bluuebunny/crossref_metadata_2025_split huggingface dataset:
Correlated Population Differences in Dry Matter Accumulation, Allocation, and Water-Use Efficiency in Three Sympatric Conifer Species
Authors: Zhang Jianwei , Marshall John D. , Fins Lauren 
Published: April 2024

Abstract
Populations of three sympatric conifer species, Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco), ponderosa pine (Pinus ponderosa Laws.), and western larch (Larix occidentalis Nutt.), were studied for growth, water-use efficiency, and dry matter allocation. Seedlings from seed collected from across the respective natural distributions were grown under two watering regimes. In addition, trees at age 12 for western larch and 20 for ponderosa pine were sampled from experimental plantings. Seedling growth was measured in terms of total dry matter, aboveground dry matter, height, diameter, and relative growth rate; tree growth in the field was measured in terms of height. Dry matter allocation was measured in terms of leaf weight ratio and root weight ratio. Water-use efficiency was measured in terms of biomass production per unit water loss and stable carbon isotope discrimination. Douglas-fir populations differed in all measured variables under both watering regimes (all P ≤ 0.04); correlations between measurements under well-watered and water-stressed conditions were high (0.69 ≤ r ≤ 0.99). Ponderosa pine populations differed consistently in leaf weight ratio and root weight ratio (all P ≤ 0.02), less consistently in growth (0.00 &lt; P ≤ 0.35); and only leaf weight ratio and height were significantly correlated between watering regimes (0.82 ≤ r ≤ 0.85). Western larch populations differed inconsistently in dry matter allocation (0.01 ≤ P ≤ 0.15) and growth (0.00 &lt; P ≤ 0.82); however, population differences in total dry matter, aboveground dry matter, relative growth rate, and leaf weight ratio were significantly correlated between watering regimes (0.56 ≤ r ≤ 0.75). Generally speaking, total dry matter was correlated with water-use efficiency (WUE) but not allocation in western larch, with allocation but not WUE in ponderosa pine, and with both allocation and WUE in Douglas-fir. Similarly, tree height was significantly correlated with carbon isotope discrimination (Δ) in Douglas-fir and in 12-yr-old trees of western larch, but not ponderosa pine. These results suggest that water-use efficiency correlated with growth much more consistently than dry matter allocation. The simplicity of measuring Δ and its stability in this and other studies lead us to suggest that carbon isotope discrimination may be used as a marker for selection and breeding programs to improve growth for Douglas-fir and western larch For. Sci. 42(2):242-249.
Ecophysiology of Seedlings of Oaks and Red Maple Across a Topographic Gradient in Eastern Kentucky
Authors: Barton Andrew M. , Gleeson Scott K. 
Published: April 2024

Abstract
Throughout much of the eastern United States, oaks (Quercus spp.) are being replaced through natural succession by more shade-tolerant species. In Robinson Forest in eastern Kentucky, A. rubrum is numerically dominant in the understory and appears to be successionally replacing five oaks that occur at different topographic positions in upland forests. To help predict future succession, we compared A. rubrum and the five oaks in terms of patterns of gas exchange and water relations in understory seedlings subjected to artificial, saturating light levels. Physiological responses exhibited clear diurnal patterns, but were not strongly related to topography (mesic versus xeric aspects). Despite their different topographic distributions, oaks differed only minimally in responses. The lack of oak species and topographic effects on physiology may have stemmed from nonlimiting moisture conditions during the study. In contrast, A. rubrum exhibited very low A and gww and very high ψleaf compared to the oaks. Furthermore, in the oaks, A was controlled mainly by gwv, whereas in A. rubrum, ψleaf and Tleaf were more strongly correlated with A than was gwv probably reflecting relatively low dehydration tolerance in A. rubrum leaves. Future light regimes should be enhanced by gap-phase dynamics. Under these conditions, the higher photosynthetic capacity of oaks compared to A. rubrum may contribute to higher leaf carbon gain. On the other hand, abundant tall understory A. rubrum may continue preempting light from smaller oak juveniles, promoting eventual replacement of oaks by A. rubrum at Robinson Forest. For. Sci. 42(3):335-342.
A Reservation Value Approach to Harvest Scheduling with Stochastic Stumpage Prices
Authors: Forboseh Philip F. , Pickens James B. 
Published: April 2024

