bluuebunny/crossref_metadata_2025_split huggingface dataset:
Predicting the Spatial Distribution of Leaf Litterfall in a Mixed Deciduous Forest
Authors: Staelens Jeroen , Nachtergale Lieven , Luyssaert Sebastiaan 
Published: April 2024

Abstract
An accurate prediction of the spatial distribution of litterfall can improve insight in the interaction between the canopy layer and forest floor characteristics, which is a key feature in forest nutrient cycling. Attempts to model the spatial variability of litterfall have been made across forest types, but the reported models have not yet been compared. We predicted the spatial distribution of leaf litterfall for the same mixed hardwood stand using inverse distance interpolation, ordinary kriging, single and multiple regressions based on plot basal area, and three individual-tree models. Models were calibrated using litterfall data (n = 67) of white birch (Betula pendula Roth), pedunculate oak (Quercus robur L.), and northern red oak (Quercus rubra L.). Model performance was compared using an independent validation data set (n = 37). Interpolation techniques did not reliably estimate spatial patterns of leaf litterfall (r &lt; 0.60, n = 37). However, models incorporating tree data, such as linear regressions and individual-tree models, successfully reproduced the observed spatial litterfall heterogeneity of each species (r &gt; 0.80). No model was able to predict the variability of the total leaf litterfall of the three species. We conclude that, for an intimately mixed forest stand, a model that simulates leaf dispersal of individual trees is likely to be the best choice for predicting the spatial distribution of leaf litterfall. FOR. SCI. 50(6):836–847.
Nonparametric Tests for Profit Maximization with Incomplete Data: Application to the Pulp and Fine Paper Production in Finland
Authors: Kallio A. Maarit I. , Hänninen Riitta 
Published: April 2024

Abstract
Forest sector models give relevant information to decision makers only if they are based on correct economic hypotheses. This requires that the data from which the model parameters are estimated are consistent with the a priori assumptions made on market agents' behavior and competition patterns. For static models, rather simple nonparametric tests exist for checking such consistency. Such tests also provide an analyst with insights on possible errors in the data and the suitability of the data for the particular econometric model that the analyst has in mind. This article proposes data tests for the competitive or noncompetitive profit-maximization hypothesis that can also be used with incomplete data. The tests are applied to quarterly data on the production of pulp and fine paper in Finland. It is found that the data may not represent profit-maximizing price takers. Although this can be due to, e.g., integrated production, missing dynamics, or noncompetitive behavior—a hypothesis that was indeed found to be consistent with the fine paper data—it is evident that the modeler should not use these data in estimating a parametric industry model that builds on price-taking profit-maximizing behavior. The results emphasize the importance of testing the data before modeling. FOR. SCI. 51(1):19–28.
Management of Mixed-Species, Uneven-Aged Forests in the French Jura: From Stochastic Growth and Price Models to Decision Tables
Authors: Rollin François , Buongiorno Joseph , Zhou Mo , Peyron Jean-Luc 
Published: April 2024

Abstract
A deterministic matrix growth model of uneven-aged stands of fir, spruce, and hardwood trees was extended to recognize random shocks. The results showed that the expected basal area of hardwoods, mainly beech, was substantially higher in the long run than that predicted by the deterministic model. A parallel stochastic model of prices was also developed from past data. It showed that real prices had no trend but that they were autocorrelated over time. The stochastic stand and price models were simulated simultaneously to obtain the probabilities of transition between stand and market states. This transition probability matrix was used in Markov decision-process models to calculate the best decision in each possible stand and market state. The policies examined included maximizing net present value, or expected tree diversity, production, or annual returns, subject to constraints on net present value, expected tree diversity, and basal area. A general mathematical programming method is presented to optimize economic or ecological objective functions subject to multiple constraints with or without time discounting. In the French Jura context, the solutions suggested that high net present value could be obtained while maintaining the average basal area near its current level, and keeping a high level of tree diversity. Accounting for risk called for more intense harvesting to raise revenues, and it led to stands that were much more diverse than suggested by deterministic solutions. FOR. SCI. 51(1):64–75.
Tree Density Estimations Using a Distance Method in Mali Savanna
Authors: Picard Nicolas , Kouyaté Amadou M. , Dessard Hélène 
Published: April 2024

