bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling Responses of Ponderosa Pine to Interacting Stresses of Ozone and Drought
Authors: Chen Carl W. , Tsai W. T. , Gomez Luis E. 
Published: April 2024

Abstract
Plant-Growth-Stress Model (PGSM) is a physiologically based process model that integrates the effects of ozone, acid deposition, elevated carbon dioxide, temperature, drought, and nutrient deficiency. The model uses an hourly time step for photosynthesis and a daily time step for all other plant and soil processes. It can be set up to run for as many years as needed. The model was applied to simulate the growth pattern of ponderosa pine seedlings under the experimental conditions of ozone and drought stresses. The simulated diameter and biomass of canopy, roots, and stem were comparable to the measured. Major effect of drought stress was root mortality; however, its sublethal effect on stomata opening caused significant reductions of photosynthesis, canopy, roots, and stem. Ozone stress increased litterfall and decreased canopy. Trees compensated by growing more new needles. The canopy photosynthesis was not reduced to the extent of an across-the-board decrease of roots and stem. Ozone and drought stresses had an antagonistic effect, in which the biomass reductions due to the combined stresses were less than the sum of reductions from individual stresses. However, the observed data indicate a protective effect, not simulated by the model. For. Sci. 40(2): 267-288.
Height Estimation in Stem Analysis Using Second Differences
Authors: Fabbio Gianfranco , Frattegiani Mauro , Manetti Maria Chiara 
Published: April 2024

Abstract
Issa, a new method for estimating heights at different ages from crosscut ring count, is discussed in this paper. Heights corresponding to the location of nodal diaphragms for 27 black pine trees were used as control values to test the precision of the Issa method in comparison with Lenhart's (1972) and Carmean's (1972) methods and with branch whorl method. The algorithms were applied at three different crosscut sampling frequencies (50-100-200 cm). The precision of the methods was tested both in height growth and in annual height increment estimation and the predicted values were analyzed for each sampling frequency. The Issa method was the most precise at a frequency of 50 cm, and the Carmean method was the most precise at a frequency of 200 cm. Lenhart's algorithm produced the least satisfactory estimations independently of crosscut sampling frequency. For. Sci. 40(2):329-340.
Relative Accuracy of a New Base-Age Invariant Site Index Model
Authors: Payandeh Bijan , Wang Yonghe 
Published: April 2024

Abstract
A new base-age invariant site index model was developed based on the constrained version of the Chapman-Richards function. It was compared with that of Goelz and Burk's (1992) in terms of relative accuracy and average bias across a range of potential base ages. The data format for fitting the above models was also simplified. Comparing the models on a set of white spruce (Picea glauca [Moench] Voss) stem analysis data indicated that the choice of predictor age influences the models' accuracy and bias. Except for very young ages, the new model performed as well as that Goelz and Burk's (1992) model in relative accuracy. For. Sci. 40(2):341-348.
Evidence of Reduced Photosynthetic Rates in Old Trees
Authors: Yoder B. J. , Ryan M. G. , Waring R. H. , Schoettle A. W. , Kaufmann M. R. 
Published: April 2024

Abstract
Wood production generally declines as forests age. The decrease in production has been attributed to higher respiration associated with increasing biomass, but direct measurements fail to support this assumption. An alternate hypothesis is that the growth decline is caused by reduced net photosynthesis. To test this hypothesis, we compared the net photosynthetic rates of foliage from trees that had ceased height growth with foliage from actively growing, mature trees. Results showed that net photosynthesis per unit area of 1-yr-old foliage from old Pinus contorta and P. ponderosa averaged 14-30% lower than the same-aged foliage from younger trees. Computer simulations from a previous study indicated that differences of this magnitude are sufficient to explain the lower wood production in old trees. The cause of the photosynthetic decline is not clear, but it did not appear to be due to a reduction in the maximum capacity for photosynthesis. Ratios of stable carbon isotopes from leaves and wood indicated a greater stomatal limitation of photosynthesis in older trees. A possible relationship between lower hydraulic conductance in the vascular systems of older trees leading to greater stomatal closure is discussed. For. Sci. 40(3):513-527.
Basal Area Growth of Individual Trees: A Model Derived from a Regional Longleaf Pine Growth Study
Authors: Quicke Harold E. , Meldahl Ralph S. , Kush John S. 
Published: April 2024

