Yellow Pine Research Articles

Aldo Leopold Among Mountains

Aldo Leopold Among Mountains Marc Hudson (bio) It is possible that Ezekiel respected the soil, not only as a craftsman respects his material, but as a moral being respects a living thing. —Aldo Leopold, "Some Fundamentals of Conservation in the Southwest," 1923 Mountains heaped on mountains to the western horizon. I gaze out from the Clinton Anderson Wilderness Overlook on Route 15, thirty miles of hairpin curves north of Silver City, a sentient mote within the Gila Wilderness of western New Mexico. A few thousand feet below, the Gila River meanders south among its gravel bars, reeds, willows, and frequent sloughs. Above the Gila, a crumbling stegosaurus spine of pale yellow and iron-streaked rimrock. Higher still, the less crenellated spine of the Mogollon Mountains, timbered with yellow pine. And yet more mountains, the Tularosas, layered shadows of them, sequestering the horizon. I drink in the view Aldo Leopold would have known, the timbered country he first measured in board feet and later sought to set aside a vast portion of as wilderness. That shift in vision is part of a remarkable transformation. During those years in the desert Southwest, from 1909 to 1923, when he was in his twenties and early thirties, Leopold lived among those mountains. He was first stationed in Springerville, Arizona, as a newly minted forest ranger, fresh from the Yale School of Forestry. He led timber surveys under the peaks of the White Range and the Blue. In 1911, he was reassigned north and east to the Carson National Forest, which straddles the San Juan and the Sangre de Cristo Mountains in Colorado and New Mexico. Later, at his desk job in Albuquerque, as a Forestry Service administrator, he could see Sandia Peak and the Manzanos out his window. As a boy, in the flatter country of eastern Iowa, his family home on [End Page 640] its bluff in Burlington was favored with a grand view over the Mississippi Valley.1 Mountains held an affectionate place in his imagination, and, throughout his life, Leopold tended to prefer wide views of space and time, ecology and evolution. But he was trained at Yale in the more down-to-earth utilitarianism of Gifford Pinchot, who established the School of Forestry there in 1900. Five years later, Pinchot was appointed by President Theodore Roosevelt to lead the newly created Forest Service.2 Pinchot, like many in the America of his day, feared that the country would not continue to thrive without careful, scientific husbandry of its land and natural resources. The government service that he led applied scientific principles to the stewardship of its forested public lands,3 and the forester whom Yale graduated in 1909 was a convert to the cause. Yet, as biographer Curt Meine suggests, "Leopold did not so much absorb the Pinchot doctrine as adopt it by default."4 Contemplative by nature, he learned his understanding of the land by his constant study of it; the mountains of the Southwest and the effects of human activity upon them taught him much. In the "Arizona and New Mexico" section of A Sand County Almanac, all three of Leopold's essays focus on mountains. White Mountain (in "On Top") and Escudilla Mountain (in "Escudilla") are literal mountains, but the mountain in "Thinking like a Mountain," Leopold's most famous essay, is not named and is more metaphorical than geological. For the older Leopold who wrote this essay in the mid-1940s, the mountain becomes a symbol for an enlightened ecological consciousness. A study of his evolution as an ecological thinker reveals Leopold shifting slowly from his progressive, Pinchot-influenced anthropocentrism toward the summit of that ecological mountain. In his foreword to his 1947 unpublished collection of essays entitled "Great Possessions," the precursor of The Sand County Almanac, Leopold provides some indices for evaluating his progress as a thinker. First, he sees that he evolved from viewing himself as a conqueror who casts the land "in the role of slave and servant" to a man who "assumes the role of citizen in a community of which soils and waters, plants and animals are fellow members, each dependent on the others, and each entitled to his place in...

