bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling Tree Recruitment with Zero-Inflated Models: The Example of Hardwood Stands in Southern Québec, Canada
Authors: Fortin Mathieu , DeBlois Josianne 
Published: April 2024

Abstract
In recruitment modeling, the response variable is a count and its distribution is often characterized by an excess number of zeros. As a result, standard distributions of probabilities, such as Poisson, are inappropriate. A common approach in forestry consists of using two-part conditional models. These models have two distinct components aimed to predicting the occurrence and abundance of recruitment, respectively. For such data, zero-inflated models might provide a more adequate framework by combining the two components into a joint distribution of probabilities. In this article, a conditional model is compared with two different zero-inflated models, namely, a zero-inflated Poisson (ZIP) and a zero-inflated discrete Weibull (ZIdiW) model. The three models were calibrated using a data set provided by permanent sample plots located in hardwood stands. Parsimony criteria (the Akaike information criterion and the Bayesian information criterion) and diagnostic plots were used to perform the comparison. The results show that the ZIdiW model has the best fit. The flexibility of the Weibull function and the possibility of obtaining a more parsimonious model are two advantages related to the use of a ZIdiW model in recruitment modeling.
Ice Damage in Loblolly Pine: Understanding the Factors That Influence Susceptibility
Authors: Aubrey Doug P. , Coleman Mark D. , Coyle David R. 
Published: April 2024

Abstract
Winter ice storms frequently occur in the southeastern United States and can severely damage softwood plantations. In January 2004, a severe storm deposited approximately 2 cm of ice on an intensively managed 4-year-old loblolly pine (Pinus taeda L.) plantation in South Carolina. Existing irrigation and fertilization treatments presented an opportunity to examine the effects of resource amendments on initial ice damage and subsequent recovery. Fertilized treatments showed more individual stem breakage, whereas nonfertilized treatments showed more stem bending; however, the proportion of undamaged trees did not differ between treatments. Irrigation did not influence the type of damage. Trees that experienced breakage during the storm were taller with larger diameter and taper and leaf, branch, and crown biomass compared with unbroken trees. One growing season after ice damage, relative height increases were significantly greater for trees experiencing stem breakage compared with unbroken trees; however, relative diameter increases were significantly lower for these trees. Relative diameter increases for broken trees were smaller for fertilized treatments compared with nonfertilized treatments. A reduction in wood strength was ruled out as the cause of greater breakage in fertilized trees; rather, fertilized trees had reached an intermediate diameter range known to be susceptible to breakage under ice loading.
Biomass Removal, Soil Compaction, and Vegetation Control Effects on Five-Year Growth of Douglas-fir in Coastal Washington
Authors: Ares Adrian , Terry Thomas , Harrington Constance , Devine Warren , Peter David , Bailey John 
Published: April 2024

Abstract
Sustainable forest production requires an understanding of the effects of site disturbance on tree growth and the consequences of soil amelioration and vegetation control practices. We assessed the impacts of biomass removals at harvest, soil compaction and tillage, and vegetation control on early growth of Douglas-fir in coastal Washington. Harvest treatments included removal of commercial bole only (BO), bole only up to 5-cm top diameter (BO5), total tree (TT), and total tree plus all legacy coarse woody debris (TTP). Vegetation control (VC) effects were tested in BO, while soil compaction (BO/SC) and compaction plus tillage (BO/SCT) were imposed in BO/VC. Five years after planting, biomass removal and soil compaction/tillage effects on tree growth were relatively small. At year 5, mean stem basal diameter in BO was greater than in TT, whereas mean height was similar in BO and BO/SC, but increased in BO/SCT. Control of competing vegetation markedly increased tree growth. At year 5, mean tree stem diameter at 1.3-m height (dbh) and height in BO/no vegetation control (NVC) were 34 mm and 308 cm, respectively, compared to 45 mm and 357 cm in BO/VC (P &lt;0.01). Mean relative growth rate in stem diameter for trees in BO/VC was greater than in BO/NVC in years 2–4, but this trend reversed in year 5, suggesting that tree intraspecific competition may be greater in BO/VC than in BO/NVC. Vegetation control also increased second-flushing (i.e., the flushing of set buds in late summer) in years 4 and 5. Vegetation competition effects on tree growth appeared to be related to changes in available soil water rather than to competition for nutrients.
δ15N Patterns of Douglas-Fir and Red Alder Riparian Forests in the Oregon Coast Range
Authors: Scott Emily E. , Perakis Steven S. , Hibbs David E. 
Published: April 2024

