bluuebunny/crossref_metadata_2025_split huggingface dataset:
Some Theory for the Application of the Moving Average Estimator in Forest Surveys
Authors: Johnson Devin S. , Williams Michael S. 
Published: April 2024

Abstract
The Forest Inventory and Analysis (FIA) and National Resources Inventory programs are two examples of large-scale survey programs that are in the process of moving from periodic surveys, where data for an area are collected once every 10–15 years, to annual surveys, where a smallersample of the data is collected every year. Each yearly sample can be referred to as a panel, and yearly estimates can be made with the data in each panel. With the change from periodic to annual surveys, there has been a substantial amount of discussion related to combining the data fromthe individual panels into a single estimator with an acceptably small mean square error. Numerous methods, each with certain advantages and disadvantages, have been proposed and tested. Testing with FIA data suggests that, in terms of mean square error, the equally weighted moving averageestimator is often as good as or better than other estimators when making estimates for individual counties or small groups of counties. This favorable performance is due to the relatively small sample sizes in these situations. One area of research that has not been addressed is the performanceof the moving average estimator when the sampling design deviates from its original protocol. Factors that cannot be controlled, such as weather, budgets, and politics, can alter the original sampling design. The purpose of this article is to propose and derive estimators that accommodatethese factors and give some guidelines on how to handle these situations when they occur. FOR. SCI. 50(5):672–681.
Predicting Parameters of a Weibull Function for Modeling Diameter Distribution
Authors: Cao Quang V. 
Published: April 2024

Abstract
The Weibull function has been widely used to characterize diameter distributions in a forest stand. Methods have been developed to predict the Weibull parameters, either directly or indirectly, from stand age, density, and dominant height. In this study, four existing methods and twonew methods of obtaining the Weibull parameters were evaluated using data from a loblolly pine (Pinus taeda L.) plantation. While both new methods performed well, one of them produced consistently better goodness-of-fit statistics than those from the existing methods. FOR. SCI. 50(5):682–685.
A Generalized Methodology for Developing Whole-Stand Survival Models
Authors: Rose Charles E. , Clutter Michael L. , Shiver Barry D. , Hall Daniel B. , Borders Bruce 
Published: April 2024

Abstract
A large source of variability in yield predictions is due to estimation of future surviving trees per unit area. Previous whole-stand survival modeling efforts have concentrated on modeling the empirical survival curve. Modeling hazard functions, an approach to survival analysis commonly used in fields such as medicine and sociology, can be applicable to plantation survival estimation. We offer a generalized method for deriving whole-stand survival models that are capable of modeling complex underlying hazard functions. We use our knowledge of the empirical hazard function to limit our selection to appropriate functions. Integrating selected functions results in initial condition difference equations that, when fitted to our data, provide biologically reasonable whole-stand survival predictions and adequately represent the underlying hazard function. Our method is relatively easy to implement and can model a whole-stand survival curve with a complex underlying hazard function. FOR. SCI. 50(5):686–695.
A Genetic Algorithm Approach to Tree Bucking Optimization
Authors: Kivinen Veli-Pekka 
Published: April 2024

Abstract
Tree bucking on modern cut-to-length harvesters is controlled by two types of matrices. The price matrix provides the bucking computer with information on how to prioritize various log grades and diameter-length combinations within the same grade, while the demand matrix specifies the desired proportion for each combination. The traditional approach has been to apply the samematrix set to all stands to be harvested within the same planning period, although the stand structure and the characteristics of trees may vary markedly from stand to stand. The purpose of this research was to test the hypothesis that controlling bucking matrices prior to harvesting would improve bucking results at the forest level. The search for stand-specific price matrices was based on a genetic algorithm (GA) that, given a desired overall log distribution and the stem profiles of all the trees in each stand, optimizes, in a parallel manner, the price matrix of a given log grade for each stand involved in the process. The mutation rate and the degree of elitism had the greatest effect on the performance of the developed GA system. In 10 test runs with the same parameter set, the fitness value of the poorest solution (price matrix string) was 98.2% of that of the best solution. The simulations with the bucking simulator, however, indicate that precontrol of price matrices does not improve the fit between the overall demand matrix and the global output matrix even if the log prices are adjusted according to stem data without estimation errors. FOR. SCI. 50(5):696–710.
Small-Mammal Relationships with Down Wood and Antelope Bitterbrush in Ponderosa Pine Forests of Central Oregon
Authors: Smith Troy G. , Maguire Chris C. 
Published: April 2024

