bluuebunny/crossref_metadata_2025_split huggingface dataset:
Using Simultaneous Regression Techniques with Individual-Tree Growth Models
Authors: Hasenauer Hubert , Monserud Robert A. , Gregoire Timothy G. 
Published: April 2024

Abstract
Individual-tree growth models basically consist of a number of equations (e.g., diameter or basal area increment model, height increment model, crown ratio model) to update tree parameters over time. These equations commonly are assumed to be independent, with parameters of each equation estimated separately rather than simultaneously with linear or nonlinear regression. However, the opposite assumption of interdependence seems more reasonable. A tree is a highly organized system, and assimilation of tissues in the form of diameter increment, height increment, and crown size does not occur independently. Procedures to simultaneously estimate systems of two or more interrelated models are well developed in the econometrics literature and are suggested as a viable alternative. Using more than 7,500 Norway spruce (Picea abies L. Karst) trees from the Austrian National Forest Inventory with remeasured breast height diameters and tree heights (5 yr interval), we compare an individual tree basal area increment model, a height increment model, and a crown ratio model separately using ordinary least squares (OLS) and simultaneously by applying two-and three-stage least squares (2SLS, 3SLS). Results indicate the presence of strong cross-equation correlations, especially between the basal area increment and height increment models. Thus, the 3SLS estimates are more efficient while the separately determined OLS estimates are biased. Two parameters that OLS indicates are significant are found to be nonsignificant when simultaneously estimating all system parameters with 3SLS. Such system simplification reduced the size of the variance-covariance matrix by 100 elements. For. Sci. 44(1):87-95.
Modeling the Basal Area-size Distribution of Forest Stands: A Compatible Approach
Authors: Gove Jeffrey H. , Patil Ganapathi P. 
Published: April 2024

Abstract
This paper presents a methodology that allows diameter distributions to be conformably modeled by letting the probability density represent either tree frequency as in the classic case, or basal area. The key to relating the two forms of the probability density is shown to lie in weighted distribution theory. The motivation for the relationship lies in the quadratic relationship between diameter at breast height and basal area. The weighted distribution approach is shown to be compatible with current methods of calculating quantities such as basal area by diameter class, but in addition, affords the development of new equations useful in parameter recovery or similar modeling strategies. Relationships are developed for all of the major distributions found to have been useful in forestry for fitting diameter distribution models. Several stands to which the two- and three-parameter Weibull distributions have been fitted are also presented. For. Sci. 44(2):285-297.
Leaf Area and Above- and Belowground Growth Responses of Loblolly Pine to Nutrient and Water Additions
Authors: Albaugh Timothy J. , Allen H. Lee , Dougherty Phillip M. , Kress Lance W. , King John S. 
Published: April 2024

Abstract
A 2 x 2 nutrient and water factorial experiment with four replications was installed in an 8-yr-old stand of loblolly pine (Pinus taeda L.) growing on an infertile, excessively drained sandy site in Scotland County, North Carolina. After the fourth year of treatment, estimated stem volume increment, total biomass production, and peak leaf area index (LAI) increased 152%, 99%, and 101%, respectively, with fertilization and 25%, 23%, 16%, respectively, with irrigation. Stem volume growth efficiency (growth per unit LAI) increased 21% with fertilization, 9% with irrigation, and 30% with both fertilization and irrigation. Total biomass production efficiency increased 91% with fertilization, 29% with irrigation, and 120% with both fertilization and irrigation. The observed increase in stem volume growth efficiency may have been due, in part, to changes in biomass partitioning. However, altered partitioning patterns alone did not explain the observed increase in total biomass production efficiency. We hypothesized that the change in total biomass production efficiency may have been a result of greater allocation to foliage (photosynthesizing tissue) and less allocation to fine roots (a high maintenance respiration tissue) under fertilization and irrigation treatments. For. Sci. 44(2):317-328.
Long-Term Dynamics of Lodgepole Needle Miner Populations in Central Oregon
Authors: Mason Richard R. , Paul H.Gene 
Published: April 2024

