bluuebunny/crossref_metadata_2025 huggingface dataset:
The Use of Ordinal Response Methodology in Forestry
Authors: Schabenberger Oliver
Published: April 2024

Ordinal regression techniques are introduced as a means to achieve multiple data analytical goals such as data smoothing for subsequent model derivation and prediction of response distributions conditional on some measurable covariates. Their usefulness to address some pertinent problems in forest biometry are discussed. For. Sci. 41(2):321-336.
Evaluation of Competition Indices in Individual Tree Growth Models
Authors: Biging Gregory S. , Dobbertin Matthias
Published: April 2024

In this paper we explore how well distance-independent competition measures explain variation in the height and diameter squared growth of individual conifer trees. We investigated a number of stand-level density indices and individual tree competition indices which incorporate tree sizes, but do not include location. We model growth of individual trees as potential growth reduced by competition. The reduction in mean square error relative to no competition index was used to judge performance of each competition index which varies by species and growth component (height or diameter squared growth). Results are summarized by species and type of competition index. The distance-independent measures are also compared to selected distance-dependent measures shown in recent research work to perform well for conifer species. It was found that a new class of distance-independent indices that includes estimated crown parameters performs on par with the best distance-dependent competition indices when used in conjunction with models of individual tree height and diameter squared growth. For. Sci. 41(2):360-377.
Growth and Management of Mixed-Species, Uneven-Aged Forests in the French Jura: Implications for Economic Returns and Tree Diversity
Authors: Buongiorno Joseph , Peyron Jean-Luc , Houllier François , Bruciamacchie Max
Published: April 2024

The forests of the Jura mountains are among the most productive in France. This study developed quantitative models to improve the management of these mixed forests of fir, spruce, and beech. A nonlinear matrix model of stand growth was estimated and validated with medium-term projections and simulations of long-term stand dynamics. The ecological criteria were Shannon's index of tree diversity by species and size, the minimum number of trees in any species-size class, and basal area. The economic criteria were the present value of harvests, gross or net of the value of the growing stock, and the rate of return on the capital invested in the growing stock. Linear and goal programming were used to determine the effects, on all criteria, of managements that would maintain the stand in a steady state, and either (i) remove only the dead trees, (ii) maintain the forest close to its current state, (iii) achieve economic efficiency, subject to a desired level of diversity, (iv) maximize diversity, with or without constraints on economic returns. The results suggested that a light management could improve tree diversity, relative to natural stand growth. Maximum economic efficiency would require a substantial reduction in basal area and average size of trees, and it would lead to low tree diversity. Maximizing unconstrained tree diversity would be costly. Managements that conciliated diversity and economic efficiency all required a decrease in the basal area of stands, relative to their current state. A simple approach to convert a stand from its current condition to a desired steady state was investigated. For. Sci. 41(3):397-429.
No Long-Term Impact of Carbaryl Treatment on Western Spruce Budworm Populations and Host Trees in the Malheur National Forest, Oregon
Authors: Torgersen Torolf R. , Powell David C. , Hosman Kevin P. , Schmidt Fred H.
Published: April 2024

The effects of a single application of carbaryl on western spruce budworm (Choristoneura occidentalis Freeman) populations on the Malheur National Forest in northeastern Oregon were examined for 7 consecutive years beginning in 1983. Budworm control was evident only in the treatment year, 1983, and the next, 1984. There was little difference in the pattern of budworm population behavior between treated and untreated sites during the 7 yr study. Defoliation of Douglas-fir and true firs was reduced slightly by the carbaryl treatment, but did not translate into increased radial growth. On the contrary, there was a general decline in annual radial increment among host trees in both treated and untreated areas from 1980 to 1987, presumably because of chronic defoliation. For. Sci. 41(4):851-863.
A Multistage Stochastic Programming Model for Sustainable Forest-Level Timber Supply Under Risk of Fire
Authors: Boychuk Dennis , Martell David L.
Published: April 2024

