bluuebunny/crossref_metadata_2025 huggingface dataset:
African Rain Forest Ecology and Conservation: An Interdisciplinary Perspective
Authors: Baker Timothy R.
Published: April 2024

Current conservation strategies focus on achieving sustainable development by viewing the protection of species and habitats within a broader economic and social context. This approach places complex demands on conservation projects, particularly within the African rain forest, with its great biological, political, and historical diversity. Originally dating from a conference organized by the Wildlife Conservation Society in 1993, this book brings together contributions that allow the examination of whether successful, integrated strategies are evident within African rain forest conservation.
Examining Different Concepts for the Development of a Distance-Dependent Competition Model for Red Pine Diameter Growth Using Long-Term Stand Data Differing in Initial Stand Density
Authors: Larocque G.R.
Published: April 2024

Red pine (Pinus resinosa Ait.) data collected from age 13 to age 43 in a spacing trial were used to develop a distance-dependent individual-tree diameter growth model. The traditional concept of zone of influence in competition indices was redefined, and differences in asymmetry in above- and below-ground competition were represented. The availability of remeasured crown dimensions data allowed for realistic representation of the dynamics of crown interference at the canopy level. Diameter at breast height (dbh) increment was expressed in terms of absolute growth rate, relative growth rate, and ratio of absolute growth rate to crown width. The best relationships accounted for at least 80% of the variability in dbh increment. When tested on an independent data set, the model predicted dbh increment relatively accurately under different conditions of stand density. In particular, the change in dbh size distribution with the increase in competitive stress was well represented. FOR. SCI. 48 (1):24–34.
Competitive Effects on Plantation White Spruce Saplings from Shrubs That Are Important Browse for Moose
Authors: Posner Scott D. , Jordan Peter A.
Published: April 2024

Conifer planting is often accompanied by herbicide control of surrounding broadleaf, woody plants that may interfere with conifer growth, a process that releases conifers from competitive suppression. Because potential competitors often provide browse for wildlife, their removal may conflict with objectives in multiple-resource management. While some agencies, such as the USDA Forest Service (USFS), have greatly reduced herbicide use, many other timber producers still rely on chemicals to release conifers from competing vegetation. In northeastern Minnesota, where moose (Alces alces) are a highly valued resource, we studied impacts of broadleaf shrubs on 4- to 16-yr-old white spruce (Picea glauca) along with the extent of browsing by moose on these shrubs. Height, diameter, and current vertical growth increment of spruce were compared among four levels of presence (density strata) of shrubs immediately surrounding each sapling. Spruce grew as well or better in the low and medium density strata as in the no-shrub stratum. In the high density stratum, height and growth increment, particularly in 10- to 16-yr-old spruce, appeared reduced. Presence of shrubs seemed to reduce frost damage in young spruce. Moose browsing reduced height of most shrub species, suggesting that these animals provide a release effect on adjacent spruce. We recommend a release strategy that avoids reduction of shrubs beyond the level that assures normal growth in young spruce, so as both to minimize loss of browse for wildlife and avoid unnecessary silvicultural costs. FOR. SCI. 48(2):283–289.
Book Reviews: The Ecology and Silviculture of Oaks
Authors: Keith Moser W.
Published: April 2024

In writing The Ecology and Silviculture of Oaks, Paul Johnson, Stephen Shifley, and Robert Rogers have performed a tremendous service to the forestry community, and the hardwood forestry community in particular. Although there have been several books on hardwoods and numerous symposia on oak ecology and management over the years, this volume provides a centralized, albeit expensive, explanation and reference to a significant body of information focusing on the various species of oaks. What was most informative and valuable to me, however, was how this book also presented a template for understanding the ecology and management of all shade-intolerant to mid-tolerant species.
A Mixed-Integer Formulation of the Minimum Patch Size Problem
Authors: Rebain Stephanie , McDill Marc E.
Published: April 2024

Forest harvest scheduling models have addressed wildlife habitat concerns in a variety of ways. One way is through minimum patch size constraints specifying that a certain amount of the forest must consist of patches meeting both minimum size and minimum age requirements. Patch size requirements may be necessary because a forest with only small patches of mature habitat may not be able to support populations of some wildlife species. Maximum harvest opening size constraints, which are often imposed for legal or policy reasons, tend to divide forest habitat into small patches. Minimum patch size constraints may be able to help mitigate the negative impact of maximum harvest opening size restrictions. Patch size requirements have been considered elsewhere, but a mixed-integer linear programming (MILP) formulation has never been presented. This article presents such a formulation, which allows minimum patch size problems to be solved using the branch and bound algorithm available through commercial solver packages. An example problem is formulated, solved, and discussed. For. Sci. 49(4):608–618.
Local Modeling of Tree Growth by Geographically Weighted Regression
Authors: Zhang Lianjun , Shi Haijin
Published: April 2024