Abstract
An individual tree basal area increment (BAI) model for thinned, even-aged stands of naturally regenerated longleaf pine (Pinus palustris Mill.) is presented. The model is an intrinsically nonlinear equation, which is constrained so that it performs within the bounds of biologically reasonable outputs for any combination of values for the independent variables. All parameters in the equation were estimated simultaneously. This is a departure from the more traditional potential-times-modifier approach in which parameters for a potential growth function are estimated from a sample of trees exhibiting the fastest growth. Independent variables used to describe BAI are stand basal area, the competitive position of an individual tree within the stand calculated as the sum of the basal areas of all trees larger than the subject tree, mean age of dominant and codominant trees, and individual tree diameter outside-bark at breast height. Noticeably absent from the model is an independent variable that explicitly characterizes site differences. For. Sci. 40(3): 528-542.
Surrogates for Foliar Dry Matter in Loblolly Pine
Authors: Valentine Harry T. , Baldwin V. C. , Gregoire Timothy G. , Burkhart Harold E. 
Published: April 2024

Abstract
Surrogates of foliar dry matter of trees commonly are used in applications of modeling and sampling. Some surrogates are linearly related to foliar dry matter. In this study, the linear relation between foliar dry matter (F) and cross-sectional area of the bole at the base of the live crown (A) was examined in loblolly pine (Pinus taeda L.). In addition, a linear relation was established between F and BR, where B is the cross-sectional area of the bole at breast height, and R is the ratio: (length of the live crown)/(tree height minus breast height). Slopes (c1 and c2) of linear models (F = c1 A and F = c2 BR) were estimated with maximum likelihood procedures with data gathered in: (1) June through mid-August 1984, in central Louisiana, (2) August and September 1991, in Virginia and North Carolina, and (3) August and September 1992, in central Louisiana. The estimates of both c1 and c2 obtained from data gathered in June through mid-August were greater than the estimates obtained from the two sets of data gathered in August and September. The estimate of c2 was as precise as the estimate of c1 obtained from each of the three sets of data. BR appears to be as good a surrogate for F as A. Linear relations between foliar dry matter and cross-sectional area of first-order branches in lower, middle, and upper crown strata also were examined. Branches in the lower stratum had less foliar dry matter per unit of cross-sectional area than branches in the other two strata. For. Sci: 40(3):576-585.
A Method to Determine Optimal Stand Data Acquisition Policies
Authors: Ståhl Göran , Carlsson Dick , Bondesson Lennart 
Published: April 2024

Abstract
A method to determine optimal forest stand data acquisition policies is presented. The method is based on a proposal about how timber management planning could be performed, recognizing that stand data cannot be exactly known. It is suggested that decisions be made using probability distributions of values in the calculations instead of point estimates. Within this planning framework, using Bayesian theory, a posterior distribution can be calculated if an inventory is carried out. The probabilities for different posterior distributions can also be calculated. As different distributions may imply different optimal harvest actions, the expected inoptimality losses from erroneous harvest decisions will decrease after an inventory. However, if an inventory is to be an adequate decision, the inventory cost must not be higher than the expected decrease in losses. The numerical results showed that the profitability of inventories depends to a large extent on factors such as the interest rate, stumpage value, compartment size, stand age, and prior distribution of true stand volume. We found inventories to be most profitable if they were undertaken well ahead of calculated optimal harvests. Moreover, we also found that a series of moderately precise but cheap inventories was superior to one single very precise but expensive inventory. For. Sci. 40(4):630-649.
Characterization of Hybrid Poplar Clones for Resistance to the Forest Tent Caterpillar
Authors: Robison Daniel J. , Raffa Kenneth F. 
Published: April 2024

