bluuebunny/crossref_metadata_2025 huggingface dataset:
Species Composition and Diversity During Secondary Succession of Coniferous Forests in the Western Cascade Mountains of Oregon
Authors: Schoonmaker Peter , McKee Arthur
Published: April 2024

Species diversity and community composition were studied at 23 sites on similar western hemlock/Douglas-fir forest habitats, in undisturbed old-growth stands and stands at 2, 5, 10, 15, 20, 30, and 40 years after clearcutting, broadcast burning, and planting with Douglas-fir. Vegetation was sampled with three 5 x 60 m transects at each site. Invading herbs, then invading and residual shrubs, and finally conifers dominated through the first 30 years. Late seral species, which account for 99% of cover in old-growth stands, are nearly eliminated immediately following disturbance, but account for almost 40% of vegetative cover after 5 years, 66% after 10 years, 83% after 20 years, and 97% at 40 years. After an initial drop following disturbance, species diversity trends weakly upward with heterogeneity peaking at 15 years and richness at 20 years. This initially high diversity (higher than that of old-growth stands) is short-lived. After the tree canopy closes, species diversity declines reaching its lowest values at 40 years. Only two species were eradicated after disturbance, both mycotrophs. Pacific Northwest old-growth forests are relatively poor in species, but moderately high in heterogeneity values. For. Sci. 34(4):960-979.
Relationships Between Fuel Properties and Slashburning-Induced Nutrient Losses
Authors: Feller M. C.
Published: April 2024

The relationships between slash load, slash and forest floor consumption variables, and species origin of slash (slash type), and nutrient (N, P, S, K, Na, Mg, and Ca) losses to the atmosphere during slashburning, were studied by burning 50 plots, each 2.25m² in area. The plots contained known amounts of slash materials derived from four major southwestern British Columbia tree species (Tsuga heterophylla, Thuja plicata, Chamaecyparis nootkatensis, and Pseudotsuga menziesii) and were burned under different fire weather conditions. Nutrient losses (g/m²) decreased in the order: N > Ca > S > K > Mg > P > Na and were generally within the range of such losses recorded for operational prescribed burns in western North America. Losses of all nutrients except Na were positively correlated with fuel consumption. Nitrogen and S exhibited the best correlations, whereas no correlations were found for Na. Of the fuel consumption variables considered, depth of forest floor consumed, then total slash consumption, were best correlated with nutrient loss. Losses (g/m²) of most nutrients generally increased with slash load and as slash type changed from Tsuga, to Pseudotsuga to Thuja/Chamaecyparis. This was partly due to the effects of slash load and slash type on fuel consumption, and partly due to their effects on burning-caused changes in nutrient concentrations in slash materials. The study suggests that nutrient losses to the atmosphere during operational slashburns can be minimized by minimizing forest floor and large diameter slash consumption during burning. For. Sci. 34(4):998-1015.
Forest Taxation and Timber Supply Under Price Uncertainty: Perfect Capital Markets
Authors: Koskela Erkki
Published: April 2024

This paper provides a detailed analysis of timber harvest decisions under price uncertainty. Specifically, the relationship between timber supply—in the sense of whether to bring harvest to the market now or in the future—and various forest taxes is analyzed by using an intertemporal consumption-savings model, which is extended to allow for harvesting decisions. In the presence of perfect capital markets and certainty, harvesting decisions of nonindustrial forest owners are independent from their consumption preferences. However, under future timber price uncertainty and risk aversion, harvesting decisions depend on the consumption preferences of forest owners. The implications of this nonseparability between consumption and harvesting decisions are developed for various individual forest taxes as well as for various changes in the structure of forest taxes, which will keep the government's tax revenue constant. Due to the nonseparability, harvest responses to changes in tax rates and in the structure of taxes may differ considerably from those under certainty. For. Sci. 35(1): 137-159.
Forest Taxation and Timber Supply under Price Uncertainty: Credit Rationing in Capital Markets
Authors: Koskela Erkki
Published: April 2024

This paper provides a detailed analysis of timber harvest decisions under price uncertainty and credit rationing. Under these circumstances the Fisherian separation theorem no longer holds. Instead, the harvesting decisions of forest owners depend on their consumption preferences. The implications of this nonseparability between consumption and harvesting decisions under credit rationing are developed for various individual forest taxes as well as for various changes in the structure of forest taxes, which will keep the government's tax revenues constant. The importance of credit rationing lies in the fact that the distribution of revenues between the current and future period affects harvesting decisions. Hence, the taxes and tax policies that affect this revenue distribution bring about liquidity effects, which may make the effects of taxes sharply different from those found in the presence of perfect capital markets. For. Sci. 35(1):160-172.
Radial Gradients in the Specific Gravity of Wood in Some Tropical and Temperate Trees
Authors: Wiemann Michael C. , Williamson G. Bruce
Published: April 2024

