bluuebunny/crossref_metadata_2025 huggingface dataset:
A Stochastic Production Frontier Analysis of Polish State Forests
Authors: Siry Jacek P. , Newman David H.
Published: April 2024

This article presents a study of the efficiency of Polish state timber production and management polices following the transition to a more competitive market. The objective is to determine how well the Polish State Forests, which manage 80% of Poland's forestland and supply 85% of its timber, have adjusted, after 40 yr of central planning, to this change. The development and estimation of a stochastic frontier production function is used to analyze and evaluate the efficiency of timber production and the effectiveness of management policies. The empirical results provide evidence for the presence of substantial technical inefficiency, along with some scale economies in timber production. In addition, policies that have led to the creation of smaller forest districts, employment reductions, and logging equipment purchases are largely ineffective and perhaps even counterproductive. On the other hand, a strong support is provided for the continued privatization of forest operations. FOR. SCI. 47(4):526–533.
Large Landscape Scale Analysis of Tree Death in the Adirondack Park, New York
Authors: Manion P.D. , Griffin D.H.
Published: April 2024

We propose that healthy forests depend on quantitatively predictable tree death as a continuous process linked to forest structure and growth. Quantifying a baseline mortality value by forest structure analysis using the Law of de Liocourt allows estimation of forest health by comparing the observed mortality to a baseline value. This method is applicable to large landscape samples, but not generally to individual forest stands. Observed relative mortality per dbh class from a random sample of the Adirondack Park (New York, USA) forest was slightly, but significantly, less than the baseline relative mortality per dbh class required for maintaining size-distribution stability of the forest. This result suggests a changing structure involving increased forest density, or future mortality increase to maintain the current structure. Differences in structure-mortality relationships among the more abundant species indicate changing composition of the forest. This reflects unhealthy conditions in some species (American beech, yellow birch, balsam fir, and red spruce) that are compensated by enhanced development of others (red maple, sugar maple, and eastern hemlock). For. Sci. 47(4):542–549.
Comparison of Estimation Techniques for a Forest Inventory in which Double Sampling for Stratification Is Used
Authors: Williams Michael S.
Published: April 2024

A number of different estimators can be used when forest inventory plots cover two or more distinctly different condition classes. In this article the properties of two approximate Horvitz-Thompson (HT) estimators, a ratio of means (RM), and a mean of ratios (MR) estimator are explored in the framework of double sampling for stratification. Relevant theoretical properties are given, and a simulation study is used to compare the properties of these estimators. It is concluded that the variance of the RM estimator is smaller than that of the approximate HT for the populations studied, but that of the MR estimator is larger. While ratio estimators are known to be biased for small sample sizes, an additional bias also occurs when the population of interest has an edge-effect. The RM classical variance estimator underestimated the true variance in the simulation study. The approximate HT estimators exhibited biases that were generally smaller than those of the RM and MR estimators for populations with an edge-effect. Its classical variance estimator was essentially unbiased. FOR. SCI. 47(4):563–576.
Combining Tabu Search and Genetic Algorithm Heuristic Techniques to Solve Spatial Harvest Scheduling Problems
Authors: Boston Kevin , Bettinger Pete
Published: April 2024

The performance of two new heuristics that combine tabu search with a genetic crossover technique was examined for their usefulness in solving spatially constrained harvest scheduling problems. One heuristic utilized tabu search with 1-opt moves and a genetic crossover technique (TS/GA), and the other utilized tabu search with both 1-opt and 2-opt moves and a genetic crossover technique (TS2/GA). The heuristics were tested on four problems. Three problems used the simple unit-restriction model (URM) to portray greenup constraints, allowing them to be solved with mathematical programming techniques and thus providing a benchmark to compare against the solutions produced by the heuristic techniques. These were considered hypothetical problems, since the datasets were grids, and the age classes were assigned with three different rules. The fourth problem uses an operational dataset and includes both a maximum opening size constraint, which limits the size of an individual opening, and a maximum average opening size constraint, which represents the greenup constraint contained in the American Forest and Paper Association (AF&PA) Sustainable Forestry Initiative (AF&PA 2000). The greenup constraints contained in these problems accurately portray the greenup constraints facing the forest industry in the United States. For the three hypothetical problems, the TS/GA technique found solutions with an objective function value between 96.6% and 99.1% of an estimated optimal value, and between 93.4% to 94.4% of a relaxed linear programming value. The TS2/GA found better solutions for all three hypothetical problems, with the objective function values between 98.2% and 99.7% of the estimated optimal value and the 96.3% to 97.2% of the relaxed linear programming value. Compared with a general tabu search technique that used 1-opt moves (TS), adding the genetic crossover technique resulted in a 2% increase in the objective function value, and adding the 2-opt intensification capability resulted in a further 1.5% improvement. A similar pattern was observed when the problem using the operational dataset was solved. The addition of the genetic crossover technique did not increase the time required to produce a solution to any particular problem, yet the addition of the 2-opt procedure did. TS2/GA required about twice as much time as did TS or TS/GA when applied to the three hypothetical datasets, and 67% more time when applied to the problem using the operational dataset. FOR. SCI. 48(1):35–46.
Growth and Nutritional Interactions of Nutrient-Loaded Black Spruce Seedlings with Neighboring Natural Vegetation Under Greenhouse Conditions
Authors: Imo Moses , Timmer Victor R.
Published: April 2024