Abstract
Forest tent caterpillar, Malacosoma disstria Hbn., behavioral and developmental interactions with 15 hybrid Populus spp. clones were studied in laboratory and glasshouse trials. Significant differences in larval preference and performance among the clones were found. Larval development time ranged from 30 to 52 days. Second-instar preference and larval development were significantly correlated, but 4th-instar preference and larval development were not. Second- and fourth-instar preferences were not correlated. Clonal productivity and tolerance of defoliation varied significantly, but were not correlated. The relationships between productivity, defoliation tolerance, and insect resistance were examined in regard to plant defense theory, host plant resistance, clonal selections for tree improvement, and assay utility. For. Sci. 40(4):686-714.
Buyer and Seller Behavior in Single-Buyer Stumpage Sales
Authors: Hardie Ian W. , Larson Douglas M. 
Published: April 2024

Abstract
While stumpage sales involving a single buyer are commonly observed, we have no evidence that lack of buyer competition will, in and of itself, result in different stumpage prices. Nor do we have an explanation why such sales continue to be made in markets where stumpage owners can instigate buyer rivalry. Finally we have no theory explaining how buyers decide what to bid when direct competition from other buyers is not present. This paper addresses these three issues. We offer evidence that price differences can exist between single-buyer and multiple-buyer sales. We show why it can be economically rational for nonindustrial private forest owners to conduct single-buyer sales. And we offer a theoretical explanation of buyer bid and owner bid-acceptance decisions in single-buyer sales that is consistent with some previously observed relationships between stumpage prices and owner characteristics. For. Sci. 40(4):759-773.
Observer Variation as a Source of Error in Assessments of Crown Condition Through Time
Authors: Ghosh Sucharita , Innes John L. , Hoffmann Christian 
Published: April 2024

Abstract
Data from the annual assessments of forest condition in Switzerland indicate that there are a number of problems with the collection of even the most basic information relating to forest condition. Of the 13 indices examined, 3 are assessed as continuous variables and 10 as categorical variables. In all cases, significant (P &lt; 0.05) differences were found in 1 or more years between the field teams and the control team(s). For two measures of defoliation, these differences were present in all years. The assessment of the categorical variables was more reliable, but the differences indicate that the data must be treated with caution, even when only two or three relatively simple options are available to the surveyors. The surveyors involved in the work were all experienced foresters who had received a high level of training. The results suggest that many data related to forest measurement and assessment that have been reported in the literature cannot be reliably compared. The results also indicate an urgent need for the intensification of quality assurance work (training and subsequent checking) within the context of forest assessment. For. Sci. 41(2):235-254.
The Effect of Soil Water on Ground Fuel Availability
Authors: Samran Supparat , Woodard Paul M. , Rothwell Richard L. 
Published: April 2024

Abstract
A determination of ground fuel hydration was carried out in an aspen forest in Alberta, Canada. The objectives of the study were: (1) to determine the relative contribution of precipitation and soil water to the upper and lower ground fuel layers, (2) to determine if the moisture status of these layers was affected by slope position (bottom, mid, and top) or distance to a water body, and (3) to determine the drying rates for these two fuel layers. Results showed that upper and lower downed and dead fuels were hydrated by soil water as well as precipitation and that both sources contributed significantly to fuel moisture. During the period May 20 to September 20, 1990, precipitation and soil water contributed about 64% and 36% of the water to fuel moisture contents to the upper layer, and 41% and 59% to the lower layer, respectively. Fuel moisture contents varied significantly by slope position. The bottom slope position was always the wettest, while the fuel moisture contents in the other two positions were similar. In the absence of hydration, the upper and lower litter layers reached equilibrium moisture contents of 15% and almost 22%, respectively, but never dried out completely. For. Sci. 41(2):255-267.
Changes in Albedo of a Northern Hardwood Forest Following Clearcutting
Authors: Bourque Charles P.-A. , Daugharty David A. , Dickison Robert B. B. , Arp Paul A. 
Published: April 2024