Pith to bark wood samples from 20 Costa Rican tropical wet forest and 17 United States temperate forest tree species showed wide variability in specific gravity trends among species. Specific gravity increased significantly from pith to bark in 16 of the tropical tree species. The increases were most dramatic (90-270%) in species that are typically colonizers of clearings and disturbed sites; species of later stages of succession showed moderate increases (20-70%) or, in some instances, no change in specific gravity from pith outward. Statistically significant linear pith to bark trends were found in only four temperate species—two of these increased specific gravity with diameter and two decreased. None of the temperate species showed a change greater than 40%, and no clear relationship between specific gravity pattern and shade tolerance was evident. In tropical wet forests, increase in wood specific gravity with diameter may be an adaptation by shade intolerant species to the highly competitive conditions on disturbed sites. For. Sci. 35(1):197-210.
Anthocyanins in Autumn Leaves of Quaking Aspen in Colorado
Authors: Chang Kuo-Gin , Fechner Gilbert H. , Schroeder Herbert A.
Published: April 2024

Two to three natural clones of quaking aspen (Populus tremuloides Michx.), selected for their yellow-, orange-, and red-colored autumn foliage, were observed during late summer and early autumn for 5 years. Pigments were extracted from both colored and green leaves and the extracts analyzed by paper chromatography. The timing and change of color varied with elevation, between clones at similar elevations, and between years, some clones reaching different peak colors in different years. An apparent, unidentified carotenoid pigment was found to be synthesized in all colored leaves during autumn. Two anthocyanin pigments, previously unreported for quaking aspen, cyanidin-3-glucoside and very probably cyanidin-3-galactoside, were found in both orange- and red-colored leaves but were lacking in yellow-colored leaves. For. Sci. 35(1):229-236.
An Alternative Estimator for Horizontal Point Clusters
Authors: Van Deusen Paul C. , Grender Julie Myers
Published: April 2024

A new approach is suggested here for estimating stand attributes when horizontal point clusters (HPCs) are used. The approach is unbiased with smaller variance than the traditional unbiased estimator for HPCs. The necessary formulas for equidistant 3-point clusters are derived. The new estimator offers an opportunity to reduce variance without changing the sample design. For. Sci 35(1):257-262.
True Separable Costs Versus Accounting-Based Separable Costs in Multiple-Use Forestry
Authors: Hof John G. , Field Richard C.
Published: April 2024

This paper evaluates, theoretically and empirically, the consistency or lack thereof between an economically correct definition of separable costs and a definition commonly applied to accounting data. Conditions under which accounting separable costs would accurately reflect true separable costs and would provide lower bounds for true separable costs are developed theoretically. And, a test case involving multiple-use forestry demonstrates a case where these conditions are not met and biases in both upward and downward directions result. For. Sci 35(1):263-270.
Tree Bucking for Optimal Stand Value with Log Allocation Constraints
Authors: Sessions J. , Olsen E. , Garland J.
Published: April 2024

Many log sellers in the western United States face price schedules requiring that a given percentage of the volume be delivered in logs of a specified length. A simple heuristic procedure was developed for deriving a set of log prices which, when used in making decisions for bucking individual trees, provides nearly optimal stand value while meeting volume-length restrictions. For. Sci. 35(1):271-276.
An Approach to the Estimation of Import Price Elasticities by Supplier
Authors: Blatner Keith A.
Published: April 2024

An approach to the estimation of import price elasticities by supplier was developed for the analysis of multilateral commodity flows, where the brevity of available annual time-series data and the lack of quarterly or monthly series precludes the direct application of more rigorous estimation procedures. Import demand functions were estimated for four commodities and four Western European and Asian countries to empirically evaluate the approach and to identify potential supplier differentiation in the market. Products considered included sulfate and sulfite pulp, and kraft paper and paperboard and paper and paperboard n.e.s. due to the relatively large number of suppliers of these products and the tendency of many importers to regularly purchase these products from a variety of suppliers. Importing countries considered included Italy, Japan, West Germany, and the United Kingdom due to their prominent market positions. Estimated differences in import price elasticities identified in 6 of the 16 models considered were relatively small in magnitude, but significantly different from one another, suggesting that some importers do differentiate among suppliers of selected forest products. For. Sci. 35(1):30-41.
Disturbance-Mediated Accelerated Succession in Two Michigan Forest Types
Authors: Abrams Marc D. , Scott Michael L.
Published: April 2024

In northern lower Michigan, logging accelerated sugar maple (Acer saccharum) dominance in a northern white cedar (Thuja occidentalis) community, and clear-cutting and burning quickly converted certain sites dominated by mature jack pine (Pinus banksiana) to early-successional hardwoods, including Prunus, Populus, and Quercus. In both forest types the succeeding hardwoods should continue to increase in the future at the expense of the pioneer conifer species. In the cedar example, sugar maple was also increasing in an undistrubed, old-growth stand, but at a much reduced rate than in the logged stand. Traditionally, disturbance was thought to set back succession to some earlier stage. However, our study sites and at least several other North American forest communities exhibited accelerated succession following a wide range of disturbances, including logging, fire, ice storms, wind-throw, disease, insect attack, and herbicide spraying. For. Sci. 35(1):42-49.
Variable Selection in Dendroclimatology: An Example Using Simulated Tree-Ring Series
Authors: Arbaugh Michael J. , Peterson David L.
Published: April 2024

