bluuebunny/crossref_metadata_2025_split huggingface dataset:
Climate and Productivity of Major Conifer Species in the Interior of British Columbia, Canada
Authors: Nigh Gordon D. , Ying Cheng C. , Qian Hong 
Published: April 2024

Abstract
Lodgepole pine (Pinus contorta var. latifolia Engelm. ex S. Wats.), interior spruce (including Picea glauca (Moench) Voss, P. engelmannii Parry ex. Engelm., P. glauca×engelmannii), and interior Douglas-fir (Pseudotsuga menziesiivar. glauca (Beissn.) Franco) are the most important commercial species in the interior of British Columbia. We develop statistical models to predict site index (a measure of site productivity) from climate for these species. Using data from 193 climate stations, we first developedmodels that predict mean annual temperature, mean temperature of the warmest and coldest months, number of frost-free days, and frost-free period from latitude, longitude, and elevation. With these models and the Parameter-elevation Regressions on Independent Slopes Model (used to predictmean annual and mean summer precipitation), we predict 10 climate attributes for site index plots of lodgepole pine, interior spruce, and interior Douglas-fir. These attributes are then used in regression models to estimate site index. The models allow us to investigate the current relationshipbetween climate (particularly temperature and precipitation) and site productivity for these species. The productivity for all the species studied increased as temperature increased, with lodgepole pine exhibiting the greatest response. The productivity of lodgepole pine and interior Douglas-firalso increased with increasing precipitation, with interior Douglas-fir having a greater response than lodgepole pine. We discuss the application of the models in relation to the impact of climate change on site productivity. FOR. SCI. 50(5):659–671.
Effects of Fertilization with Dolomite Lime+PK or Wood Ash on Root Distribution and Morphology in a Norway Spruce Stand in Southwest Sweden
Authors: Majdi Hooshang , Viebke Claes-Göran 
Published: April 2024

Abstract
Pelleted wood ash (A) or crushed dolomite lime with added potassium and phosphorous (CaMgPK) was applied to plots in a 60-yr-old Norway spruce stand in Southwest Sweden. Eight years later, we measured the effect of these treatments on a number of root parameters, including root biomass and distribution (in different diameter classes), root length density (cm cm-3 soil), specific root length (SRL, m g-1 DM), and number of mycorrhizal root tips. Layers sampled included the humus layer and the upper 30 cm of the mineral soil. The total fine root (0–1 mm) biomass in the mineral soil layer was lower in the A plots than the control plots, and the fine root (1–2 mm) systems were shallower in the A plots compared to both the control and CaMgPK plots. SRL was higher in the humus layer in both the CaMgPK and A plots than in the controls, and higher in the CaMgPK than in the A plots. The number of mycorrhizal root tips was also higher in the treated plots than in the controls, with the highest numbers being found in CaMgPK plots. Based on our results, we conclude that both the CaMgPK and ash treatments resulted in changes in root morphology and, therefore, presumably increased the capacity for nutrient uptake. FOR. SCI. 50(6):802–809.
Book Reviews: Analysis of Ecological Communities
Authors: Battles John J. 
Published: April 2024

Abstract
As an aspiring student in forest ecology, I was never more distressed about my career choice than when a senior graduate student predicted that I would spend more time learning statistics than any other subject. Twenty years later, the contents of my bookshelf and hard drive provide compelling evidence of the truth of this prediction. Community ecology has collected an eclectic mix of multivariate techniques to quantify the relationships among species and their environment. The challenge has always been to sort through the lot to find the most appropriate approach given the question and the data. While I still sometimes pine for the simplicity of a two-way analysis of variance (ANOVA), Bruce McCune and James Grace's book, Analysis of Ecological Communities satisfies my craving for statistical clarity. They provide an exemplary guide to the convoluted terrain of multivariate data analysis.
An Evaluation of Spatial Dependency in Juvenile Loblolly Pine Stands Using Stem Diameter
Authors: Bullock Bronson P. , Burkhart Harold E. 
Published: April 2024