The Effect of Multiple Knots in Close Proximity on Southern Pine Lumber Properties

Abstract Lumber grade rules address well-spaced single-knot and combination-knot sizes. Information is lacking, however, with respect to multiple knots in close proximity. The term “well-spaced” appears to lack quantitation. This research investigates the effect that knots in close proximity (not necessarily combination knots) have on the strength properties of southern yellow pine (SYP; Pinus spp.) lumber. This study attempts to use a statistical model to determine the modulus of rupture (MOR) for SYP having multiple knots in close proximity using variables including the knot diameter (KD), amount of clear wood (CW) present, knot area (KA), and modulus of elasticity (MOE) of the lumber. This study investigated specimens of 2 by 4-inch SYP dimensional lumber exhibiting multiple knots in close proximity. The basic density (D) was determined by dividing the entire specimen weight by its volume. Third-point bending tests were used in flatwise orientation to quantify the MOR and MOE. There were significant correlations among all parameters analyzed. Multiple regression analysis with one dependent variable, MOR, and three independent variables, KD, MOE, and D, resulted in a coefficient of determination value (r2) of 0.702. When using only the MOE to predict MOR, an r2 value of 0.564 was found.

Industrial-scale Pelletization of Southern Pine Energy Pellets with Various Additives

Abstract. The energy pellet industry desires to improve processing techniques and the characteristics of fuel pellets by including additives with the feedstock. In this study, the industrial-scale pelletization of southern yellow pine (SYP) planer shavings was performed along with experiments involving the effect of production rate and moisture on the energy required for production (measured in kWh Mg-1). Multiple additives were investigated to determine their effects on southern yellow pine pelletization performance and pellet characteristics. These additives included southern-yellow-pine-derived biochar (BC), southern-yellow-pine-derived bio-oil (BO), corn starch (CS), vegetable oil (VO), sweet potatoes (SwP), microcrystalline cellulose (MCC), micronized rubber powder (MRP), and mixed hardwood planer shavings (HW). A control was compared to 20 different treatments at various additive concentrations, and the effect on pellet durability, bulk density, and higher heating value was determined. The production rate of the pellets with additives varied but were able to be compared with the baseline regression line (production rate vs. energy required for production per Mg) control trials so that the appropriate amount of energy required to produce one Mg of biomass could be compared to the control. The data for the additives, which outperformed the control using the economic study, are listed below. The control, HW10%, HW 25%, HW 50%, BC 0.5%, BC 1%, BC 2%, BC 4%, MRP 1%, and BO 0.5% had a mean pellet durability index (PDI) of 97.9%, 98.1%, 98.1%, 97.7%, 98.2%, 98.6%, 98.4%, 98.7%, 98.0%, and 98.0%, respectively. The control, HW10%, HW 25%, HW 50%, BC 0.5%, BC 1%, BC 2%, BC 4%, MRP 1%, and BO 0.5% had mean bulk density values of 703.0, 700.8, 704.8, 692.2, 693.9, 695.6, 695.6, 683.2, 658.8, and 684.6 kg m-3, respectively. The mean higher heating values (HHV) for the control, HW10%, HW 25%, HW 50%, BC 0.5%, BC 1%, BC 2%, BC 4%, MRP 1%, and BO 0.5% were 19.0, 18.9, 18.6, 18.2, 19.4, 19.5, 19.6, 19.6, 19.6, and 19.2, MJ kg-1, respectively. The normalized energy requirements for production for the control, HW10%, HW 25%, HW 50%, BC 0.5%, BC 1%, BC 2%, BC 4%, MRP 1%, and BO 0.5% were 112.0, 110.5, 112.1, 115.3, 110.7, 111.7, 112.1, 118.1, 108.5, and 111.1 kWh Mg-1, respectively. An economic feasibility analysis showed that the discounted net present value (NPV) at a rate of 12% could be improved when using certain pellet additives in the feedstock. The following additives could increase the profit of the mill over just using the control: hardwood planer shavings at 10%, 25%, and 50%, biochar at 0.5%, 1%, 2%, and 4%, MRP at 1% and bio-oil (with volatiles removed) at 0.5% (all on a dry basis). Keywords: Biochar, Biomass pellets, Bio-oil, Corn starch, Hardwood, Micronized rubber powder, Microcrystalline cellulose, Sweet potato, Vegetable oil.