Regression analysis is often used to select important climatic variables from a group of candidate variables in dendroclimatology. Model R² and F statistics are commonly used as a measure of the importance of these variables. The reliability of these selections in the presence of substantial unexplained variance has not been previously considered (with the exception of some climatic reconstruction studies). In this study multiple regression analysis with stepwise (forward inclusion and backward elimination), best subsets, and principal components was conducted on simulated tree-ring index series constructed from linear combinations of temperature and precipitation data with varying amounts of white noise. Regression techniques increasingly failed to select correct and/or complete sets of variables with increasing proportions of introduced noise, even with a limited number of candidate variables and a known relationship between predictor and dependent variables. R² estimates were inflated with increasing noise for all techniques used. The results imply that climatic regression models may be incorrectly specified when large proportions of unexplained variability are present. There are implications for the analysis of data in other areas of forestry in which variable selection is attempted with datasets containing large amounts of unexplained variability. For. Sci. 35(2):294-302.
Inbreeding Effective Population Size Under Some Artificial Selection Schemes. II. Normal Distribution of Breeding Values
Authors: Kang Hyun
Published: April 2024

Two selection systems, truncation selection followed by a balanced mating (truncation selection) and a selection scheme that assigns mating frequencies to individuals according to their breeding values (weighting system), were compared with respect to inbreeding effective population size. This comparison was made with the condition that both selection schemes give the same expected performance of selected individuals (selection differential). Breeding values of selected individuals were assumed to be normally distributed on a performance scale. Two functions, linear and Beta, were used to represent weighting systems. The results showed that (1) depending on the distribution of breeding values, inbreeding effective population number of some weighting systems can be greater than that of a truncation selection that generates the same selection differential, and (2) because the difference in inbreeding effective population size using different systems can be substantial, it is worth examining for the presence of desirable weighting systems in practical tree breeding situations. For. Sci. 35(2):303-318.
A Model of National Forest Timber Supply and Stumpage Markets in the Western United States
Authors: Adams Darius M. , Haynes Richard W.
Published: April 2024

This paper presents an aggregate regional model of the National Forest timber supply process and the interaction of National Forest and non-National Forest supply in the determination of regional stumpage prices and harvest volumes. Endogenous elements of National Forest supply include establishment of the appraised price, bid price, volumes sold and unsold, the uncut volume under contract, volumes harvested, and harvest price. Components of the model describe the distribution of volumes sold and harvested by bid price and contract duration classes. Estimation results for bid price relations in several western regions indicate that prices bid for stumpage depend on a short (one-year) distributed lag in product prices and production costs. Application of the full model in the Douglas-fir region suggests that short-term National Forest supply may be more elastic with respect to harvest price than industrial private supply. Model simulations track actual behavior in the Douglas-fir region stumpage market with reasonable accuracy over the period of extreme price and volume movements during 1977-1985. Model projections also appear reasonable and internally consistent in a projection to the year 2000 under a less volatile product market scenario. For. Sci. 35(2):401-424.
Selecting Populations in Tree Breeding: An Alternative to Multiple Comparisons
Authors: Falkenhagen Emile R. , Gibbons Jean D.
Published: April 2024

This paper explains the indifference zone and subset selection methods of selecting populations. We recommend them as preferable to pairwise multiple comparisons for selecting the best genetic material in tree breeding, especially when a large number of groups with small differences must be tested. Subset selection permits the data to determine the number of groups designated as including the best genetic material with preassigned probability. Numerical examples of selection procedures are given. For. Sci. 35(2):425-436.
Interregional Impacts of Forest-Based Economic Activity
Authors: Teeter Lawrence , Alward Gregory S. , Flick Warren A.
Published: April 2024

A view of forest-based economic activity is presented that highlights the interdependence among industries in separate producing regions. Interindustry transactions for the United States and four subregions (the Northeast, South, West, and Midwest states) were obtained from IMPLAN (IMpact analysis for PLANning), the USDA Forest Service's input-output modeling system. This information was combined with interregion product trade flow estimates obtained from a gravity model to yield an interregional input-output model of the United States emphasizing forest-based industries. The input-output model is used to determine the interregional output, employment, and income effects of final demand changes for products in particular regions. In general, the model reveals that forest-based industries are regionally interdependent, with the greatest spillover effects associated with forest-based industries in the Midwest and Northeast. For. Sci. 35(2):515-531.
Effects and Adjustments of Competition Bias in Progeny Trials with Single-Tree Plots
Authors: Magnussen Steen
Published: April 2024