Abstract
We used naturally occurring stable isotopes of N to compare N dynamics in near-stream and upslope environments along riparian catenas in N-fixing red alder (Alnus rubra) and Douglas-fir (Pseudotsuga menziesii) forests in the Coast Range of western Oregon. Based on the existing literature, we expected soil δ15N to be enriched closer to streams owing to inputs of isotopically heavy, marine-derived N by spawning salmon, higher rates of denitrification near the stream, or both. However, it has been unclear what effect red alder might have on soil δ15N patterns near streams. We found a consistent −1‰ δ15N signature in red alder foliage, and δ15N of total N in soils under red alder averaged 2.2‰ along sampling transects extending 20 m upslope from the stream. Surprisingly, δ15N of total N in soil under Douglas-fir was progressively depleted nearer to streams, opposite from the pattern expected from N losses by denitrification or N inputs from anadromous salmon. Instead, δ15N of total N in soil under Douglas-fir converged toward soil δ15N values typical of red alder sites. We consider that the historic presence of red alder may have contributed a legacy of lower soil δ15N nearer to streams on sites that are currently dominated by young Douglas-fir forest.
Differences in Spruce Budworm Defoliation among Balsam Fir and White, Red, and Black Spruce
Authors: Hennigar Chris R. , MacLean David A. , Quiring Dan T. , Kershaw John A. 
Published: April 2024

Abstract
Spruce budworm (Choristoneura fumiferana Clem.) outbreaks severely reduce growth and survival of balsam fir (Abies balsamea [L.] Mill.) and spruce (Picea spp. A. Dietr.) over much of eastern North America, resulting in major reductions in yield and disruption of harvest schedules. This is the first study to rigorously quantify defoliation differences among all four spruce budworm host tree species at a stand level. An extensive permanent sample plot data set, with more than 27,000 tree and 1,117 stand measurements from 1984 to 1992 in New Brunswick, Canada, revealed a clear and consistent hierarchy of host species defoliation susceptibility. Regardless of defoliation severity and other stand variables tested, white (Picea glauca [Moench] Voss), red (Picea rubens Sarg.), and black spruce (Picea mariana [Mill.] B.S.P.) had approximately 72, 41, and 28% as much defoliation as balsam fir, respectively. Balsam fir defoliation was a highly significant predictor of white, red, and black spruce defoliation. Of the variation in defoliation of red-black spruce hybrids, 34% was explained by balsam fir defoliation and an interaction with spruce hybrid index. This is the first model to quantify hybrid red-black spruce defoliation across a full range of severities. Quantitative models of stand-level defoliation differences among host species will improve spruce budworm stand impact forecasts and decision support prioritization of bioinsecticide or salvage operations and provide information to calibrate population-defoliation models for host species in mixed species stand types.
Characterizing Family Forest Owners: A Cluster Analysis Approach
Authors: Majumdar Indrajit , Teeter Lawrence , Butler Brett 
Published: April 2024

Abstract
For policy implementation to promote better stewardship on family forestlands, it is necessary to understand what motivates landowners. This study characterizes family forest owners in Alabama, Georgia, and South Carolina, based on their feelings about forest stewardship and their stated reasons for owning forestland. Multivariate cluster analysis suggests that family forest owners are, in fact, a diverse set of owners who can be grouped into three attitudinal types, namely, multiple-objective, nontimber, and timber. The multiple-objective ownership type was found to be the largest group (49.1% of respondents) with almost half the family forest owners in the sample population belonging to this category. Owners belonging to the timber cluster (29.4%) indicated only timber management and land investment as strong motivating factors behind their forestland ownership, whereas owners belonging to the nontimber cluster (21.5%) value the nonconsumptive uses of their forestland such as aesthetic values, biodiversity, recreation, and privacy.
An Integrated Approach to Evaluating the Economic Costs of Wildfire Hazard Reduction through Wood Utilization Opportunities in the Southwestern United States
Authors: Lowell Eini C. , Becker Dennis R. , Rummer Robert , Larson Debra , Wadleigh Linda 
Published: April 2024