β-Cyclodextrins as sustained-release carriers for natural wood preservatives

Natural preservatives for wood protection have gained increasing attention due to their intrinsic antimicrobial properties, renewability, and lower impact on the environment. We report a study on the use of β-cyclodextrin (βCD) derivatives as sustained-release carriers of allyl isothiocyanate (AITC), as a model natural preservative compound. The formation of AITC inclusion complex in βCDs is qualitatively confirmed by FT-IR and the maximum inclusion yield is estimated to be 39%. Impregnation of wood with the water-borne βCD-AITC complexes allows penetration and even distribution of the preservative in the lumen and possibly in the cell walls. The efficacy of the βCD-AITC complexes as wood preservatives of southern yellow pine is examined by the AWPA E10-16 standard. Compared with the water-treated and AITC-treated wood, βCD-AITC-treated wood exhibits decrease in mass loss from 45% to 25% and no visible cell wall damage after exposure to brown and white rot fungi. The results indicate that βCD suppresses the premature leaching of otherwise volatile AITC and suggests a novel approach of application of volatile or water-immiscible natural preservatives for wood protection.

Ballistic performance of Cross-laminated Timber (CLT)

Cross-laminated Timber (CLT) is a relatively new building material that has gained recent attention in the United States construction industry. CLT is a prefabricated, engineered wood product, composed of three or more plies of lumber with alternating ply directions. CLT is relatively strong and stiff, with the potential to meet the requirements for structures that are subjected to a variety of loading conditions. While CLT’s response to static, dynamic (i.e., seismic), and fire loads has been characterized in the past, its response to the loads seen in force protection scenarios (i.e., blast or ballistic) is much less understood.In order to begin to fill this gap in knowledge, one of the first known sets of ballistic experiments were conducted on CLT and the results were used to develop and validate predictive models. This article describes the results of 122 ballistic experiments conducted at the United States Army Engineer Research and Development Center (ERDC). The experiments were conducted on two species of CLT of varying thicknesses: Spruce Pine Fir-South and Southern Yellow Pine. The experiments measured either penetration depth or residual velocity over a range of intermediate striking velocities. The effects of weathering (i.e., moisture content) were also explored on a data set.The results of the experiments were compared to existing United States Unified Facilities Criteria models for predicting the ballistic response of wood. The findings show the deficiencies in utilizing this wood model for CLT and explore alternate models for prediction. In general, it was found that models that incorporate both projectile and CLT target parameters most accurately predict the response. Most importantly, the results reinforce the necessity for re-calibration of models as new parameters are added to the CLT ballistic characterization database.

School Turnaround: A Rural Reflection of Reform on the Reservation and Lessons for Implementation

Rural communities traditionally enjoy an intimate relationship between stakeholders and the local school system. While preliminary research exists to suggest rural school turnaround might be more likely to occur when a strong communal connection exists (Mette, 2014), little is known about rural school turnaround efforts serving predominantly Native American students. This article reports findings of a School Improvement Grants (SIG) funded effort to digitize curriculum and deliver instruction through the use of tablets in Yellow Pine, a school district on a Native American reservation in a rural, Upper Midwestern state. Data were collected through interviews with school and district leaders, as well as through teacher focus groups. Findings highlight the failure to engage a historically disenfranchised community from the beginning of the improvement process, particularly the lack of involvement of students, parents, and teachers, which in turn led to little impact on student achievement.

Released Volatile Organic Compounds in Southern Yellow Pine before and after Heat Treatment.