Nutrient loading during nursery culture to improve early outplanting performance of black spruce (Picea mariana [Mill.] BSP) seedlings on weed prone sites is increasingly practiced in northern Ontario, but more insight is needed on the competitive mechanisms involved. Vector competition analysis was used to examine nutrient loading on interspecific growth and nutritional interactions between planted seedlings and neighboring natural vegetation under controlled greenhouse conditions. Nutrient loaded and conventional (nonloaded) seedlings were raised in a commercial green-house and then transplanted in bioassay soil substrates retrieved from two forest sites [Hardwood (OG 10) and Feathermoss (OG 4)], with weeds removed or left to grow naturally. Weed control increased seedling growth on the Hardwood substrates (103–194% height increase), but had no effect on the Feathermoss substrates suggesting that no seedling–natural vegetation interactions occurred on the latter site. Nutrient loading, however, countered weed competition on the competition-prone Hardwood site, reflecting the high competitiveness of these seedlings. Vector competition analysis revealed that tree-vegetation interactions on the Hardwood site caused antagonistic nutrient dilution primarily due to competition for N. Nutrient interactions were more symmetric with nutrient-loaded trees, indicating that these seedlings were less sensitive to competition than were nonloaded seedlings. For. Sci. 48(1):77–84.
Correction for Slope in Point and Transect Relascope Sampling of Downed Coarse Woody Debris
Authors: Ståhl Göran , Ringvall Anna , Gove Jeffrey H. , Ducey Mark J.
Published: April 2024

In this article, the effect of sloping terrain on estimates in point and transect relascope sampling (PRS and TRS, respectively) is studied. With these inventory methods, a wide angle relascope is used either from sample points (PRS) or along survey lines (TRS). Characteristics associated with line-shaped objects on the ground are assessed, e.g., the length or volume of downed logs. In their basic forms, the methods only work in flat terrain, and thus bias is incurred under sloping conditions.

Two different possibilities to correct for bias due to slope are presented. The first one involves using a slightly modified relascope device and making a measurement of the angle of inclination of each sampled object. The second involves applying correction factors based on the steepness of the terrain in the area surveyed. However, it is shown that moderate slopes cause only limited bias and in such cases there is little need to adjust the measurement procedures or apply correction factors. For. Sci. 48(1):85–92.
Regional and National Issues for Forest Wildlife Research and Management
Authors: DeStefano Stephen
Published: April 2024

Biologists and managers face a broad range of issues related to research and management of forest wildlife. To assess current trends in research, I reviewed 12 scientific journals (1992–2001) that published articles on wildlife, general ecology, and forestry and summarized articles by location, topic, issue, and species. To assess management concerns and issues, I interviewed professional biologists from across the United States, asking their opinions on important forest wildlife topics, approaches to improve research design, how management differs on public versus private lands, and which species they thought were underrepresented, overrepresented, or of special concern in their region. Most scientific articles focused on habitat selection, effects of forest alteration, and demography of birds and mammals. Herpetofauna (i.e., amphibians and reptiles) and invertebrates, although the subjects of some studies, made up only 10% each of all research papers. Biologists were most concerned with the alteration of forest vegetative structure due to timber harvest and its effects on wildlife populations and communities, but also recognized other issues such as changes in natural disturbance patterns such as fire, effects of road building, and loss of early successional vegetative communities as well as fragmentation of older forests. Most biologists agreed that long-term, large-scale, experimental studies, which document the demographic response of forest wildlife to alterations in forest cover, are needed. FOR. SCI. 48(2):181–189.
Models for Mapping Potential Habitat at Landscape Scales: An Example Using Northern Spotted Owls
Authors: McComb William C. , McGrath Michael T. , Spies Thomas A. , Vesely David
Published: April 2024

We are assessing the potential for current and alternative policies in the Oregon Coast Range to affect habitat capability for a suite of forest resources. We provide an example of a spatially explicit habitat capability model for northern spotted owls (Strix occidentalis caurina) to illustrate the approach we are taking to assess potential changes in habitat capability for vertebrates across the Coast Range. The model was based on vegetation structure at five spatial scales: the potential nest tree, a 0.5 ha potential nest patch, 28 ha around a potential nest patch, 212 ha around a potential nest patch, and a 1,810 ha home range area around a potential nest patch. Sensitivity analyses indicated that the proportion of the 28 ha patch in large trees around a potential nest patch, and the number of potential nest trees per ha in the nest patch, had the greatest influence on habitat capability estimates. The model was verified using georeferenced locations of spotted owl nests from systematically surveyed areas. Logistic regression analysis indicated that habitat capability scores were significantly associated with the probability of a site having a nest. Alternative model structures were tested during verification to test assumptions associated with four variables. The final model allowed development of a map of habitat capability for spotted owl nesting. The model will be linked to a model of forest dynamics to project changes in habitat capability under alternative land management policies. FOR. SCI. 48(2):203–216.
Floristics and Avian Community Structure: Implications for Regional Changes in Eastern Forest Composition
Authors: Rodewald Amanda D. , Abrams Marc D.
Published: April 2024