Abstract
A simultaneous autoregressive model (SAR) was used to evaluate the amount of spatial influence juvenile loblolly pine (Pinus taeda L.) stems in a plantation have on one another. The presence of spatial autocorrelation between stems in a stand indicates that the characteristics of one stem are related to the characteristics of neighboring stems. The stands evaluated in this study had planting densities that varied from 747 to 6,727 trees per hectare. The SAR model contains a spatial dependency parameter that captures the inter-tree influences. Analysis on detrended diameter data showed that across ages 2 to 5 for groundline diameter measurements and ages 5 to 11 for breast height diameter measurements, the simultaneous autoregressive model indicated significant spatial dependency parameters in 23.2% of the plots (alpha-level = 0.10). A generally increasing trend in the occurrence of significant spatial influence from 18.2% to 28.4% was noted with an increase in planting density from 747 to 3,364 trees per hectare, beyond which the trend decreased. Estimation of the spatial dependency parameter will aid in describing juvenile competition processes and developing a more precise representation of juvenile forest stands. FOR. SCI. 51(2):102–108.
Influence of Fire and El Niño on Tree Recruitment Varies by Species in Sierran Mixed Conifer
Authors: North Malcolm , Hurteau Matthew , Fiegener Robert , Barbour Michael 
Published: April 2024

Abstract
The influence of fire and climate events on age structure of different species was examined in old-growth mixed conifer in the southern Sierra Nevada. Within a 48-ha stem-mapped sample area, after a mechanical thinning, all stumps were examined for fire scars and 526 stumps were cut to ground level and aged. Before 1865, which was the last widespread fire event, the mean interval between scars for an individual tree was 17.3 years and the mean fire return interval for the period with the greatest number of recording trees was 11.4 years. A significantly greater than expected number of fires occurred in dry La Niña years, but these fires were not significantly larger in size than fires in other years. The response of mixed-conifer recruitment to climate and fire events varied by species. Before 1865, Jeffrey pine and sugar pine recruitment were correlated with wet El Niño years, but only sugar pine establishment was associated with fire. Red fir recruitment did not follow fire events but was associated with El Niño years before and after 1865. Most white fir and incense cedar (84%), including many large-diameter trees (&gt;76 cm dbh), recruited after the last widespread fire in 1865. Although tree distribution is clustered in the southern Sierra Nevada, mixed-conifer groups are not age cohorts because species have different recruitment patterns relative to climate and fire events. In mixed conifer, top-down effects of fire and weather on recruitment are mediated by different species responses to these effects and within-stand differences in where species are located. FOR. SCI. 51(3):187–197.
Stand Conditions Associated with Tree Regeneration in Sierran Mixed-Conifer Forests
Authors: Gray Andrew N. , Zald Harold S. J. , Kern Ruth A. , North Malcolm 
Published: April 2024

Abstract
Fire suppression has significantly increased canopy cover, litter depth, and stem density in many western forests, altering microsite conditions that affect tree seedling establishment. We conducted studies in a mixed-conifer forest in the Sierra Nevada, California, to determine relationships between established understory trees and microsite quality, and to examine the effect of fire intensity and shrub cover on seedling establishment. Most of the conifer species were found on microsites with relatively high soil moisture and relatively low direct solar radiation. All species had greater frequency under shadier conditions except for Jeffrey pine, which was found on drier, more open microsites. Although seedlings were more abundant on mineral soil than expected, intact litter and forest floor was not a barrier to establishment. Mortality of planted seedlings was high, particularly in exposed areas. Although shrub cover may initially aid survival, few conifer saplings were present in shrub-dominated patches, possibly because shrubs can be aggressive competitors for soil moisture. The lack of regeneration, logs, or snags in many openings suggest that large gaps are hostile environments for tree seedlings. Results suggest that reductions in shrub cover may benefit tree establishment, but increasing understory light and decreasing surface soil moisture through canopy cover reductions may not. FOR. SCI. 51(3):198–210.
A Re-Evaluation of Reineke's Rule and Stand Density Index
Authors: Pretzsch Hans , Biber Peter 
Published: April 2024

