bluuebunny/crossref_metadata_2025 huggingface dataset:
Canopy Arthropod Assemblages in Four Overstory and Three Understory Plant Species in a Mixed-Conifer Old-Growth Forest in California
Authors: Schowalter Timothy D. , Zhang Yanli
Published: April 2024

We compared canopy arthropod assemblages among overstory conifer and understory angiosperm species at Teakettle Experimental Forest in the Sierra Nevada in California during 1998–2000. Arthropods were sampled from upper, middle, and lower crown levels of one overstory tree of each of the four dominant conifer species (Jeffrey pine, sugar pine, white fir, and incense cedar), and from three understory plants of each of the major understory species (California black oak, manzanita, and white-thorn ceanothus) in each of five replicate plots during June and Aug. in each of the 3 years to represent seasonal and annual variation in abundances. Many taxa differed significantly in abundance among plant species, with one to five taxa being significant indicators for each plant species. Five to eight taxa on each plant species showed significant differences in abundance among years. Aphids and scale insects, predaceous mirids, and some detritivores showed peak abundances in 1999, a particularly dry year, whereas most other taxa showed lowest abundances during 1999 or declining abundances during this period, suggesting association with wetter conditions. Nonmetric multidimensional scaling (NMS), supported by multi-response permutation procedure (MRPP), showed that arthropod assemblages differed significantly among the seven plant species, especially between overstory conifers and understory angiosperms, and among the 3 years. These data indicate that the diversity and structure of arthropod communities depend on vegetation structure and/or condition, perhaps as modified by annual variation in weather conditions. FOR. SCI. 51(3):233–242.
Patterns of Mortality in an Old-Growth Mixed-Conifer Forest of the Southern Sierra Nevada, California
Authors: Smith Thomas F. , Rizzo David M. , North Malcolm
Published: April 2024

Mortality patterns in an old-growth, mixed-conifer forest, in the absence of wildfire, were investigated at the Teakettle Experimental Forest from 2000 to 2002. We tested the hypothesis that after a century of fire suppression, pathogen- and insect-associated mortality (between episodic droughts) would be significantly greater on ingrowth trees (i.e., smaller-diameter, shade-tolerant species in high-density clusters). Using a survey of over 30,000 mapped trees, overall mortality, as measured by standing dead trees, was 8.7% of all stems ≥5 cm dbh. Mortality levels were proportional to the population size of the five dominant conifer species, white fir (Abies concolor), red fir (A. magnifica), incense cedar (Calocedrus decurrens), Jeffrey pine (Pinus jeffreyi), and sugar pine (Pinus lambertiana). There was also no significant difference in mortality between shade-tolerant and shade-intolerant species. All dead trees were clustered within plots. Mortality was significantly higher than expected for large-diameter trees (>100 cm dbh) with all conifer species combined and for each individual species, except Jeffrey pine. Small-diameter dead trees were grouped in high-density clusters. Mortality was less than expected among small-diameter trees (5–20 cm dbh) for all species combined, red and white fir, and sugar pine. Mortality for all conifers was higher than expected in areas of high stand density and lower in areas of low stand density. Mortality of small-diameter trees was clustered and particularly high in areas of high stand density. Our data suggest pathogen- and insect-associated mortality is significantly greater in areas of high stand density but it is not higher for shade-tolerant species. Furthermore, mortality is higher than expected for large-diameter trees, suggesting an acceleration of old-tree mortality under current fire suppression conditions. FOR. SCI. 51(3):266–275.
Aquatic Invertebrate Responses to Timber Harvest in a Bottomland Hardwood Wetland of South Carolina
Authors: Batzer Darold P. , George Bagie M. , Braccia Amy
Published: April 2024

We used aquatic invertebrates to assess environmental impacts of timber harvest on a bottomland hardwood wetland in the Coosawhatchie River floodplain, Jasper County, SC. Two years (1998, 1999) of preharvest baseline data were collected during winter floods in three 11–13-ha tracts of wetland forest. The following autumn of 1999 one tract was completely clearcut. In a second tract the majority of the area was also clearcut, but three 0.2–0.6-ha islands of intact forest were retained (i.e., patch-retention treatment). The third tract remained intact and served as the control. We continued to sample invertebrates in the three tracts for another 2 years (2000, 2001) after harvests. Invertebrate communities in the clearcut tract differed significantly from previous baseline conditions in that habitat and also from the nearby control tract. The patch-retention tract induced a lesser response than the clearcut, suggesting that retention islands helped mitigate impacts. Timber harvest caused a decline in some invertebrate populations (Asellidae, Crangonyctidae, Planorbidae), but an increase in others (Culicidae). Overall invertebrate abundance and family richness was not affected by harvest, only community composition. Invertebrate change probably reflected a conversion of a fauna typical of forested wetland to one typical of herbaceous wetland. FOR. SCI. 51(4):284–291.
Assessment of Sustainability in Intensively Managed Forested Landscapes: A Case Study in Eastern Texas
Authors: Azevedo João C. , Wu X. Ben , Messina Michael G. , Fisher Richard F.
Published: April 2024