Abstract
A semi-empirical model designed to stimulate seasonal and midsummer albedo of a northern tolerant hardwood stand following clearcutting was developed from field determinations conducted in west-central New Brunswick. In this model, changes in albedo are related to (1) vegetative regrowth (spreading of newly developing foliage over the cut area); (2) the gradual addition of vegetation layers within the forest canopy; and (3) seasonal variations from bud burst to fall. The field data indicated that (1) cutting reduced the albedo; (2) foliage regrowth rapidly increased the albedo to a maximum similar to that of a continuous single leaf layer within a few years after the cutting operation; (3) deepening of the canopy gradually decreased the albedo after its initial peak; and (4) albedo values were highest in early summer, except in the first year after the cutting operation. For. Sci. 41(2):268-277.
Potential Volume Yield for Mixed-Species Douglas-Fir Stands in the Northern Rocky Mountains
Authors: Sterba Hubert , Monserud Robert A. 
Published: April 2024

Abstract
A procedure for estimating potential volume yield is developed for stands containing dominant Douglas-fir in the Northern Rocky Mountains. Earlier work on site index and height growth and maximum stand density was the basis for deriving a stand form factor equation that provides potential volume estimates for a continuum of even- to uneven-aged mixed-species stands. The coefficients of this equation (which explained 84% of the variation) differ with respect to habitat type. The combination of asymptotic dominant height, potential basal area, and stand form factor allows for estimating potential total volumes as a function of site index and age of dominant Douglas-fir, habitat type, and the skewness of the dbh1.5-distribution (which characterizes stand structure). Potential volume yield levels vary with respect to habitat type and stand structure (skewness), indicating that much information on potential total volume is lost if only site index is used to measure productivity. These discrepancies between productivity estimates based on site index and potential volume are the result of different yield levels sensu Assmann existing within a given site index class. For the majority of habitat types, volume growth potential would have been underestimated using site index alone. For. Sci. 41(3):531-545.
Chlorophyll Fluorescence as a Measure of Cold Hardiness and Freezing Stress in 1 + 1 Douglas-Fir Seedlings
Authors: Fisker Susan E. , Rose Robin , Haase Diane L. 
Published: April 2024

Abstract
Two-year-old seedlings of Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) from two seed lots with different levels of predicted cold hardiness were grown in separate nurseries. Seedlings were lifted every 4 wk from October 1991 through March 1992 and exposed to controlled freezing temperatures. Fluorescence emissions of the seedlings were measured before and 1 and 3 days after each freezing test. Destructive morphological assessments were made 7 days after freezing. Unstressed seedlings were measured during 6 additional test periods through September 1992. Chlorophyll fluorescence had a significant linear relationship to needle freezing damage and seedling survival, but there was no significant linear relationship between fluorescence of control seedlings and frost hardiness. The LT50 (lethal temperature for 50% of the seedlings) fluorescence measurements, however, tended to be lower before and higher after the seedlings were hardened off. These results indicate that chlorophyll fluorescence is capable of detecting nonvisible damage to seedlings. Continued research may show this to be a valuable tool for rapidly identifying damaged seedlings in nurseries and hence for aiding vital management decisions. For. Sci. 41(3):564-575.
Stochastic Frontier Estimation and Sources of Technical Efficiency in Southern Timber Harvesting
Authors: Carter Douglas R. , Cubbage Frederick W. 
Published: April 2024

Abstract
This research provides estimates of average industry and firm-specific technical efficiency using an econometric stochastic frontier production function for individual firms operating in the southern U.S. pulpwood harvesting industry in both 1979 and 1987. The stochastic frontier production function is capable of distinguishing deviations from the frontier due to uncontrollable stochastic elements, as well as provide a pure measure of technical efficiency. Results indicate that mean industry technical efficiency was nearly constant at 60% in both periods while frontier technical change averaged 1.8% annually over the period. Elements of human capital, technology, and production scale were influential in explaining efficiency differentials among firms. However, the relative influence of these factors changed over time. For. Sci. 41(3):576-593.
Compatible Estimation of Components of Forest Growth from Remeasured Point Samples with Restricted Generalized Least Squares
Authors: Lynch Thomas B. 
Published: April 2024