Abstract
A 30 yr time series of larval densities of lodgepole needle miner (Coleotechnites sp. nr. milleri[Busck][Lepidoptera:Gelechiidae]) populations in central Oregon was analyzed. The series included parts of two needle miner outbreaks and an extended interval between outbreaks when populations were at low densities. Complete data sets and subsets were examined by conventional methods of population and time-series analysis to detect patterns of needle miner abundance and to determine the feedback structure of the series. A 141 yr tree-ring chronology also was constructed for the same area from which the regional history of needle miner outbreaks was determined. Analyses revealed two kinds of concurrent cycles: 8 to 10 yr oscillations of needle miner densities apparently caused by time delays in the regulatory (density-dependent) feedback effect of natural enemies, and recurrent outbreaks at 20 to 25 yr dependent on overall recovery rate of the population between outbreaks and the degree of tree susceptibility to infestation. In general, populations fluctuated around an equilibrium determined by favorability of the local environment for population increase. The equilibrium density was many times higher for a needle miner population on a site with high-risk trees than for populations elsewhere. It is hypothesized that accelerated thinning and harvesting of lodgepole pine and stand-replacing outbreaks of mountain pine beetle (Dendroctonus ponderosae Hopkins) between 1970 and 1990 increased the overall resistance of lodgepole stands to infestation and prevented an isolated outbreak in the 1990s from being more widespread. For. Sci. 45(1):15-25.
Evaluation of the Barr & Stroud FP15 and Criterion 400 Laser Dendrometers for Measuring Upper Stem Diameters and Heights
Authors: Williams Michael S. , Cormier Kenneth L. , Briggs Ronald G. , Martinez Donald L. 
Published: April 2024

Abstract
Calibrated Barr & Stroud FP15 and Criterion 400 laser dendrometers were tested for reliability in measuring upper stem diameters and heights under typical field conditions. Data were collected in the Black Hills National Forest, which covers parts of South Dakota and Wyoming in the United States. Mixed effects models were employed to account for differences between users of the dendrometers and to test for significant differences between the heights and diameters measured indirectly (by dendrometer) and directly (by caliper and linear tape). The location at which measurements were taken on each tree was determined by paint marks along the bole. No significant differences between users were found. The Barr & Stroud consistently overestimated diameters by approximately 0.3 cm (0.1 in). Unbiased estimates of diameter were obtained with the Criterion 400. For height measurements, neither the Barr & Stroud nor the Criterion 400 produced unbiased measurements. The effect of distance to the base of the tree and height of the diameter measurement on the variability of the measurements was also studied. As distance increased, the variability of diameter measurements increased for both dendrometers. For the measurement of height, only the Barr & Stroud exhibited an increase in the variability of measurements with increasing distance. After correcting the data for their biases, taper equations were fitted to them and analyzed. The equations generated from the Barr & Stroud were not significantly different from those generated from direct measurement, unlike the Criterion 400 where taper equations generated were statistically different. A brief study of the effects of familiarity with each dendrometer indicated that the measurement error and variability decreased as the user became more familiar with the Criterion. This was not the case for the Barr & Stroud. For. Sci. 45(1):53-61.
Tree Mortality Following Defoliation by the European Gypsy Moth (Lymantria dispar L.) in the United States: A Review
Authors: Davidson Christopher B. , Gottschalk Kurt W. , Johnson James E. 
Published: April 2024

Abstract
This review presents information related to defoliation by the European gypsy moth (Lymantria dispar L.) and subsequent tree mortality in the eastern United States. The literature describing defoliation-induced tree mortality is extensive, yet questions still remain concerning (1) the association between initial stand composition and subsequent tree mortality, (2) the influence of site quality on tree mortality, and (3) observed differences between mortality rates in initial and subsequent outbreaks. Our review and analysis of the available literature indicates that initial species composition affects subsequent defoliation. Stands with predominantly susceptible host species have higher levels of species-specific and total mortality than mixed stands of susceptible, resistant, and immune host species. Differences in mortality on sites of varying productivity do not appear to be a direct result of site quality; rather, site quality indirectly influences mortality rates through its effect on species composition and therefore defoliation. Differences between initial and subsequent outbreaks appear to be due primarily to losses of vulnerable oaks and lower canopy species during the initial outbreak; oak mortality in initial outbreaks was found to be significantly greater (P = 0.0727) than oak mortality in subsequent outbreaks. For. Sci. 45(1):74-84.
Estimating Economic Gains for Landowners Due to Time-Dependent Changes in Biotechnology
Authors: Wagner John E. , Holmes Thomas P. 
Published: April 2024