Abstract
This research provides an important step in the conceptualization and development of an integrated wildfire fuels reduction system from silvicultural prescription, through stem selection, harvesting, in-woods processing, transport, and market selection. Decisions made at each functional step are informed by knowledge about subsequent functions. Data on the resource characteristics of small-diameter ponderosa pine (Pinus ponderosa Dougl. ex Laws.), harvest equipment productivity, lumber recovery, and net profit (loss) by level of fuels reduction achieved were collected from four 8.1-ha (20 ac) sites in northern Arizona. These data were used to develop a Windows-based, financial and engineering software program, the harvest cost-revenue (HCR) estimator, to identify the economic costs of wildfire fuel reduction treatments that may be used to evaluate cost per acre thresholds for logging contractors, appraise contract bid rates, or assess stumpage values for ponderosa pine stands in the southwestern United States. Application of the model illustrates variability in fuels reduction costs owing to the level of fuels reduction achieved, the volume of merchantable wood removed from different forest stands, and the availability of markets for removed material. Machine productivity helps predict differences in harvest costs but is secondary to market constraints and the volume of wood harvested.
Bivariate Distribution Modeling of Tree Diameters and Heights: Dependency Modeling Using Copulas
Authors: Wang Mingliang , Rennolls Keith , Tang Shouzheng 
Published: April 2024

Abstract
Models of diameter and height distributions play an important role in forest mensuration and inventory, and many models and fitting methods are available for fitting these distributions separately. Very few models and methods appropriate for fitting the joint distribution of diameters and heights are available. The S BB and distributions obtained using Plackett's method are the only appropriate models published in the forestry literature to date. A bivariate joint distribution can be represented in terms of its underlying marginals and a copula function that models the dependency structure. A copula is a function that joins or “couples” a multivariate distribution function to its one-dimensional marginal distributions. The copula approach provides a general way of constructing bivariate distributions, including previously used bivariate models. The basics of the copula representation, the most useful copula functions, and maximum likelihood estimation (MLE) of the copula function are introduced. The emphasis of this article is on the choice of copula function(s) appropriate for modeling the joint distribution of tree diameters and heights. Using an empirical dataset of 102 Chinese fir (Cunninghamia lanceolata Lamb.) plantation plots, we fit each of the copula functions that we considered to each sample-plot joint distribution of tree diameters and heights. A two-stage MLE approach with a nonparametric (empirical) approach to the marginal distributions is adopted. In this case study the normal copula proves to be the best for modeling the joint distribution (dependence) of tree diameters and heights.
Generalized Algebraic Difference Approach Derivation of Dynamic Site Equations with Polymorphism and Variable Asymptotes from Exponential and Logarithmic Functions
Authors: Cieszewski Chris J. , Strub Mike 
Published: April 2024

Abstract
The generalized algebraic difference approach (GADA) uses both: two-dimensional functions of explicit time and two-dimensional functions of explicit site to derive a single dynamic equation that is a three-dimensional function of explicit time and implicit site. In 2004 Cieszewski advanced dynamic site equations with polymorphism, and variable asymptotes (Cieszewski, C.J. 2004. GADA derivation of dynamic site equations with polymorphism and variable asymptotes from Richards, Weibull, and other exponential functions. PMRC Tech. Rep. 2004-5, p. 16.) were built with GADA using one general function of time T and two general functions of site X. The function of time is the exponential function Y = MTb , and the functions of site are the quadratic function Z = b1 + b2X + b3X 2 and the inverse half-saturation function Z = b1 + b2/(X + b3). We discuss the new dynamic equations based on five exponential substitutions (Richards, Gompertz, Korf, logistic, and log-logistic) and one new logarithmic model substitution in the exponential function of time and 10 special cases of the two functions of site corresponding to their different parameter values. The new dynamic equations presented offer breakthrough flexibility in modeling of the self-referencing dynamics with the exponential and logarithmic functions considered in this article.
A Geographically Weighted Regression Analysis of Douglas-Fir Site Index in North Central Idaho
Authors: Kimsey Mark J. , Moore James , McDaniel Paul 
Published: April 2024