As the main material in indoor furniture, southern yellow pine (Pinus spp.) releases volatile organic compounds (VOCs) into the environment during use. To better understand variations in the contents of VOCs in southern yellow pine before and after heat treatment, this study conducts dry heat treatment on southern yellow pine at 140 °C and 220 °C. Headspace solid phase micro-extraction was used to extract VOCs from southern yellow pine. The VOCs of southern yellow pine before and after heat treatment were identified via gas chromatography-mass spectrometry, and chemical component differences were characterized via Fourier transform infrared spectroscopy. Results reveal 86 VOCs in pure southern yellow pine, including alcohols, aromatics, acids, aldehydes, alkanes, alkenes, and some trace compounds (e.g., furans, ketones, phenols, and esters). With an increase in heat-treatment temperature, the contents of alkanes increased, whereas those of alcohols and alkenes decreased. The contents of aromatics, acids, and aldehydes were highest when heat treated at 140 °C. At 220 °C, the total contents of key VOCs in southern yellow pine were lowest.

Ionic liquid pretreatment of yellow pine followed by enzymatic hydrolysis and fermentation.

In this study, it was aimed to enhance the enzymatic hydrolysis of recalcitrant yellow pine wood and subsequently to produce ethanol efficiently through the application of 1-ethyl-3-methylimidazolium acetate (EMIMAc) ionic liquid. The effect of biomass particle size (<2.5 mm, 500-850 μm, 363-500 μm, and <363 μm) prior to pretreatment and pretreatment time (15, 30, and 45 min) on the structural properties and enzymatic hydrolysis yield of EMIMAc pretreated pine wood were also investigated. In general, EMIMAc functioned more efficiently at larger biomass particle sizes compared to smaller ones. Dissolution of solids by pretreatment, amount of lignin extracted from biomass as well as biomass to glucose yield was increased with increasing pretreatment time. The conversion of biomass to glucose was 56% under the selected optimum conditions (500-850 μm particle size; 5% biomass concentration and 140°C-45 min EMIMAc pretreatment). The biomass samples pretreated at the optimal conditions were subjected to simultaneous saccharification and fermentation (SSF) and separate hydrolysis and fermentation (SHF) which resulted in ethanol yields of 86 and 96%, respectively. The results presented in this study give a general framework for reducing the recalcitrance of pine to enzymatic saccharification and microbial fermentation by EMIMAc pretreatment without need for long pretreatment times and size reduction. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 2018.

Camelina protein adhesives enhanced by polyelectrolyte interaction for plywood applications

Camelina protein is a major by-product created after oil extraction from camelina seeds; it has drawn research attention as an economical material for bio-industrial implications. The present study investigates the influence of polyelectrolyte interaction on camelina protein structure and effects on wood bonding performance when used as a bio-adhesive. Infrared spectroscopy (IR) and transmission electron microscopy (TEM) images revealed that after interacting with polymeric amine epichlorohydrin (PAE), a cationic polyelectrolyte, camelina protein is partly unfolded with more flexible chain structures. PAE works as a bridge among different protein molecules primarily through electrostatic and hydrophobic interactions. Separation by size exclusion chromatography showed that soluble PAE modified proteins are smaller in molecular size. Polymeric amine epichlorohydrin modified proteins had reduced solubility, possibly indicating increased hydrophobicity. The PAE treatment of camelina protein greatly improved both dry and wet adhesion strength when used as an adhesive. Dry bond strength increased from 2.39 ± 0.52 MPa to 5.39 ± 0.50 MPa with 100% wood failure and wet bond strength was dramatically increased from 0.37 ± 0.22 to 2.35 ± 0.17 MPa on two layer cherry wood tests. Two aliphatic structures with hydrophobic chains were introduced into the PAE modified protein system to further improve water resistance and get wet bond strength increase from 0 to 1.30 ± 0.23 MPa on three layer yellow pine wood tests. This study demonstrates the possibility of camelina as a green resource for the adhesive industry.