Because many forest stands are increasingly dominated by maple (Acer spp.) in eastern North America, there will likely be a relative scarcity of mature oak (Quercus spp.) forests within the next several decades. In an effort to understand how avian communities may be affected by a regional change in forest composition from oak to maple dominance, we compared bird communities in both oak- and maple-dominated forest stands in three seasons (winter, spring, and fall). In 1998 and 1999, birds were surveyed and habitat characteristics were measured in six mature forest woodlots in central Pennsylvania. Total abundance of birds was greater within oak- than maple-dominated stands in all seasons, whereas species richness was greater in oak stands only in the spring. Resident species, long-distance migrants, woodpeckers, bark-gleaners, and 11 individual species were more abundant within oak than maple stands in at least one season. Differences in avian community structure between oak and maple stands were greatest in the fall when oaks produced hard mast and in the spring when insectivorous birds gleaned arthropods from tree substrates. This pattern was consistent with our expectations based on mast characteristics and tree physiognomy of maples and oaks as well as the diet and foraging behavior of birds. Our results suggest that a regional change from oak- to maple-dominated forests may strongly affect avian community structure and populations of some common bird species associated with eastern deciduous forests. FOR. SCI. 48(2):267–272.
The Effect of Gypsy Moth Defoliation on Cavity-Nesting Bird Communities
Authors: Showalter Christopher R. , Whitmore Robert C.
Published: April 2024

Gypsy moths (Lymantria Dispar) kill trees and create snags, a resource vital to cavitynesting birds. With this in mind, population trends of 11 cavity-nesting birds and their relationship to snags in an area that was defoliated by gypsy moths were investigated from 1984 to 1999. Vegetation and bird point-count data from before a major gypsy moth outbreak (1984–1986), during (1987–1988), and after (1989–1999) enabled us to ake inferences about this forest bird community. The combined abundance of the 11 cavity-nesting species examined increased during the years immediately after the outbreak (1989–1993) followed by a decline in the last 6 yr (1994–1999). The abundance of snags also increased from 1989 to 1993 followed by a decline from 1994 to 1999. Regression analysis confirmed that cavity-nesting bird populations were highly associated with snag abundance. These data suggest the importance of snags to cavity-nesting birds and that cavity-nesters were able to take immediate advantage of a new population of snags. FOR. SCI. 48(2):273–281.
Influences of Hardwood Stand Area and Adjacency on Breeding Birds in an Intensively Managed Pine Landscape
Authors: Turner J. Chris , Gerwin John A. , Lancia Richard A.
Published: April 2024

We compared species richness, abundance, and community composition of breeding landbirds among three areal classes of mature hardwood stands within an intensively managed pine (Pinus taeda) landscape in the Lower Coastal Plain of South Carolina. We also compared these community metrics among rotation-age pines (≈20 yr old), the pine matrix (regenerated to rotation-age pine stands comprising 50% of the landscape), and all hardwood stands regardless of area. Approximately 220 fixed-radius point counts were conducted in 1995 and 1996. Species richness (21, 23, and 25 species, respectively) within small (n = 19; 1.0–4.4 ha), medium (n = 17; 6.0–34.4 ha), and large (n = 6; 65–560 ha) hardwood islands within the pine matrix was the same, but the trend was for richness to increase with island area. Forest interior, neotropical migrants dominated all hardwood stand areas. Most species were common to all areal classes, with only a few restricted to a particular areal class. Thus, there was little evidence that these hardwood islands, embedded in a managed pine landscape context, harbored unique bird communities. Species richness (40) was greatest within the matrix of pine stands of all ages, intermediate (32) in hardwood stands, and least (27) in rotation-age pine stands. Hardwood stands supported the highest total bird densities as well as the highest densities of neotropical migrants. Pine stands hosted high densities of both resident and early successional neotropical migrants. We concluded that the presence of hardwood stands embedded within a matrix of different age classes of pine likely allowed forest-interior neotropical migrants typical of hardwood stands to “spill over” into adjacent, structurally similar pine stands and vice versa. FOR. SCI. 48(2):323–330.
The Effect of Forest Roads on the Reproductive Success of Forest-Dwelling Passerine Birds
Authors: King David I. , DeGraaf Richard M.
Published: April 2024

