bluuebunny/crossref_metadata_2025_split huggingface dataset:
Genetic Improvement Effects on Growth and Yield of Loblolly Pine Plantations
Authors: Buford Marilyn A. , Burkhart Harold E. 
Published: April 2024

Abstract
A series of hypotheses concerning stand dynamics and growth patterns in loblolly pine plantations of improved stock relative to plantations of unimproved stock were developed and tested. Results of these tests indicated that at the seed source and family levels: (1) the shape of the height-age curve is influenced by the site, but the level of the height-age curve is influenced by the seed source or family; (2) at the seed source and family levels, the shape of the height-diameter relationship at a given age is influenced by the site and by the initial density; and (3) the level of the height-diameter relationship is affected by the seed source or family and is directly related to the dominant height of the seed source or family at that age. Indications are that by choosing the height curve carefully, differences in development among seed sources and families on a given site can be modeled by altering the level of the height-age curve. Data from temporary plots in stands planted operationally with genetically improved stock were used to test for differences in stem quality and volume relationships as compared to comparable plots from unimproved plantations. Stem quality in the improved stands was not substantially different than in unimproved stands in the same region and of the same age range. There was no difference in stem taper or individual tree volume between improved and unimproved stock. Yield equations, based on the independent variables age, average height of dominants and codominants, and surviving number of trees, were fitted to these same plot data from operationally planted improved and unimproved stands. There were no significant differences in the yield equations, indicating that a single yield equation should suffice when the independent variables are correctly specified. For. Sci. 33(3):707-724.
The Impact of Site Value Taxation on the Optimal Time To Cut Timber when Borrowing and Lending Rates Diverge
Authors: Merz Thomas E. 
Published: April 2024

Abstract
The economic literature on forest taxation concludes that the timber cutting time is independent of changes in a site value tax, assuming such changes are fully capitalized into the market value of land. Adopting a continuous-time theoretical model that incorporates an imperfect capital market, it is demonstrated why empirical evidence might reject this hypothesis of "fiscal neutrality." For. Sci. 33(3):763-766.
Ozone Uptake and Effects on Transpiration, Net Photosynthesis, and Dark Respiration in Scots Pine
Authors: Skärby Lena , Troeng Erik , Boström Curt-Åke 
Published: April 2024

Abstract
Ozone uptake, transpiration, net photosynthesis, and dark respiration were studied in the field by using an open gas exchange system in a 20-year-old stand of Scots pine (Pinus sylvestris L.). A current shoot was treated with ozone concentrations ranging from 120 to 400 μg · m-3 during one month. During daytime there was a linear relationship between ozone concentration and ozone uptake, and the deposition rate varied between 0.05 and 0.13 cm · s-1. Ozone at the highest concentrations seemed to decrease transpiration somewhat during daytime. At night, ozone was taken up only at the highest concentration. Both transpiration and stomatal conductance increased at night when ozone concentration was 250 μg · m-3 and higher. There was no significant influence on the net photosynthetic performance during exposure to ozone. Dark respiration, however, increased throughout the experimental period, and the accumulated respiration was about 60% higher for the ozone-exposed shoot at the end of the experiment. For. Sci. 33(3):801-808.
Nitrogen Concentrations in Biomass Components of White Spruce Seedlings in Interior Alaska
Authors: Gordon Andrew M. , Van Cleve Keith 
Published: April 2024

Abstract
Nitrogen concentrations were determined for biomass components of white spruce (Picea glauca [Moench.] Voss) seedlings growing beneath a mature spruce stand and in adjacent cleared areas. Nitrogen concentrations were significantly higher in current needles and roots of seedlings from the clearcut areas. Nitrogen uptake into current needles of seedlings was also significantly increased by harvesting. Root/shoot data generally reflected the more abundant resources (light, water, nutrients) often found in cleared forest areas. There is a potential for using seedlings as a nutrient bioassay indicative of site nutrient regime. For. Sci. 33(4):1075-1080.
The Impact of Soil Degradation on the Expected Present Net Worth of Future Timber Harvests
Authors: Routledge R. D. 
Published: April 2024