We developed a methodology to analyze the effects of management practices on landscape structure and function to be used in the assessment of sustainability in intensively managed forest landscapes. It is based on modeling and simulation of landscape and stand structure as well as biological and physical processes. The methodology includes a landscape structure model and several forest stand-level models to simulate the dynamics of landscapes and stands as a function of management rules. It also includes habitat models to evaluate landscape quality and spatial characteristics of vertebrate habitat, and a hydrologic model to simulate water and sediment yield at the subarea and watershed levels. The application of this methodology to the Sustainable Forestry Initiative (SFI) program in eastern Texas indicated that this is an effective way to evaluate effects of sustainable forestry programs on landscape structure and processes. During simulation years, the habitat of pine warbler, the species used as an example to illustrate the methodology, became apparently fragmented under the SFI scenario. This fragmentation was caused mainly by narrow, forested streamside management zones dissecting pine stands and should have little negative influence on the pine warbler habitat. Sediment yield at the landscape level decreased by the implementation of SFI measures, particularly by the reduction of channel degradation. FOR. SCI. 51(4):321–333.
A Variance and Covariance Equation for Area Estimates with a Geographic Information System
Authors: van Oort P. A. J. , Stein A. , Bregt A. K. , de Bruin S. , Kuipers J.
Published: April 2024

Geographic Information Systems automatically calculate the area of a polygon from the coordinate values of the vertices that describe its boundary. Uncertainty in these coordinate values results in uncertainty in area estimates. Earlier articles showed how area uncertainty of individual polygons could be calculated. In this article we propose a covariance equation to quantify the impact of uncertainty in the position of a vertex on uncertainty in the area of all polygons sharing this vertex. The approach is based on the assumption of absence of spatial correlation in positional errors, but includes variation in the positional accuracy. The equations were implemented and applied to a case study area, described by a set of 97 adjacent polygons with different per unit area utility values (€/ha). We were then able to calculate how uncertainty in the coordinate values propagated into uncertainty in the utility value of the complete set of polygons. FOR. SCI. 51(4):347–356.
Multilevel Nonlinear Mixed-Effects Models for the Modeling of Earlywood and Latewood Microfibril Angle
Authors: Jordan Lewis , Daniels Richard F. , Clark Alexander , He Rechun
Published: April 2024

Earlywood and latewood microfibril angle (MFA) was determined at 1-millimeter intervals from disks at 1.4 meters, then at 3-meter intervals to a height of 13.7 meters, from 18 loblolly pine (Pinus taeda L.) trees grown in southeastern Texas. A modified three-parameter logistic function with mixed effects is used for modeling earlywood and latewood MFA. By making the parameters of the logistic function linear functions of height, a three-dimensional model was developed that describes the changes of earlywood and latewood MFA within the tree. A first-order autoregressive correlation structure and a variance model corresponding to a variance covariate given by the fitted values for each wood type, but in which the proportionality constant differs according to the level of wood type, was identified as the within-group correlation and variance structures. Cross-validation was used to determine model accuracy and precision. The methods of model development including determination of the height structure, which parameters should be considered random or fixed, determination of an appropriate variance-covariance structure, and prediction are addressed. Model performance was evaluated utilizing informative statistics including likelihood ratio tests (LRTs), Akaike information criterion (AIC), and Bayesian information criterion (BIC). FOR. SCI. 51(4):357–371.
Forest and Pasture Carbon Pools and Soil Respiration in the Southern Appalachian Mountains
Authors: Bolstad Paul V. , Vose James M.
Published: April 2024

Our ability to estimate the changes in carbon (C) pools and fluxes due to forest conversion is hampered by a lack of comparative studies. We measured above- and belowground C pools and soil respiration flux at four forested and four pasture sites in the southern Appalachian Mountains. Above- and belowground C pools were significantly larger (P < 0.01, t-test) at forested sites relative to pasture sites. The largest differences were in aboveground live biomass, which averaged 152 Mg ha−1 C at the forested sites and 1.9 Mg ha−1 at the pasture sites. Coarse root and stump C and surface detritus were also substantially different, averaging 41.3 and 32.6 Mg ha−1 C, respectively, at the forested sites, and less than 1 Mg ha−1 at the pasture sites. Fine root C was higher and mineral soil C lower at pasture sites relative to comparable forested sites, but neither difference was statistically significant. Soil respiration at a given temperature was generally lower at pasture sites relative to forest sites. However, soil temperatures at pastures were consistently higher than at forest sites. Estimated annual soil respiration flux averaged 10.9 Mg C ha−1 at the pasture sites and 12.6 Mg C ha−1 at the forested sites. FOR. SCI. 51(4):372–383.
An Alternative Incentive Structure for Wildfire Management on National Forest Land
Authors: Donovan Geoffrey H. , Brown Thomas C.
Published: April 2024

Wildfire suppression expenditures on national forest land have increased over the last 35 years, exceeding US$1 billion in 2000 and 2002. These increases in expenditure have been attributed, in part, to a century of aggressive wildfire suppression, resulting in a buildup of fuel on the nation's forests. The efficiency of the current incentive structure faced by Forest Service fire managers is analyzed. An alternative incentive structure is presented that encourages fire managers, as they work to limit wildfire damages, to contain costs and consider the beneficial effects of wildfire. FOR. SCI. 51(5):387–395.
Changes in Snag Populations in Northern Arizona Mixed-Conifer and Ponderosa Pine Forests, 1997–2002
Authors: Ganey Joseph L. , Vojta Scott C.
Published: April 2024