Recent studies indicate that forest roads may affect the distribution of forest-dwelling birds. However, previous studies have not demonstrated any significant effects of forest roads on avian productivity. We studied the effect of maintained and unmaintained forest roads on (1) forest bird nest survival, (2) reproductive parameters of ovenbirds (Seiurus aurocapillus) potentially associated with food abundance, and (3) habitat and microclimate at six sites on the White Mountain National Forest, New Hampshire, during two breeding seasons. Nest survival did not differ between areas near (0–150 m) and far (>150 m) from maintained forest roads, and was marginally (P=0.08) higher in areas near (0–150 m) unmaintained roads. When the 0–150 m distance class was subdivided, however, nest survival was significantly higher within 0–75 m of maintained roads than >75–150 m away. Ovenbird nest initiation dates, clutch size, and fledging success did not differ between areas near (0–150 m) and far (>150 m) from maintained and unmaintained forest roads, and this result did not change when the distance class 0–150 m from roads was subdivided. There were no relationships between habitat or microclimate and distance from maintained roads. We conclude that small, unsurfaced forest roads at low road density do not result in decreases in forest passerine bird productivity in extensively forested areas in New England. FOR. SCI. 48(2):391–396.
Herpetofaunal Response to Gap and Skidder-Rut Wetland Creation in a Southern Bottomland Hardwood Forest
Authors: Cromer Robert B. , Lanham Joseph D. , Hanlin Hugh H.
Published: April 2024

We compared herpetofaunal communities in recently harvested gaps, skidder trails, and unharvested depressional wetlands to assess the effects of group-selection harvesting and skidder traffic on reptiles and amphibians in a southern bottomland hardwood forest. From January 1, 1997 to December 31, 1998 we captured 24,292 individuals representing 55 species of reptiles and amphibians at the Savannah River Site in Barnwell County, South Carolina. Forty-two species (n = 6,702 individuals) were captured in gaps, 43 species (n = 8,863 individuals) were captured along skid trails between gaps and 43 species (n = 8,727 individuals) were captured in bottomland depressions over the 2 yr period. Three vegetation variables and six environmental variables were correlated with herpetofaunal abundance. Salamander abundance, especially for species in the genus Ambystoma, was negatively associated with areas with less canopy cover and pronounced rutting (i.e., gaps and skidder trails). Alternatively, treefrog (Hylidae) abundance was positively associated with gap creation. Results from this study suggest that group selection harvests and skidder rutting may alter the herpetofaunal species composition in southern bottomland hardwoods by increasing habitat suitability for some species while diminishing it for others. FOR. SCI. 48(2):407–413.
Polya Posterior Frequency Distributions for Stratified Double Sampling of Categorical Data
Authors: Magnussen Steen , Köhl Michael
Published: April 2024

Estimates of category frequencies in stratified double sampling are generally obtained by methods of maximum likelihood assuming a multinomial distribution of data. Although the distribution of estimation errors is asymptotically normal, a reliance on the normal assumption for inference can be problematic for low frequency categories (<10%) and small sample sizes (<1,000). In these situations, a Bayesian approach appears more robust. A vague Dirichlet prior is adopted to compute a Polya posterior distribution. In a simulation study of sampling from eight small-to medium-sized populations, we found that the resampling distributions of maximum likelihood estimates were generally closer to the Polya posteriors than to the assumed normal distributions. Resampling distributions and Polya posteriors deviated frequently and significantly from a normal distribution. A Polya posterior was often orders of magnitude faster to compute than a resampling distribution. FOR. SCI. 48(3):569–581.
A Method for Characterizing and Mimicking Forest Canopy Gaps Caused by Different Disturbances
Authors: Lundquist John E. , Beatty Jerome S.
Published: April 2024

Forest canopy gaps are measurable indicators of past small-scale disturbances. These disturbances can impact forest stand dynamics in ways that help maintain and enhance many ecosystem values. Impacts are commonly assessed using timber production metrics based on average stand values, but metrics based on smaller scales are needed to assess impacts on nontimber resources. In this study, we developed a multivariate method of quantitatively characterizing individual canopy gaps in Douglas-fir/grand fir stands in the Blue Mountains of eastern Oregon. We then established a reference or target range of variability by profiling gaps according to numbers of snags, downed logs, gap size and shape, and recolonizing vegetation. Cluster analysis, multidimensional scaling, and classification “trees” were used with these profiles to quantify similarity among individual gaps. Gaps fell into four groups, which could be interpreted as three ecologically functional groups on the basis of their role in stand development. Gaps caused by the same agents commonly fell within the same functional group: (1) flooding, logging, spruce budworm, and windfall cause stand level impacts that reset the stand development sequence; (2) bark beetles, tree fall, and root diseases cause within stand impacts that altered the rate of stand development; and (3) stem decay and dwarf mistletoe, and, under some circumstances, all disturbance agents, could kill trees yet have no impact on stand development except create space into which neighboring trees expand. We present a simple test to monitor how gaps change with silvicultural manipulations. Results indicate that this method offers (1) a way to systematically guide silvicultural manipulations aimed at mimicking natural disturbances at the canopy gap scale, and (2) a way to monitor the effectiveness of such silvicultural treatments and management actions using gap-based silviculture prescriptions. FOR. SCI. 48(3):582–594.
Resource Assessment of Non-Wood Forest Products: Experience and Biometric Principles
Authors: Pilz David
Published: April 2024