Abstract
An analysis of Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco var. glauca) site index (SI) was performed in north central Idaho using two forms of linear regression: standard multiple linear regression (MLR) and geographically weighted regression (GWR). The hypothesis was that the GWR model would provide better estimates of SI using edaphic, topographic, and climatic predictor variables than ordinary MLR. Elevation, volcanic ash depth, slope, and aspect were significantly correlated with Douglas-fir SI (R A 2 = 0.5). GWR accounted for an additional 29% of the variation in SI and reduced the error sum of squares by approximately 53%. The geographically weighted parameter estimates of the model intercept and elevation were nonstationary, which indicates that geographic location determines the influence of a variable on SI. Residual analysis from a MLR model showed large SI prediction error throughout the study area. This prediction error was significantly reduced using the GWR model. GWR shows promise for biological modeling.
Suppression Cost Forecasts in Advance of Wildfire Seasons
Authors: Prestemon Jeffrey P. , Abt Karen , Gebert Krista 
Published: April 2024

Abstract
Approaches for forecasting wildfire suppression costs in advance of a wildfire season are demonstrated for two lead times: fall and spring of the current fiscal year (Oct. 1–Sept. 30). Model functional forms are derived from aggregate expressions of a least cost plus net value change model. Empirical estimates of these models are used to generate advance-of-season forecasts. Cost forecasts involve estimation of suppression cost equations by geographical region based on a time series of historical data (1977–2006) of costs, a time trend, and climate variables, forecasts of the next season's suppression costs, by region and in total across all regions, and generation of suppression cost forecast probability distributions by region and in aggregate. The forecasts are also evaluated historically for their goodness of fit using cross-validation techniques. The two lead time forecast models are compared with the 10-year moving average of suppression costs, currently used as a budget request formula by the US Forest Service. Results show that the spring forecast of suppression costs is statistically no better than the fall forecast for predicting the coming season's costs. However, both the spring and fall forecasts significantly outperform the 10-year moving average, reducing forecast errors by approximately 60%.
Adjacency Branches Used To Optimize Forest Harvesting Subject to Area Restrictions on Clearfell
Authors: McNaughton Alastair J. , Ryan David 
Published: April 2024

Abstract
Consider a forest containing units of various sizes for which a maximum clearfell area has been specified along with an associated green-up time period. For such an application it is customary to use adjacency constraints to produce a harvesting plan. These constraints control the availability for harvest of specific units relative to the harvesting of certain adjacent units. However, such constraints are difficult to formulate and often precipitate major difficulties in the implementation of the solution algorithm. A new concept, a nuclear set, is introduced. This concept allows the unit-specific aspects of the problem to be analyzed in an insightful manner. Any adjacency violation can be detected in relation to these nuclear sets. Suitable adjacency branches can be implemented to remove these violations. The form of these branches derives from the same nuclear sets. A remarkably small number of these branches are required to obtain a feasible solution. These ideas are incorporated into a column generation and constraint generation model. This new forest harvesting model solves the clearfell area restriction problem in an exact sense. Results are included for numerical trials involving simulated data representing moderately sized applications with a planning horizon of up to one rotation. The output from these trials suggests that this algorithm is suitable for large commercial applications. Several applications of 1,600 units are solved over 25 time periods with multiple green-up.
Spatial Scale and Stand Structure in Northern Hardwood Forests: Implications for Quantifying Diameter Distributions
Authors: Janowiak Maria K. , Nagel Linda M. , Webster Christopher R. 
Published: April 2024