A competition model based on the height difference between a subject tree and its neighbors was used to adjust annual growth data (age 1-5) in a close-spaced single tree plot trial of 25 open-pollinated Pinus banksiana progenies. Competition effects in tree height, basal area, and volume growth were estimated within each of eight classes of dominated oppression. This procedure allowed a differential adjustment of family performances of their large plot expectations. It is limited to the absence of competition effects on height growth. Response to competition was the same in all families. Variance components and heritability estimates of basal area and stem volume were inordinately inflated by competition. For. Sci. 35(2):532-547.
Characterizing Spatial Patterns of Gypsy Moth Regional Defoliation
Authors: Liebhold Andrew M. , Elkinton Joseph S.
Published: April 2024

Aerial sketch maps of defoliation caused by the gypsy moth, Lymantria dispar (L.), in Massachusetts from 1961 to 1986 were digitized into an array of 1.9 x 1.9 km cells. Defoliation frequency was mapped by summing defoliation incidence for each cell. Spatial autocorrelation analysis indicated that defoliation was not distributed randomly over the state but was instead distributed in clumps of varying size. Directional spatio-temporal autocorrelation analysis showed no evidence for unidirectional spread of defoliation through time. Yearly defoliation, as a proportion of maximum, was used in a clustering algorithm to categorize different portions of the state in terms of defoliation synchrony, Two-state transition models were used to characterize defoliation initiation and termination. Different regions showed different probabilities of both outbreak initiation and termination. Transition probabilities varied substantially relative to the amount of defoliation in adjoining areas, indicating an apparent "spread" of defoliation. For. Sci. 35(2):557-568.
Growth, Xylem Pressure Potential, and Nutrient Absorption of Loblolly Pine on a Reclaimed Surface Mine as Affected by an Induced Pisolithus tinctorius Infection
Authors: Walker R. F. , West D. C. , McLaughlin S. B. , Amundsen C. C.
Published: April 2024

The effects of Pisolithus tinctorius ectomycorrhizae on survival, growth, xylem pressure potential, and nutrient uptake of loblolly pine on a southern Appalachian coal surface mine were examined. One-year-old bareroot seedlings artificially inoculated with P. tinctorius and control seedlings with Thelephora terrestris ectomycorrhizae were outplanted on a surface-mined site in Tennessee. The site had previously been contoured and hydroseeded with a mixture of herbaceous ground cover species. A soil fertility variable was imposed in the study by broadcast fertilization at outplanting of one-half of the plots of each mycorrhizal treatment at the rate of 336 kg/ha NPK. After 7 years, survival and growth of trees previously inoculated with P. tinctorius were significantly improved relative to control trees. Fertilization elicited a significant reduction in survival and a negligible growth response in trees of both mycorrhizal treatments due primarily to its stimulation of competing herbaceous species. During the third growing season, xylem pressure potential of seedlings with P. tinctorius ectomycorrhizae was significantly less negative than that of control seedlings during a prolonged period of moisture stress. Analyses of foliar samples collected during the third growing season revealed that seedlings infected by P. tinctorius had more NO3 and less Zn in their needles than control seedlings. The results of this study provide evidence that the benefits afforded loblolly pine on surface mines by P. tinctorius ectomycorrhizae include enhanced absorption of water as well as increased uptake of nutrients, and these benefits are not compromised by the presence of competing herbaceous species. For. Sci. 35(2):569-581.
Spectral Characteristics of Tree Components of Balsam Fir and Spruce Damaged by Spruce Budworm
Authors: Leckie D. G. , Ostaff D. P. , Teillet P. M. , Fedosjevs G.
Published: April 2024

Spectral reflectances from 360 to 1100 nm at 5 nm intervals in 6 nm bands were measured with a laboratory spectrometer for samples of the components of balsam fir and white spruce trees defoliated by the spruce budworm. These components included current-year needles, 1-year-old needles, 2-year and older needles, budworm feeding debris, twigs, bark, and lichen. Current-year needles had significantly higher reflectances than older needles in the green and yellow parts of the spectrum. Feeding debris, which is visually red, had a smooth spectral curve of increasing reflectance with wavelength. The greatest difference between needles and feeding debris was in the short near-infrared wavelengths and at the chlorophyll absorption maximum near 670 nm. The reflectance of twigs and bark changed with age and exposure to weathering. Variability in their reflectance was large. There were no distinct narrow band features of twig or feeding debris reflectance, which would be characteristic of defoliation. Lichen is highly reflective, and its presence on branches of defoliated trees will greatly alter branch reflectance characteristics. Changes in spectral reflectance of trees throughout the various stages of a spruce budworm outbreak depend on a complex interrelationship of the reflectances of individual components which, in turn, are complex and changing. For. Sci. 35(2):582-600.
Estimation of Juglans Nigra L. Mating System Parameters
Authors: Rink George , Carroll Elizabeth R. , Kung Fan H.
Published: April 2024

Average heterozygosity, fixation index, and outcrossing rate were estimated for Juglans nigra embryos using starch-gel electrophoretic allozyme data collected from 26 open-pollinated families. Parameter values suggested that inbreeding was a relatively minor component of the black walnut mating system for this population. For. Sci. 35(2):623-627.
Estimating and Interpreting the Variation in the Local Demand for Stumpage
Authors: Majerus Gerard A. , Jackson David H. , Connaughton Kent P.
Published: April 2024