Forest managers increasingly recognize that management of non-wood forest product (NWFP) harvesting is important for conserving biological diversity and sustaining human use of forests. Importantly, many of these products, and the forests they grow in, are integral to the persistence of indigenous cultures. Similarly, rural communities are more likely to support forest conservation or longer timber rotations if they can annually harvest and market products derived from local forests. Managing NWFP resources poses a daunting task, however, because such products are numerous and diverse; the organisms that produce them differ widely in form, abundance, distribution, and autecology; and harvesting typically occurs in a complex social, economic, political, land tenure, and forest management context. Nevertheless, forest managers, researchers, development workers, harvesters, and affected local communities agree that assessing the status of, and changes in, resource abundance is central to sustainable NWFP management.
Economic Analysis of the Canada–United States Softwood Lumber Dispute: Playing the Quota Game
Authors: van Kooten G. Cornelis
Published: April 2024

The Canada–U.S. Softwood Lumber Agreement (SLA) was the latest measure to restrict Canadian exports of softwood lumber to the United States. Rather than a countervail duty or export tax, SLA employed a quota that provides a large windfall (quota) rent to Canadian lumber producers in addition to extra quasi-rents to U.S. producers, all at the expense of U.S. consumers. However, Canadian producers have not taken full advantage of the quota regime to maximize their overall gains, which exceed what they could earn under free trade or an export/import tax. This is demonstrated using a theoretical framework and numerical illustration. It is shown that the net gain to Canadian producers does not occur when the quota rent is maximized, but rather when the sum of producer surplus and quota rent is maximized. It is also argued that the existence of resource rents from logging does not constitute a subsidy to lumber producers. It is concluded that, from Canada's perspective, export quotas are preferred to both free trade or an export/import tax, at least in the short run, but only if all provinces and all softwood lumber products are included in the Agreement and a means for sharing the windfall rents can be found. For. Sci. 48(4):712–721.
Periodicity of Two-Year Cycle Spruce Budworm Outbreaks in Central British Columbia: A Dendro-Ecological Analysis
Authors: Zhang Qi-Bin , Alfaro René I.
Published: April 2024

An outbreak of the two-year cycle budworm (Choristoneura biennis Freeman) has caused defoliation damage to interior spruce (Picea engelmannii Parry × P. glauca (Moench)) and subalpine fir (Abies lasiocarpa [Hook.] Nutt.) forests of north central British Columbia for more than 10 yr and was ongoing in 1999. A sample of 429 increment cores from spruce, subalpine fir, and lodgepole pine (Pinus contorta var. latifolia Engelm.) was collected in areas of chronic defoliation, and used in a dendro-ecological study. The objective was to develop accurately dated ring-width chronologies of each species and, by comparing growth rates of the budworm host tree species (spruce and fir) with those of the nonhost pine, to determine the past history of budworm outbreaks in the region. This history would help in estimation of the potential duration and severity of the current outbreak in the region.Four periods of decade-long reduced growth attributable to budworm defoliation were identified in the increment cores from both spruce and subalpine fir. These occurred in the mid-1890s to the early 1900s, the mid-1920s to the mid-1930s, the 1950s to the early 1960s, and the late 1980s to present (1999). Outbreaks recurred approximately every 32 yr. The reduced growth period, indicative of past outbreaks, consisted of a growth reduction phase lasting 7 to 11 yr in which rings generally exhibited a pattern of alternating wide and narrow rings (a “saw-tooth” pattern). This pattern was attributed to the biennial nature of the life cycle of this budworm, in which severe damage is caused every other year. The growth reduction phase was followed by a growth recovery phase lasting 3 to 5 yr in which ring-width gradually returned to pre-outbreak levels. Thus, the entire growth loss period could last from 10 to 16 yr and cause an average annual loss in radial increment from 16 to 21%. The 32 yr cycle of outbreak recurrence was attributed to changes in forest structure in which the forest evolves from a nonsusceptible to a susceptible state as the proportion of subalpine fir present in the upper canopy increases relative to the spruce component. A 2 yr cycle budworm outbreak will selectively remove the subalpine fir component returning the forest to a less susceptible state. It was concluded that the 2 yr cycle budworm is an important disturbance agent of northern British Columbia forests causing significant growth loss. FOR. SCI. 48(4):722–731.
Potential Demand for Certified Wood Products in the United Kingdom and Norway
Authors: Veisten Knut
Published: April 2024