Abstract
The standard Faustmann method for computing soil expectation values and economically optimal rotation times ignores potential declines in future soil productivity. In reality, common forestry practices can lead to substantial declines in soil productivity through such factors as soil compaction and nutrient losses. Adjustments to the Faustmann formulation that account for soil degradation are developed in this paper. A dynamic programming algorithm is developed, which permits the assessment of direct, long-term losses associated with destructive logging practices. Sample calculations of these losses demonstrate both the crucial impact of the discount rate and the limited role of projections for distant rotations. For. Sci. 33(4):823-834.
Estimating Genetic Parameters of Height Growth in Seven-Year Old Coastal Douglas-Fir from Disconnected Diallels
Authors: Yeh F. C. , Heaman J. C. 
Published: April 2024

Abstract
A disconnected diallel mating scheme was carried out on 10 sets of 6 parents each for coastal Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco). After 7 growing seasons in 11 plantations, the total phenotypic variation in height was partitioned into portions of additive genetic effect (GCA) within sets, dominance genetic effect (SCA) within sets, interaction of plantations with additive and dominance genetic effects within sets, residual effect, and random error. The GCA effect of the parent trees within the sets was highly significant, and its variance was the most important genetic source of variation. The GCA by plantation interaction was large, and its variance was approximately 42% of the GCA variance. There were some striking rank changes among the parent trees within sets on different plantations, but such changes in the rank within the sets were confined primarily to those parents in the 18th to 82nd percentlie of the 7-year height distribution. The ranks of the top and the worst general combiners within the sets were generally consistent across the plantations. Effects owing to SCA of parent trees and SCA by plantation interaction were also significant, but their variances were small relative to the GCA variance. The heritability estimate appropriate for mass selection on 7-year height was 0.13. The results are discussed in relation to the gains to be expected from tree improvement for the species. For. Sci. 33(4):946-957.
Ontogenetic Patterns of CO2 Exchange of Quercus rubra L. Leaves During Three Flushes of Shoot Growth I. Median Flush Leaves
Authors: Hanson P. J. , Isebrands J. G. , Dickson R. E. , Dixon R. K. 
Published: April 2024

Abstract
Oak (Quercus) seedlings exhibit a pattern of shoot growth known to place demands on carbohydrate and nutrient reserves. This study was designed to determine ontogenetic patterns in CO2 exchange properties of red oak leaves, and to determine if individual leaf CO2 exchange rates (CER) increase in response to the assimilate demand placed on a seedling during flushing. Northern red oak (Q. rubra L.) seedlings were grown in environments favorable for multiple flushes of shoot growth. Measurements of CER on single, attached, median leaves from each flush were made over a range of photosynthetic photon flux densities on plants at nine stages of seedling development through three flushes of growth. Carbon dioxide exchange rate of red oak leaves increased during leaf development up to and beyond full leaf expansion before decreasing —an unusual pattern of photosynthesis during leaf ontogeny. Furthermore, first- and second-flush leaf CER initially decreased and then increased in conjunction with the third flush of shoot growth. These patterns indicate that red oak leaves have a capacity for CER adjustment in response to increased sink demand. For. Sci. 34(1):55-68.
Influence of Ceanothus velutinus and Associated Forbs on the Water Stress and Stemwood Production of Douglas-Fir
Authors: Petersen T. D. , Newton M. , Zedaker S. M. 
Published: April 2024