Abstract
This paper presents a model for examining the economic value of biotechnological research given time-dependent changes in biotechnology. Previous papers examined this issue assuming a time-neutral change in biotechnology. However, when analyzing the genetic improvements of increasing a tree's resistance to a pathogen, this assumption is untenable. We derive analytical expressions for the optimal rotation age given non-constant changes in biotechnology. Our model is then implemented using (1) growth and yield simulations, (2) optimal rotation calculations, and (3) survey data on genetic resistance of slash pine (Pinus elliottii) to fusiform rust. Non-parametric regression models are used to estimate the economic gain functions which, for the cases considered, averaged about 1% of forestland value per year. For. Sci. 45(2):163-170.
Effect of Western Spruce Budworm Defoliation on the Physiology and Growth of Potted Douglas-Fir Seedlings
Authors: Kolb Thomas E. , Dodds Kimberly A. , Clancy Karen M. 
Published: April 2024

Abstract
Interactions between effects of insect defoliators on tree physiology and growth and soil nutrient and water availability are poorly understood. We addressed whether the western spruce budworm influences nutrient and water relations, ectomycorrhizae, leaf gas exchange, and growth of Douglas-fir seedlings under different environmental conditions. Four-year-old, potted seedlings were grown in two soil types (basalt-derived, limestone-derived) with two levels of soil moisture (high, low) and were subjected to three levels of budworm defoliation (none, moderate, heavy) and two levels of frass and litter produced by budworm feeding (with, without) over 2 yr in a greenhouse environment. Defoliation, soil moisture, and soil type influenced allocation of seedling biomass to leaves, stems, and roots. The addition of frass and litter had no effect on any measured soil or tree characteristic. Interactions between defoliation and other experimental factors were not important except for the defoliation x soil moisture interaction where heavy defoliation reduced the negative effects of low soil moisture on seedling predawn water potential, net photosynthetic rate, and stomatal conductance. Heavily defoliated seedlings had less biomass, higher foliar concentrations of N, Ca, and Mg, less ectomycorrhizae, and higher net photosynthetic rate and stomatal conductance compared with nondefoliated seedlings. For. Sci. 45(2):280-291.
Incomplete Block Designs for Genetic Testing: Statistical Efficiencies with Missing Observations
Authors: Fu Yong-Bi , Yanchuk Alvin D. , Namkoong Gene , Clarke G. Peter Y. 
Published: April 2024

Abstract
Missing observations are common in forest genetic field trials and are expected to reduce statistical efficiencies of any applied field designs. Such reductions could lower the presumed efficiency and other benefits of implementing any incomplete block designs (ICBs). In this study, we addressed this by computer simulation of a full-sib progeny trial with up to 20% of the observations missing. Four scenarios of missing observations (random, row, column, and genetic mortality) and tests of both clones and seedling families were examined. Two types of ICBs (alpha and no constraint) with single-tree plots, and their corresponding randomized complete block design (RCB), were considered on test sites with gradient and patchy environmental variation. Our simulations show that: (1) the statistical efficiencies of estimating family (or clone) means with both ICB and RCB were very sensitive to the percentage, not the scenarios, of missing observations examined; (2) the statistical efficiencies for both ICB and RCB were reduced as the number of missing observations increased, except in the cases of clonal genetic mortality; (3) the relative efficiency of ICB over RCB (at equal levels of missing observations) was reduced slightly as the level of missing observations increased; (4) the relative efficiencies for the seedling family tests were a little more sensitive to the levels of missing observations than those for the clonal tests, and; (5) the two ICBs showed little variation in the relative efficiencies across the missing observation scenarios and test conditions examined. Implications of these results for forest genetic field trials are discussed. For. Sci. 45(3):374-380.
Sweetgum and Broomsedge Response to Competition Across a Range of Soil Organic Matter During the First Year of Plant Establishment
Authors: Zutter Bruce R. , Glover Glenn R. , Mitchell Robert J. , Gjerstad Dean H. 
Published: April 2024