This paper provides a technique for quantifying the precision and assessing the relative reliability of local demand relations that have been derived from estimates of demand and nonlocal supply for stumpage within a region. Evaluation of local demand relations for the ten National Forests in Montana indicated that the forests with the larger timber harvests were more reliable because they had the lower percent standard errors of local demand. The technique should be useful to those who must assess the effect on stumpage prices of changes in public and private timber programs. For. Sci 35(2):628-631.
A Simple Procedure for Mapping Tree Locations in Forest Stands
Authors: Reed David D. , Liechty Hal O. , Burton Andrew J.
Published: April 2024

A procedure is presented for mapping tree locations directly into a Cartesian coordinate system without requiring distance and bearing measurements in the field. An independent check of the locations of 401 trees by different field crews at different times showed the method to be both accurate (with an average difference between the two measurements of 0.01 m) and precise (with the standard deviation of the differences being 0.22 m). The method is most efficient with a three-person crew. The time required to map a given area is dependent on tree density and visibility. In well-stocked (600 to 1100 trees/ha) northern hardwood stands it is possible to map 1 hectare per day with an experienced crew. The procedure is designed for square plots, but it can be adapted easily to circular plots. For. Sci. 35(3):657-662.
Nonindustrial Private Forest Landowners as Timber Marketers: A Field Study of Search for Market Information and Decision Quality
Authors: Rosen Barry Nathan , Kaiser H. Fred , Baldeck Marianne
Published: April 2024

While it is widely assumed that nonindustrial private forest (NIPF) landowners need better information on timber markets, no studies have examined the actual extent, quality, and determinants of NIPF owners' search and decisions. Drawing from the consumer behavior literature on search and decision processes, this paper proposes that because NIPF landowners are nonprofessional marketers, their search and decision processes as sellers may be similar to those they execute as consumers. Based on that theoretical framework, the paper presents the results of a field study of search and usage of market information by NIPF timber marketers in New York state. The study found that owners typically engage in little search and that their harvesting decisions differ greatly from professionally determined norms. The results suggest that future NIPF educational efforts should focus on three objectives: (1) making owners more aware of the returns to better search and decisions, (2) informing owners about the availability, role, and value of alternative sources; and (3) teaching owners how to use that information. For. Sci. 35(3):732-744.
Effects of Chronic Doses of Ozone on Loblolly Pine: Photosynthetic Characteristics in the Third Growing Season
Authors: Sasek Thomas W. , Richardson Curtis J.
Published: April 2024

Gas exchange characteristics of loblolly pine seedlings were measured in the third growing season of ozone fumigations to determine the effects of long-term ozone exposure on photosynthetic capacity. Light and CO2 response curves indicated significant decreases of 21% and 27%, respectively, in light-saturated and CO2-saturated photosynthetic capacities at 2 x ambient ozone (92 ppb 12-hr seasonal mean) compared to charcoal-faltered (CF) air, approximately 0.5 x ambient ozone (29 ppb 12-hr seasonal mean). Differences in the response curves suggest changes in light-harvesting and biochemical efficiencies as well as changes in the activity of RuBP Carboxylase and the regeneration rate of RuBP. Chlorophyll and carotenoid conditions per unit leaf area were decreased at the high ozone treatment in older flushes. Stomatal resistance limited photosynthesis by about 29% in both CF and 2 x ambient ozone treated plants, suggesting that chronic ozone exposure did not affect stomatal control in loblolly pine. For. Sci. 35(3):745-755.
Distance-Dependent Competition Measures for Predicting Growth of Individual Trees
Authors: Tomé Margarida , Burkhart Harold E.
Published: April 2024

Modified distance-dependent competition indices were developed for predicting tree growth in plantations. These modified indices adjust the growth of an average tree up and down depending on the size of competitors as compared to the subject tree. A neighbor larger than the subject tree--dominant neighbor--places the subject tree at a competitive disadvantage, whereas a smaller neighbor--suppressed competitor--places it at a competitive advantage. Dead neighbors are included as a special kind of suppressed neighbor. Based on this philosophy, new versions and modifications of distance-weighted size ratio and area overlap indices were developed and compared to some previously published indices. Data from a spacing study established in eucalypt plantations in Portugal were used for the empirical aspects of this study. Single correlations with growth, on a spacing X age basis, were generally higher for the modified indices than for their original unmodified counterparts. Modified indices, in conjunction with stand-level variables, also performed well in multiple linear regression equations for predicting growth of individual trees. For. Sci. 35(3):816-831.
Study of Production Functions for Modeling Forest Biomass: An Area for Research
Authors: Nautiyal J. C. , Belli K. L.
Published: April 2024

