did not vary with treatment and were, on average, 0.8 mm d−1 in summer and 0.4 mm d−1 in winter. Increasing management intensity increased L by as much as 76% and sapwood area up to 68%, but had no influence on ΔΨ G, G S, or leaf specific hydraulic conductance. High L values realized by intensive management resulted in regulation of A L:A S to maintain ΔΨ with increasing canopy development.
Market Performance of the Government-Controlled but Market-Based Stumpage System of Ontario
Authors: Yang Feng'e , Kant Shashi , Shahi Chander
Published: April 2024

The market performance of the government-controlled stumpage system of Ontario is investigated by examining the relationships between the stumpage prices and the market prices of end products (lumber, composites, and pulp) produced from standing timber, using monthly data from June 1995 to Feb. 2005. The long-run equilibrium relationship between the stumpage price and the relevant market price is tested using Johansen's multivariate co-integration approach. In addition, the Granger-causality between the stumpage price and the relevant market price is also analyzed. Test results indicate that the Ontario stumpage system is working well with respect to the stumpage prices of SPF (spruce, pine, fir) for softwood lumber and pulp, while there is a need for changes and modifications in terms of revising different parameters of the system with respect to stumpage prices of SPF for composites, and stumpage prices of red pine and white pine timber for lumber. Test results are inconclusive for the stumpage price of red pine and white pine for composites.
Consequences of Neglecting National Product Differentiation in Assessing the Impact of U.S.–Canada Softwood Lumber Disputes
Authors: Gan Jianbang
Published: April 2024

This study, using the Armington approach, analyzes the consequences of omitting national product differentiation on the impact assessment of U.S.–Canada softwood lumber disputes. Omitting national product differentiation is found to cause differences in the estimated impacts ranging from a 38% underestimation to a 340% overestimation under the quantity-based Canadian export tax, and from a 61.5% underestimation to a 413% overestimation under the value-based (ad valorem) U.S. import tariff. Demonstrated as an approach to alleviating the biases, a computable general equilibrium model is developed to simulate the impacts of the 1996 Softwood Lumber Agreement (SLA) and the countervailing duty (CVD) and anti-dumping duty (AD) imposed under the current round of the dispute. The SLA and the CVD and AD seem more likely to cause the redistribution of welfare than to improve the market share of U.S. domestic softwood lumber. The CVD and AD would be more beneficial to the U.S. in terms of overall welfare but causing greater distortions in both the U.S. and Canada than the SLA.
Incidence of the 1996 U.S.–Canada Softwood Lumber Agreement among Landowners, Loggers, and Lumber Manufacturers in the U.S. South
Authors: Li Yanshu , Zhang Daowei
Published: April 2024

A framework was developed to estimate the welfare incidence of the 1996 U.S.–Canada Softwood Lumber Agreement among producers in two-processing-stage markets—timberland owners, loggers, and lumber manufacturers—in the U.S. South. Timberland owners are the largest beneficiary whereas lumber manufacturers are the second and loggers the least. Empirically, without considering substitution effects among production inputs, timberland owners have 47.4% of total incremental producer surplus, whereas lumber manufacturers have 39.4% and loggers 13.2%. When the substitution effects are considered, timberland owners gain slightly less whereas lumber manufacturers and loggers gain slightly more.
Comparative Views of Different Stumpage Pricing Systems: Canada and the United States
Authors: Sedjo Roger A.
Published: April 2024

Canada and the United States have many similarities, but major differences in the ownership and tenure of forestlands. These differences generate substantial differences in the way stumpage prices are determined in the two countries. These differences, including the argument that the absence of stumpages markets results in the de facto subsidization of Canadian stumpage prices, are used to justify the host of US trade restrictions on Canadian softwood lumber imports. This article examines the differences in the tenure systems. It cites the arguments commonly given in the dispute and draws out the implications of these systems on softwood resource prices. It discusses some studies, and alternative markets systems, currently under discussion to addresses the criticisms of the Canadian system and critiques one of the major proposals.
Transaction Evidence Appraisal: Competition in British Columbia's Stumpage Markets
Authors: Niquidet Kurt , van Kooten G. Cornelis
Published: April 2024