Abstract
The self-thinning rule established by Reineke in 1933, N α d−1.605 (N, d = number of stems and quadratic mean diameter, respectively) assumes the same allometric relationship between size and density for a wide spectrum of species under self-thinning conditions. We re-evaluate this rule based on 28 fully stocked pure stands of common beech (Fagus sylvatica L.), Norway spruce (Picea abies [L.] Karst.), Scots pine (Pinus sylvestris L.), and common oak (Quercus petraea [Mattuschka] Liebl.) in Germany that date back to the year 1870. OLS regression of the model ln(N) = a + b · ln(d) results in b values of −1.789 for common beech, −1.664 for Norway spruce, −1.593 for Scots pine, and −1.424 for common oak. The allometric coefficient for common beech differs significantly from the other species. There is also a significant difference between the b values of Norway spruce and common oak. Except for Scots pine, the above allometric coefficients deviate significantly (common beech) and close-to-significantly (Norway spruce, common oak) from the coefficient −1.605 postulated by Reineke in 1933. To cover the species–specific oscillation of mortality rates, we additionally calculate the self-thinning coefficient for each survey period. Ecological implications of the species-specific scaling exponents are stressed and consequences regarding tools for regulating stand density are discussed. FOR. SCI. 51(4):304–320.
Provenance Trials of Ponderosa Pine in Northern California
Authors: Kitzmiller Jay H. 
Published: April 2024

Abstract
Growth of 17 ponderosa pine populations transferred within the southern Cascades–Sierra Nevada ranges were tested for 19 years on two contrasting sites, Cherry Hill (CH) and Peanut Springs (PS). Seven additional southern Sierra populations were tested at PS. Results provide guidance to forest managers seeking to reforest ponderosa pine after large wildfires or to improve productivity of plantations. PS represented warm, moist, lower mixed-conifer sites in the central Sierra. CH represented colder, drier climates at the southern limit of the Cascades in upper elevation mixed-conifer. High inherent site productivity at PS was reduced by topsoil displacement and brush competition for moisture and/or nutrients. Contrasting magnitudes and patterns of growth among provenances were expressed between sites. The local provenance at PS outgrew more distant sources by 12 to 74%. However, high elevation, nonlocal Sierra sources grew best at CH, where volume decreased with source latitude and increased with source elevation. All sources had stockier form at CH. In both tests, Sierra sources outgrew and were stockier than Cascade sources; stockiness increased with source elevation. Current results at CH support matching provenance elevation with site, using southern sources. Results at PS strongly support the use of local seed, with allowance for transferring seed to adjacent zones. FOR. SCI. 51(6):595–607.
Litterfall Dynamics of an Evergreen Broadleaf Forest and a Pine Forest in the Subtropical Region of China
Authors: Li Zhi An , Zou Bi , Xia Han-ping , Ren Hai , Mo Jiang-ming , Weng Hong 
Published: April 2024

Abstract
Monthly litterfall was monitored over a 10-year period from an evergreen broadleaf forest (EBF) and a pine forest (PF) in subtropical South China. During this period, litter was also collected bimonthly from the forest floor for 2 years. Total annual litterfall in EBF fluctuated around 9 Mg ha−1 with leaves, branches, and miscellanea accounting for 52.5%, 22.2%, and 25.3%, respectively. Total annual litterfall alternated between high and low values in consecutive years. Storms and pest outbreaks were responsible for most of the peaks in both monthly and annual litterfall. Litter from each of 43 species was recorded, but 9 species contributed about 85% of total litterfall. Dominant species shed their leaves in a more regular pattern with peaks mainly from Jan. to Mar. Pine forest (Pinus massoniana) produced much less litterfall than EBF, with a mean of 2.7 Mg ha−1. Here, leaves accounted for 73.2% of total litterfall, branches only 11.4%, and miscellanea 15.4%. Litter on the ground amounted to 5.2 Mg ha−1 in EBF and 2.9 Mg ha−1 in PF. The results show that this climax forest has much higher litterfall and forest floor mass than the pine forest, and litterfall is rather stable with regard to annual variation. FOR. SCI. 51(6):608–615.
BOOK REVIEWS: Valuing Agroforestry Systems: Methods and Applications
Authors: Luckert Martin K. 
Published: April 2024