Snags (standing dead trees) are important components of forests that contribute to ecological processes and provide habitat for many life forms. We monitored dynamics of snag populations on 1-ha plots in southwestern mixed-conifer (n = 53 plots) and ponderosa pine (Pinus ponderosa, n = 60 plots) forests in north-central Arizona from 1997 to 2002. Of 2,240 snags marked in 1997, at least 76% remained standing in 2002, 17% had fallen and were relocated as logs, 0.5% were cut down, and the remainder (6%) were unaccounted for. Snag density increased significantly in mixed-conifer forest but not in ponderosa pine forest. Snag density increased mainly in the smaller size classes in both forest types. Density of large snags (≥46 cm in diameter and 9 m in height) increased slightly but nonsignificantly from 1997 levels in both forest types, and fell below current targets for retention. Species composition of snags differed between 1997 and 2002 in ponderosa pine forest, but not in mixed-conifer forest, and decay-class distributions differed among years in both forest types. A classification-tree analysis indicated that a ratio of height to diameter, species, and diameter were key variables in predicting whether a snag survived from 1997 to 2002. These results provide empirical data on snag populations and dynamics in this area and establish a basis for longer-term monitoring of snag populations and dynamics. FOR. SCI. 51(5):396–405.
A New Simulator for the Spread of Forest Root Diseases by Individual Root Contacts
Authors: Peet F. G. , Hunt R. S.
Published: April 2024

A new simulator for the spread of forest root diseases, and the testing of it, is presented. It differs from earlier models in that it represents a first step to incorporate the basic processes of spread by individual root contact. It therefore has a generality that allows its use in different host–pathogen and geographic situations. It stochastically grows individual roots longitudinally outward from the stem. They are tapered, turn, and contact other roots as they grow. The simulator transfers fungus stochastically at points of contact between healthy roots and infected stump or tree roots and moves the fungus along infected tree roots stochastically. The fungus can girdle the rootcollar, move out into other roots, and eventually kill the tree. Growth of roots and fungus movement along infected roots is on an annual basis for up to 200 years. Root growth, fungus growth along roots, disease spread, and stand openings are displayed dynamically in color on the computer screen as the simulation proceeds. Estimates for numbers of infected trees and mortality are provided in tabular and graphical form. Results from the simulator were close to the field data it was tested against. FOR. SCI. 51(5):425–437.
Effects of Fertilization and Vegetation Control on Microbial Biomass Carbon and Dehydrogenase Activity in a Juvenile Loblolly Pine Plantation
Authors: Blazier Michael A. , Hennessey Thomas C. , Deng Shiping
Published: April 2024

To characterize the influences of fertilization and understory vegetation suppression on microbial biomass and activity in a juvenile loblolly pine plantation, we measured microbial biomass C (Cmic) and dehydrogenase activity in soil monthly in response to (1) untreated control (CONT), (2) understory suppression with glyphosate (BC), (3) pine removal (NP), (4) pine removal with understory suppression (NPBC), (5) urea + diammonium phosphate with understory suppression (UDBC), and (5) slow-release urea with understory suppression (CUFBC). Cmic and dehydrogenase activity were significantly decreased relative to the CONT treatment by the NP, NPBC, UDBC, and CUFBC treatments. These reductions likely indicate a dependence of soil microbes on labile C sources derived from living vegetation. Fertilization + brush control decreased Cmic and dehydrogenase activity to a greater extent than brush control alone, suggesting that the availability of labile C sources was adversely affected by fertilization. Short-term reductions in Cmic were correlated with increases in soil NO3−. Results of this study demonstrate that, in this young, intensively managed pine plantation, labile C substrates from vegetation may be a predominant determinant of soil N availability through its influence on microbial biomass and activity. FOR. SCI. 51(5):449–459.
Airtanker Flight Distance between Fires: Random Fire Starts on Line Segments
Authors: Greulich Francis E.
Published: April 2024

Under high initial attack fire loads, dispatchers sometimes redirect airtankers that are working on other fires. The inherent variability of flight distance between random fire locations is a potentially important aspect of any model that would reallocate the airtanker resource between fires. Requisite formulas are derived, and computational procedures are provided in this article for the stochastic description of airtanker flight distances between fire-start locations randomly located along straight-line segments. Numerical approximations and comparisons with prior work confirm the results of detailed examples that establish a blueprint for application and continued model development. FOR. SCI. 51(5):460–471.
Variation in Wood Density and Shrinkage and Their Relationship to Growth of Selected Young Poplar Hybrid Crosses
Authors: Pliura Alfas , Yu Qibin , Zhang S. Y. , MacKay John , Périnet Pierre , Bousquet Jean
Published: April 2024