Representative samples of the British and Norwegian population were surveyed by telephone and asked to make a hypothetical choice between unlabeled wooden furniture and more expensive eco-labeled wooden furniture. Choice behavior was modeled as a random utility model with utility-theoretic restrictions on choice and estimated willingness to pay (WTP). To counteract upward biased hypothetical values, a followup question assessed the certainty of respondents' choices. For those not choosing the eco-labeled alternative, another followup question assessed if these individuals could be regarded as indifferent.Compared to the unlabeled wooden furniture with a price of US$332 in the UK and US$275 in Norway, the extra median WTP for the eco-labeled alternative was estimated to be US$5.16 (1.6%) in the UK and US$2.79 (1%) in Norway, with a censored log-logistic binary choice model. In these estimates only the “absolutely sure ” were counted as valid choices of the eco-labeled alternative. The censoring implied that those who indicated indifference between unlabeled and eco-labeled furniture had their estimated WTP adjusted to 0. About 39% of the UK population and 32% of the Norwegian population are predicted to choose the eco-labeled alternative when the price difference is less than 5%. FOR. SCI. 48(4):767–778.
Effects of Registration Errors Between Remotely Sensed and Ground Data on Estimators of Forest Area
Authors: Patterson Paul L. , Williams Michael S.
Published: April 2024

The estimation of area by land cover type is a key component of most large-scale forest inventories. Historically, these estimates were derived from a large sample of points, taken from aerial photos, followed by a smaller sample of ground points, which were used to correct errors in the classification of the aerial photo points. There has been interest in replacing aerial photography with satellite imagery. One problem with using satellite imagery is the registration errors between a pixel and a plot or a point on the ground. The estimators and modes of inference can differ substantially depending on whether the sample unit is a plot or point on the ground. Two terms, tessellated and point paradigm, are used to differentiate between the two approaches when the ground data consists of plots or points, respectively. The effects of registration errors are compared using the two paradigms for estimating the area of land by cover type. The effects of registration errors on the expected value and variance of the forest area estimator under both the tessellated and point paradigm were studied using a simulation study, where a percentage of the samples had a random one- or two-pixel registration error. The simulation study shows that registration errors increased the variance of the estimator of forest area from 4% to 434%. The estimator of forest area under both the tessellated and point paradigm exhibited no detectable bias. In the presence of registration errors, the estimated variance under the tessellated paradigm tended to overestimate the true variance with the achieved coverage rate for a nominal 80% confidence interval ranging from about 81% to 86%. For sample sizes of fewer than 100 ground points, the estimated variance under the point paradigm tended to underestimate both the 80% confidence interval and the true variance, regardless of whether there were registration errors. Further testing showed that sample sizes of between 100 and 250 ground points were needed before the estimator of the variance under the point paradigm converged to within 5% of the true variance of the estimator of forest area. Thus, we conclude that registration errors can drastically increase the variance of area estimators and the resulting confidence intervals will not achieve their nominal coverage rates. In this study, the forest area estimator under the tessellated paradigm was clearly more robust to registration errors than the area estimator under the point paradigm. FOR. SCI. 49(1):110–118.
Production Efficiency and Productivity Growth in Norwegian Sawmilling
Authors: Nyrud Anders Q. , Baardsen Sjur
Published: April 2024

Production efficiency of Norwegian sawmilling was examined using Data Envelopment Analysis. The analysis was carried out on an extensive panel data set, including about 200 sawmills during the period 1974 to 1991. Productivity growth throughout the period was investigated using the Malmquist productivity index. The results indicate that approximately 30% of the sawmills were producing efficiently when assuming constant returns to scale. Estimated production growth approximated 1% per year. FOR. SCI. 49(1):89–97.
Scaling Growth Relationships from Seedling Plots Using Similarity Analysis
Authors: Amateis Ralph L. , Sharma Mahadev , Burkhart Harold E.
Published: April 2024

Data from a small-scale loblolly pine seedling experiment established at 1/16 scale to an operational study were used to develop height and diameter development models appropriate for either scale. An additional model was constructed that analytically relates stand development between the two scales and links the size of trees grown at small scale to operational scale counterparts. Results suggest that important stand characteristics associated with forest productivity develop similarly at the two scales. The models presented here can be used to evaluate the effects of stand density on tree growth at either scale and make inferences to operational scales from small-scale seedling studies. FOR. SCI. 49(2):188–195.
Inherent Correlations Between Stand Biomass Variables Calculated from Tree Measurements
Authors: Dean Thomas J. , Cao Quang V.
Published: April 2024

Correlating stand-level variables is an important component of forest production ecology; however, correlations among variables calculated with equations having common independent variables are potentially spurious. Monte Carlo simulation techniques were used to determine the inherent or null correlation coefficients among stand-level biomass variables calculated with published, individual-tree equations using loblolly pine (Pinus taeda L.) data. Null correlations of foliage mass/ha with branch mass/ha, stem mass/ha, and periodic annual increments of biomass were high with similar equation forms and exponents in the equations. Most, but not all, correlation coefficients of foliage mass/ha with other biomass components and periodic annual increments of biomass were significantly different from the corresponding, null correlation coefficients. Stating the probability of a greater difference between the observed and the null correlation coefficients proved crucial in distinguishing between potentially meaningful and spurious correlations because in many cases, the observed correlation coefficients were close to the null values. Interpretation of the correlations among stand variables varied with the equations used to predict the variables. Consequently, in addition to comparing correlation coefficients to appropriate null values, conclusions drawn from the correlation among stand-level variables depend on the accuracy and precision of the equations used to calculate them. FOR. SCI. 49(2):279–284.
A Reformulation of the Cost Plus Net Value Change (C+NVC) Model of Wildfire Economics
Authors: Donovan Geoffrey H. , Rideout Douglas B.
Published: April 2024