Abstract
Sweetgum (Liquidambar styraciflua L.) seedlings and broomsedge (Andropogon virginicus L.) rooted tillers were planted in a factorial combination of densities (additive series) in east central Alabama on a formerly cultivated field which varied in soil organic matter (soil OM). Mean plant aboveground biomass of sweetgum one growing season after planting declined in a hyperbolic fashion as a function of increasing density of either itself or broomsedge. Broomsedge biomass over the same time period also declined in a hyperbolic fashion as a function of increasing density of itself and sweetgum, except for sweetgum densities from 0 to 1 m-2, where biomass did not change. Sweetgum response was positively correlated with soil OM across all species-density combinations, whereas broomsedge response was correlated with soil OM only at higher densities of broomsedge. Nonlinear models including both species density and soil OM explained a nearly equal amount of variation in response of each species: 74 to 75% for sweetgum and 70% for broomsedge. Relative effects of intraspecific versus interspecific competition on the response of each species was dependent on the density of one or both species. Effect of sweetgum on broomsedge response was two to three times that of broomsedge on itself, with the effect decreasing slightly as soil OM decreased. Over a common range of densities of each species, effects of broomsedge on sweetgum were slightly greater than or nearly equal to effects of sweetgum on itself. The greater interspecific effects on the response of each species suggests no niche differentiation between broomsedge and sweetgum through one growing season. For. Sci. 45(3):423-432.
Forest Stand Structure of the Northern Spotted Owl's Foraging Habitat
Authors: North Malcolm P. , Franklin Jerry F. , Carey Andrew B. , Forsman Eric D. , Hamer Tom 
Published: April 2024

Abstract
Although the spotted owl's close association with old growth has been extensively studied, it has been more difficult to identify and quantify the abundance of particular stand structures associated with preferred owl foraging sites. Old-growth forests have a suite of characteristics that distinguish them from younger forests but which also make it difficult to isolate individual structural features important to the spotted owl. This study used an analysis of use-only sites in areas where natural disturbance had created a gradient of old-growth structural characteristics. We used radio telemetry data collected from reproducing owl pairs to locate sample stands and compute a relative measure of owl-use intensity in each stand. Snag volume and tree height class diversity (a measure of canopy layering) were the stand structures significantly associated with owl foraging intensity. Stands with 142 m³/ha of intact snags and a high diversity of tree heights had medium or high foraging use by spotted owls. In these old-growth stands, biological legacies (e.g., large trees and snags) produced by past disturbance provide important forest structures associated with spotted owl foraging use. For. Sci. 45(4):520-527.
Assessing Uncertainty in a Stand Growth Model by Bayesian Synthesis
Authors: Green Edwin J. , MacFarlane David W. , Valentine Harry T. , Strawderman William E. 
Published: April 2024

Abstract
The Bayesian synthesis method (BSYN) was used to bound the uncertainty in projections calculated with PIPESTEM, a mechanistic model of forest growth. The application furnished posterior distributions of (a) the values of the model's parameters, and (b) the values of three of the model's output variables--basal area per unit land area, average tree height, and tree density--at different points in time. Confidence or credible intervals for the output variables were obtained directly from the posterior distributions. The application also provided estimates of correlation among the parameters and output variables. BSYN, which originally was applied to a population dynamics model for bowhead whales (Raftery et al. 1996, JASA 90:402-442), is generally applicable to deterministic models. Extension to two or more linked models is discussed. A simple worked example is included in an appendix. For. Sci. 45(4):528-538.
Dynamics of Coarse Woody Debris Placed in Three Oregon Streams
Authors: Keim Richard F. , Skaugset Arne E. , Bateman Douglas S. 
Published: April 2024