Abstract
Certain of the estimators which have been proposed for estimation of components of forest growth from remeasured horizontal point samples are not restricted to ensure that the initial volume estimate plus the growth estimate is equal to the final volume estimate. By viewing the initial volume, the final volume, and the components of growth as parameters in a linear model within the framework of restricted generalized least squares, estimates can be obtained which satisfy logical restrictions relating to forest growth. The model should be fitted to data obtained from a relatively large sample of points. Estimates of growth components are obtained on each point in the usual way. However, rather than simply averaging these estimates over all points, restricted generalized least squares can be used to estimate growth components in the linear model described above. Since the estimation technique can handle missing or extra points at the two measurement times, the technique can be applied to data obtained by sampling with partial replacement. For. Sci. 41(3):611-628.
Competitive Relations Between Douglas-Fir and Pacific Madrone on Shallow Soils in a Mediterranean Climate
Authors: Wang Zheng Qi , Newton Michael , Tappeiner John C. 
Published: April 2024

Abstract
A large area of Pacific Coast forests is characterized by shallow soil, with negligible rainfall in the growing season. This study explores water-seeking strategy on such a site. We studied availability of bedrock water and its effects on growth and ecophysiology of 11-yr-old planted Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) and sprouting Pacific madrone (Arbutus menziesii Pursh). The study was carried out at three regulated densities of madrone sprouts on shallow (&lt;50 cm) residual soils in southwest Oregon. Total bedrock water depleted from March to September, as observed in drill holes by neutron probe, did not differ significantly (P &gt; 0.05) among three densities of madrone. However, cover in plots with the highest density of madrone (1322 sprout clumps/ha) depleted 50 mm of water from the 1.5 m layer by June, whereas vegetation on lower density treatments withdrew 15-28 mm by June, with later withdrawal distributed more uniformly through the growing season. Madrone density significantly affected basal diameter (P ≤ 0.0001) and height growth (P ≤ 0.002) of Douglas-fir. Madrone was consistently taller than Douglas-fir in all plots. The height of 11-yr-old madrone sprout clumps (424-465 cm) did not differ significantly among densities. Madrone leaf area index and biomass were higher at the high density of madrone than at medium density (P ≤ 0.045, LAI; P ≤ 0.001, biomass). Physiological advantages and rooting habits of madrone give it a competitive advantage over Douglas-fir in this area that it might not have if bedrock did not provide the principal water reservoir for summer growth. For. Sci. 41(4):744-757.
Design-Based Approaches to Horizontal-Point-Sampling
Authors: Eriksson Marian 
Published: April 2024

Abstract
Horizontal-point-sampling is formalized under three different unequal probability finite population sample designs and an infinite population formulation. All four approaches result in unbiased estimators for the per-area total and the variance of the total. It is argued that, of the four approaches, the infinite population formulation corresponds more closely to the need for per-area estimation and to the physical process of randomization. It results in components of change estimators that are additive over time as well as compatible with net change, and it is easier to explain. Regardless of the view accepted, it is demonstrated that horizontal-point-sampling can be formally described in a variety of ways. Examples provide insight into horizontal-point-sampling and into design-based sampling and the generality of the Horvitz-Thompson estimator. For. Sci. 41(4):890-907.
Procedures to Handle Inventory Cluster Plots that Straddle Two or More Conditions
Authors: Hahn Jerold T. , MacLean Colin D. , Arner Stanford L. , Bechtold William A. 
Published: April 2024

Abstract
We review the relative merits and field procedures for four basic plot designs to handle forest inventory plots that straddle two or more conditions, given that subplots will not be moved. A cluster design is recommended that combines fixed-area subplots and variable-radius plot (VRP) sampling. Each subplot in a cluster consists of a large fixed-area subplot for estimating area and tallying large trees, a microplot (small fixed-area subplot) for tallying small trees, and a variable-radius plot for tallying intermediate size trees. Subplots are assigned a condition class based on a classification algorithm. For subplots that straddle conditions, boundaries are mapped for area estimation, and the condition class of each tree is recorded. For some straddler subplots, there may be insufficient trees for specific conditions to allow unambiguous classification by computer algorithm. We discuss several possible solutions for this problem. For. Sci. Monogr. 31:12-25.