Regional and local controls on historical fire regimes of dry forests and woodlands in the Rogue River Basin, Oregon, USA

Fire regimes structure plant communities worldwide with regional and local factors, including anthropogenic fire management, influencing fire frequency and severity. Forests of the Rogue River Basin in Oregon, USA, are both productive and fire-prone due to ample winter precipitation and summer drought; yet management in this region is strongly influenced by forest practices that depend on fire exclusion. Regionally, climate change is increasing fire frequency, elevating the importance of understanding historically frequent-fire regimes.We use cross-dated fire-scars to characterize historical fire return intervals, seasonality, and relationships with climate beginning in 1650 CE for 13 sites representative of southwestern Oregon dry forests. Using systematic literature review, we link our local fire histories to a regional dataset and evaluate our data relative to more intensively studied conifer/hardwood forest types in California.Fire-scars show that fires in the Rogue Basin were frequent and regular until disrupted in the 1850s through 1910s, corresponding with forced displacement of Native Americans and Euro-American settlement. Median historical fire return intervals were 8 years at the stand-scale (<25 ha), with site medians ranging from five to 14 years and no significant differences between sampled vegetation types. Burn seasonality was broadly distributed with 47% of recorded fires in the latewood (midsummer), 30% at the ring boundary (late summer and fall), and 23% in the earlywood (spring and early summer).The number of sites recording fire each year was associated with Palmer Drought Severity Index (PDSI) and El Niño Southern Oscillation Index (ENSO). Fires were detected in the study area every other year, and synchrony among sites was associated with stronger annual drought. The ENSO synchronization of fire suggests an herbaceous fuel signal, with warm winters/wet summers two years prior to widespread fire-years, a pattern observed globally in fuel-limited systems.Stand-scale fire histories in the Klamath, southern Cascades, and northern Sierra Nevada ecoregions resemble Rogue River Basin stand-scale fire histories. Across dry mixed conifer, yellow pine, and mixed evergreen forests, fire return intervals converged on 8 years. Moist mixed conifer and red fir forests exhibited 13-year fire return intervals. Across ecoregions, fire periodicity was weakly correlated with climatic water deficit, but well-modeled by elevation, precipitation, and temperature. These data highlight the need for decadal fire and burning outside of the contemporary fire season for forest restoration and climate adaptation in the dry forests of the Rogue Basin.

From the stand scale to the landscape scale: predicting the spatial patterns of forest regeneration after disturbance.

Shifting disturbance regimes can have cascading effects on many ecosystems processes. This is particularly true when the scale of the disturbance no longer matches the regeneration strategy of the dominant vegetation. In the yellow pine and mixed conifer forests of California, over a century of fire exclusion and the warming climate are increasing the incidence and extent of stand-replacing wildfire; such changes in severity patterns are altering regeneration dynamics by dramatically increasing the distance from live tree seed sources. This has raised concerns about limitations to natural reforestation and the potential for conversion to non-forested vegetation types, which in turn has implications for shifts in many ecological processes and ecosystem services. We used a California region-wide data set with 1,848 plots across 24 wildfires in yellow pine and mixed conifer forests to build a spatially explicit habitat suitability model for forecasting postfire forest regeneration. To model the effect of seed availability, the critical initial biological filter for regeneration, we used a novel approach to predicting spatial patterns of seed availability by estimating annual seed production from existing basal area and burn severity maps. The probability of observing any conifer seedling in a 60-m2 area (the field plot scale) was highly dependent on 30-yr average annual precipitation, burn severity, and seed availability. We then used this model to predict regeneration probabilities across the entire extent of a "new" fire (the 2014 King Fire), which highlights the spatial variability inherent in postfire regeneration patterns. Such forecasts of postfire regeneration patterns are of importance to land managers and conservationists interested in maintaining forest cover on the landscape. Our tool can also help anticipate shifts in ecosystem properties, supporting researchers interested in investigating questions surrounding alternative stable states, and the interaction of altered disturbance regimes and the changing climate.

Nanoscale zero-valent iron/magnetite carbon composites for highly efficient immobilization of U(VI).