Abstract
Many streams of the North American west coast are deficient in coarse woody debris (CWD) and have been subjected to aquatic habitat restoration by adding CWD. The ready availability of alder (Alnus rubra Bong.) CWD makes it attractive for such uses, but the dynamics of this relatively small debris are poorly understood. We placed CWD in three third-order streams in western Oregon either as large, key pieces (pulled-over streamside alders or bucked conifer logs) or as smaller logging debris (mostly alder). This treatment immediately increased CWD in the streams by 86% to 155%. We used chronosequences of surveys to evaluate whether the increased loadings of CWD persisted for more than a year, and whether the key pieces trapped smaller debris to create accumulations. Although there was more CWD in all three streams during the 3 yr after treatment than there had been before treatment, rates of movement were high. Aggregation of CWD increased in all three streams for at least 1 yr, and accumulations of CWD associated with key pieces were larger after 3 yr than immediately after treatment. Pulled-over alders were more stable and more effective in forming accumulations than bucked conifers but were subject to rapid decay. For. Sci. 46(1):13-22.
Logistic Regression for Southern Pine Beetle Outbreaks with Spatial and Temporal Autocorrelation
Authors: Gumpertz Marcia L. , Wu Chi-tsung , Pye John M. 
Published: April 2024

Abstract
Regional outbreaks of southern pine beetle (Dendroctonus frontalis Zimm.) show marked spatial and temporal patterns. While these patterns are of interest in themselves, we focus on statistical methods for estimating the effects of underlying environmental factors in the presence of spatial and temporal autocorrelation. The most comprehensive available information on outbreaks consists of binary data, specifically, annual presence or absence of outbreak for individual counties within the southern United States. We demonstrate a method for modeling spatially correlated proportions, such as the proportion of years that a county experiences outbreak, based on annual outbreak presence or absence data for counties in three states (NC, SC, and GA) over 31 yr. In this method, the proportion of years in outbreak is predicted using a marginal logistic regression model with spatial autocorrelation among counties, with adjustment of variance terms to account for temporal autocorrelation. This type of model describes the probability of outbreak as a function of explanatory variables such as host availability, physiography, climate, hurricane incidence, and management type. Explicitly including spatial autocorrelation in the model improves estimates of the probability of outbreak for a particular county and of the importance of the various explanatory variables. For. Sci. 46(1):95-107.
Modeling the Size–Density Relationship in Direct-Seeded Slash Pine Stands
Authors: Cao Quang V. , Dean Thomas J. , Baldwin V. Clark 
Published: April 2024

Abstract
The relationship between quadratic mean diameter and tree density appeared curvilinear on a log–log scale, based on data from direct-seeded slash pine (Pinus elliottii var. elliottii Engelm.) stands. The self-thinning trajectory followed a straight line for high tree density levels and then turned away from this line as tree density decreased. A system of equations was developed to model the reciprocal effects of stand diameter and density through time. The equations performed well for these data. Since the model is constrained according to the self-thinning rule, it should provide reasonable extrapolation. FOR. SCI. 46(3):317–321.
The Economics of Prescribed Burning: A Research Review
Authors: Hesseln Hayley 
Published: April 2024

Abstract
Prescribed burning has, in the past decade, become the focus of debate among policy makers, federal and private land managers, and the public. To manage fire effectively, the USDA Forest Service has formally recognized the need for economic analysis. It is stated in the Federal Wildland Fire Policy of 1995 that fire management alternatives will be based on science and sound ecological and economic principles. This article briefly examines key issues of the Federal Wildland Fire Policy from an economic perspective, and reviews the economic literature pertaining to prescribed burning. In particular, attention is paid to research regarding costs and benefits, efficiency, risk, and the wildland–urban interface. Recommendations for future economic research include focusing on defining a production function that relates economic and ecological outcomes with respect to prescribed fire; assessment of long-term cumulative effects; and finally, a comprehensive assessment of risk including decision making at the agency level. FOR. SCI. 46(3):322–334.