Abstract
This article presents a formulation of the multistand harvest scheduling problem with stochastic stumpage prices, where demand constraints on the periodic yield of some products exist over a long planning horizon. The model incorporates explicit information about future yields and the possibility of a future high stumpage price simultaneously for each analysis area and prescription. The underlying price uncertainty is modeled as a stationary process with normally distributed deviations. A test case, which involves two products, sawtimber and pulp, is introduced to illustrate the formulation. Sawtimber is assumed to be sold on the open market, while a certain periodic pulp harvest is required by contract to supply a mill at a set price. By maximizing the sum of current revenues and future reservation values subject to yield constraints, the model optimally decides when to harvest immature stands in response to low sawtimber prices, while retaining mature areas for future high prices. Results show significant present value improvements and a much greater probability of feasibility compared to traditional formulations. In addition, because of the possibility of a future high price, some stands are retained to and beyond the culmination of mean annual increment, thereby creating a residual forest with a greater diversity of age classes and more mature timber than is the case with traditional formulations. For. Sci. 42(4):465-473.
Regression Methods for Spatially Correlated Data: An Example Using Beetle Attacks in a Seed Orchard
Authors: Preisler Haiganoush K. , Rappaport Nancy G. , Wood David L. 
Published: April 2024

Abstract
We present a statistical procedure for studying the simultaneous effects of observed covariates and unmeasured spatial variables on responses of interest. The procedure uses regression type analyses that can be used with existing statistical software packages. An example using the rate of twig beetle attacks on Douglas-fir trees in a seed orchard illustrates the problem and the recommended statistical procedures. Use of this procedure revealed spatial patterns in beetle attacks that were not otherwise evident. We also found that the covariates, tree vigor, cone crop, and host genotype (i.e., clone) apparently had significant effects on number of beetle attacks within a model that also included location effects. This procedure should prove useful in other situations where spatial trends are of interest in themselves and are not simply viewed as nuisance parameters to be dealt with by the proper experimental design. For. Sci. 43(1):71-77.
Dynamic Selection of Harvests with Adjacency Restrictions: The SHARe Model
Authors: Snyder Stephanie , ReVelle Charles 
Published: April 2024

Abstract
A dynamic forest management model is developed that incorporates spatial and temporal harvesting adjacency restrictions. The spatial harvesting requirements are modeled through the use of 0-1 integer programming models. A variety of different specifications of harvest adjacency constraints is developed and their relative impact on computational efficiency examined. Many researchers have turned to heuristic methods to approach such spatially constrained integer programming problems in the past, especially problems which include harvest flow restrictions. However, the spatially constrained integer programming model developed here, SHARe (Selecting Harvests with Adjacency Restrictions), can be solved optimally. We solve problems up to 441 units on a square grid (21 x 21) using exact optimization methods. Multiple solutions are provided for hypothetical data. In most cases, depending on the structure of the adjacency constraints, the model solved without any or only a few branch and bound nodes. This result is due, in large part, to the model being based on the classic shortest path network flow model, which is known to have special integer solution properties. In addition, we also determined that certain adjacency constraint structures are more favorable to achieving all-integer solutions than others, when used in conjunction with the network flow model developed here. For. Sci. 43(2):213-222.
Implications of Disaggregation in Forest Growth and Yield Modeling
Authors: Ritchie Martin W. , Hann David W. 
Published: April 2024