The spatial heterogeneity of multivariate relationships between tree growth and diameter is explored using geographically weighted regression (GWR). GWR attempts to capture spatial variation by calibrating a multiple regression model fitted at each tree in a sample plot, weighting all neighboring trees by a function of distance from the subject tree. GWR produces a set of parameter estimates and model statistics (e.g., model R2) for each tree in the sample plot. It is evident that the GWR model not only predicts individual tree growth better than the traditional ordinary least-squares model, but also provides useful information on the nature of the growth variation caused by neighboring competitors and surrounding environmental factors. The parameter estimates and model statistics of the GWR model can be mapped using visualization tools, such as geographic information systems (GIS), to illustrate local spatial variation in the regression relationship under study. Consequently, the influence of microsite variation, competition status, growth potential, and the impacts of management activities on trees can be evaluated, tested, modeled, and readily visualized. GWR is a useful tool that provides much more information on spatial relationships to assist in model development and further our understanding of spatial processes. FOR. SCI. 50(2):225–244.
Predicting Forest Attributes in Southeast Alaska Using Artificial Neural Networks
Authors: Corne Simon A. , Carver Stephen J. , Kunin William E. , Lennon Jack J. , van Hees Willem W. S. van
Published: April 2024

Artificial neural network (ANN) methods are used to predict forest characteristics. The data source is the Southeast Alaska (SEAK) Grid Inventory, a ground survey compiled by the USDA Forest Service at several thousand sites. The main objective of this article is to predict characteristics at unsurveyed locations between grid sites. A secondary objective is to evaluate the relative performance of different ANNs. Data from the grid sites are used to train six ANNs: multilayer perceptron, fuzzy ARTMAP, probabilistic, generalized regression, radial basis function, and learning vector quantization. A classification and regression tree method is used for comparison. Topographic variables are used to construct models: latitude and longitude coordinates, elevation, slope, and aspect. The models classify three forest characteristics: crown closure, species land cover, and tree size/structure. Models are constructed using n-fold cross-validation. Predictive accuracy is calculated using a method that accounts for the influence of misclassification as well as measuring correct classifications. The probabilistic and generalized regression networks are found to be the most accurate. The predictions of the ANN models are compared with a classification of the Tongass national forest in southeast Alaska based on the interpretation of satellite imagery and are found to be of similar accuracy. FOR. SCI. 50(2):259–276.
Book Reviews: Toward Forest Sustainability
Authors: Roberts Scott D.
Published: April 2024

A major issue facing forestry these days is whether forests can be actively managed while supporting diversity and maintaining their natural range of ecological processes and functions. In other words, can forests be managed sustainably? This book contains a collection of essays written by participants of a sustainable forestry roundtable held in 2002 in Marysville, Victoria, Australia. Although much of the conference focused on Australia's montane ash forests, the purpose of the book is to share the wisdom and experience of experts from countries throughout the temperate regions of the world as their countries struggle to learn how to manage forests more sustainably in the face of changing political and environmental pressures. Some of the contributors will be very familiar to readers who have followed the sustainable-forest management debates in North America, including Jerry Franklin, Michael Soulé, David Perry, and Frank Bunnell. Other contributors may not be as familiar to the North American audience, but will certainly be recognized by those who have followed the international sustainable-forestry debate. These include, among others, David Lindenmayer and Per Angelstam.
A Critical Evaluation of Fire Suppression Effects in the Boreal Forest of Ontario
Authors: Bridge S.R.J. , Miyanishi K. , Johnson E.A.
Published: April 2024

Although fire suppression is widely believed to have changed the “natural” fire regime in the boreal forest, empirical evidence for this effect is limited and usually involves a comparison of fire sizes, average annual area burned, and fire cycle between areas with and without fire suppression. We critically evaluate this empirical evidence and discuss problems with untested assumptions, data quality, statistical analyses, interpretations, and inferences. Furthermore, to test the hypothesis that fire suppression has changed the natural fire regime, we apply time-since-fire techniques to spatial fire data (1921–1995) for the western and eastern boreal regions of Ontario and compare temporal and spatial variation in fire cycle for areas with and without fire suppression. There is no detectable temporal change in fire cycle between 1921 and 1995 in areas with aggressive fire suppression; however, interpretation of the fire cycle in areas without aggressive fire suppression is confounded by insufficient data. Also, although the western region shows an increase in fire cycle from fully protected to less protected areas, the eastern region shows the shortest fire cycle in the most protected area. Thus, to date there is insufficient empirical evidence that fire suppression has significantly changed the fire cycle in the boreal forest of Ontario. FOR. SCI. 51(1):41–50.
Juvenile Genetic Parameters and Genotypic Stability of Pinus pinaster Ait. Open-Pollinated Families under Different Water and Nutrient Regimes
Authors: Zas Rafael , Fernández-López Josefa
Published: April 2024