Abstract
Agroforestry has long been touted as a management approach with potential for gaining synergies between agricultural and forest production. A staple approach in developing-country situations, agroforestry systems are increasingly being considered in developed-country settings. However, socioeconomic analyses of agroforestry systems have long lagged behind natural science contributions. This volume, the second in the series “Advances in Agroforestry,” makes a significant step in promoting the social science importance of agroforestry. The editors have assembled a nice collection of studies regarding the valuation of agroforestry systems around the world, encompassing developing and developed country settings. The approaches used arise largely from an economics disciplinary background, but there is much in here of interest to a broader, multidisciplinary audience.
Cost-Sharing and Private Timber Stand Improvements: A Two-Step Estimation Approach
Authors: Ovaskainen Ville , Hänninen Harri , Mikkola Jarmo , Lehtonen Emmi 
Published: April 2024

Abstract
The effects of cost-sharing and information assistance on nonindustrial private forest owners’ investment in timber stand improvements are analyzed using a two-step estimation method. We use survey data on Finnish nonindustrial private forestland owners’ stand improvements in 1994–1998, including precommercial thinnings, cleaning of seedling stands, and restoration thinnings of juvenile stands. The investment decision is theoretically considered in a two-period model with amenity values. To allow for the joint determination of participation in the cost-sharing program and the decision to invest, a two-step estimation method is used. The predicted probability of using public subsidy from the first-step model is included in the second-step model for the probability or relative extent of stand improvements. For robust inference, quasi-maximum likelihood estimation is applied. Public subsidy, personal assistance, and forest planning expectedly increased the probability of investing. Public subsidy especially had substantial effects on the probability and extent of stand improvements. Besides overcoming the endogeneity of cost-sharing, the two-step approach showed that personal assistance also encourages stand improvements indirectly through its effect on the use of public subsidy.
Detailed Stem Measurements of Standing Trees from Ground-Based Scanning Lidar
Authors: Henning Jason G. , Radtke Philip J. 
Published: April 2024

Abstract
A commercially available pan-and-tilt mount laser scanner was used to acquire data for subsequent three-dimensional modeling and measurement of standing forest trees. Methods were developed for identifying trees in range images and co-registering range images acquired from different vantage points. Upper-stem diameters and branch heights derived from the range images were compared to measurements made after the felling of a small number of loblolly pine (Pinus taeda L.) trees. Tree identification assumed bole cross-sections were circular, estimating their geometric centers at successive heights up the stem. Tree center estimates at multiple heights were then used to co-register images made from different vantage points. Co-registration (x, y) errors did not exceed 2.1 cm in any of the 18 pairwise registrations carried out. Results showed excellent agreement (average error &lt; 1 cm) between the lidar-derived diameter estimates and caliper measurements for bole sections below the base of live crown. Less accurate estimates (&lt;2 cm) were obtained for stem heights up to 13 m. Results indicated the potential for accurate assessment of branch or whorl heights using ground-based scanning lidar, with the greatest accuracy likely to be realized for branches near the base of the live crown and below it.
Horizontal Line Sampling for Riparian Forests without Land Area Estimation
Authors: Lynch Thomas B. 
Published: April 2024