Abstract
Growth and yield simulators may be characterized with regard to the aggregation structure employed. Individual-tree simulators are an example of a passive aggregation approach. Whole-stand models represent an active aggregation structure. Of particular interest is the disaggregative modeling approach, which employs elements of both individual-tree and whole-stand simulators. The apparent resolution of the disaggregative model is at the tree-level; however, the functional resolution is at the stand level. Disaggregation may be achieved with either additive or proportional allocation of growth. Additive allocation may not ensure positive individual-tree projections of growth. Either may be constrained so as to maintain symmetry between the whole-stand projection of growth and the aggregate of predicted tree growth. Traditionally, the disaggregative approach has seen the application of very simple structures for allocation of growth depending on tree dimension alone. However, the concept may be generalized to include traditional individual-tree growth equations constrained so as to act as an allocation of predicted stand growth. For. Sci. 43(2): 223-233.
Vector Diagnosis of Nutrient Dynamics in Mesquite Seedlings
Authors: Imo Moses , Timmer Victor R. 
Published: April 2024

Abstract
This paper reports an application of vector analysis to interpret temporal interrelationships between plant biomass and nutrient status with time, as demonstrated using young mesquite (Prosopis chilensis) seedlings. Conventional (single dose or constant top dressing), and exponential (pure or modified exponential) fertilization schedules were used to induce contrasting plant nutrient status in the seedlings over a 12 wk growing season. Progressions in nutrient status showed that conventional fertilization resulted in nutrient dilution whereas pure exponential fertilization achieved steady-state nutrient conditions after an initial deficiency. The modified exponential schedule attained steady-state nutrition for most of the experimental period. These trends were similar for all the three elements (N, P, and K). This study demonstrated that dynamic time dependent responses such as steady-state nutrient conditions, nutrient dilution, and accumulation can be identified using traditional vector analysis provided a fourth variable, time (t), is introduced. This approach also allows simultaneous comparisons of multiple elements on the same nomogram, facilitating assessment of differential nutrient absorption during seedling development. For. Sci. 43(2):268-273.
A New Height Growth Model for Dominant and Codominant Trees
Authors: Meng Fan-Rui , Meng Chao Ho , Tang Shouzheng , Arp Paul A. 
Published: April 2024

Abstract
A model was developed to predict height growth for dominant and codominant trees, using asymptotic tree height, and tree height at the age of maximum height growth as principal characteristics to express the influence of site on tree height. The proposed model has many desirable attributes: it (1) produces polymorphic site-index curves, (2) contains an inflection point, (3) asymptotically approaches maximum tree height as age increases, (4) is mathematically defined at the point of origin, and (5) has a theoretical base (pipe model theory) for height growth. Model performance was evaluated with stem analysis data taken from naturally regenerated forest stands of mature to overmature balsam fir (Abies balsamea [L.] Mill.) and black spruce (Picea mariana Mill.) growing in two separate regions within New Brunswick, Canada. The model was also evaluated by analyzing its ability to reproduce existing site index curves for red pine (Pinus resinosa Ait.). The results indicate that the proposed model performs slightly better than an existing 5-parameter model based on the Richards' growth function. For. Sci. 43(3):348-354.
Genetic Control of Rooting Ability of Lodgepole Pine Cuttings
Authors: Fries Anders , Kaya Zeki 
Published: April 2024

Abstract
This study evaluates the genetic control of rooting ability ex vitro for cuttings of lodgepole pine (Pinus contorta var. latifolia Engelm.). More than 200 clones from 21 full-sib families were studied during 4 yr in the greenhouse. Clonal averages in rooting frequency, root size score, shoot extension during rooting, and vitality score were calculated, together with variance components and phenotypic and genetic correlations among variables. Years, families within latitude of origin, clones within families within latitudes, and cutting type (type of shoot used as cutting) had statistically significant effects on rooting traits of cuttings. Years and clones within families had significant effects on height increment. Broad-sense heritabilities of clonal means were 0.55 for rooting frequency, 0.66 for root size, 0.56 for height increment, and 0.34 for vitality. To reduce the nongenetic variation when estimating genetic parameters, cuttings should not be taken from different shoot types. Genetic correlations among the variables were generally negligible. Cutting propagation of lodgepole pine seems possible for producing plants for genetic tests. After refinement of the methods it may also be used operationally, but clones that produce few shoots and have low rooting ability might be lost. For. Sci. 43(4):582-588.
Notes: Effect of Desiccation, Temperature, and Moisture Content on Seed Storage of Three Tropical Tree Species
Authors: Gonzalez J. Eugenio , Fisher Richard F. 
Published: April 2024