Nanoscale zerovalent iron/magnetic carbon (NZVI/MC) composites were successfully synthesized by simply calcining yellow pine and iron precursors. NZVI/MC pyrolyzed at 800°C (NZVI/MC800) had a higher percentage of NZVI and displayed better resistance to aggregation and oxidation of NZVI than samples prepared at other temperatures. The NZVI/MC800 material was applied for the elimination of U(VI) from aqueous solutions. The results suggested that the NZVI/MC800 displayed excellent adsorption capacity (203.94 mg/g) toward U(VI). The significant adsorption capacity and fast adsorption kinetics were attributed to the presence of well-dispersed NZVI, which could quickly reduce U(VI) into U(IV), trapping the guest U(IV) in the porous biocarbon matrix. The removal of U(VI) on the NZVI/MC samples was strongly affected by solution pH. The NZVI/MC samples also displayed outstanding reusability for U(VI) removal after multiple cycles. These findings indicate that NZVI/MC has great potential for remediation of wastewater containing U(VI).

The changing landscape of wildfire: burn pattern trends and implications for California’s yellow pine and mixed conifer forests

Wildfire spatial patterns drive ecological processes including vegetation succession and wildlife community dynamics. Such patterns may be changing due to fire suppression policies and climate change, making characterization of trends in post-fire mosaics important for understanding and managing fire-prone ecosystems. For wildfires in California’s yellow pine and mixed-conifer forests, spatial pattern trends of two components of the post-fire severity matrix were assessed for 1984–2015: (1) unchanged or very low-severity and (2) high-severity, which represent remnant forest and stand-replacing fire, respectively. Trends were evaluated for metrics of total and proportional burned area, shape complexity, aggregation, and core area. Additionally, comparisons were made between management units where fire suppression is commonly practiced and those with a history of managing wildfire for ecological/resource benefits. Unchanged or very low-severity area per fire decreased proportionally through time, and became increasingly fragmented. High-severity area and core area increased on average across most of California, with the high-severity component also becoming simpler in shape in the Sierra Nevada. Compared to suppression units, managed wildfire units lack an increase in high-severity area, have less aggregated post-fire mosaics, and more high-severity spatial complexity. Documented changes in severity patterns have cascading ecological effects including increased vegetation type conversion risk, habitat availability shifts, and remnant forest fragmentation. These changes likely benefit early-seral-associated species at the expense of mature closed-canopy forest-associated species. Managed wildfire appears to moderate some effects of fire suppression, and may help buy time for ecosystems and managers to respond to a changing climate.

Precision dating and cultural history of the La Pointe-Krebs House (22JA526), Pascagoula, Mississippi, USA

The La Pointe-Krebs House in Pascagoula, Mississippi is an important archaeological site (22JA526) located in the southeast United States (US). Despite being subjected to several independent archaeological and architectural studies, the exact calendar year(s) of construction for the original building and subsequent additions was unknown. We identified and sampled 26 timbers throughout the structure that contained bark or a smooth, curved outer surface that would return near-cutting or cutting dates using techniques of dendroarchaeology. A total of 14 samples came from timbers associated with the original 2-room Center Room, 9 from the East Room addition, and 3 from the West Room addition. All sampled timbers derived from a southern yellow pine tree species, most likely Pinus palustris (Mill.; longleaf pine) which was once widely distributed across the southeast US. The structure chronology spanned the period 1572–1932 CE with an inter-series correlation of r = 0.49 (1595–1788; p < 0.001) and was correlated against a regional P. palustris reference chronology from Eglin Air Force Base, Florida (n = 194 years, r = 0.40; t = 6.03, p < 0.001). Compilation of the cutting- and near-cutting dates revealed three distinct dating groups of timbers. First, three timbers from the Center Room have cut dates of 1757 CE. Second, two timbers in the East Room had cutting dates of 1762 CE. Third, three timbers with bark located over the Center and East Rooms dated to 1772 CE and were most likely repairs made to the roof following Bernard Roman's Hurricane in September 1772. No samples collected from the West Room provided near-cutting or cutting dates. The Gulf Coast region of the US has strong ties to French culture, heritage, and history, and the La Pointe-Krebs House played an important role during the creation of that culture in the region that still exists today.