Abstract
Diameter distributions are frequently used to describe northern hardwood stand structure and serve as a structural guide for management. Several diameter distribution shapes have been found in managed and unmanaged uneven-aged northern hardwood stands, and it is unclear which patterns are due primarily to natural processes that could be self-perpetuating versus patterns that may be transient or aberrant. Variability in research methods has clouded consistent interpretation of resulting distributions. In this study, we evaluated northern hardwood stands in Michigan to determine how management and sample area affect interpretation of diameter distribution shape. Managed stands had a higher degree of variability in distribution shape and a tendency toward the increasing-q pattern. Unmanaged uneven-aged stands (i.e., old-growth remnants) were predominantly rotated sigmoid in shape. Patterns for each type of management became more consistent as sample area increased. Our data suggest a minimum sample area of 13% of total stand area may be needed to accurately capture diameter distribution shape; in this study that was 0.4 ha of a 3.2-ha sample plot. Additionally, greater heterogeneity in the structure of unmanaged stands resulted in the need for larger sample areas compared with that for managed stands.
Drought-Induced Changes in C and N Stoichiometry in a Quercus ilex Mediterranean Forest
Authors: Sardans Jordi , Peñuelas Josep , Ogaya Romà 
Published: April 2024

Abstract
A 6-year field experiment of drought manipulation was performed in a Mediterranean forest with the aim of determining the effects of the drought predicted by most climate and ecophysiological models on the C and N concentration, accumulation, and stoichiometry in plants and soil. Drought had different effects among dominant species. In Quercus ilex, it increased the C/P ratio in wood and roots, N concentrations in roots and litter, and N/P ratio in wood and roots and decreased the C concentration in roots, C/N ratio in roots and litter, and C/P ratio in litter. In Arbutus unedo, drought increased the N concentration in litter and decreased the N concentration in leaves, thus decreasing N leaf reabsorption. No significant changes in C and N concentrations were found in Phillyrea latifolia. Drought affected the P plant absorption capacity more than that of N (more mobile). There was a general decreasing trend of C and N accumulation in aboveground biomass, with this effect being significant in A. unedo, which accumulated 80% less C and lost 2 kg ha−1 of N in aboveground biomass in drought plots in the period 1999–2005, whereas in this same period it accumulated 9 kg ha−1 of N in total aboveground biomass in control plots. Total soil N and soil organic C increased in droughted soils. The effects of drought on C/N/P stoichiometry and N uptake capacity were different among the three dominant plant species. Q. ilex and A. unedo were more sensitive to drought than P. latifolia. The increase in C/P and N/P ratios in Q. ilex and the decrease in N uptake in A. unedo might decrease their competitive capacity under drought by decreasing water use efficiency. These results altogether indicated slower C and N mineralization and lower N plant capture, N leaf reabsorption, and N accumulation in some dominant plant species in response to drought, thus reducing C and N soil turnover, increasing C and N accumulation in soil, and reducing C and N at the stand level.
Effects of Microsites Created by Selective Harvesting on Growth of Microstegium vimineum in a Central Hardwood Forest
Authors: Marshall Jordan M. , Buckley David S. 
Published: April 2024

Abstract
Disturbances related to silvicultural activities are inevitable and may facilitate the spread of established populations of exotic species. Microstegium vimineum is an annual exotic grass that has spread throughout the eastern United States. Different categories of understory microsites resulting from cutting and the operation of logging machines within three selective harvest units were identified and characterized by measuring several environmental variables. M. vimineum was sown within the microsites categorized. Differences in growth of M. vimineum across different microsites were quantified. As percent canopy cover increased, M. vimineum percent cover, mean length, and mean number of nodes decreased. Also, as litter depth increased, M. vimineum percent cover and stem length decreased. In undisturbed microsites in which M. vimineum was not sown, the exotic grass was not a dominant species, whereas in all other microsites created by logging machine operation M. vimineum was a dominant species whether those areas were sown or colonized by wild populations. These results suggest that unique microsites created by logging may facilitate M. vimineum invasion of central hardwood forests. The apparent connection between soil and canopy disturbance and invasion by M. vimineum provides further impetus for careful planning and use of haul roads and skid trails.