Wood density, various shrinkages and several growth traits were measured in two 10-year-old clonal trials at sites of contrasting growth potential. The material studied consisted of 12 clones of three poplar hybrid crosses, Populus deltoides × P. nigra, P. trichocarpa × P. deltoides, and P. maximowiczii × P. balsamifera, as well as P. deltoides. Wood density and longitudinal and radial wood shrinkages were significantly lower at the St-Ours than at the Windsor site, by 6.7, 46.7, and 14.9%, respectively, while growth rate was increased. The differences among hybrid crosses were significant for all growth traits and wood properties except for radial and tangential shrinkages of juvenile wood. P. deltoides had the highest wood density of 363.2 kg/m3, whereas P. maximowiczii × P. balsamifera wood had the lowest density of 299.8 kg/m3. The differences among hybrid crosses were significant for growth traits, primarily due to the fast growth of P. trichocarpa × P. deltoides and slow growth of P. deltoides. Among the wood properties measured, only tangential wood shrinkage exhibited clear radial intertree changes with cambial age. The tangential wood shrinkage increased from pith to mid-diameter and then started to decrease outward, with each hybrid showing a different pattern of variation. Phenotypic clonal mean correlations among growth traits and wood density were weakly negative. Correlations among growth traits and radial wood shrinkage ranged from weakly to strongly negative. Longitudinal shrinkage displayed strong negative correlations with radial and tangential shrinkages. Negative correlations found between wood density and longitudinal shrinkage and positive correlations between density and both radial and tangential shrinkages suggest that selection for high wood density may lead to increased transverse wood shrinkage but decreased longitudinal shrinkage. FOR. SCI. 51(5):472–482.
Acacia mangium, a Nurse Tree Candidate for Reforestation on Degraded Sandy Soils in the Malay Peninsula
Authors: Norisada M. , Hitsuma G. , Kuroda K. , Yamanoshita T. , Masumori M. , Tange T. , Yagi H. , Nuyim T. , Sasaki S. , Kojima K.
Published: April 2024

We investigated the suitability of Acacia mangium Willd., a fast-growing tropical leguminous tree, as a nurse tree for reforestation with indigenous species on severely degraded sandy soils in southern Thailand. Planting A. mangium yielded a survival rate of 91% and satisfactory growth (7.7 m height, 56 mm dbh, 59 Mg dry weight ha−1 aboveground biomass) 45 months after planting, indicating the species' suitability for reforestation. Three dipterocarp species (Dipterocarpus alatus Roxb. ex G. Don, Hopea odorata Roxb., and Shorea roxburghii G. Don.) planted simultaneously with A. mangium showed better growth than when planted alone. Seedlings of all three dipterocarp species that survived transplanting showed better survival when planted with A. mangium. The findings suggest A. mangium is an effective nurse tree for dipterocarp seedlings. The carbon and nitrogen contents of surface soil did not increase in the A. mangium stands. Microclimate measurements showed moderated air temperature, relative humidity, and soil temperature in the mixed planting. The moderated microclimate under the A. mangium canopy is thought to be responsible for the improved growth of the dipterocarp seedlings. If dipterocarp seedlings are planted after A. mangium grows enough to provide shade, initial survival rates should improve. FOR. SCI. 51(5):498–510.
Rhizobacteria Isolated from Loblolly Pine Seedlings Mediate Growth-Promotion of Greenhouse-Grown Loblolly, Slash, and Longleaf Pine Seedlings
Authors: Enebak S. A.
Published: April 2024

Loblolly (Pinus taeda L.), slash (Pinus elliottii Engelm.), and longleaf pine (Pinus palustris Mill.) seeds were inoculated in the greenhouse with rhizobacteria recovered from 4-month-old bareroot loblolly pine seedlings. Emergence and seedling densities were determined at 3- and 8-week intervals after sowing, respectively, with root and shoot biomass measured at 12 weeks. All bacterial strains significantly increased the speed of seedling emergence relative to untreated loblolly and slash pine seeds, while five strains significantly slowed longleaf germination. For loblolly and slash pine, there were no differences in percentage germination when comparing treated and untreated seed. However, all bacterial strains significantly reduced longleaf germination over nontreated seed. Treatment with rhizobacteria had significant positive and negative effects on seedling growth and biomass, depending on the tree species and bacteria isolate used. Five of the eight bacterial isolates tested increased shoot length of loblolly pine seedlings, whereas one strain increased above- and belowground biomass. Slash pine seedlings experienced growth increases with three bacterial strains. However, two bacterial strains, ALA-41G and ALA-54G, resulted in shorter slash pine shoots. Only strain ALA-3G increased shoot biomass of longleaf pine over nontreated longleaf seed. Increased seedling emergence and growth promotion by rhizobacteria collected from Pinus sp. is a potential useful tool for management of these forest species. The effect may be species-specific and the use of bacteria in forest nurseries for growth promotion will need to take this into account. FOR. SCI. 51(6):541–545.
Foliar δ13C and δ15N Response of Lodgepole Pine and Douglas-Fir Seedlings to Soil Compaction and Forest Floor Removal
Authors: Choi Woo-Jung , Chang Scott X. , Curran Michael P. , Ro Hee-Myong , Kamaluddin Mohammed , Zwiazek Janusz J.
Published: April 2024