The purpose of this study was to estimate the impact of genotype × nutrient and genotype × water availability interactions in the maritime pine (Pinus pinaster Ait.) breeding program in Galicia (northwestern Spain). Twenty-nine open-pollinated families, randomly selected in a seed orchard, were cultivated for 23 weeks in a greenhouse in a split-plot design under controlled conditions. Two water regimes (high and low water supply) combined with two nutrient regimes (high and low nutrient supply) were applied by subirrigation. Both the irrigation and the fertilization treatments had a strong effect in all the assessed traits. Heritabilities for growth and biomass traits were moderate to high (0.2–0.5) in individual treatments, especially in those treatments that led to intermediate growth. However, when analyzing all treatments together, the impact of the family × treatment interactions led to an important reduction (0.1–0.2) of the heritability estimates. The results indicated that the genotype × water and genotype × nutrient interactions may be important and could not be ignored in the Galician maritime pine breeding program. However, the study of the family ecovalence values indicated that interactions are mainly due to some interactive families (7 to 31% of families). Culling several of the female parents with high ecovalence values would result in a stable breeding population and would be enough to overcome the interaction handicap in the breeding program. FOR. SCI. 51(2):165–174.
Finding the Efficient Frontier of a Bi-Criteria, Spatially Explicit, Harvest Scheduling Problem
Authors: Sándor F. Tóth , McDill Marc E. , Rebain Stephanie
Published: April 2024

The effects of cost-sharing and information assistance on nonindustrial private forest owners’ investment in timber stand improvements are analyzed using a two-step estimation method. We use survey data on Finnish nonindustrial private forestland owners’ stand improvements in 1994–1998, including precommercial thinnings, cleaning of seedling stands, and restoration thinnings of juvenile stands. The investment decision is theoretically considered in a two-period model with amenity values. To allow for the joint determination of participation in the cost-sharing program and the decision to invest, a two-step estimation method is used. The predicted probability of using public subsidy from the first-step model is included in the second-step model for the probability or relative extent of stand improvements. For robust inference, quasi-maximum likelihood estimation is applied. Public subsidy, personal assistance, and forest planning expectedly increased the probability of investing. Public subsidy especially had substantial effects on the probability and extent of stand improvements. Besides overcoming the endogeneity of cost-sharing, the two-step approach showed that personal assistance also encourages stand improvements indirectly through its effect on the use of public subsidy.
The Law of One Price in the North American Softwood Lumber Markets
Authors: Shahi Chander , Kant Shashi , Yang Feng'e
Published: April 2024

The existence of the Law of One Price (LOP) in the North American (10 regional) markets for aggregate softwood lumber and homogeneous softwood lumber products is tested using the Johansen co-integration test and monthly price data for the Softwood Lumber Agreement (SLA) (1996–2001) period and the post-SLA (2001–2004) period. For the aggregate softwood lumber market, the LOP exists neither in the North American aggregate market nor in any combination of one regional market of Canada and all the five regional markets of the United States, nor in one regional market of the United States and all five regional markets of Canada; however, some of the regional markets are co-integrated. The regional markets of homogeneous softwood products in the two countries are co-integrated during both the SLA and post-SLA period. Further studies are essential to understand the difference between the aggregated and homogeneous softwood products market co-integration and to develop a comprehensive and comparative perspective of the Canadian and the US softwood lumber markets.
U.S.–Canada Softwood Lumber Trade: Measuring the Market and Welfare Impacts of Restrictions
Authors: Baek Jungho , Yin Runsheng
Published: April 2024

The U.S.–Canada softwood lumber trade dispute is the largest and most contentious one between the two countries. Using a simultaneous system of equations and a vector auto-regression model, and quarterly data for over the last two decades, this article assesses the impacts of the Memorandum of Understanding (MOU) and Softwood Lumber Agreement (SLA). We find that the MOU causes Canadian exports to drop by 8.4–9% during 1986:4–1991:3, which in turn pushes up the U.S. production by 3%. But it does not lead to higher lumber prices. The SLA does not have any significant impacts on the lumber market during 1996:2–2001:1. In addition, the price elasticities of domestic and Canadian export supply are smaller than those commonly used in evaluating the gains and losses of the U.S. restrictions, whereas such factors as exchange rates, housing starts, and log prices have played major roles in shaping the lumber markets. Combining the modest market impacts and smaller price elasticities, we obtain only moderate welfare consequences of the trade restrictions.
Bird–Habitat Relationships in Grand Fir Forests of the Blue Mountains, Oregon
Authors: Sallabanks Rex , Riggs Robert A. , Cobb Lynda E. , Dodson Steven W.
Published: April 2024