Forest management planning models are highly developed and used extensively, but few explicitly consider the effects of fire and other uncertain losses which can be significant. Previous studies recommended contradictory responses to potential fire loss. We developed forest-level timber management optimization models with deterministic average and stochastic fire loss and used them to develop insight into the impact of uncertainty on forest management planning. Our analysis indicated that producing a stable timber supply requires the establishment of a buffer stock of timber. This strategy reduces the short-term harvest quantity, but increases the expected long-term harvest quantity. Paradoxically, the timber supply is both more stable, and larger. The results are sensitive to the method of regulating timber production: profit maximizing behavior of future producers requires a much greater buffer stock. In addition, bounds on the effect of transportation were developed, conditions where the mean value problem is adequate were identified, and the effect of a downward sloping demand curve was investigated. For. Sci. 42(1):10-26.
Forests, Agriculture, and Child Health in Zaire: A Household Modeling Approach
Authors: Larson Bruce A. , Barnes Grenville , Rogers Glenn , Larson Joy Green
Published: April 2024

In the Kwilu subregion of Zaire, where malnutrition rates are among the highest in rural Zaire, farm households depend directly on forested land for agricultural production and harvesting of nontimber forest products. A nonseparable model of an agricultural household, where production and consumption decisions are simultaneously determined, is developed in this paper based on several specific characteristics of the Kwilu. The model is used to examine the internal nonmarket and external market adjustments that rural households can make when forested land becomes less available to households because of, for example, population growth and deforestation. When forested land becomes less available, the specific conditions are identified where farmers (women) work harder for less return while allocating less time to child care activities. The end result is poorer child health. For. Sci. 42(1):3-9.
Implications of Modern Successional Theory for Habitat Typing: A Review
Authors: Cook James E.
Published: April 2024

The habitat type classification system (HTCS) is widely used in the western United States and has recently been applied in the Lake States. This classification system is based on three premises, two of which are embodied in the Clementsian theory of succession. These premises are (1) the climatic or potential climax is the same for all sites that have similar growing environments within a region, (2)the climax stage of succession reflects the inherent productivity of a site better than any other stage, and (3) after disturbance, the understory stabilizes more quickly than, and independent of, the overstory. The current understanding of succession, disturbance, and interactions between overstory and understory was reviewed and showed that the three premises on which HTCSs are based cannot be accepted a priori as widely applicable. In particular, it was concluded that (1) most sites will never support a climax stage (sensu Clements); (2) disturbances, past land use, and stochastic events can lead to multiple pathways on a single "type" of site; and (3) the overstory often exerts a significant effect on the understory. Thus, a land classification system that relies solely or heavily on vegetation, such as the HTCS, should be based on a new theoretical foundation and incorporate the known variation and stochasticity of vegetation dynamics. This means a new standard and additional analyses must be incorporated during the development of HTCS's so that the systems are more accurate, widely applicable and as useful as possible. For. Sci. 42(1):67-75.
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

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 < 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 < 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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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 >50 cm were killed by the fire. For. Sci. 44(2):341-355.
Technical Note: Nitrogen Supply, Nitrogen Use, and Production in an Age Sequence of Lodgepole Pine
Authors: Olsson Ute , Binkley Dan , Smith F. W.
Published: April 2024

Forest productivity typically declines after reaching a peak early in stand development. Historically this pattern was attributed to constant or declining stand photosynthesis and increasing stand respiration, but this explanation has been largely invalidated by field measurements and modeling. Production in older stands might decline as a result of declining soil nutrient supply. To test this idea, we examined patterns of productivity and nitrogen (N) supply and use in four age classes of lodgepole pine (Pinus contorta Dougl. ex. Loud.) ecosystems in southeastern Wyoming. Aboveground net primary production (ANPP) increased from 2200 kg ha-1 yr-1 at age 30 to 4600 kg ha-1 yr-1 at age 50, then declined to 2000 kg ha-1 yr-1 at age 200. Soil N supply (indexed with ion exchange resin bags) was highest in the 30-yr-old sites, but showed no further pattern with age in older sites. The ratio of ANPP to the supply of N rose sharply from age 30 to age 50, and then declined slowly. The ratio of ANPP to the N actually taken up was high for the three youngest age classes, but declined substantially in the old-growth (200 yr) site. We conclude that the low ANPP of the old-growth stands was probably not driven by changes in stand nutrition; the decline in efficiency of N use indicates some other factor probably constrains productivity of old-growth stands. For. Sci. 44(3):454-457.
Using Expert Judgment to Model Initial Attack Fire Crew Effectiveness
Authors: Hirsch Kelvin G. , Corey Paul N. , Martell David L.
Published: April 2024