The usefulness of production functions, mathematical descriptions of production processes, has long been recognized by economists in manufacturing industries, and more recently by agricultural scientists in the field of biological production. As increasing emphasis in forestry is placed on short-rotation, intensive crop management it would seem that foresters would also require production functions for rational timber management planning. These functions could be useful in a number of areas such as: crop tree growth prediction, control of stand development, economic analysis for decision-making purposes, and for determining the so-called elasticities of inputs and outputs. A very general functional form that may be appropriate for the development of forestry models is the transcendental logarithmic, or translog, function. Unfortunately, at this time, sufficiently detailed data do not seem to be available for any tree species to estimate a production function that could make sophisticated intensive forest management possible. For. Sci. 35(3):843-849.
Nonsymbiotic Biological Dinitrogen Fixation (Acetylene Reduction) in an Age Sequence of Slash Pine Plantations in North Florida
Authors: DiStefano J. F. , Gholz H. L.
Published: April 2024

An age sequence of slash pine plantations (clearcut site, 9-year-old and 29-year-old plantations) in North Florida was investigated to determine nonsymbiotic biological nitrogen fixation rates in the surface mineral soil (A horizon), decomposing wood, and litter. Rates were measured using the acetylene reduction technique during summer and fall of 1983 and spring of 1984. In order to help determine the factors that affect rates in the mineral soil, three treatments were applied: PK fertilization, prescribed burning, and controls (no treatment). In addition, the added effects of N fertilization were investigated in the 29-year-old plantation. In general, low rates were measured in the mineral soil, especially in the fall and in the 29-yr-old plantation, and high spatial variability was observed in all sites and seasons. Computed maximum values for fixation rates were less than 5 kg N · ha-1 · yr-1, with an average of 2-3 kg N · ha-1 · yr-1. Little or no stimulus was obtained following treatment, although a consistent reduction in the rates occurred with NPK fertilization. Computed rates for the litter layer were very low, less than 0.1 kg N · ha-1 · yr-1. Rates in decomposing wood were considerable, but because of the small area covered by this material, they amount to only a small annual input. For. Sci. 35(3):863-869.
Iron, Copper, and Manganese Complexation by Forest Leaf Litter
Authors: Senesi Nicola , Sposito Garrison , Bradford Gordon R.
Published: April 2024

Natural and acid-treated leaf litter samples from western white pine (Pinus monticola), willow (Salix Sp.), and chinquapin (Castanopsis sempervirens) and their laboratory-prepared complexes with Fe3+, Cu2+, and Mn2+ were characterized chemically by total metal analysis, infrared (IR) spectroscopy, and electron spin resonance (ESR) spectroscopy. Both the natural and the acid-treated litter samples took up large amounts of Fe, Cu, and Mn from 0.1M solutions, complexing the metals in forms of differing stability against extensive water-washing and proton- or metal-exchange treatments. The IR spectra indicated that carboxyl groups were the most important metal-binding sites in the litter samples. The ESR data showed that the complexes of M2+ involved principally electrostatic forces between the hydrated metal ion and oxygen-containing litter ligands. These complexes were water stable at neutral pH, but easily disrupted by proton or metal exchange. The litter samples bound Fe3+ and, to a lesser extent, Cu2+ in highly water-stable complexes involving direct metal ion contact with oxygen-containing litter ligands. Some of these complexes were resistant to highly acidic conditions or to metal exchange, although reversibility was evident when they were reacted with solutions of differing pH or metal composition. Good correlation existed between trends in total metal content and the ESR data for the metal-litter products obtained after various treatments, suggesting that the metal-litter complexes detected spectroscopically were representative of the dominant speciation of the metals in the litter. For. Sci. 35(4):1040-1057.
Ecological Species Groups of Oak Ecosystems of Southeastern Michigan
Authors: Archambault Louis , Barnes Burton V. , Witter John A.
Published: April 2024

Ecological species groups were developed for oak forest ecosystems of southeastern Michigan that had been moderately disturbed. Species groups were determined from field observations and sample plot data arranged and analyzed in association tables. The groups were defined on the basis of species patterns of presence, absence, and coverage values along gradients of soil moisture and fertility. Thirteen ecological species groups were developed using 68 herbaceous and shrub species. Detailed descriptions of the relationships of the groups to soil moisture, soil fertility, and light conditions are presented. A continuum of groups from very dry to wet sites were identified. Some groups had a relatively broad range of soil moisture and fertility, whereas others were relatively narrow in their requirements. The groups were more easily differentiated along a soil moisture gradient compared to a soil fertility gradient. Most of the species within groups had similar ecological responses. There was a certain degree of overlap among the groups and usually more than one group occurred in any ecosystem. Despite disturbances caused principally by cutting, ecological species groups could nevertheless be constituted and were useful in identifying major and minor site differences. However, in such disturbed forests, it is recommended that they be used together with physiographic and soil attributes to estimate site quality or identify ecosystem types. For. Sci. 35(4): 1058-1074.
First-Year Growth of Hybrid Poplar Shoots from Cutting or Coppice Origin
Authors: Bergez Jacques-Eric , Auclair Daniel , Bouvarel Luc
Published: April 2024