Abstract
Stem dimensions for two age groups of Douglas-fir growing in the central Cascade Mountains of western Oregon were related to water stress and the amount of interference from dense Ceanothus velutinus and forbs 8 years earlier. In 1978, three regimes were established in four 5-year-old and four 10-year-old stands by means of controls (no treatment) and two herbicide treatments to individual trees in each stand: a partial treatment (C. velutinus eliminated) and a complete treatment (both shrubs and forbs eliminated). In the subsequent year, soil water potential during late summer was &lt; - 1.5 MPa at 10-, 40-, and 100-cm depths, where C. velutinus was growing with forbs. In the absence of shrubs and forbs, soil water potential at 100 cm was near field capacity throughout the 1979 growing season. Predawn stem water potential and Douglas-fir during late summer was significantly lower for trees competing with C. velutinus and forbs than for trees without competitors in the complete treatment, or for trees competing with forbs in the partial treatment, in the four 5-year-old stands and in two of the 10-year-old stands. By 1986, Douglas-fir stems were 2 to 6 cm larger in basal diameter and 1 to 2 m taller in the absence of competitors. Interference from C. velutinus and forbs had a greater effect on stem size of 5-year-old than 10-year-old trees. The correlation between growth and water stress suggests that interspecific competition for soil water during summer drought is a factor limiting stemwood production. For. Sci. 34(2):333-343.
Effects of Timber Harvest on Stream Chemistry and Dissolved Nutrient Losses in Northeast Oregon
Authors: Tiedemann Arthur R. , Quigley Thomas M. , Anderson Tom D. 
Published: April 2024

Abstract
Streamwater chemistry and nutrient inputs and outputs of four small (24 to 118 ha) catchments in the Blue Mountains of eastern Oregon were compared before and after timber harvest treatments. Three harvested watersheds were also compared to a control watershed. Treated watersheds included 41% clearcut in two large blocks; 17% clearcut in 0.8- to 2.4-ha patches; and selection harvest. Residues were piled and burned on the watersheds with clearcuts; on the selection harvest watershed, residues were yarded to an area off-site and burned. Chemical parameters and constitutents measured were: pH, electrical conductivity (EC), nitrate-N (NO3-N), dissolved Kjeldahl N (DKN), total dissolved PO4-P (TDP), calcium (Ca), magnesium (Mg), sodium (Na), and potassium (K). Nitrate-N concentrations in streamflow increased in response to both clearcutting treatments. The maximum level observed (0.52 mg/l) was, however, far below the maximum allowable for drinking water standards (10 mg/l). Concentration of TDP increased significantly on the 41% clearcut watershed and small but significant increases in cation concentrations were observed with both clearcutting treatments. Outputs (kg · ha-t · yr-1) of N increased with both clearcutting treatments but losses were balanced by precipitation inputs. Cation outputs were not affected by harvest treatments. For. Sci. 34(2):344-358.
Dwarf Mistletoes on Western White Pine and Whitebark Pine in Northern California and Southern Oregon
Authors: Mathiasen Robert L. , Hawksworth Frank G. 
Published: April 2024

Abstract
Western white pine (Pinus monticola) is a principal host of Arceuthobium californicum in the Siskiyou Mountains of northern California and southern Oregon, and suffers extensive mortality in some stands. Whitebark pine (P. albicaulis) is a principal host and western white pine is a secondary host for A. cyanocarpum in northern California. Mortality of whitebark pine caused by this dwarf mistletoe on Mount Shasta, California, is as high as 58%. Western white pine is occasionally infected in A. tsugense-infested mountain hemlock stands in California and southern Oregon. However, no infection of western white pine occurred in A. tsugense-infested western hemlock stands in southern Oregon, indicating there are physiologically distinct races of A. tsugense parasitizing western hemlock and mountain hemlock. For. Sci. 34(2):429-440.
Measuring Foliar Flammability with the Limiting Oxygen Index Method
Authors: Mak Edwin H. T. 
Published: April 2024

Abstract
This paper stresses the importance of measuring flammability as a combination of ignitability, sustainability, and combustibility in quantitative terms. The Limiting Oxygen Index (LOI) method is selected and evaluated as a means to measure ignitability and sustainability. The results demonstrated that the technique can distinguish small differences in ignitability and sustainability with good precision. This can be useful for assessing the influence of foliage properties such as chemical composition on these two flammability components. The third component of flammability, combustibility, has to be measured by a different technique. For. Sci. 34(2):523-529.
Effects of Crown Expansion into Gaps on Evaluation of Disturbance Intensity in Northern Hardwood Forests
Authors: Frelich Lee E. , Martin George L. 
Published: April 2024