An expert judgment elicitation methodology was developed and used to encode subjective assessments of fire crew effectiveness from experienced initial attack crew leaders. During structured individual interviews, experts from four Canadian forest fire management agencies provided assessments of the probability of fire containment (POC) by a "medium" (5- to 7-person) initial attack crew for 35 initial attack scenarios that varied in terms of fire size and head fire intensity. This repeated-measures data was used to develop individual, logistic response curves for 34 of the experts. Analysis of the coefficients of these response curves showed that fire size, fire intensity, and the interaction between size and intensity significantly influenced the POC assessments. Using data for seven ancillary variables concerning the background and experience of the experts, it was found that agency had the greatest influence on the POC estimates. Random coefficient regression modeling was used to develop composite probability of containment models for the entire data set, each agency, and suppression with and without bucketing. For. Sci. 44(4):539-549.
Guided Transect Sampling for Assessing Sparse Populations
Authors: Ståhl Göran , Ringvall Anna , Lämås Tomas
Published: April 2024

Guided Transect Sampling is suggested for transect based surveys when sampling sparse and geographically scattered populations. It is a two-stage design in which wide strips are selected in the first stage followed by a subsampling procedure guided by prior information in the second stage. As a basis for the second stage, the target area is divided into grid-cells containing covariate data obtained, for example, by remote sensing. The general principle can be coupled with different transect based survey methods such as strip sampling or line transect sampling. Also, different strategies for the second stage guidance can be used, resulting in estimators with different properties. In this study, Guided Transect Sampling was compared with a traditional strip survey under different simulated forest conditions. The comparisons indicated that the proposed method can improve the efficiency of transect based inventories of sparse populations. For. Sci. 46(1):108-115.
A Three-Stage Heuristic for Harvest Scheduling with Access Road Network Development
Authors: Clark Mark M. , Meller Russell D. , McDonald Timothy P.
Published: April 2024

In this article we present a new model for the scheduling of forest harvesting with spatial and temporal constraints. Our approach is unique in that we incorporate access road network development into the harvest scheduling selection process. Due to the difficulty of solving the problem optimally, we develop a heuristic that consists of a solution construction stage and two solution improvement stages. We call our approach INROADS and compare it to three other approaches by employing hypothetical example problems with 225 stands (or cut blocks) over a three-period planning horizon. Thirteen example forests that vary in terms of stand value and spatial dispersion are used to evaluate our heuristic, which outperforms the other approaches tested. For. Sci: 46(2):204-218.
Modeling Tree-Ring Growth Responses to Climatic Variables Using Artificial Neural Networks
Authors: Zhang Qi-Bin , Hebda Richard J. , Zhang Qi-Jun , Alfaro René I.
Published: April 2024

Modeling the nonlinear and complex relationships between climate and tree-ring growth is of significance in dendroclimatic studies, but difficult to implement using traditional linear regression approaches. To overcome this difficulty, the technique of Artificial Neural Network (ANN) was employed in this study to develop the growth response models using the climate/growth database for Douglas-fir (Pseudotsuga menziesii var. menziesii [Mirb.] Franco) on southern Vancouver Island, Canada. The results show that the ANN models are able to extract nonlinear growth response patterns from the observed climate/tree-ring datasets, and to generate more accurate predictions than multiple linear regression approaches. The ANN-extracted climate-growth relationships can be displayed by scenario analysis; for example, when all other input variables are held fixed at their means, the limiting effect of April-July precipitation on tree growth decreases with increased precipitation. The main difficulty of applying ANN technique in dendroclimatology is the problem of overlearning (i.e., the ANN learns too many specific climate-growth patterns and loses the ability to generalize between similar climate-growth patterns). This problem can be alleviated by carefully designing the ANN, such as reducing the number of input variables, choosing a variety of training/testing sets, designing partially connected architectures with a small number of neurons in the hidden layer, and using early stopping during training process. The reliability of the derived ANN models is assessed by validation on independent testing datasets. The main advantages of the ANN technique over traditional dendroclimatic approaches are its ability to capture nonlinear climate-growth response, and its nonreliance on preassumed functional relationships for describing the observed datasets. The ANN method introduced in this article is sufficiently general to be applicable to many forest ecological modeling applications. For. Sci. 46(2):229-239.
Asymmetric Day/Night Temperature Elevation: Growth Implications for Yellow-Poplar and Loblolly Pine Using Simulation Modeling
Authors: Constable John V.H. , Retzlaff William A.
Published: April 2024