Abstract
Sampling forests in riparian areas presents unique difficulties that can be addressed by judicious application of line sampling. Land areas associated with riparian forests often have highly irregular boundaries, making accurate area determination difficult. Therefore, estimators for total amounts of forest attributes that do not depend on land area are desirable. Such estimators can be obtained by using horizontal line sampling from sample lines that are located at random intervals along a straight baseline and which extend entirely through the riparian area of interest. Horizontal line sampling selects sample trees that subtend an angle whose vertex is located on a length of line. This is conceptually similar to Ståhl's transect relascope sampling (Ståhl, G. 1998. Transect relascope sampling—A method for the quantification of course woody debris. For. Sci. 44:58–63), which estimates total amounts of coarse woody debris from lines established at fixed intervals. Use of a control variate or importance sampling based on predicted line length (where available) is suggested as a variance reduction technique. An unbiased estimator for sampling at intervals along the line is suggested. Monte Carlo integration estimates of riparian land area are proposed for estimation of per-unit area quantities. These estimators could be applied to any forested area but appear to be most well suited to long, relatively narrow riparian areas.
Applying an Efficient k-Nearest Neighbor Search to Forest Attribute Imputation
Authors: Finley Andrew O. , McRoberts Ronald E. , Ek Alan R. 
Published: April 2024

Abstract
This article explores the utility of an efficient nearest neighbor (NN) search algorithm for applications in multisource kNN forest attribute imputation. The search algorithm reduces the number of distance calculations between a given target vector and each reference vector, thereby decreasing the time needed to discover the NN subset. Results of five trials show gains in NN search efficiency ranging from 75 to 98% for k = 1. The search algorithm can be easily incorporated into routines that optimize feature subsets or weights, values of k, distance decomposition coefficients, and mapping.
Base–Age Invariance Properties of Two Techniques for Estimating the Parameters of Site Index Models
Authors: Strub Mike , Cieszewski Chris J. 
Published: April 2024

Abstract
Using eight hypothetical data points (four growth series with two observations each) the difference between two site index curve parameter estimation methods, the base–age invariant stochastic regression approach (BAI) and the method of all base ages (BAA), is illustrated. The anamorphic form of the Schumacher log-transform height–age equation is used for the comparison. The two estimation techniques are equivalent for the linear case of the model but produce different parameter estimates for its nonlinear form. For both linear and nonlinear cases the BAI approach produced a lower root-mean-squared error than the BAA method. Only the BAI approach produced unique estimates for the site-specific parameters of both model forms and both growth series.
Variance Reduction for Sector Sampling
Authors: Lynch Thomas B. 
Published: April 2024

Abstract
Variance reduction techniques used in Monte Carlo integration including control variates and importance sampling can use estimated or actual shapes of vegetated land areas to reduce the variance of estimators from sector sampling. The estimated shapes of forested areas could come from maps, aerial photos, or similar sources. Antithetic variates for variance reduction in Monte Carlo integration can be applied to sector sampling without using any estimated shape or map. Sector sampling selects as samples all trees or other vegetation of interest located in randomly chosen sectors that have a vertex at a common point located in the interior of a forested area. Each sector is associated with an angle of fixed magnitude emanating from the interior point. Sector orientation is based on a randomly selected azimuth originating at the interior point that is the vertex for each sector. This technique is well adapted to application on relatively small areas that have irregularly shaped boundaries. Sector sampling can be demonstrated to be unbiased. Unbiasedness holds with angle reduction for adjustment of sample size and with the variance reduction techniques that are proposed. The method is not restricted to application with trees because sector sampling methods could be applied just as well to other vegetation types or any other objects located in the land area of interest.
Competitiveness in the Sawmills and Wood Preservation Industry in the United States and Canada
Authors: Nagubadi Rao V. , Zhang Daowei 
Published: April 2024

Abstract
We examine relative prices, relative productivity levels, and competitiveness in the sawmills and wood preservation industry in the United States and Canada between 1958 and 2003 by using purchasing power parities and bilateral translog production function. Our results show that the competitiveness of the Canadian industry is facilitated by higher relative productivity levels and depreciation of the Canadian dollar relative to the US dollar on both inputs and outputs in earlier periods, and only due to depreciation of the Canadian dollar in later periods. The average annual rate of productivity growth was higher for the US industry. Although Canadian relative productivity levels were higher before 1994, the US industry's relative productivity level eventually surpassed the Canadian industry.