The Cost plus Net Value Change (C+NVC) model provides the theoretical foundation for wildland fire economics and provides the basis for the National Fire Management Analysis System (NFMAS). The C+NVC model is based on the earlier least Cost plus Loss model (LC+L) expressed by Sparhawk (1925). Mathematical and graphical analysis of the LC+L model illustrates two errors in model formulation. First, suppression is incorrectly modeled as a model output. Second, suppression and primary protection are incorrectly modeled as negatively correlated. These errors are shown to be perpetuated by the contemporary C+NVC model and to have serious implications for the model's capacity to correctly identify the most efficient level of fire management expenditure. A corrected graphical representation of the C+NVC model is presented, which allows the most efficient level of fire management expenditure to be correctly identified. FOR. SCI. 49(2):318–323.
Selecting a Level of Conditioning for the Segmented Polynomial Taper Equation
Authors: Sharma Mahadev , Burkhart Harold E.
Published: April 2024

Using tree data collected from loblolly pine thinning study plots, different levels of conditioning were examined for the segmented polynomial taper equation presented by Max and Burkhart (1976). An eight-parameter model with minimum constraints (diameter at the tip of a tree is zero and the adjacent functions are continuous at the join points) did not perform better than a six-parameter model with an additional smoothness constraint in terms of fit and predictive ability.

The join points where the adjacent segments of a tree meet, the inflection points, were assumed known to further reduce the number of parameters in the model. A four-parameter model with inflection points at 11 and 75% of total tree height was slightly superior to the six- and eight-parameter models in estimating tree diameters. The fit statistics and predictive ability of the model were not sensitive to the lower and upper inflection points in the range of 9–12% and 70–80%, respectively. For. Sci. 49(2):324–330.
Modeling Tree Mortality Following Wildfire in the Southeastern Canadian Mixed-Wood Boreal Forest
Authors: Hély Christelle , Flannigan Mike , Bergeron Yves
Published: April 2024

We modeled tree mortality three months after a wildfire in the mixed-wood boreal forest (Quebec, Canada) using data from 1963 trees in 36 stands burned under a wide range of fire behavior conditions during the 1997 Val Paradis fire. Stand composition influenced the char height: height of burn was lower in deciduous stands than mixed or coniferous stands. Analysis of species mortality rates revealed that Populus tremuloides Michx. was the least fire-resistant species, whereas Picea mariana Moench and Pinus banksiana Lamb. were the most resistant species. Efficient interactions for conifers exist between crown and cambial resistance to injury and fire behavior, as diameter at breast height (DBH), total tree height (TOTH), and mean bark thickness are characteristic variables throughout the fire behavior range. The best logistic regressions, relating probability of wildfire-induced mortality to morphology and fire variables, always entered char height (CH) at the first step of the stepwise procedure, followed by a morphological variable (DBH or TOTH). The Kappa coefficient used for model validations revealed that logistic regressions using morphologic and fire variables were very efficient as compared to logistic regressions based only on morphologic variables. Potential applications of these results by land managers are discussed. FOR. SCI. 49(4):566–576.
Efficiency and Merger Gains in the Danish Forestry Extension Service
Authors: Bogetoft Peter , Thorsen Bo Jellesmark , Strange Niels
Published: April 2024

In Denmark, many small-scale forest owners are affiliated to local district offices of The Danish Forestry Extension Service. In this article, the efficiency of the different offices is evaluated using Data Envelopment Analysis (DEA). Furthermore, recent theoretical developments in DEA are used to assess the gains from a number of potential mergers and to decompose these gains into those from technological improvements, harmony effects, and scale effects. The results show that inefficiency is widespread and may in some cases be improved through mergers due to potential harmony gains and scale returns. However, the dominant part of the inefficiency is technical, and this suggests that improved learning and sharing of know-how or key resources across offices may improve efficiency. For. Sci. 49(4):585–595.
Book Reviews: Forest Policy for Private Forestry—Global and Regional Challenges
Authors: Bentley William R.
Published: April 2024

This volume is a collection of the best papers presented during a 2001 international conference in Atlanta titled Global Initiatives and Public Policies: First International Conference on Private Forestry in the 21st Century. The papers are grouped in four sections, with the broadest views in the first and most detailed in the last two sections.
Book Reviews: The Potential of U.S. Forest Soils to Sequester Carbon and Mitigate the Greenhouse Effect
Authors: Jose S.
Published: April 2024