Abstract
We studied the viability of seeds of Hyeronima alchorneoides Fr. Allemao, Virola koschnyi Warb. and Vochysia guatemalensis D. Smith in relation to desiccation, seed moisture content, and storage temperature. Seed was either desiccated in chambers with activated silica gel or using air passed through columns of activated silica gel. Two seed moisture contents were achieved: 25-30% and 6-8%. Desiccated seeds were stored at either room temperature (25±1°C ) or in a cold room (4±1°C). Seeds of V. koschnyi and V. guatemalensis did not tolerate the loss of moisture and lost their viability completely. The seeds of H. alchorneoides tolerated desiccation treatments without significant loss of viability. A combination of low temperatures (4±1°C) and low seed moisture content (6-8%) allowed seeds to be stored for 6 mo. However, mean germination was reduced by storage. We also attempted to inhibit the germination of V. guatemalensis by treatment with five concentrations of abscisic acid: 10-4, 10-6, 10-10, 10-15, and 10-20 M. Abscisic acid failed to stop the germination of fresh seeds at any concentration tested. For. Sci. 43(4):595-601.
The Design of Second Best Forest Incentives in Small Open Economies
Authors: Amacher Gregory S. , Rios Monica , Constanino Luis , Brazee Richard J. 
Published: April 2024

Abstract
In this article, we examine the design and choice of forest incentives under second best conditions. The government faces constraints on uses of funds, the government has decided to use a subsidy system despite the welfare costs that exist with these programs, and the government has different preferences for landowner income, nontimber benefits production, and revenue generation. In particular, we examine how government preferences affect the decision to use harvest tax exemptions and the decision to subsidize expansion of the forest tax base through forest conversion. A new approach to studying forest incentive design is proposed where the government is treated as the decision maker and chooses policies to maximize welfare of the forest sector subject to its revenue constraint. This approach allows investigation of efficient reform in an existing forest subsidy system. For an empirical application of the model, we use data from Chile's forest sector to determine short-run dead weight losses of existing subsidies as a basis for reform recommendations. The basic approach in the article should be useful in predicting the behavior of revenue constrained governments. For. Sci 44(1):165-175.
Tax Incidence and Optimal Forest Taxation under Stochastic Demand
Authors: Koskela Erkki , Ollikainen Markku 
Published: April 2024

Abstract
This article examines the incidence and welfare effects of forest taxation in the competitive roundwood markets when future demand for timber is uncertain, thus making the future timber price stochastic. It turns out that the nature of timber price risk is crucial for the behavioral, incidence and welfare effects of forest taxes. Under private risk, when some do well and others poorly, the land site tax is like a pure profit tax and is fully borne by forest owners, while the burden of the yield tax is generally shared by both sides of the market. The incidence of the yield tax does not, however, matter qualitatively for the optimal structure of taxation. It is desirable to supplement the land site tax by a distortionary yield tax, because it provides social insurance by decreasing the after-tax timber price risk, which overweighs its distortionary effect. The level of the optimal yield tax is determined by the trade-off between its social insurance and distortionary effects. Under aggregate risk, when all either gain or lose, government budget constraint is stochastic. Given the optimal land site tax, optimal yield tax is nondistortionary and thus fully borne by forest owners. The neutrality of the optimal yield tax is due to the fact that it has no social insurance role in the presence of aggregate risk. The level of the yield tax depends on the risk attitudes toward variability of after-tax timber revenue and government consumption. For. Sci. 44(1):4-16.
The Optimal Timber Rotation: An Option Value Approach
Authors: Plantinga Andrew J. 
Published: April 2024