Height growth, mortality, and dry woody biomass were studied on hybrid poplar shoots during their first year after coppicing or during the year of establishment from cuttings. Two coppice treatments (1- and 2-year rotations) and two treatments for cuttings (irrigated or not) were compared. A slight delay was observed in the height growth of cuttings compared to coppice treatments, but total height growth was not significantly different between treatments at the end of the growing season. Irrigation reduced mortality during establishment of cuttings. Total biomass produced was higher in the coppice stands, due to a greater number of shoots per stool. Coppice maintained its growth capacity even after the fifth 1-year cycle. For. Sci. 35(4):1105-1113.
Effects of Goats on Understory Vegetation and Fire Hazard Reduction in a Coastal Forest in California
Authors: Tsiouvaras C. N. , Havlik N. A. , Bartolome J. W.
Published: April 2024

This paper examines the effects of goat grazing on understory forage utilization and fire hazard reduction in a 1 ha area of a Monterey pine (Pinus radiata) and red gum (Eucalyptus camaldulensis) forest as well as in a 1 ha area of an adjacent fuelbreak. Stocking rates of 600 Spanish goats/ha for 1 day reduced cover of the brush understory in the forest by 41% and 48% respectively at heights of < 0.5m and 0.5-1.5m. In the fuelbreak stocked at 280 Spanish goats/ha for 3 days the reduction was 46% and 82% at < 0.5m and 0.5-1.5m, respectively. Forage biomass utilization reached 75% in the brush understory and 84% in the fuelbreak. In the brush understory goats grazed more at the upper height (84%) than at the lower (64%). Grazing reduced 1- and 10-hour dead fuels 33% and 58% respectively, while the litter depth was reduced as much as 27%. For. Sci. 35(4):1125-1131.
Factors Affecting the Supply and Demand of Timber from Private Nonindustrial Lands in Sweden: An Econometric Study
Authors: Hultkrantz Lars , Aronsson Thomas
Published: April 2024

This is an econometric study of the roundwood market and, in particular, the supply of roundwood from private nonindustrial forest lands in Sweden from 1961-1984. The independent variables of the supply function are the price of roundwood, the unit felling cost, the net (post-taxation) real rate of return on capital, and the resource inventory of mature trees ready for final feiling. The short-run roundwood demand is dependent on capacity, roundwood short-run average revenue product and the price of roundwood. All the coefficients exhibited the signs suggested by economic theory. For. Sci. 35(4):946-961.
Phenological and Morphological Responses of Mesic and Dry Site Sources of Coastal Douglas-fir to Water Deficit
Authors: Joly Robert J. , Adams W. T. , Stafford Susan G.
Published: April 2024

Patterns of genetic variation in morphological and phenological responses to water deficit are described in seedling progeny of four populations of coastal Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco var. menziesii), sampled from coastal and inland sites in Oregon. Progeny of coastal and inland populations differed for all traits measured, and differences appear to reflect adaptation to the source environment. Inland populations were characterized by early budset, slower rates of shoot extension, and higher root-shoot ratios. A significant fraction of total variability was attributable to differences among families within populations. Little evidence for irrigation X population interaction was found when seedling traits were examined singly. Of 16 traits analyzed, only average daily rate of growth and seedling height had significant interaction terms. Interactions between irrigation and families-within-population were more prevalent. A canonical discriminant analysis was used to identify a subset of variables that best reveals differences among progeny of coastal and inland populations. Implications for seed transfer and for selection and breeding of genotypes suitable for xeric environments are discussed. For. Sci. 35(4):987-1005.
Genetic and Environmental Components of Variation of Site Index in Inland Douglas-Fir
Authors: Monserud Robert A. , Rehfeldt Gerald E.
Published: April 2024

Results from two disparate and independent studies of inland Douglas-fir (Pseudotsuga menziesii [Mirb] Franco var. glauca) were combined to answer the following questions: First, how much variation in site index is associated with genetic variation? Second, what is the relative importance of the genetic and environmental components of phenotypic variation in explaining differences in mean height among stands of mature trees? Third, what is the magnitude of the interaction? An index to genetic variation, based on 3-year seedling height in provenance tests, accounted for approximately 40% of the variation in both 50-year and 100-year dominant height (i.e., site index) among 135 natural stands in northern Idaho and western Montana. Combining the genetic index and simple environmental variables (elevation, habitat series, latitude, longitude) accounted for nearly half the variation in site index. Path analyses estimated a strong correlation (0.76) between genotype and environment, reflecting the steep adaptive clines that are well known for this species. The analysis also indicated that the genotype is about a third more important than the contemporary environment in determining phenotypic variation in dominant height of natural stands. The results suggest that a combined genetic/mensuration model has potential to improve both tree breeding efforts and stand management. For. Sci. 36(1):1-9.
Stability Parameter Estimates for Stem Volume for Loblolly Pine Families Growing in Different Regions in the Southeastern United States
Authors: McKeand S. E. , Li Bailian , Hatcher A. V. , Weir R. J.
Published: April 2024

Stability analyses to evaluate genotype x environment (G x E) interaction for individual stem volume at 8 years of age were conducted in trials of open-pollinated loblolly pine (Pinus taeda L.) families established along an East-West (E-W) transect in coastal Mississippi, Alabama, Georgia, and Florida and along a North-South (N-S) transect from Virginia to Florida. The E-W analysis included 21 sites, and the N-S anlaysis included 20 sites. The stability analyses regressed the family-site means against site means. A family had average stabilty if the slope of the regression line (b) did not differ from the expected value of b = 1.0 and if the coefficient of determination (R²) of the regression was high. The family was unstable but responsive to site changes if the slope was b > 1.0. The family was very stable across sites (i.e., did not respond to site changes) when the slope was b < 1.0 across sites.