In recent years, the growing realization that as much as 40–60% of the carbon in forest ecosystems is stored belowground has sparked a great deal of interest in exploring forest soil processes and their relation to carbon dynamics. Because of its slower turnover rates, soil organic carbon offers considerable potential to mitigate the increase in atmospheric carbon dioxide and alleviate the greenhouse effect. Through the publication of this book, the editors have done a remarkable job in bringing together the collective wisdom of 41 prominent soil scientists in analyzing the carbon sequestration potential of U.S. forest soils and the implications for policy decisions. This book is the third one in a series of books addressing the carbon sequestration potential of U.S. land use systems. The first two books examined the potential of crop and grazing lands and were published in 1999 and 2001, respectively.
Light Transmittance Estimates in a Longleaf Pine Woodland
Authors: Battaglia Michael A. , Mitchell Robert J. , Mou Paul P. , Pecot Stephen D.
Published: April 2024

While the importance of canopy structure in open woodlands and savannas on regulating the flow of energy and matter is well known, few studies have investigated how variation in overstory abundance influences canopy light transmission and the extent that estimates vary in their ability to characterize the light environment in these ecosystems. Canopy light transmittance (% photosynthetic photon flux density, or %PPFD) was measured with gallium arsenide phosphide (GaAsP) photodiodes and was monitored throughout the growing season in an open-canopy longleaf pine (Pinus palustris Mill.) woodland across an overstory abundance gradient. Several estimates of canopy light transmittance were also measured, including 10 minute averages of %PPFD under clear and overcast sky conditions during summer, fall, and winter, as well as light estimates derived from hemispherical photographs (gap fraction, GF: gap light index, GLI; and weighted canopy openness, WCO). Linear and curvilinear regression were used to analyze the relationship between (1) light measurements and canopy structure and (2) light estimates and growing-season % PPFD measured by light diodes. Of all light measurements in this study, ten-minute average % PPFD measurements during clear days were the most variable: only a small proportion in the 10-minute average of light reaching the understory was correlated to either overstory structure or growing-season canopy transmittance. While measures on overcast days improved the correlations, they tended to overestimate transmittance. Gap fraction (GF) and gap light index (GLI) were strongly correlated with % PPFD and overstory structure, and the relationship between GLI and % PPFD was improved by using a direct light setting of 60%. In addition to strong correlation, hemispherical photographic estimates of light fell along a 1:1 line with % growing-season PPFD; thus, estimates were relatively unbiased. Measures of light in this ecosystem need to incorporate the large spatial and temporal variation in light transmittance that is characteristic of this ecosystem if investigators are to understand the relationship between open-canopy woodlands and their light environments.
Spatial and Temporal Disturbance Characteristics of Oak-Dominated Old-Growth Stands in the Central Hardwood Forest Region
Authors: Rentch James S. , Fajvan Mary Ann , Hicks Ray R.
Published: April 2024

Using a radial growth averaging technique, decadal-scale growth changes of 150- to 350-yr-old overstory oaks were used to identify canopy disturbance events in five old-growth stands, and canopy disturbance intervals were estimated using frequency analysis. Stem maps and tree-establishment and canopy-accession chronologies were then used to reconstruct the size of canopy openings. Between 1700 and 1990, median canopy disturbance interval was approximately 3 yr for each stand; larger disturbances involving two or more trees occurred about every 16 yr per stand. Based on age distribution of the oldest cohorts, three stands became established after a major disturbance, but the majority of multiple-tree disturbances were associated with gaps < 200 m2 in area. Historic disturbance frequency and size distribution of canopy gaps suggest that the oak components of these stands persisted by utilizing a variety of growth strategies appropriate to large and small openings. The absence of significant changes in overstory disturbance frequencies further suggests that increases in the level of understory competition are responsible for the present-day decline in oak dominance.
Relationship Between Foliar δ13C and Hydraulic Pathway Length in Pinus palustris
Authors: Samuelson Lisa J. , McLemore Price C. , Somers Greg L.
Published: April 2024

Because of the importance of hydraulic architecture in understanding physiological differences between small and large trees, we tested the hypothesis that foliar δ13C increased with aboveground flow-path length in longleaf pine (Pinus palustris Mill.) trees of varying age and size at two sites in the lower Coastal Plain. This species offered a unique opportunity to examine variability in foliar δ13C in relation to pathway length because of the open, well-mixed canopy in savanna-like stands and concentration of foliage in splayed tufts on branch ends. At both sites, models with total flow-path length (bole + branch) explained 78–81% of the variation in foliar δ13C, and a full model with separate slopes and intercepts for each tree was required. Branch flow-path length was highly correlated with foliar δ13C and the models accounted for 76–88% of the variation in foliar δ13C, and a reduced model with one slope was suitable for each site. Flow-path length was not as well correlated to foliar N concentration, specific leaf area or tuft leaf area. Greater δ13C enrichment with increasing flow-path length indicates the need for mechanistic studies to better understand the role of hydraulic resistance in controlling leaf-level physiology within the canopy and among different size longleaf pine trees.