During the breeding seasons of 1994–1996, we sampled bird communities and habitat characteristics in grand fir (Abies grandis) forests of the Blue Mountains, northeastern Oregon, at the stand- and landscape-level with the objective of explaining variation in the composition and abundance of forest avifauna. We analyzed data from 77 forest stands that varied in size from 16 to 213 ha. Canonical correlation analysis (CANCOR) indicated that stand-level features accounted for more variance in the relative abundance of bird species than did landscape-level features (35 versus 14%, respectively). The most important stand-level features were overstory canopy cover, density of large-diameter live trees, and understory structure (especially herbs and shrubs). Important landscape features for predicting the abundance of species within a forest stand included stand isolation and the percentage of surrounding landscape within a 4-km radius that was occupied by forest cover. Using the information-theoretic approach to model selection and inference, we built models of bird–habitat relationships to forecast abundance of 24 species. Consistent with CANCOR results, species–specific habitat models were dominated by stand-level variables. Overstory cover was a significant predictor of abundance for 17 of 24 species modeled (71%). We conclude that in forests represented by our sample, management for most avian species can be usefully focused on within-stand dynamics of structure, but that efforts to forecast abundance of some species can be enhanced by integration of landscape metrics as well.
Timber Harvest Impacts on Water Yield in the Continental/Maritime Hydroclimatic Region of the United States
Authors: Hubbart Jason A. , Link Timothy E. , Gravelle John A. , Elliot William J.
Published: April 2024

The inland Pacific Northwest of the United States is influenced by both maritime and continental hydrometeorogical conditions. To date there are limited studies of hydrologic impacts resulting from contemporary timber harvest in this region. Streamflow data were collected since 1991 at the Mica Creek Experimental Watershed (MCEW) in northern Idaho. Treatments were designed to isolate the effects of road construction and two different harvest practices (50% clearcut, 50% partial cut). The change in water yield was assessed using linear regression and analysis of covariance (ANCOVA). Water yield increased in excess of 270 mm/yr (P < 0.01) after clearcut harvesting, and by more than 140 mm/yr (P < 0.01) after partial cut harvesting. Monthly and seasonal analyses revealed the largest impacts of harvest practices on water yield during the snow deposition and melt season from November through June. Dry season analyses (July through October) indicated negligible water yield increases after treatments. Estimates of evapotranspiration (ET) as the residual of the catchment water balance suggest that ET was reduced by 35% and 14% after clearcut and partial cut harvest, respectively. These results establish a base on which to develop tools for effective watershed management in the northern Idaho continental/maritime hydroclimatic region.
NetMap: A New Tool in Support of Watershed Science and Resource Management
Authors: Benda Lee , Miller Daniel , Andras Kevin , Bigelow Paul , Reeves Gordon , Michael David
Published: April 2024

An integrated suite of numerical models and analysis tools (NetMap) is created for three purposes: (1) Develop regional scale terrain databases in support of watershed science and resource management, (2) Automate numerous kinds of watershed analyses keying on environmental variability for diversifying resource management options, and (3) Improve tools and skills for interpreting watershed-level controls on aquatic systems, including natural disturbance. Hillslope attributes, such as erosion potential, sediment supply, road density, forest age, and fire risk are aggregated down to the channel habitat scale (20–200 m) allowing unique overlap analyses, and they are accumulated downstream in networks revealing patterns across multiple scales. Watershed attributes are aggregated up to subbasin scales (10,000 ha), allowing comparative analyses across large watersheds and landscapes. Approximately 25 automated tools address erosion risk, habitat indices, channel classification, habitat core areas, habitat diversity, and sediment and wood supply, among others. Search functions target overlaps between specific hillslope and channel conditions and between roads and landslide or debris flow potential. To facilitate its use, NetMap contains hyperlinked users' manuals and reference materials, including a library of 50 watershed parameters. NetMap provides decision support for forestry, restoration, monitoring, conservation, and regulation.
On Debris Flows, River Networks, and the Spatial Structure of Channel Morphology
Authors: Bigelow Paul E. , Benda Lee E. , Miller Daniel J. , Burnett Kelly M.
Published: April 2024

We evaluated the morphological effects of debris flows from headwater streams in larger, fish-bearing channels of the central Oregon Coast Range, including their influence on fans, wood recruitment, and channel morphology. Continuous channel surveys (6.4 km) were conducted in third- through fifth-order streams (drainage area <10 km2 and slope <7%) where debris fan effects at confluences were most evident. This basin size contains the majority of channels (67%) in the central Coast Range with gradients that are used by coho salmon (Oncorhynchus kisutch Walbaum). The close spacing between headwater tributaries susceptible to debris flows (118 m average) resulted in long continuous sections of fish-bearing streams that were bordered by debris fans (103 m average) and debris fans impinging on 54% of the total channel length surveyed. Debris flows also supplied the majority of wood (58% of pieces) to the surveyed fish-bearing channels. The highest values of large wood, boulders, and channel gradients were associated with debris fans at confluences with headwater tributaries, while deeper sediment deposits were often associated with fans but also extended up and downstream from fans. The spacing and network pattern of debris flow-prone headwater tributaries influenced the spatial structure of channel morphology and aquatic habitats leading to a high degree of physical heterogeneity and patchiness in channel environments. Our study contributes to a growing emphasis on the role of tributary confluences in structuring channel morphology and aquatic habitats in mountain drainage basins and argues for including a confluence component to stream classification and habitat typing schemes.
Stream Macroinvertebrate Community Responses as Legacies of Forest Harvest at the H.J. Andrews Experimental Forest, Oregon
Authors: Frady Charles , Johnson Sherri , Li Judy
Published: April 2024