Abstract
Crown encroachment by trees surrounding newly formed gaps reduces their size, a fact that may cause error in area-based analyses of rate of gap formation and disturbance intensity. Generally, an estimate of proportional area occupied by age classes within a stand of trees can be obtained by determining the age of a selected canopy tree nearby each of randomly or uniformly located sample points. Possible methods of selecting nearby canopy trees include: (1) the nearest-tree selection method, in which the canopy tree with its stem closest to the sample point is chosen; and (2) the overhead-crown selection method, in which the canopy tree whose crown is directly above the sample point is chosen. These two methods of selecting sample trees differ greatly in their sensitivity to crown encroachment. In sugar maple stands, the nearest-tree selection method leads to better estimates of the area originally occupied by a cohort of trees. The overhead-crown selection method leads to an unbiased estimate of area currently occupied by a cohort. For. Sci. 34:(2):530-536.
On the Economic Value of Genetic Progress in Forestry
Authors: Löfgren Karl-Gustaf 
Published: April 2024

Abstract
This paper extends previous analyses of the economics of tree improvement by introducing a number of general theorems on the properties of the present value function as a function of biotechnological parameters. More specifically it is shown how the economic gains from the improvement can be given upper and lower bounds, which to a certain extent are expressable in entities known from current management practices.
The general theorems are derived from a model of a present value maximizing forestry firm with an initial endowment consisting of trees in different age classes, which is facing a competitive environment. However, since certain types of improvements are more easily handled at the stand level, a special section is devoted to the economics of genetic progress at the stand level.
The core results show that straightforward calculation methods often have theoretical support. An empirical application at the end of the paper also shows that the theory has practical implications. For. Sci. 34(3):708-723.
Hazard Rating Forest Sites for Pine Tip Moth, Rhyacionia spp., in the Upper Piedmont Plateau
Authors: Hood W. Michael , Hedden Roy L. , Berisford C. Wayne 
Published: April 2024

Abstract
Hazard rating models for pine tip moths (Rhyacionia spp.) were developed from vegetative, physiographic, and other site characteristics of loblolly pine (Pinus taeda L.) stands in the upper Piedmont of South Carolina. Results of regression models show that site preparation intensity, site index, soil calcium, and depth of the "A" horizon are the most important predictors of tip moth infestation levels. For management of loblolly pine, minimum site preparation and forest practices that favor high site quality will reduce the hazard of tip moth. The severity of tip moth damage to loblolly pine stands is inversely related to site quality and positively related to the intensity of site preparation. For. Sci. 34(4): 1083-1093.
Mathematical Analysis and Modeling of Epidemics of Rubber Tree Root Diseases: Probability of Infection of an Individual Tree
Authors: Chadoeuf J. , Joannes H. , Nandris D. , Pierrat J. C. 
Published: April 2024

Abstract
The spread of root diseases in rubber tree (Hevea brasiliensis) due to Rigidoporus lignosus and Phellinus noxius was investigated epidemiologically using data collected every 6 months during a 6-year survey in a plantation. The aim of the present study is to see what factors could predict whether a given tree would be infested at the following inspection. Using a qualitative regression method we expressed the probability of pathogenic attack on a tree in terms of three factors: the state of health of the surrounding trees, the method used to clear the forest prior to planting, and evolution with time. The effects of each factor were ranked, and the roles of the various classes of neighbors were established and quantified. Variability between successive inspections was small, and the method of forest clearing was important only while primary inocula in the soil were still infectious. The state of health of the immediate neighbors was most significant; more distant neighbors in the same row had some effect; interrow spread was extremely rare. This investigation dealt only with trees as individuals, and further study of the interrelationships of groups of trees is needed. For. Sci. 34(4):831-845.
Stochastic Representation of Fire Occurrence in a Wildland Fire Protection Planning Model for California
Authors: Fried J. S. , Gilless J. K. 
Published: April 2024

Abstract
A fire occurrence module was developed for CFES-IAM Version 2, a stochastic simulation model of initial attack on wildfires in California. The module is designed to generate annual sequences of fire start times that are consistent with local fire history. A three-stage approach was employed: (1) For each day of a simulated fire season, a random draw from a Bernoulli distribution is used to determine if any fires occur; (2) if any do occur, a random draw from a geometric multiplicity distribution determines theft number; (3) ignition times for each fire are then randomly drawn from a time of day (beta or Poisson) distribution. This approach and specific distributional forms were selected after analysis of historical fire records from California's Sierra foothills and Central Valley. Fire sequences generated with the module appear to capture historical patterns with respect to diurnal distribution, interfire times, and total number of fires per year. For. Sci. 34(4):948-959.
Gains Expected from Clonal Orchards under Alternative Breeding Strategies
Authors: Cotterill Paul P. , Jackson Neville 
Published: April 2024