Using the TREGRO simulation model we examined the relative impact of asymmetric and symmetric elevations of day/night temperatures on 3 yr biomass gain of yellow-poplar (Liriodendron tulipifera L.) and loblolly pine (Pinus taeda L.). Temperature elevation scenarios used were: (1) an asymmetric 0.3°C/0.9°C increase in day/night temperature (T + 0.3/0.9) as observed since the turn of the century; (2) a symmetric 4°C elevation during both day and night periods (T + 4) as predicted by general circulation models; and (3) an asymmetric 2°C/6°C elevation of day/night temperature (T + 2/6). TREGRO incorporates temperature effects on photosynthesis, respiration, growth rate, and phenology. In both species for all temperature elevation scenarios, respiratory increases exceeded photosynthetic increases and reduced belowground growth. In yellow-poplar, belowground growth was reduced by 7.6% in the T + 0.3/0.9 scenario, whereas the T + 4 and T + 2/6 scenarios reduced belowground growth by 145% and 155%, respectively. The elevated temperature scenarios increased total tree biomass of loblolly pine, but belowground growth was reduced by 24%, 111%, and 113% by the T + 0.3/0.9, T + 4, and T + 2/6 scenarios, respectively. Reductions in root biomass at elevated temperatures may influence competitive interactions between forest tree species and susceptibility to environmental fluctuations. For. Sci. 46(2):248-257.
Root Chemistry of Mature Douglas-Fir Differs by Habitat Type in the Interior Northwestern United States
Authors: Moore James A. , Mika Peter G. , Shaw Terry M.
Published: April 2024

Carbon compound concentrations in plant tissues depend on the environment in which plants grow. However, little is known about how these concentrations vary across a range of forest environmental conditions. Our study examined root tissue (phloem, cambium, phellum, and phello-derm) collected from naturally regenerated mature Douglas-fir (Pseudotsuga menziesii var. glauca [Bessn.] Franco) trees in eight stands on three habitat type series encompassing a range of temperature and moisture conditions. The objective was to determine root chemical composition (sugar, starch, phenol, and tannin) differences among the habitat types. Douglas-fir roots collected from dry, warm Douglas fir habitat types had sugar concentrations of 4% compared to 3% for roots from cool, moist habitat types. Root samples collected from Douglas-fir habitat types showed tannin concentrations about double those from grand fir or western redcedar habitat types. Phenol/tannin ratios for the cool, moist habitat types were about double those from warm, dry Douglas-fir habitat types. Roots sampled from western redcedar habitat types had phenol concentrations and phenol/sugar ratios more than 50% higher than those from Douglas-fir and grand fir habitat types. We speculate that root chemistry of Douglas-fir growing on Douglas-fir habitat types could make them more drought resistant but less disease resistant, while Douglas-fir growing on western redcedar types would be less drought resistant but more disease resistant. Douglas-fir growing on warm, dry sites allocated more carbon to tannin production and less to phenols. FOR. SCI. 46(4):531–536.
Optimal Forest Conservation: Competitiveness Versus Green Image Effects
Authors: Koskela Erkki , Ollikainen Markku
Published: April 2024