To evaluate long-term effects of forest harvest, we sampled benthic and emergent macroinvertebrate communities in headwater streams through young-growth and old-growth forests in the H.J. Andrews Experimental Forest, Oregon, from June, 2003 to June, 2004. Thirty to forty years after harvest, macroinvertebrate density and richness did not differ among streams through young growth and old growth. Effects of deciduous riparian vegetation, including seasonal canopy openings and litterfall, continue to influence patterns of macroinvertebrate responses to forest harvest, as shown by higher densities of shredders in young-growth sites, the timing of emergence within basin pairs, and assemblage differences in two of the pairs of basins. The paired-basin design helped in distinguishing the specific influences of forest age from natural variability of macroinvertebrate distributions within the 5th order Lookout Creek basin. Our study suggests that understanding how macroinvertebrates respond to historical disturbances is enhanced by measures sensitive to changes in life history, such as rates of emergence, and to functional composition that reflect resource availability.
Productivity of Three Young Mixed-Species Plantations Containing N2-Fixing Acacia and Non-N2-Fixing Eucalyptus and Pinus Trees in Southeastern Australia
Authors: Forrester David I. , Bauhus Jürgen , Cowie Annette L. , Mitchell Peter A. , Brockwell John
Published: April 2024

Mixed species plantations have the potential to exceed the biomass production of monocultures. This study examined the productivity of three mixed species plantations in southeastern Australia. Two of these trials contained a Eucalyptus sp. (E. saligna Smith or E. nitens [Deane & Maiden] Maiden) planted with Acacia mearnsii De Wild., and the other contained Pinus radiata D. Don with A. mearnsii, A. decurrens Willd., E. benthamii Maiden & Cambage, or E. smithii R. Baker. Each trial contained both monocultures and mixtures, and was replicated three or four times. Tree diameters or heights were smaller in mixture than monocultures for some species (P. radiata diameters of 5.9 cm and 7.0 cm in 2:1 mixtures with A. mearnsii and monocultures, respectively) but tended to increase (not significantly) for other species (E. nitens diameters of 10.6 cm and 8.5 cm and A. mearnsii diameters of 9.2 cm and 8.8 cm in 1:1 mixtures and monocultures, respectively). As a result, mixtures were intermediate in aboveground biomass production between monocultures of the mixed species in each trial, or they were not significantly different from the monocultures. Competition for resources other than nitrogen (N), such as light, soil moisture, or other nutrients, appeared to balance any positive effects that might have occurred, such as through increased N availability. For example, foliar N concentrations of E. saligna were higher in mixture (23.1 mg g−1) than monoculture (17.7 mg g−1); however, this did not result in greater aboveground tree biomass. The range of different growth responses from mixing different species in this study and in other studies shows that a fundamental understanding of the underlying processes is required to enable a greater predictive capacity of the circumstances under which mixtures can be successful.
Does Monopolistic Competition Explain Intraindustry Trade of Forest Products?
Authors: Zhang Sijia , Buongiorno Joseph
Published: April 2024

Intraindustry trade occurs when countries import and export the same product. We found, based on Grubel-Lloyd indices, that there is substantial intraindustry trade of forest products. The explanation of intraindustry trade by the Helpman-Krugman theory of monopolistic competition implies a unit elasticity of exports with respect to production. We studied the existence of such a relationship for 11 forest industries that produce and export roundwood, sawnwood, wood-based panels, wood pulp, and paper and paperboard. The hypothesis was tested with cross-section and time-series data from 43 countries observed from 1961 to 2002. We formulated static and dynamic versions of the relationship between exports and production and estimated them with panel data methods. The best results, based on pattern of the residuals and forecasting errors, were obtained with the static and the dynamic models estimated by ordinary least squares after differencing the time series. The strongest evidence of monopolistic competition was for the pulp and paper industries: newsprint, printing and writing paper, other paper and paperboard, and chemical and semichemical woodpulp. For other forest products, although there was a statistically significant relationship between production and exports, the long-run elasticity was significantly less than unity.
Leaf Nutrient Concentrations and Timber Productivity in the Dry Sclerophyll Forests of South-East Queensland, Australia: Implications for Arboreal Marsupials
Authors: Wormington Kevin Ray , Lamb David , McCallum Hamish Ian , Moloney Damien John
Published: April 2024