Abstract
The influence of down wood on fire behavior in ponderosa pine (Pinus ponderosa) forests in central Oregon is much understood. However, little is known about down-wood affiliations with wildlife in this area. Antelope bitterbrush (Purshia tridentata) contributes to wildfires, nitrogen fixation, and the food web, yet its influence on small-mammal populations remains poorly defined. In this study, population density, survival, and reproductive status of yellow-pine chipmunks (Tamias amoenus), golden-mantled ground squirrels (Spermophilus lateralis), and deer mice (Peromyscus maniculatus) are estimated under three down-wood and shrub-cover conditions in ponderosa pine/antelope bitterbrush forests of Oregon. The odds for golden-mantled ground squirrel survival are 4.2 times greater on units with high (x¯ = 117.8 m3/ha) versus low down-wood volume (x¯ = 15.8 m3/ha), and each 35.1-m3/ha increase in down wood coincides with a 10% increase in ground squirrel density. Yellow-pine chipmunk densities are 57% higher on units with high (x¯ = 31.2%) versus low total shrub cover (x¯ = 9.2%), and 4.4 and 2.3% increases in total shrub and live bitterbrush cover, respectively, coincide with 10% increases in chipmunk density. Deer mouse populations are little affected by down-wood volume or shrub cover. Study results suggest that management activities influencing down wood or bitterbrush will likely affect the composition of small-mammal communities through population changes in one or more small-mammal species. FOR. SCI. 50(5):711–728.
Young Stand Growth Modeling for Intensively-Managed Loblolly Pine Plantations in Southeastern U.S
Authors: Westfall James A. , Burkhart Harold E. , Allen H. Lee 
Published: April 2024

Abstract
Intensively managed loblolly pine stands are often subjected to a variety of silvicultural treatments at time of planting or shortly thereafter. However, most loblolly pine growth-and-yield models predict growth after crown closure has occurred. In this article, we describe the development and implementation of a system of equations designed to simulate growth of loblolly pine before the onset of intraspecific competition. Treatment response functions were also developed for various site preparation, herbaceous weed control, and fertilization practices. These functions modify the baseline model predictions to simulate the effects of treatments on tree growth and stand development. This system was incorporated into the PTAEDA2 growth-and-yield simulator to make growth projections from time of planting through rotation age for intensively managed stands of loblolly pine in the southeastern United States. Growth simulations specifying either bedding or disking showed increases in volume growth for both treatments. The shear-and-pile site-preparation method reduced growth rates slightly. Volume growth responses to herbaceous weed control were positive, with magnitude of increase largely depending on duration of treatment. Increases in volume attributable to fertilization at planting were related to types of element applied. The largest predicted response was for phosphorus fertilization, whereas application of potassium was the least effective fertilization treatment. Site preparation, weed control, and fertilization treatment combinations produced additional volume gains when compared to single treatments, while maintaining predicted values that are within biological limits for loblolly pine growth. Levels of response to treatments are consistent with results from published studies on intensive management practices. The addition of the precompetitive growth system did not significantly affect the predictive behavior of the PTAEDA2 model for untreated stands. FOR. SCI. 50(6):823–835.
Are Self-Thinning Constraints Needed in a Tree-Specific Mortality Model?
Authors: Monserud Robert A. , Ledermann Thomas , Sterba Hubert 
Published: April 2024

Abstract
Can a tree-specific mortality model elicit expected forest stand density dynamics without imposing stand-level constraints such as Reineke's maximum stand density index (SDImax) or the −3/2 power law of self-thinning? We examine this emergent properties question using the Austrian stand simulator PROGNAUS. This simulator was chosen specifically because it does not use stand density constraints to determine individual tree mortality rates. In addition, it is based on a probability sample of the population that includes the span of the data being used to test the hypothesis. Initial conditions were obtained from 27 permanent research plots that were established in young pure stands of Norway spruce (Picea abies L. Karst.) and Scots pine (Pinus sylvestris L.) in Austria. A growth period of 250 years was simulated. We conduct our test in two parts. First, we compare our simulated results to Reineke's theory of maximum density and stand density index by examining the self-thinning relationship between stem number per hectare and quadratic mean diameter (log-log scale). Second, we compare our results to Sterba's full competition density rule, which incorporates dominant height along with stem number and quadratic mean diameter. From the results for Norway spruce, we conclude that stand-level density constraints are not necessary to obtain Reineke's maximum size-density relations. Norway spruce results confirm that the maximum size-density relationship reflects reasonable and stable stand dynamics and conforms to that expected by Reineke's theory. Results from simulation of Scots pine also display reasonable and stable stand dynamics, except that they greatly exceed Reineke's maximum stand density index determined empirically from the literature. This Scots pine result argues for stand-level constraints (such as specifying SDImax) to ensure that the appropriate intercept for the maximum density line is used. Our second test revealed that the estimated maximum stand density index according to Sterba's theory was too high for both species, but that the relative rankings across plots were correct. Thus, we are left with ambiguous results. First, that a density-dependent individual-tree mortality model, developed on an adequate data set, is sufficient for the desired stand-level behavior of Reineke to emerge. Second, that stand-level constraints on SDImax need to be imposed if the underlying mortality modeling database is not adequate. FOR. SCI. 50(6):848–858.
Improved Estimation for Multiple Means with Heterogeneous Variances
Authors: Green Edwin J. , Strawderman William E. , Amateis Ralph L. , Reams Gregory A. 
Published: April 2024