The effects of soil compaction, forest floor (FF) removal, and rehabilitation treatments on foliar δ13C and δ15N of lodgepole pine (Pinus contorta) and Douglas-fir (Pseudotsuga menziesii) were studied on a calcareous soil. Regardless of soil compaction, FF removal (which reduces soil water potential) resulted in less negative foliar δ13C values of lodgepole pine (from −25.9 to −23.4‰), whereas soil compaction effects on foliar δ13C were observed only within the FF intact treatment. This result and the more negative foliar δ13C with increasing seedling growth most likely reflected limitation on CO2 diffusion due to water stress caused by those treatments. However, foliar δ13C of Douglas-fir (range −25.0 ∼ −24.5‰) were not affected by the treatments, indicating less susceptibility to water stress. Soil compaction reduced NH4+-N concentrations in the FF (from 48.5 to 28.0) and NO3−-N concentrations in the FF (from 13.8 to 6.4) and mineral soil (from 4.3 to 2.1 mg kg−1), and FF removal tended to decrease NH4+-N concentrations in the mineral soil. Foliar δ15N of both species were not affected by soil compaction but were increased by the FF removal and rehabilitation treatments, indicating that the latter two treatments dramatically altered soil N dynamics. FOR. SCI. 51(6):546–555.
Production Efficiency and Radiation Use Efficiency of Four Tree Species Receiving Irrigation and Fertilization
Authors: Allen Christopher B. , Will Rodney E. , Jacobson Marshall A.
Published: April 2024

To determine the effect of resource availability on efficiency of stemwood production, we calculated radiation use efficiency (Εstem = stem production/photosynthetically active radiation [PAR] interception) and production efficiency (PEstem = stem production/leaf area index [LAI]) from measurements of LAI, intercepted photosynthetically active radiation (IPAR), and stem production on stands of Pinus taeda, Pinus elliottii, Liquidambar styraciflua, and Platanus occidentalis during the sixth growing season. Treatments were control, irrigation only, and irrigation plus 57, 85, or 114 kg N ha−1 y−1. Compared to the control, irrigation plus 85 kg N ha−1 increased stem production: 8.7–15.0 Mg ha−1 y−1 (loblolly), 6.0–10.7 Mg ha−1 y−1 (slash), 1.2–12.8 Mg ha−1 y−1 (sweetgum), and 0.5–9.6 Mg ha−1 y−1 (sycamore). Annual PAR capture and LAI were correlated with stem production (r2 = 0.80, r2 = 0.66, respectively, average of 4 species). Fertilization and irrigation increased Εstem and PEstem for sycamore, whereas only fertilization increased efficiencies for sweetgum. Irrigation increased PEstem for the pines. Foliar [N], often a surrogate for photosynthetic efficiency, was positively correlated with both efficiency variables for the hardwoods (r2 from 0.65 to 0.79). For the pines, canopy size was the primary growth determinant. FOR. SCI. 51(6):556–569.
Estimating Supply Elasticity for Disaggregated Paper Products: A Primal Approach
Authors: Brown Roger , Zhang Daowei
Published: April 2024

Most existing elasticity estimates for the pulp and paper industry are based on aggregate products (e.g., total paper, paperboard, or paper except newsprint). Using United States data, we present and evaluate econometric output supply models for four relatively disaggregated paper products: newsprint paper (NP), printing/writing paper (PWP), tissue paper (TP), and packaging paper (PP). Sample periods vary from 14 years for PP (1987–2001) to 20 years for NP and PWP (1981–2001). Each paper type is specified using a two-stage least squares geometric distributed lag model in log–log form using monthly data. Estimated long-run (short-run) output price elasticities are 2.75 (0.69) for NP, 2.45 (1.07) for PWP, 1.77 (1.77) for TP, and 0.41 (0.24) for PP. Input demand elasticities for capital, wood fiber, labor, electricity, and wastepaper are also estimated for each paper type. FOR. SCI. 51(6):570–577.
Parsimonious and Completely Compatible Taper, Total, and Merchantable Volume Models
Authors: Jordan Lewis , Berenhaut Kenneth , Souter Ray , Daniels Richard F.
Published: April 2024

A parsimonious and compatible system of taper, total, and merchantable volume equations sharing a common vector of three parameter estimates was derived from Clark and Saucier's (1990) volume ratio model. Clark and Saucier's model expresses volume inside bark as a function of outside bark diameter and is itself not compatible with the derived taper equation. To ensure compatibility, models were fit to express volume outside bark as functions of diameter outside bark. By constraining the limits of integration of the taper function to go from the tip to groundline diameter, a completely compatible system of taper, total, and merchantable volume equations were developed. Systems of equations were fit using nonlinear seemingly unrelated regressions with nonlinear cross-equation constraints to account for contemporaneous correlations in the data. The system fit was found to account for at least 96% of the variation in diameter outside bark, total, and merchantable outside bark volume. FOR. SCI. 51(6):578–584.
Tropical Forest Measurement by Interferometric Height Modeling and P-Band Radar Backscatter
Authors: Neeff Till , Dutra Luciano Vieira , dos Santos João Roberto , Freitas Corina da Costa , Araujo Luciana Spinelli
Published: April 2024