The species richness and abundance of arboreal marsupials are positively related to the proportion of total stand basal area occupied by Corymbia citriodora ssp. variegata and tree height in South-East Queensland and have been related to nutrient availability and productivity in other parts of Australia. The objectives of this study were to assess the relationships of stand basal area occupied by C. citriodora and tree height, and the available nutrients and productivity in the dry sclerophyll forests of South-East Queensland. Leaf nutrient analysis of seven species of trees in South-East Queensland showed that the percentage by weight of phosphorus in leaves increased with the proportion of the total stand basal area of C. citriodora. This rate of increase was greater for C. citriodora than other species, indicating that C. citriodora may be more competitive on soils with greater available phosphorus. C. citriodora leaves also contained higher concentrations of nitrogen and potassium than the other tree species on multispecies sites. Timber productivity was greater at the sites where trees were taller, and tree height was positively correlated to the proportion of total stand basal area of C. citriodora and rainfall but was negatively correlated to the slope. These findings indicate that the most used habitat by arboreal marsupials in the dry sclerophyll forests of South-East Queensland (i.e., taller forests with a high proportion of the stand basal area occupied by C. citriodora) had higher concentrations of foliar nutrients and were more productive than less used habitats.
Tree Mortality in Mixed Pine–Hardwood Stands Defoliated by the European Gypsy Moth (Lymantria dispar L.)
Authors: Eisenbies Mark H. , Davidson Christopher , Johnson James , Amateis Ralph , Gottschalk Kurt
Published: April 2024

Defoliation by the European gypsy moth (Lymantria dispar L.) and subsequent tree mortality have been well documented in the northeastern United States. In this study we evaluate tree mortality after initial defoliation in mixed pine–hardwood stands in the southeastern United States as the range of European gypsy moth expands. In 1993, 46 mature pine–oak and pine–sweetgum stands were selected on the coastal plain in Maryland and Virginia along the advancing gypsy moth front. Initial stand conditions, defoliation, and tree mortality after a single defoliation outbreak were monitored for 4 years. Susceptible oaks and sweetgum were defoliated at the greatest intensities. After defoliation, mortality in attacked stands was 4.4 m2/ha higher in pine–oak stands and 1.7 m2/ha higher in pine–sweetgum stands, representing 13 and 3% of the total basal area, respectively. Mortality of pines was observed mainly among suppressed and intermediate trees. Logistic regressions were derived to correlate individual tree mortality to stand and tree factors associated with gypsy moth attack. On the basis of these models, susceptible understory species with degraded crowns in pine–oak stands were at the greatest risk of mortality. Dominant overstory pines in pine–hardwood stands appear to be at low risk.
Using Inventory Projections to Evaluate Management Options for the Nontimber Forest Product of Epiphytic Moss
Authors: Peck JeriLynn , Hoganson Howard , Muir Patricia , Ek Alan , Frelich Lee
Published: April 2024

Several US national forests have implemented moratoria on harvesting moss in the absence of management plans that can demonstrate long-term sustainability. To fill this gap, harvest schedules are presented for epiphytic moss in northwestern Oregon based on a variation of the classic volume control model. Commercial moss inventory over a 150-year simulation period was estimated as initial inventory plus biomass increment minus mortality and legal harvest. A 50-year exclusion period between harvests was chosen based on the minimum time estimated to replenish moss and to maintain acceptable species richness for the moss and the invertebrate taxa that inhabit it. Mean estimates for the input parameters were used for a “baseline” scenario and the upper and lower 95th percentile confidence intervals for the estimates were used for “optimistic” and “conservative” scenarios describing moss growth and yield estimates. Recent moss harvest permit levels exceed those that would sustain resource yield and biodiversity even under the optimistic scenario. Avoiding resource depletion would require reducing permit levels by 3.5- and 1.4-fold under baseline and optimistic scenarios, respectively. Sustained yield would require reductions of 6.8- and 1.7-fold, respectively.
Stochastic Simulation of Forest Regeneration Establishment Using a Multilevel Multivariate Model
Authors: Miina Jari , Heinonen Jaakko
Published: April 2024

Here we present a method for simulating high unexplained variation in establishment of tree seedlings in planted Norway spruce (Picea abies [L.] Karst.) stands. The simulation method is based on an existing hierarchical multilevel multivariate model for establishment of regeneration (Miina, J., and T. Saksa. 2006. New For. 32:265–283). The model includes seven simultaneously estimated models for numbers and heights of tree seedlings on 20-m2 plots within a regeneration area. The variation in plot-level expectations is described by fixed effects and two nested multivariate normal random effects. Conditionally, given the expected values, one of the count variables is underdispersed and four are overdispersed relative to Poisson law. The conditional distributions of the square roots of the height variables are normal. For the conditional joint distribution, the model defines the product-moment cross-correlation matrix, which includes both positive and negative cross-correlations. The first two moments do not, however, uniquely define the marginal distributions of the count variables or the joint distribution of all seven variables. We applied binomial distribution for the underdispersed Poisson variation and negative binomial distribution for the overdispersed Poisson variation. The conditional joint distribution was defined by a multivariate normal copula and the marginal distributions. Despite relatively low cross-correlations among responses, if the cross-correlations among random components of the responses were ignored in stochastic simulations, the amount and costs of precommercial thinning (i.e., cleaning out competing broadleaves) were greatly underestimated. If all random effect components in model parameters were dropped, the error increased markedly.
Seed Germination: Mathematical Representation and Parameters Extraction
Authors: El-Kassaby Yousry A. , Moss Ian , Kolotelo Dave , Stoehr Michael
Published: April 2024