Abstract
Two new estimators are presented for use in situations where simultaneous estimation of more than two sample means is required and alternative, possibly biased information is available. The new estimators are modifications to an older estimator by Green and Strawderman. The latter estimator assumed homogeneous variances, whereas the new ones are designed for the more usual case of heterogeneous variances among the sample means. In simulation experiments, the new estimators yielded superior performance to that of the ordinary sample mean vector (X). Surprisingly, the estimator designed to dominate X under precision-weighted loss was apparently the best estimator, even under nonprecision-weighted loss. Use of the new estimators should allow foresters to achieve considerable savings in estimation precision. FOR. SCI. 51(1):1–6.
Genotype by Environment Interactions in an Australia-Wide Radiata Pine Diallel Mating Experiment: Implications for Regionalized Breeding
Authors: Wu Harry X. , Matheson A. Colin 
Published: April 2024

Abstract
Genotype by site interactions were studied in an Australia-wide diallel experiment covering 10 testing sites for stem dbh, stem straightness, branch angle and size, and number of branch clusters on the stem at age 10.5 to 11.5 years. The size and practical importance of genotype by site interactions were examined by four approaches: (1) the ratio of interaction variance to general combining ability (GCA) variance; (2) additive genetic correlations among sites; (3) testing whether the interaction was a result of a few families reacting more than others; and (4) by the size of genetic gains through a proposed regionalization. The genotype by site interaction for dbh observed in this experiment was larger than reported earlier for radiata pine because two high-elevation sites were included. There were more interactions between the two high-elevation sites and other lower elevation sites than interactions between lower elevation sites. The large genotype by region interaction was attributed to the extensive snow loading at the two higher elevation sites. Gain predictions from five regionalization schemes in this experiment favor regionalization of radiata pine breeding into two main regions: higher elevation and lower elevation sites. FOR. SCI. 51(1):29–40.
Forest Fragmentation Estimated from Remotely Sensed Data: Is Comparison Across Scales Possible?
Authors: García-Gigorro Soledad , Saura Santiago 
Published: April 2024

Abstract
Remotely sensed data with different spatial resolutions are being used as the primary information source for the analysis of forest fragmentation. However, there is currently a lack of appropriate methods that allow for the comparison of forest fragmentation estimates across various spatial scales. To provide insights into this problem we analyzed a forested study area in central Spain and a set of 10 widely used fragmentation indices. Forests were mapped from two simultaneously gathered satellite images with different spatial resolutions, 30 m (Landsat-TM) and 188 m (IRS-WiFS). TM forest data were transferred to WiFS resolution through different aggregation rules and compared with actual WiFS data. We found that incorporating sensor point spread function (which replicates the real way in which remote sensors acquire radiation from the ground) greatly improved comparability of forest fragmentation indices. We found a poor performance of power scaling laws for estimating forest fragmentation at finer spatial resolutions, and suggest that the true accuracy and practical utility of these scaling functions may have been overestimated in previous literature. Finally, we report an unstable behavior of three cell-based fragmentation indices (clumpiness, aggregation, and patch cohesion indices), for which spuriously high values can be obtained by resampling forest data to finer spatial resolutions. We believe that the results and guidelines provided may significantly contribute to an adequate analysis and comparison across scales of forest fragmentation estimations. FOR. SCI. 51(1):51–63.
Motivations and Behaviors of New Forest Owners in Virginia
Authors: Kendra Angelina , Hull R. Bruce 
Published: April 2024

Abstract
Forestry must find ways to remain relevant to its changing constituency and client base. Market segmentation techniques can help. This study assessed the motivations and forest practices of 661 people who recently purchased forested lands ranging in size between 0.8 and 20 ha in rapidly growing counties in Virginia. Cluster analysis techniques were used to identify six market segments: absentee investors (4%), professionals (13%), preservationists (16%), young families (19%), forest planners (21%), and farmers (21%). (The remaining 6% demonstrated no variance in their responses and were not clustered.) The results suggest that lifestyle and amenity concerns are much more important motivations for landownership than are timber production and economic concerns. We discuss communication strategies, management services, and landowner assistance programs that might appeal to people in each of the six market segments. FOR. SCI. 51(2):142–154.
Nitrogen Management in a Fraser Fir (Abies fraseri [Pursh] Poir.) Christmas Tree Plantation: Effects of Fertilization on Tree Performance and Nitrogen Leaching
Authors: Rothstein David E. 
Published: April 2024