Effect of Knots on Horizontal Shear Strength in Southern Yellow Pine

Knots are inevitable components found in wood that can adversely affect the mechanical properties of the lumber. The objective of this study was to investigate the effect of knots on the horizontal shear strength of southern yellow pine. Knot condition (sound/unsound) and shear plane (radial/tangential face) were studied as the factors of shear strength. The standard ASTM D143-94 (2014) was used to compare 120 pairs of clear shear blocks and shear blocks containing knots. Paired t-test results showed that regardless of the direction of the grain compared with the shear plane (perpendicular or parallel), sound knots increased the shear strength and the unsound knots decreased shear strength. Based on this study, the unsound knot volume was found to be a significant factor in decreasing the shear strength in the radial or tangential face direction. Furthermore, no significant relationship between the knot angle and shear strength was found. Shear failure occurred in the wood when an encased knot sample was tested and shear failure occurred in the knot when an intergrown knot sample was tested.

Landscape heterogeneity following high‐severity fire in California's forests

ABSTRACTMany at‐risk wildlife species depend upon high‐severity fire patches to create “complex early seral forest” (CESF) land cover, characterized by an abundance of snags, downed logs, shrub patches, and regeneration of trees. However, concern has been expressed about whether high‐severity fire might result in persistent type conversion to nonforest, or from pine (Pinus spp.) dominance to forest predominantly consisting of white fir (Abies concolor), Douglas‐fir (Pseudotsuga menziesii), and incense‐cedar (Calocedrus decurrens), as opposed to heterogeneous natural succession and ephemeral occurrence of CESF. If type conversion is common, it could in time harm other at‐risk species that depend on dense, late‐successional forest for some of their habitat needs. I investigated postfire patterns in high‐severity fire patches within yellow pine (Pinus ponderosa and Pinus jeffreyi) and mixed‐conifer forests in California, USA, using field plots evenly spaced along random transects into the interior of patches within fires that occurred from 1999 to 2013. I found natural conifer regeneration in ≥80% of plots, even &gt;300 m into patches. Conifer regeneration was greater closer to low–moderate‐severity areas. Areas with lower conifer regeneration, where CESF would have the greatest longevity—comprised only 4.6% of these fire areas. Pine species dominated regeneration deeper into the interior of large high‐severity patches, and fir–cedar‐dominated at patch edges. Shrubs did not impede conifer regeneration, but greater densities of conifer saplings reduced shrubs, and sapling growth increased with time‐since‐fire. My findings suggest heterogeneous land‐cover patterns are resulting from natural succession in high‐severity fire patches. © 2018 The Wildlife Society.

Analyses of the Structural and the Temperature-Dependent Magnetic Properties of Pine Resin and Pine Bark from the Oltu/Erzurum Region in Turkey

In the present paper, our aim is to investigate the structural, compositional and temperaturedependent magnetic properties of pine resin and pine bark obtained from a yellow pine forest situated in Oltu/Erzurum, a tertiary depositional area, located on the central area of the Northeast Anatolian Fault Zone. With the purpose of understand the regional effects on pine resin and pine bark obtained from a yellow pine forest, electron paramagnetic resonance spectroscopy is used to determine paramagnetic features at different temperatures (room temperature, 65 ◦ C, 75 ◦ C and 85 ◦ C). An X-ray diffraction experiment is performed to obtain the crystalline nature of the resin and the bark. Also, scanning electron microscopy and energy dispersive spectroscopy methods are preferred for analyzing the surface morphology and the elemental composition of the samples, respectively.

Multi-locus phylogenetics, lineage sorting, and reticulation in Pinus subsection Australes.