A method for mathematically describing cumulative seed germination using the four-parameter Hill function is described. The function's four parameters allowed both direct or indirect biological interpretation of germination behavior and the impact of seed pretreatments on germination improvement. Three parameters, a, b, and c, allowed direct assessment of germination capacity (%), the shape and steepness of the germination course, and germination speed (time to reach 50% germination). The fourth parameter y0 permitted estimation of the lag time (germination onset). The mathematical expression of cumulative seed germination of unstratified and stratified seed made it possible to quantitatively estimate seedlot dormancy and the amount of germination improvement caused by a specific seed pretreatment. This was accomplished by estimating the area between the two cumulative germination curves through integration. The utility of the proposed approach was demonstrated using germination data from wind-pollinated, individual genotypes (half-sib families) of lodgepole pine (Pinus contorta var. latifolia) and bulk seedlots of lodgepole pine and white spruce (Picea glauca).
How (Un)Certain Is the Future in Forestry? A Comparative Assessment of Uncertainty in the Forest and Agricultural Sector
Authors: Hoogstra Marjanke A. , Schanz Heiner
Published: April 2024

Several authors have stated that, because of the long time horizons underlying forestry processes, the forest sector encounters far more uncertainty than is experienced by any other industrial or agricultural production processes, especially regarding the long future. To gain more insight into the extent to which foresters experience uncertainty in their work field, a content analysis has been carried out to reveal how foresters from the United States and (Germanic) Central Europe (Germany, Austria, and Switzerland) experience uncertainty. The outcomes were compared with the experiences of uncertainty in a more short-term oriented sector, namely the agricultural sector (also in the United States and in Central Europe). Although the findings must be interpreted carefully, the research reveals that, in contrast to what was expected, foresters experience the future as the most certain time period. Decisionmakers in forestry, as in other business sectors, seem to ignore the uncertainty and pretend that the future is certain. This strategy implies considerable risk and, therefore, for forest management to be effective, there is no other way than actively confronting the futurity dilemma.
A Gamma-Poisson Distribution of Point to k Nearest Event Distance
Authors: Magnussen Steen , Picard Nicholas , Kleinn Christoph
Published: April 2024

Distance sampling of events in natural or seminatural populations often indicates a larger variance in the distance to the kth nearest event than expected for events distributed completely at random. Overdispersion contributes to the well-known bias problem of distance sampling density estimators. Distance distribution models that accommodate overdispersion in the data should lead to more robust estimators of density. To this end we propose a gamma-Poisson distribution model for distances from a point to k nearest events. The model assumes a gamma distribution of local densities of randomly distributed events. Properties of the distribution and estimation of the parameters and event density are detailed for both constrained and unconstrained sampling. Four examples, one with simulated data from a known negative binomial distribution and three with simulated distance sampling in natural and seminatural stem-mapped tree stands, illustrate the promising performance of this new distribution, both as a model for distances and for density estimation. The modeling approach extends to other mixing distributions.
Simulating Light Availability under Different Hybrid Poplar Clones in a Mixed Intensive Plantation System
Authors: Paquette Alain , Messier Christian , Périnet Pierre , Cogliastro Alain
Published: April 2024

Fast-growing hybrid poplars have been proposed as a means of achieving restoration objectives on former agricultural land by providing shelter for slower-growing species. Intensive two-stage scenarios of mixed plantations are also possible using valuable hardwoods interplanted among hybrid poplars. The latter would be harvested at maturity (approximately 20 years) once their protective role has been accomplished, leaving more space for the full development of the second cohort. We implemented simulations of hybrid poplar growth in the SORTIE-ND model and used it to test scenarios with clones varying in growth and crown allometry, different hardwood species, and spatial arrangements, to maximize production of both groups. Important differences in growth and allometry were manifested among clones over time, which translated into important differences in available light between rows. Sustained growth for most hardwoods appeared optimal using wider spacings of 16 m, compared with 12 m, between poplar rows. To our knowledge, this is the first attempt to integrate fast-growing hybrids and intensive silviculture scenarios into spatially explicit models. These models are necessary support tools for the efforts now being invested in intensive silviculture in the face of diminishing forest resources, increasing wood and fiber demands, and climate change.
Using the Space-Time Permutation Scan Statistic to Map Anomalous Diameter Distributions Drawn from Landscape-Scale Forest Inventories
Authors: Rubin Benjamin , MacFarlane David
Published: April 2024