As a potential resolution to the softwood lumber dispute, the US Department of Commerce recommends that administered stumpage prices in Canada be determined using information from competitive timber auctions. Previous research indicates that the degree of competition significantly influences bidding behavior. In this article, therefore, a truncated hedonic timber sale model was developed to investigate the influence of competition on stumpage markets in the interior of British Columbia. Results indicate that lower bids in several northern zones of the province are due, at least in part, to lack of competition, but that market power appears limited by spatial arbitrage. In one zone characterized by monopsony, we estimate bids are shaded below their true valuation by $12.56/m3, which approximates the calculated transportation costs ($14.90/m3) to an adjacent more competitive zone. Furthermore, the significance of the inverse mills ratio suggests that ordinary least-squares regression leads to biased estimates. Our findings have policy implications for the future development and use of transaction evidence appraisal models as a potential solution to the long-standing softwood lumber trade dispute.
Early Evaluation of Intra- and Inter-Provenance Hybrids of Loblolly Pine for Planting in Piedmont Regions of the Southern United States
Authors: Alizoti Paraskevi G. , Li Bailian , McKeand Steven E.
Published: April 2024

Two intra-provenance [Atlantic Coastal (C×C), Piedmont (P×P)] and two inter-provenance [Atlantic Coastal × Piedmont (C×P), Piedmont × Atlantic Coastal (P×C)] loblolly pine (Pinus taeda L.) populations, represented by 80 polycross families, were assessed for height, volume, and survival in five Piedmont regions at four years of age. The hybrid populations (C×P, P×C) were intermediate among the pure populations (C×C, P×P). Across and within regions the C×P hybrids were significantly taller and more productive in volume than the pure P×P, with performance comparable to that of C×C. The C×P hybrids exhibited stronger additive genetic control for both height and volume across and within regions, except for the two inland regions, where the P×C hybrids' genetic control for height was stronger. Stability of performance in height and volume varied among families within populations. These early results suggest that the C×P hybrids will perform better in milder Piedmont environments, while the P×C hybrids could be suitable for more inland and northern Piedmont sites. Long-term evaluation of population performance and adaptability is essential before implementing such a plan in the Piedmont.
Tree-Level Models for Predicting Lumber Volume Recovery of Black Spruce Using Selected Tree Characteristics
Authors: Liu Chuangmin , Jiang Z.H. , Zhang S.Y.
Published: April 2024

Four model forms (linear, polynomial, power, and exponential) and their extensions with different independent variables were studied for their predictive ability for lumber volume recovery from black spruce (Picea mariana [Mill.] B.S.P.) trees at two types of sawmills (a stud mill and a random length mill) using basic tree characteristics (dbh, tree height, and stem taper). Of the three tree characteristics, dbh was identified as having the most predictive ability for lumber volume recovery. We found that all models predicted lumber volume recovery more precisely for small-sized and medium-sized (≤23 cm) trees than for large-sized (>03E23 cm) trees. In terms of the selected statistical criteria such as adjusted R2, root-mean-square error (RMSE), predicted error sum of squares (PRESS), and prediction error, the best models for predicting lumber volume recovery were considered to be the following forms for both types of sawmills: (1) the second-order polynomial function with dbh alone, (2) the polynomial function with an interaction term of squared dbh and tree height, and (3) the power function with dbh and tree height. For both types of sawmills, the three final fitted model forms accounted for over 91% of the total variation. Model validation using independent data from a stud mill indicated that by using measured tree characteristics the three model forms were able to accurately and precisely predict lumber volume recovery, especially from small- and medium-sized trees.
Historical Fire Cycles in the Canadian Rocky Mountain Parks
Authors: Wagner Charles E. Van , Finney Mark A. , Heathcott Mark
Published: April 2024

The subject of this article is the fire history of seven contiguous national and provincial parks in the Canadian Rocky Mountains, four to the east of the continental divide and three to the west. Seven centuries of time-since-fire data were combined and arrayed in three sets: all seven parks together, then the east-side and west-side groups separately. Fire cycles were estimated by four different methods: two of them statistical and two deterministic. Statistical evidence of distinct changes in fire regime, always toward a lower burning rate, was uncovered, with transitions in 1760 and 1940 on the east side, and in 1840 on the west side. The principal conclusions were: The seven parks as a unit supported a fire cycle of 60–70 yr for nearly five centuries before 1760. The burning rate then dropped sharply and a longer cycle of about 175 yr prevailed until 1940. Fire history in the combined large parks on the east side was similar to the above. By contrast, the smaller west-side parks group sustained a fire cycle of about 90 yr for at least five centuries before 1840; the burning rate then decreased irregularly to 2000. On the east side, the near absence of burned area after 1940 was attributed to the onset of effective fire protection. Possible prior causes of the earlier transitions on east and west sides include changes in climate or aboriginal fire practices, but this issue is left unresolved.