A new approach to tropical forest biomass monitoring with airborne interferometric X and P-band synthetic aperture radar (SAR) data is presented. Forest height, basal area, and aboveground biomass are modeled from remote sensing data for a study site in the Brazilian Amazon. Radar data quality has improved: A novel digital model of vegetation height from X- and P-band interferometry is available along with the usual P-band backscatter information. The digital vegetation height model is derived from the interferometric surface models of the ground (from P-band) and the forest canopy (from X-band). The difference between the surface models is called “interferometric height,” and is used as a measure of vegetation height. Interferometric height is shown to relate to a subset of the forest trees that changes according to the forest successional stages. The suitability of radar backscatter and interferometric height as a means for forest and biomass monitoring was explored by relating forest parameters as measured in the field to remote sensing data. Basal area and biomass were related to radar backscatter with limited precision of r2 = 0.19 and r2 = 0.34, respectively. Mean forest height is shown to relate to interferometric height with good precision (r2 = 0.83, RMSE = 4.1 m). A statistical model for forest biomass as a function of both P-band backscatter and interferometric height information not only arrives at high values of precision (with r2 = 0.89 and a RMSE from cross-validation of only 46.1 t/ha), but also overcomes the well-known issue of backscatter saturation. This research shows that tropical forest biomass can be quantified and mapped over large areas for a range of forest structures with reasonably tight and similar errors. FOR. SCI. 51(6):585–594.
Comparison of Experimental Designs for Clonal Forestry Using Simulated Data
Authors: Gezan Salvador A. , White Timothy L. , Huber Dudley A.
Published: April 2024

Various alternatives for the design of clonal field trials in forestry were studied using simulated data to identify “optimal𠇍 or “near-optimal𠇍 scenarios for the estimation of genetic parameters. The simulated field site consisted of a rectangular grid on which 256 clones with 8 ramets each were installed. Estimates of genetic parameters were compared for (1) single-tree and four-tree row plots; (2) several experimental designs (completely randomized, randomized complete block, incomplete blocks of various sizes, and row–column); (3) no mortality versus 257% mortality; and (4) different patterns of environmental variability (only patches, only gradients, and both patches and gradients). Use of single-tree plots, on average, increased the correlations between true and predicted clonal values by 57% over four-tree row plots and increased genetic gain from selection. Starting with a parametric broad-sense heritability (H B 2) of 0.25 for a completely randomized design, the experimental designs resulting in the highest H B 2 were row–column designs for single-tree plots and incomplete blocks with 32 blocks per replication when four-tree row plots were used. These designs increased average heritability 107% and 147% over a randomized complete block design, respectively. The only effect of 257% mortality was an increase in the variability of some variance component estimates.
Does Faustmann Rotation Apply to Fully Regulated Forests?
Authors: Tahvonen Olli , Viitala Esa-Jussi
Published: April 2024

Forest economics literature contains two lines of research in which the Faustmann rotation is taken to be invalid for continuous harvesting, i.e., for normal or fully regulated forests. As alternatives, a “marginal model for divisible forest capital𠇍 and a “regular profit model for timber production𠇍 have been proposed and applied. In contrast, recent forest economics has provided vast evidence that the Faustmann rotation is the long-term stationary state in rotation models with multiple age classes. In this article, we attempt to clear up this contradiction in the literature by showing that the two approaches deviating from the Faustmann approach yield the same rotation period. The deviations from the Faustmann approach are because the models are based on incorrect formulas for the value of a normal forest.
A Multilevel Approach to Individual Tree Survival Prediction
Authors: Rose Charles E. , Hall Daniel B. , Shiver Barry D. , Clutter Michael L. , Borders Bruce
Published: April 2024

Traditionally, modeling of permanent plot individual tree survival has not considered the multiple sources of heterogeneity and correlation that may arise due to the multilevel data structure inherent in the design (e.g., clustering of trees within a plot). Permanent plots are sampled periodically; therefore, data are interval-censored because it is only known that a tree died between two successive measurement occasions. Here, we adopt the complementary log–log (CLL) function for modeling permanent plot interval-censored individual tree survival data. The CLL function is derived directly from the likelihood function of a fully specified statistical model that accounts for interval censoring. In addition, our CLL model considers silvicultural treatment effects on survival. Our data are from young permanent plot loblolly pine plantations that have been measured annually beginning at age 1 year. Each plot was randomly assigned one of four cultural treatments:control (C), herbicide (H), fertilization (F), and herbicide and fertilization (HF). Here we extend the individual tree survival CLL model to allow for trees within a plot and plot level random effects. We demonstrate individual tree survival predictions with and without the inclusion of random effects.
Corrections for Cluster-Plot Slop
Authors: Valentine Harry T. , Ducey Mark J. , Gove Jeffrey H. , Lanz Adrian , Affleck David L.R.
Published: April 2024

Cluster-plot designs, including the design used by the Forest Inventory and Analysis program of the USDA Forest Service (FIA), are attended by a complicated boundary slopover problem. Slopover occurs where inclusion zones of objects of interest cross the boundary of the area of interest. The dispersed nature of inclusion zones that arise from the use of cluster plots precludes the use of most of the slopover-correction methods that apply to solitary plots. One exception is the walkthrough method, which corrects for slopover bias in radially symmetric cluster-plot designs. In this article, we provide a modification of the walkthrough method, the “walkabout method,𠇍 which is applicable to some asymmetric cluster-plot designs, such as the one used by FIA. We also present two general correction methods, the “vectorwalk method𠇍 and the “reflection method,𠇍 both of which are applicable to cluster-plot designs with satellite subplots arranged in a regular or irregular pattern. The reflection method has two sets of protocols, one that applies to radially symmetric designs and to asymmetric designs with random orientation; the other set applies to asymmetric designs with fixed orientation. Both the vectorwalk and reflection methods incorporate the walkthrough method on a subplot-by-subplot basis. All four methods correct for slopover bias for straight or curved boundaries, and where work outside the tract is impossible.
Application of the Algebraic Difference Approach for Developing Self-Referencing Specific Gravity and Biomass Equations
Authors: Jordan Lewis , Souter Ray , Parresol Bernard , Daniels Richard F.
Published: April 2024