The vast majority of the families tested had average stability for volume at age 8. In the E-W tests, 35/43 families had b ≈ 1.0 with high R² values. In the N-S tests, 32/43 had b ≈ 1.0 with high R² values. Although significant G x E interaction was found for the other families in the tests, the biological and economic importance of the interaction was minimal, since there was a relatively strong positive relationship between family stability value (b) and family mean volume performance (r = 0.75 in E-W tests, r = 0.62 in N-S tests). The convergence of the heterogeneous family slopes across sites to a common point indicated that very little family rank change occurred. The stability values in the E-W and the N-S tests were highly correlated (r = 0.94) to each other. With such high repeatability among the 34 common families, the inheritance of stability values appears strong. For. Sci. 36(1):10-17.
Effects of Phosphorus and Ectomycorrhizas on the Carbon Balance of Loblolly Pine Seedlings
Authors: Rousseau J. V. D. , Reid C. P. P.
Published: April 2024

The influence of phosphorus fertilization and mycorrhizal development on net photosynthesis, dry matter, shoot-root partitioning, and shoot dark respiration was examined in loblolly pine. Seedlings, initially grown for 10 weeks under low phosphorus (P) conditions, were either fertilized with 0.1, 1.0, 4.0, 8.0, or 12.0 μg g-1 p and left nonmycorrhizal, or inoculated with three different concentrations of a mycelial slurry of Pisolithus tinctorius and fertilized with only 0.1 μg g-1 p. After an additional 7 weeks, net photosynthetic rate of all seedlings was measured followed by harvesting and determination of P content of foliage, and dry matter of foliage, stem, and roots. Both phosphorus fertilization and mycorrhizal development caused a substantial increase in the net rate of photosynthesis and dry matter accumulation, but neither treatment resulted in significant changes in shoot-root allocation of dry matter or shoot dark respiration. At low and medium levels of mycorrhizal development, the net photosynthetic response to mycorrhizal formation appeared to be due to enhanced P nutrition. However, at high levels of mycorrhizal development, as much as 17% of the total increase in the net photosynthetic rate that resulted from mycorrhizal development, may be attributed to mechanisms other than enhanced phosphorus nutrition. For. Sci. 36(1):101-112.
Improved Chestnut Tree Condition Maintained in Two Connecticut Plots after Treatments with Hypovirulent Strains of the Chestnut Blight Fungus
Authors: Anagnostakis Sandra L.
Published: April 2024

In two forest plots, competing trees were killed or cut around stump sprouts of American chestnut trees. Chestnut blight cankers were treated with hypovirulent (dsRNA-containing) strains at least once a year for 4 years to control the blight disease. Nine years after the first treatment, abnormal cankers were found as far as 75 and 55 meters from the edges of the treatment areas, and strains isolated from these cankers contained dsRNA molecules. The dsRNA was found in strains with vegetative compatibility types different from those of the treatment strains, indicating that dsRNA had spread to other strains and had been maintained in the pathogen population. Trees in areas with abnormal cankers had more live stems per sprout clump and more cankers per live stem than trees in a comparison area with a similar harvest history, and more than trees in an undisturbed forest area. For. Sci. 36(1):113-124.
Nematode-Induced Pine Wilt Disease: Factors Influencing Its Occurrence and Distribution
Authors: Rutherford T. A. , Mamiya Y. , Webster J. M.
Published: April 2024

Bursaphelenchus xylophilus, pinewood nematode, and B. mucronatus are members of the pinewood nematode species complex (PWNSC) from forested areas of the northern hemisphere. In the presence of suitable vectors, pathogenic forms of the PWNSC cause pine wilt disease in susceptible tree species in very warm climates. Pine wilt disease is expressed rarely in the northern hemisphere outside of Japan and south China. The disease is expressed only where susceptible pines have been introduced into environments warmer than their natural climatic range, or where pathogenic isolates of the PWNSC have been introduced into warm climates containing susceptible tree species. It is probable that the pine wilt epidemic in Japan is a result of a pathogenic form of the PWNSC being introduced around the turn of the century. Pine wilt disease has not been recorded for any part of North America, Europe, or Asia where mean daily summer temperatures are 20°C or below regardless of the presence of susceptible trees or pathogenic PWNSC isolates. Some PWNSC isolates from northern regions of Europe and North America move and reproduce more rapidly at lower temperatures than do PWNSC isolates from warmer climates. These characteristics may be factors that contribute to the differences in pathogenicity of different isolates of the PWNSC to different pine species. For. Sci. 36(1):145-155.