Abstract
The biological characteristics of trees in tropical dry savannas make it difficult to conduct inventories of tree density, and this has aroused interest in distance-based methods. This study proposes a distance-based tree density estimator using Matérn point processes, generating clustered spatial patterns. It was defined as the maximum likelihood estimator of the density, based on an approximate distribution of the distance from a random point to the pth nearest tree. It was compared with seven estimators identified in the literature as the most efficient. The estimators were compared on a benchmark of 10 point processes, with six being adjusted to observed tree patterns in six Mali savannas (West Africa). The proposed estimator was generally the most efficient. However, this result ignores that (i) all estimators do not require the same effort on the field, (ii) the point-processes benchmark was restricted to Matérn processes, and (iii) all estimators are not equivalent with respect to measurement errors. FOR. SCI. 51(1):7–18.
Developmental Pathways following the Harvest of Oak-Dominated Stands
Authors: Gould Peter J. , Steiner Kim C. , Finley James C. , McDill Marc E. 
Published: April 2024

Abstract
The postharvest development of 90 formerly oak-dominated stands in Pennsylvania was examined to identify developmental pathways that led to a range of stand compositions and structures in the third decade after harvest. Operational data collected through the course of timber sale administration were used to quantify preharvest overstory composition and the distribution and composition of advance regeneration and regeneration 2 years after harvest. Stands were re-measured during their third decade of development. Based on their third-decade compositions, stands were grouped into four distinct classes. The development of each class was then traced by comparing preharvest overstory, advance regeneration, and postharvest regeneration compositions between classes. Stands in the OAK class maintained dominance by oaks throughout stand development, resulting in an average of 83.8% oak stocking in the third decade after harvest. Stands in the MIXED and RED MAPLE classes began with lower levels of advance oak regeneration and lost oak dominance relative to preharvest stand compositions. The MIXED class experienced recruitment of pioneer species after harvest, resulting in stands where black birch (Betula lenta L.) and other species are important components, despite being poorly represented as advance regeneration. The RED MAPLE class had abundant red maple (Acer rubrum L.) advance regeneration and lacked postharvest recruitment of oaks or pioneer species, leading to the development of red maple-dominated stands. Stands in the UNSTOCKED class suffered preharvest mortality and regeneration (primarily red maple) declined after harvest, resulting in regeneration failures. The four developmental pathways demonstrate the importance of specific stand conditions at the time of harvest and, to a lesser extent, just after harvest to future stand development. FOR. SCI. 51(1):76–90.
Trees, Crops and Soil Fertility: Concepts and Research Methods
Authors: Nichols J. Doland 
Published: April 2024

Abstract
Up until about 20 years ago, agroforestry literature was generally vague and descriptive–“trees are good and farmers and graziers should plant more of them.” Existing systems, especially ones developed in the tropics, were described, but usually not systematically studied, and an overall optimism about the benefits of trees on farms prevailed. Many years were spent in international research and development projects promoting “agroforestry,” particularly the use of nitrogen-fixing, multiple-use (products and services) trees, especially Leucaena leucocephala. Often farmers have not taken up the recommended systems. Although they may not have phrased it in academic language, their basic objections were something like, “aggressive fast-growing trees will take up space and compete with crops or pasture for water, nutrients, or light; and the benefit-to-cost ratio, at least in the short term, is not favorable.”
Comparison of Nearest Neighbor Methods for Estimating Basal Area and Stems per Hectare Using Aerial Auxiliary Variables
Authors: LeMay Valerie , Temesgen Hailemariam 
Published: April 2024

Abstract
Simulations were used to compare variable-space nearest neighbor methods for imputing stems per ha and basal area per ha (ground measured) for complex stands (many species and sizes) of southeastern British Columbia, Canada. Species composition and other characteristics obtained for every stand by interpreting aerial photography were used as auxiliary variables. The simulations included three distance metrics (squared Euclidean distance, most similar neighbor, and absolute distance), three intensities of stands with full information (20%, 50%, and 80%), two sets of aerial variables (mixed versus moderately high correlations with ground variables), and three averaging methods (nearest neighbor, average of three nearest neighbors, and distance weighted average of three nearest neighbors weighted). Increasing the number of stands with full information to 50% from 20% resulted in increased accuracy, with no noticeable improvement with a further increase to 80%. Of the three distance metrics, the most similar neighbor measure gave good results in imputing stems per ha and basal area per ha, particularly when there was a mixture of correlations, high and moderate, between the auxiliary (aerial) variables, and the ground variables. No large gain was noted in using the average of three neighbors rather than a single neighbor. FOR. SCI. 51(2):109–119.
Is There a Single National Lumber Market in the United States?
Authors: Yin Runsheng , Baek Jungho 
Published: April 2024