This article provides a theoretical framework to study the behavioral and welfare effects of forest conservation, which leads to a binding harvesting constraint for landowners. The economy is modeled as a three-stage game by the interaction of the government's conservation policy, with consequent adjustments in the domestic timber market, and in output determination in a Cournot rivalry with the foreign forest industry. More specifically, we study how the forest industry's competitiveness constrains forest conservation and whether the “green image” demand resulting from forest conservation compensates the loss in competitiveness. It is shown that although the green image effect may locally be strong enough to even increase the profits of the domestic forest industry, at the socially optimal forest conservation level it never dominates the competitiveness effect. Hence, there is a trade-off between forest conservation and competitiveness. These findings are robust to the issue of whether timber markets are perfectly or imperfectly competitive. FOR. SCI. 47(2):178–187.
Estimating Contingent Values for Protection from Wildland Fire Using a Two-Stage Decision Framework
Authors: Winter Gregory J. , Fried Jeremy S.
Published: April 2024

The ongoing expansion of human populations into wildland areas dominated by flammable vegetation, and the concomitant increased frequency of uncontrolled wildfires that result in losses of property and human lives, has raised new questions about the optimal level of fire protection. The morphing of the problem conception from minimizing costs plus losses of natural resources to responding to the concerns of people whose homes are at risk has stimulated fire protection planners to account for potential changes in people's well-being beyond what is reflected by insured value. Knowing the perceived value of an increase in collective (agency-provided) fire protection that achieves a risk reduction target can contribute much to policy debates on the restructuring and funding of fire protection infrastructure and fuel management.

To evaluate the utility of contingent valuation for assessing such risk reduction value, the value of collective fire protection at the wildland-urban interface was assessed for residents of a Michigan jack pine forest. Seventy-five percent of the 265 residents interviewed chose to participate in a hypothetical market for a 50% reduction in risk and, on average, were willing to pay over $57 a year for such risk reduction. Results were consistent with a two-stage decision model: (1) participation in the hypothetical market for risk reduction, and (2) how much the risk reduction is worth. Homeowner risk perception and objectively assessed risk both influenced the probability of market participation. For market participants, willingness to pay was related to property value and household income, suggesting that value at risk and ability to pay weigh heavily in this decision. FOR. SCI. 47(3):349–360.
Forest Productivity, Leaf Area, and Terrain in Southern Appalachian Deciduous Forests
Authors: Bolstad Paul V. , Vose James M. , McNulty Steven G.
Published: April 2024

Leaf area index (LAI) is an important structural characteristic of forest ecosystems which has been shown to be strongly related to forest mass and energy cycles and forest productivity. LAI is more easily measured than forest productivity, and so a strong relationship between LAI and productivity would be a valuable tool in forest management. While a linear relationship has been observed between LAI and forest productivity, most of these data have been collected in needle-leaved evergreen stands. The generality and consistency of the relationship between LAI and productivity has not been as well established for deciduous forests.

Leaf area index (LAI) and aboveground net primary production (ANPP) were measured on 16 forest stands in the southern Appalachian Mountains. These stands span a range of elevation, slope position, temperature, and moisture regimes. LAI averaged 5.8 m2 m-2 and ranged from 2.7 to 8.2. ANPP averaged 9.2 Mg ha-1 yr-1 and ranged from 5.2 to ll.8 Mg ha-1 yr-1.

LAI and ANPP decreased significantly from cove to ridge sites, and ANPP decreases significantly from low to high elevation (P < 0.05, linear regression slope). Elevation-related differences in ANPP do not appear to be due to changes in precipitation, leaf nitrogen content, or site N mineralization rates.

Linear ANPP-LAI equations fit to the data measured in this study were significant (P < 0.05). These relationships were not significantly different (P > 0.1) from linear relationships based on data reported in most other studies of ANPP and LAI in eastern deciduous forests of North America. However, the slope of a linear regression model based on North American eastern deciduous forests was significantly different (P < 0.05) from one based on data collected in temperate deciduous forests for the rest of the globe. The differences were slight over the range of observed data, however, and the difference may be due to a narrower range of data for North American deciduous forests. For. Sci. 47(3):419–427.