Both incomplete lineage sorting and reticulation have been proposed as causes of phylogenetic incongruence. Disentangling these factors may be most difficult in long-lived, wind-pollinated plants with large population sizes and weak reproductive barriers. We used solution hybridization for targeted enrichment and massive parallel sequencing to characterize low-copy-number nuclear genes and high-copy-number plastomes (Hyb-Seq) in 74 individuals of Pinus subsection Australes, a group of ~30 New World pine species of exceptional ecological and economic importance. We inferred relationships using methods that account for both incomplete lineage sorting and reticulation. Concatenation- and coalescent-based trees inferred from nuclear genes mainly agreed with one another, but they contradicted the plastid DNA tree in recovering the Attenuatae (the California closed-cone pines) and Oocarpae (the egg-cone pines of Mexico and Central America) as monophyletic and the Australes sensu stricto (the southern yellow pines) as paraphyletic to the Oocarpae. The plastid tree featured some relationships that were discordant with morphological and geographic evidence and species limits. Incorporating gene flow into the coalescent analyses better fit the data, but evidence supporting the hypothesis that hybridization explains the non-monophyly of the Attenuatae in the plastid tree was equivocal. Our analyses document cytonuclear discordance in Pinus subsection Australes. We attribute this discordance to ancient and recent introgression and present a phylogenetic hypothesis in which mostly hierarchical relationships are overlain by gene flow.

Physical chemical properties and cell toxicity of sanding copper-treated lumber

To protect against decay and fungal invasion into the wood, the micronized copper, copper carbonate particles, has been applied in the wood treatment in recent years; however, there is little information on the health risk associated with sanding micronized copper-treated lumber. In this study, wood dust from the sanding of micronized copper azole-treated lumber (MCA) was compared to sanding dust from solubilized copper azole-treated wood (CA-C) and untreated yellow pine (UYP). The test found that sanding MCA released a much higher concentration of nanoparticles than sanding CA-C and UYP, and the particles between about 0.4–2 µm from sanding MCA had the highest percentage of copper. The percentage of copper in the airborne dust from sanding CA-C had a weak dependency on particle size and was lower than that from sanding MCA. Nanoparticles were seen in the MCA PM2.5 particles, while none were detected in the UYP or CA-C. Inductively coupled plasma mass spectrometry (ICP-MS) analysis found that the bulk lumber for MCA and CA-C had relatively equal copper content; however, the PM2.5 particles from sanding the MCA had a higher copper concentration when compared to the PM2.5 particles from sanding UYP or CA-C. The cellular toxicity assays show that exposure of RAW 264.7 macrophages (RAW) to MCA and CA-C wood dust suspensions did not induce cellular toxicity even at the concentration of 200 µg PM2.5 wood dust/mL. Since the copper from the treated wood dust can leach into the wood dust supernatant, the supernatants of MCA, CA-C and UYP wood dusts were subjected to the cellular toxicity assays. The data showed that at the higher concentrations of copper (≥5 µg/ml), both MCA and CA-C supernatants induced cellular toxicity. This study suggests that sanding MCA-treated lumber releases copper nanoparticles and both the MCA and CA-C-treated lumber can release copper, which are potentially related to the observed in vitro toxicity.

Sodium Hydroxide and Calcium Hydroxide Hybrid Oxygen Bleaching with System

This study investigates the replacement of sodium hydroxide in the oxygen bleaching stage using a hybrid system consisting of sodium hydroxide calcium hydroxide. Commercial Kraft pulping was studied using yellow pine Kraft pulp obtained from a company in the US. The impact of sodium hydroxide, calcium hydroxide hybrid system in regard to concentration, reaction time and temperature for Kraft pulp was evaluated. The sodium hydroxide and calcium hydroxide dosage was varied between 0% and 15% based on oven dry fiber content. The bleaching reaction time was varied between 0 and 180 minutes whereas the bleaching temperature ranged between 70 °C and 110 °C. The ability to bleach pulp was measured by determining the Kappa number. Optimum bleaching results for the hybrid system were achieved with 4% sodium hydroxide and 2% calcium hydroxide content. Beyond this, the ability to bleach pulp decreased.