Biomass estimation is critical for looking at ecosystem processes and as a measure of stand yield. The density-integral approach allows for coincident estimation of stem profile and biomass. The algebraic difference approach (ADA) permits the derivation of dynamic or nonstatic functions. In this study we applied the ADA to develop a self-referencing specific gravity function and biomass function as part of a density-integral system composed of taper, volume, specific gravity, and biomass functions. This was compared to base systems of similar equations that did not have the self-referencing parameter specifications. Systems of equations were fit using nonlinear, seemingly unrelated regressions with nonlinear cross-equation constraints to account for contemporaneous correlations in the data. Results suggest that correct volume determination is more critical than specific gravity for accurate biomass estimates. The goodness-of-fit statistics clearly show that the self-referencing system provided a better fit than the base system.
Potential of Aerial Image-Based Monoscopic and Multiview Single-Tree Forest Inventory: A Simulation Approach
Authors: Korpela Ilkka Sakari , Tokola Timo Erkki
Published: April 2024

Two aerial image-based estimation chains were compared for their potential in the assessment of timber resources. The two chains consisted of two- and three-dimensional image measurements followed by indirect model estimation. The effects of various errors at both the single-tree and stand levels were examined with Monte Carlo simulation. The three-dimensional multiview estimation chain with height measurements of individual trees proved less prone to random and systematic errors than the monoscopic chain. An upper limit of accuracy at the single-tree level is determined mainly by the allometric correlations. Volume estimates of single trees showed estimation accuracies (root-mean-square error, RMSE) of 15–20% and 35–40% in the multiview and monoscopic chains, respectively. This is lower than the accuracy achievable in the field, which is 6%. Image-based single-tree forest inventory is prone to systematic measurement and model errors, and in a simulation for the total effect of error sources, upper estimation accuracies (RMSE) of 15% and 30% for stand volume were computed using full mapping of the stand with the multiview and monoscopic estimation chains, respectively.
A New Type of Sample Plot that Is Particularly Useful for Sampling Small Clusters of Objects
Authors: Iles Kim , Smith Nicholas J.
Published: April 2024

The sampling method presented here uses a new type of plot, with surprising characteristics. Although useful in sampling any grouping of objects, it is illustrated here by correctly sampling small patches of trees remaining after harvest. Small patches are difficult to sample unbiasedly because of the “edge effect𠇍 caused by sampling with fixed or variable plots. By this we do not refer to a biological effect on trees near an edge, but to a common sampling bias that distorts the selection probabilities of those trees. Groups of objects that are small and irregular are very prone to this “edge effect bias𠇍 when using typical sampling systems. “Sector plots𠇍 will allow the user to sample the trees in a small patch, and the method can also be extended to small trees planted outside the patch after harvesting, or to solitary “dispersed𠇍 trees outside the patch but within the harvested area. The method can unbiasedly select sample trees along an irregular border. The method eliminates all bias from edge effect. It can balance the tree selection on opposite sides of the patch, and the pivot point of the plot can be arbitrarily placed by the sampler in any convenient location without introducing any bias to the selection process. This new plot shape might be described as “a constrained angle shape with variable area, randomly oriented around an arbitrary sample point, which selects objects with equal probabilities.𠇍
Developing Dynamic Site Index Curves for European Beech (Fagus sylvatica L.) in Denmark
Authors: Nord-Larsen Thomas
Published: April 2024

In base-age specific methodologies, assessment of base age and site index may be a problem when developing site curves from repeated measurements on permanent sample plot data. In most cases, such data will not contain measurements at any base age that is common for all the sample plots, and some sort of interpolation or even extrapolation would have to be applied to address this issue. Base-age invariant methodologies pose the desirable property of estimating the curves without prior arbitrary assumptions about values of the site indices. Presented here is the development of such base-age invariant site index curves for European beech (Fagus sylvatica L.) in Denmark, fitted to permanent sample plot data. The developed polymorphic dynamic site equations with variable asymptotes are based on the generalized algebraic difference approach, and the parameters of the model were estimated with correction for first-order serial correlation.
Analysis of Different Base Models and Methods of Site Model Derivation for Scots Pine
Authors: Cieszewski Chris J. , Zasada Michał , Strub Mike
Published: April 2024

Using an example of averaged growth series data of Scots pine (Pinus sylvestris L.), we examine several approaches to site-dependent height-age model derivation. We consider several renowned base models (two-dimensional equations, such as Y = f(t)) and derive from them anamorphic and polymorphic dynamic site equations (three-dimensional site-height-age models, such as Y = f(t, t 0, y 0)) of different complexities. The considered base models were selected previously as suitable for Scots pine in other studies, and are different variations of exponential and fractional functions. We compare all of the base models fit to individual site classes and the derived base-age invariant anamorphic and polymorphic dynamic site equations fit to all sites pooled together. All the fits of site equations to the pooled data from different site productivity series were based on base-age invariant stochastic regressions, in which the global model parameters that are common to all data are estimated simultaneously with the site effects unique for each site productivity series. The results show that: (1) choice of definition describing changes across site qualities may be more important than the choice of base equation defining changes over time; (2) a base model with high cost of deriving self-referencing function may sometimes be better than a base model with low cost of deriving the self-referencing function; and (3) superior base models may not produce superior anamorphic or simple polymorphic site models, but can produce superior advanced polymorphic site models, which can describe the growth patterns in data better than either anamorphic or simple polymorphic models.
Flight Periodicities, Phoresy Rates, and Levels of Pseudopityophthorus minutissimus Branch Colonization in Oak Wilt Centers
Authors: Ambourn Angie K. , Juzwik Jennifer , Eggers Jordan E.
Published: April 2024