Landscape-scale tree stem diameter distributions contain information that is potentially useful for evaluating the structural sustainability of forests, describing the impacts of past disturbances, and predicting future forest structure. One obstacle to interpreting diameter distributions at large scales is that typical boundaries used to define populations, such as ecoregions or counties, may not correspond to areas with different diameter distributions. We modified the space-time permutation scan statistic (STPSS), a disease outbreak detection technique, to identify and map areas in Pennsylvania, USA, where diameter distributions based on Forest Inventory and Analysis plots appeared different from the diameter distributions of the state as a whole. We used linear, exponential, and polynomial regressions to model the diameter distributions of the entire state and of areas indicated by the STPSS. The best fit regression models were linear and polynomial as determined by Akaike's information criterion and log likelihood statistics. Regression models confirmed that the STPSS identified areas where the diameter distributions of all species, oaks, and red maple differed from their corresponding statewide populations. Through a nested application of the STPSS at successively smaller spatial scales, we mapped core zones within each area where the difference was greatest.
Assessing the Relative Importance of Tangible and Intangible Resources: Empirical Results from the Forest Industry
Authors: Lähtinen Katja , Haara Arto , Leskinen Pekka , Toppinen Anne
Published: April 2024

The importance of a diverse resource base to competitiveness of firms has been emphasized in resource-based view (RBV) literature and empirical studies done on various industries. Despite this emphasis, resource assessment methodologies within the RBV framework have been seldom approached, and the relative importance of different resources for business operations is not well understood. The data of the study were collected among large- and medium-sized sawmills within the Finnish forest industry. The objective of this study was to assess within the RBV framework the importance of tangible and intangible resources in business operations of sawmills. This was accomplished by introducing a multicriteria decision analysis (MCDA) method suitable for practical resource assessment. According to the results, personnel, managerial, raw material, and financial resources were the most crucial for sawmills. In the future, applying the MCDA to resource assessments could be combined, e.g., with a financial statement analysis to evaluate the effects of resource usage decisions on business performance.
Canopy Cover Estimation in Semiarid Woodlands: Comparison of Field-Based and Remote Sensing Methods
Authors: Ko Dongwook , Bristow Nathan , Greenwood David , Weisberg Peter
Published: April 2024

Canopy cover is a widely used measurement for characterizing forest structure. Numerous comparative studies have been conducted for a variety of canopy cover field methods. However, comparisons of canopy cover methodology are lacking for semiarid woodland, characterized by short-statured trees, simple vertical canopy structure, and relatively low canopy cover. Furthermore, there is limited knowledge on the compatibility between field and remote sensing methods, despite the increasing interest in scaling up canopy cover estimates from forest stands to large landscapes. In this study we investigated the use and functional similarity of various canopy cover field methods and a remote sensing method in semiarid pinyon-juniper woodlands in the Great Basin of the western United States. We compared line intercept, vertical densitometer, spherical densiometer, and crown radius methods with each other and with a remote sensing method using object-oriented image classification of digital orthophotography. Our results show that methods using a wider angular view generated higher canopy cover estimates. This difference may be greater in semiarid woodland that in mesic forest because of differences in canopy architecture. Canopy cover from remote sensing showed a nonlinear relationship with that from field-based methods. Such nonlinearities need to be considered when remote sensing is used to extrapolate canopy cover from stand to landscape scales or when field-based canopy cover estimates are used to calibrate or validate remote sensing classifications.
Facilitating Integrated Recreation Management: Assessing Conflict Reduction Benefits in a Common Metric
Authors: Lindberg Kreg , Fredman Peter , Heldt Tobias
Published: April 2024

Recreation management on public land often involves trade-offs. For example, cross-country skiers may experience conflict with snowmobiles. A potential management response is trail separation, which may lead to gains to skiers but also ecological and financial costs associated with creation of a new trail. If separation involves snowmobile access restrictions, there may be experiential losses for that user group. Management responses are not always based on explicit identification and integration of the gains and losses accruing across diverse stakeholders and dimensions; economics provides a criterion, a metric, and measurement tools to facilitate such integration. A Swedish case study illustrates this approach and assesses values accruing to skiers from reduced snowmobile presence. Cross-country skiers were sampled on-site in the southern Jämtland mountain region, and follow-up mail surveys included choice experiment scenarios. Conditional logit analysis of the 1,468 completed scenarios indicates that skier welfare gains from conflict reduction are substantial and reflect both direct and indirect contact. A change from sharing trails to not seeing, hearing, or smelling snowmobiles leads to gains of 185 kronor (US$23) per skier party.