Abstract
Gain equations were developed under the assumption of an additive genetic model and were used to calculate responses from clonal seed orchards under six strategies for breeding trees. The six strategies involve combinations of phenotypic or combined index selection to establish orchards, and polycross, single-pair, or half-diallel mating for progeny testing to cull orchards and for regenerating the breeding population. Open-pollinated mating was considered for progeny testing only.
Combined index selection with half-diallel mating produced the greatest gains from orchards. Single-pair mating used in conjunction with open-pollinated progeny testing proved to be the next best option under the range of heritabilities studied (heritabilities from 0.05 to 0.6). However, combined index selection with single-pair mating (and no open-pollinated testing) was also very efficient. Combined index selection with poly-cross mating produced substantial gains from culled orchards but was less appealing for unculled orchards. For. Sci. 35(1):183-196.
Microgeographical Patterns of Allozyme Differentiation in Douglas-Fir from Southwest Oregon
Authors: Moran G. F. , Adams W. T. 
Published: April 2024

Abstract
The genetic structure of stands of Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco var. menziesii) from two areas in southwest Oregon was examined. In the Little Butte Creek study area, stands on north- and south-facing slopes at each of three elevations were sampled. In the Applegate area, stands on opposing north- and south- facing aspects in each of three V-shaped canyons were sampled at a single elevation. Although considerable genetic variation was present in all stands, no significant differences among stands were found in single-locus measures of genetic diversity. The expected heterozygosity had a mean of 0.164 and a range of 0.128 to 0.189 among stands. Observed heterozygosities were not significantly different from expected heterozygosities. Associations of allele frequencies with slope aspect or elevation were either very weak or lacked consistency between the two study areas. Indeed, only 1.8% of the total genetic diversity could be apportioned among stands. Of this 1.8%, only 13% of the variation could be attributed to differences between aspects. Thus, in marked constrast to variation in the quantitative characters of seedlings as reported in other studies, there was very little allozyme differentiation between stands of different aspect or elevation within populations of Douglas-fir in southwest Oregon. Possible reasons for these conflicting findings are discussed. For. Sci. 35(1):3-15.
Estimating Site Index of Douglas-Fir (Pseudotsuga menziesii [Mirb.] Franco) from Ecological Variables in Southwestern British Columbia
Authors: Green R. N. , Marshall P. L. , Klinka K. 
Published: April 2024

Abstract
Relationships were examined between Douglas-fir site index (at 50 years breast height age), understory vegetation, and site classification units based on 88 sample plots from south coastal British Columbia. Analysis of variance showed differences in site index (P &lt; 0.01) among the site units. Of the regression models tested, the one based on site units plus indicator species groups was most successful in predicting site index (R² = 0.87, SE = 2.96 m, and 75% of cases classified within 3 m of actual site index). The models using indicator species alone as variables had consistently poorer performance, which we attribute largely to inherent variation in understory vegetation. Further testing of the models over a wider range of sites and in earlier seral stages is suggested. For. Sci. 35(1):50-63.
Perceived Scenic Beauty and Contingent Valuation of Forest Campgrounds
Authors: Daniel Terry C. , Brown Thomas C. , King David A. , Richards Merton T. , Stewart William P. 
Published: April 2024

Abstract
Campers' photo-based scenic beauty judgments of 35 forest areas were compared with other campers' photo-based judgments of their willingness to pay to camp at the same areas. A nearly perfect linear relationship was found between the scenic beauty and willingness to pay judgments, indicating that respondents using either response mode were sensitive to the same variations in forest characteristics in providing their judgments. Forest conditions that produced perceptions of greater scenic beauty also increased the value that recreationists verbally assigned to their campground experience. For. Sci. 35(1):76-90.