Oak bark beetles, Pseudopityophthorus minutissimus and P. pruinosus, are considered important vectors of the oak wilt fungus, Ceratocystis fagacearum, in Missouri and Ohio. However, the frequency of the species’ association with diseased oaks in Minnesota and their relative importance in pathogen spread in the state are unclear. Window traps were placed in canopies of recently killed northern pin oaks to determine seasonal flight periodicities of dispersing oak bark beetles and their phoresy (pathogen presence) rates. Branch samples were collected from diseased northern pin and northern red oak canopies in May and Aug., life history data obtained, and oak bark beetles emerging from the branches assayed for the pathogen. Only P. minutissimus was found in the study areas. In 2003, peak flight of P. minutissimus in Minnesota occurred 12 May to 19 May, with 869 beetles being trapped. Dispersing beetles carried viable pathogen propagules at low frequencies (4 to 13 per 1,000) in May and June. Branches of oak wilt-killed trees were commonly colonized by the beetle. More beetles emerged from branch samples collected in May than in Aug., but none yielded C. fagacearum. These results support the hypothesis that the relative importance of P. minutissimus in the overland transmission of the pathogen in red oak species in Minnesota is minor.
Dynamic Site Model for Loblolly Pine (Pinus taeda L.) Plantations in the United States
Authors: Diéguez-Aranda Ulises , Burkhart Harold E. , Amateis Ralph L.
Published: April 2024

Data from a large, long-term loblolly pine (Pinus taeda L.) plantation study including 186 permanent sample plots were used to evaluate four dynamic site equations derived with the generalized algebraic difference approach (GADA). All of the equations are base-age invariant and directly estimate height and site index from any height and age. The fittings were done in one stage using the base–age invariant dummy variables method. A first-order autoregressive error structure was used to correct the serial correlation of the longitudinal data used in this study. Cieszewski’s model (Cieszewski, C.J. 2002. Comparing fixed- and variable-base–age site equations having single versus multiple asymptotes. For. Sci. 48:7–23) best described the data.
Timber Harvesting Margins in the Southern United States: A Temporal and Spatial Analysis
Authors: Sun Changyou , Zhang Daowei
Published: April 2024

This study focuses on the logging sector by analyzing timber harvesting margins in the southern United States between 1977 and 2001. The real growth rate of harvesting margins has been negative for pine pulpwood, while positive for pine sawtimber, hardwood pulpwood, and hardwood sawtimber. Harvesting margins for pulpwood are more stable over time and more integrated spatially when compared with those for sawtimber. There is no perfect integration in the logging sector by timber product and no individual state is found to lead the logging service market. The revealed patterns are explained in terms of changing demand for forest products and forest industry structure.
Evaluation of Selfing Effects on Western Redcedar Growth and Yield in Operational Plantations Using the Tree and Stand Simulator (TASS)
Authors: Wang Tongli , Russell John H.
Published: April 2024

Seed lots of western redcedar (Thuja plicata) from both wild stands and seed orchards contain a relatively large proportion of self-pollinated seeds compared to other tree species. Selfed seeds do not exhibit early inbreeding depression, and thus have the same probability of producing acceptable seedlings for field planting as outcrossed ones. However, selfed trees show, on average, about 10% reduction in 9-year height after outplanting. To evaluate the potential negative effects of selfing on productivity at harvest, growth and yield of stands comprising selfs were simulated using TASS (tree and stand simulator) with various planting sites and initial planting densities in this study. Height distributions of selfed and outcrossed individuals were also compared and modeled, which provided a solid basis for accurate TASS simulations and some inside view of selfing in this species. Our results indicate that effects of selfing are smaller on stand final productivity (8% on average) than on 9-year-young trees due to natural selection (competition) against slower-growing trees after crown closure, resulting in more selfs being purged than outcrossed trees. Using better planting sites with higher initial planting densities can substantially intensify the selection and reduce the negative effects of selfing on final productivity.
Impact of Globalization and Policy Change on United States Softwood Lumber Trade
Authors: Xiang Qing , Yin Runsheng
Published: April 2024

To examine the effects of global economic integration, public policy, and other factors on US softwood lumber trade, a demand and supply system for both exports and imports is estimated with panel data sets. We find that the combined impact of trading price and exchange rate before 2003 has made foreign lumber products much cheaper than those manufactured domestically. Furthermore, domestic economic conditions and production capacity strongly affect the exports and imports of both the United States and its trade partners. Also, the US federal harvest reduction policy and the Asian financial crisis influenced both export and import markets. All of these suggest the need for more integrated market analysis and strategic business thinking.