Abstract
Previous analyses of the timber rotation problem under price uncertainty find that timber owners can increase the expected values of their stands by using a reservation price policy that exploits stochastic variations in prices. This result is found when the process governing prices is stationary and with nonstationary prices when there are fixed costs. This paper highlights the role of option values in influencing the optimal timing of harvests. In this context, the option value is a premium over the expected net present value of a timber stand reflecting the opportunity cost of harvesting now and foregoing the option to delay harvest until information on future stand values is revealed. With stationary prices, option values arise from two sources of forthcoming information: the level of the stumpage price relative to the long-term mean and the stand value relative to fixed costs. With nonstationary prices, option values are associated only with the latter information. This paper demonstrates analytically that reservation price policies act as a mechanism for incorporating the option value into the calculus of the optimal rotation length. Numerical simulations provide further insights into the effects of option values on rotation lengths, expected stand values, and reservation prices. For. Sci. 44(2):192-202.
Does Thinning Affect Gypsy Moth Dynamics?
Authors: Liebhold Andrew M. , Muzika Rose-Marie , Gottschalk Kurt W. 
Published: April 2024

Abstract
In northeastern U.S. forests there is considerable variation in susceptibility (defoliation potential) and vulnerability (tree mortality) to gypsy moth (Lymantria dispar [L.]). Thinning has been suggested as a way to reduce susceptibility and/or vulnerability. We evaluated how thinning affected the dynamics of gypsy moth populations by experimentally thinning half of each of eight oak-mixed hardwood stands in the Central Appalachians. Population dynamics of gypsy moth were monitored using yearly counts of egg masses, numbers of larvae hatching per mass, estimates of larval density, and weekly collections of larvae and pupae which were reared to quantify mortality due to parasitoids and disease. During the 8 yr study, three stands were heavily defoliated by outbreak populations of gypsy moth, three were sprayed with pesticides accidentally, and two were not disturbed. Egg-mass densities were slightly lower in the thinned portions of the undisturbed stands, but thinning had little or no effect on gypsy moth densities in defoliated and sprayed stands. Variation in mortality of gypsy moth caused by parasitoids and disease was related to variation in egg-mass densities in the current and/or preceding years. After adjusting for the effect of gypsy moth density, thinning had no significant effect on mortality from parasitoids or pathogens. We conclude that any reduction in egg mass densities as a result of thinning is likely related to the reduction in foliar biomass, not increased natural enemy activity. For. Sci. 44(2):239-245.
Reconciling Multivariate Calibrations of Volume Estimates in Two-Phase Forest Inventories
Authors: Magnussen Steen , Boudewyn Paul 
Published: April 2024

Abstract
Univariate approaches to ratio of means calibration of phase I variables in two-phased forest inventories may lead to suboptimal properties when calibrated results are used in a multivariate context, as exemplified by a growth model. Application of bootstrap resampling techniques makes it possible to find a multivariate set of ratios of means with optimum properties in terms of global performance criteria. For. Sci. 44(2):266-271.
Mixed Conifer Forest Mortality and Establishment Before and After Prescribed Fire in Sequoia National Park, California
Authors: Mutch Linda S. , Parsons David J. 
Published: April 2024

Abstract
Pre- and post-burn tree mortality rates, size structure, basal area, and ingrowth were determined for four 1.0 ha mixed conifer forest stands in the Log Creek and Tharp's Creek watersheds of Sequoia National Park. Mean annual mortality between 1986 and 1990 was 0.8% for both watersheds. In the fall of 1990, the Tharp's Creek watershed was treated with a prescribed burn. Between 1991 and 1995, mean annual mortality was 1.4% in the unburned Log Creek watershed and 17.2% in the burned Tharp's Creek watershed. A drought from 1987 to 1992 likely contributed to the mortality increase in the Log Creek watershed. The high mortality in the Tharp's Creek watershed was primarily related to crown scorch from the 1990 fire and was modeled with logistic regression for white fir (Abies concolor [Gord. and Glend.]) and sugar pine (Pinus lambertiana [Dougl.]). From 1989 to 1994, basal area declined an average of 5% per year in the burned Tharp's Creek watershed, compared to average annual increases of less than 1% per year in the unburned Log Creek watershed and in the Tharp's watershed prior to burning. Post-burn size structure was dramatically changed in the Tharp's Creek stands: 75% of trees ≤50 cm and 25% of trees &gt;50 cm were killed by the fire. For. Sci. 44(2):341-355.