Abstract
There is increasing concern over the effects of nitrogen (N) pollution resulting from fertilizer inputs to food and fiber production systems. Christmas tree production is one segment of the forestry sector that uses substantial fertilizer inputs. However, we know very little about the environmental costs and production benefits of N fertilization in Christmas tree plantations. I studied the costs and benefits of 2 years of N applications (as ammonium sulfate) at 0, 47, 95, and 140 kg N ha−1 year−1 to 4-year-old Fraser fir (Abies fraseri) Christmas trees. These rates correspond to 0, 50, 100, and 150% of the amount recommended for 4-year-old trees, and 33, 67, and 100% of recommendations for 5-year-old trees. There were no significant effects of fertilization rate on tree growth or morphology. In contrast, foliar N concentrations increased with increasing rates of N application, and there was a trend toward improved foliage health (indicated by chlorophyll fluorescence) at the lowest application rate. Mineral N (NH+4 + NO−3) concentrations in water leaching below the rooting zone increased markedly with increasing N application rates. Lysimeter NO−3 concentrations in the highest application treatment were consistently 20–30 times greater than the safe drinking water standard of 10 mg NO−3-N/l. Together, these results suggest that conventional guidelines for fertilization of Michigan Fraser fir plantations greatly exceed the capacity of trees and surface soils to store N, provide no benefit to tree growth, and create the potential for significant N pollution of ground and surface waters. Furthermore, these results indicate that applying N at a lower rate of 47 kg N ha−1 year−1 substantially reduced NO−3 leaching with no decline in growth rates or tree quality. FOR. SCI. 51(2):175–184.
Hypogeous Ectomycorrhizal Fungal Species on Roots and in Small Mammal Diet in a Mixed-Conifer Forest
Authors: Izzo Antonio D. , Meyer Marc , Trappe James M. , North Malcolm , Bruns Thomas D. 
Published: April 2024

Abstract
The purpose of this study was to estimate the portion of an ectomycorrhizal (ECM) fungi root community with a hypogeous fruiting habit. We used molecular methods (DNA sequence analysis of the internally transcribed spacer [ITS] region of rDNA) to compare three viewpoints: ECM fungi on the roots in a southern Sierra Nevada Abies-dominated old-growth forest, fungi in scat samples collected from small mammals in the same forest, and hypogeous sporocarps found throughout the Sierra Nevada. We found that hypogeous taxa accounted for a minimum of 21% of the species and 25–40% of the dry root biomass of all samples. This estimate is two to three times greater than estimates from previous studies. This difference may be due to methodological advantages of this study, but may also be related to conditions in dry forests typical of western North America where prolonged drought may favor this form of fruiting. Although molecular analysis of scat samples did not add to our view of the ECM roots, we readily isolated sequences from Rhizopogon species. From these results we inferred that two species, R. occidentalis and R. olivaceotinctus, are represented primarily in the spore bank and may be dependent on substantial disturbance to become abundant on roots. FOR. SCI. 51(3):243–254.
Comparing and Combining Stem Analysis and Permanent Sample Plot Data in Site Index Models
Authors: García Oscar 
Published: April 2024

Abstract
Most site index models are built either from repeated measurements on permanent sample plots or by using data obtained by stem analysis. Sometimes both types of data are available. It is then of interest to test them for consistent height-age trends, and to estimate model parameters using all the data. Efficient procedures should take into account the difference in error patterns between the two data sources. A stochastic differential equation model is proposed in which trend and error parameters can take either different or common values for various data groups. All parameters are simultaneously estimated by maximum-likelihood, and computed likelihoods and likelihood-ratio tests can be used for comparing model variants and for hypothesis testing. The methods are applied to Pinus pinaster plantations in northern Spain. FOR. SCI. 51(4):277–283.
Localizing a Predicted Diameter Distribution Using Sample Information
Authors: Mehtätalo Lauri 
Published: April 2024

Abstract
This study presents a new method for predicting the diameter distribution of a stand, utilizing the percentile-based diameter distribution. The expected diameter percentiles are first predicted using stand measurements. Subsequently, the distribution is calibrated (localized) for the stand using sample order statistics, which consist of one or more diameters of sample trees and their ranks on the sample plot(s). These measurements can be quickly carried out in the field, because the rank can be assessed visually. The sample order statistics can be interpreted as measured sample percentiles. The expectations, variances, and covariances of the measured sample order statistics are derived using the theory of order statistics. Regression models are used to predict the conditional expectations of predefined percentiles, which are then combined with the measured percentiles using the best linear unbiased predictor. The method was tested in a real data set using simulated sample plots. The test showed that, even with a small number of sample measurements, the relative root mean square error and bias of volume per hectare could be decreased remarkably. Furthermore, increasing the number of measurements steadily improved the prediction. The proposed method seems to be a promising tool in the prediction of diameter distributions of various forms, including those found in complex stands. FOR. SCI. 51(4):292–303.