Abstract
This article revisits the question of whether the law of one price (LOP) holds for the United States lumber markets, with the most disaggregate data and a large number of price combinations for different products, regions, and species. We also paid close attention to issues related to how we should conduct unit root tests with a potential structural break, whether we should include intercept and time trend in a co-integration model, and what lag length should be chosen. After exhaustive investigations, we find overwhelming evidence supporting the LOP for the entire United States softwood lumber market. We believe that this finding has profound implications on our market modeling and policy analysis. FOR. SCI. 51(2):155–164.
Effects of Vegetation Patches on Soil Nutrient Pools and Fluxes within a Mixed-Conifer Forest
Authors: Erickson Heather E. , Soto Patricia , Johnson Dale W. , Roath Brent , Hunsaker Carolyn 
Published: April 2024

Abstract
At a spatially heterogeneous mixed-conifer forest in the central California Sierras, we quantified total carbon (C) and nitrogen (N), inorganic N, and net N mineralization in organic (O) and surface (0–15 cm) mineral soils, and in situ fluxes of inorganic N and ortho-phosphate using resin lysimeters under three patch types: closed canopy conifer, sparsely vegetated open canopy, and Ceanothuscordulatus thickets. In O horizons, total N and C pools ranked: closed canopy &gt; Ceanothus &gt; open canopy. In mineral soils, total N pools under Ceanothus exceeded those under closed canopy patches by about 30%. For 2 years, nitrate concentrations and rates of net N mineralization in O horizons were 4× greater under Ceanothus than under the other patch types. Similarly, ammonium concentrations and net N mineralization in mineral horizons were more than 80 and 200% greater, respectively, under Ceanothus than under the other patch types. In situ fluxes of nitrate were 4× greater beneath Ceanothus for 1 year, and no differences were found among the patch types for another year. Despite the interannual variability, our data suggest that Ceanothus contributes to a greater proportion of total N mineralized than based on cover alone, and may be important for forest nutrition under current conditions and after forest burning. FOR. SCI. 51(3):211–220.
Biophysical Controls on Soil Respiration in the Dominant Patch Types of an Old-Growth, Mixed-Conifer Forest
Authors: Ma Siyan , Chen Jiquan , Butnor John R. , North Malcolm , Euskirchen Eugénie S. , Oakley Brian 
Published: April 2024

Abstract
Little is known about biophysical controls on soil respiration in California's Sierra Nevada old-growth, mixed-conifer forests. Using portable and automated soil respiration sampling units, we measured soil respiration rate (SRR) in three dominant patch types: closed canopy (CC), ceanothus-dominated patches (CECO), and open canopy (OC). SRR varied significantly among the patch types, ranging from 2.0 to 4.5 µmol m−2 s−1 and from 0.9 to 2.9 µmol m−2 s−1 during the 1999 and 2000 measuring periods, respectively, with the maximum in CECO and the minimum in OC. Multiple peaks of seasonal SRR were functions of soil temperature and moisture dynamics. The relationship between SRR and soil temperature switched from a positive to a negative correlation when soil moisture dropped from saturation to drought. Time lag, as a function of soil moisture, was included in an exponential model to assess the effects of soil moisture on SRR in this seasonal water-stressed ecosystem. The total soil C flux summed by an area-weighted average across all three patch types was 660 ± 163 g C m−2 from May to Oct. 2000. These results may be applicable to other water-stressed forests in the Mediterranean climate zone, and have implications for the conservation of soil carbon. FOR. SCI. 51(3):221–232.
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

Abstract
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

Abstract
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 (&gt;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

Abstract
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

Abstract
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

Abstract
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.