Appalachian Hardwoods Research Articles

Mechanical Properties of Selected Thermally Modified Appalachian Hardwoods

Mechanical Properties of Selected Thermally Modified Appalachian Hardwoods

Fire exclusion vs. a fire-free interval following repeated prescribed fire: Consequences for forest stand structure and species composition in an upland oak forest

In the Central Appalachian forest region, oaks (Quercus L.) and other disturbance-dependent tree species are experiencing widespread regeneration failure after decades of fire suppression. Managers use prescribed fire to decrease basal area with the aim of facilitating oak regeneration and shifting species composition toward pyrophytic species that dominate the overstory. Although fire may set the stage for improved oak regeneration, a fire-free period is necessary for oak seedlings to develop into fire-resistant stems. The effects of prescribed fire have been amply investigated across the region, but few studies have examined changes to stand structure and oak regeneration after cessation of burning. We followed the effects of three treatments, fire-excluded, 3x-burned, and 4x-burned, for 20 years. After a fire-free interval of approximately ten years, burned treatments had significantly lower total basal area and greater relative density of oaks in the subcanopy (10–20 cm DBH) than the fire-excluded treatment. The 4x-burned, which had the greatest reduction in basal area, also had greater relative density of midstory oaks (2–10 cm DBH), and higher stem density of oak regeneration (<2 cm DBH) than the fire-excluded. Despite these trends towards increased regeneration of oaks and other pyrophytes, red maple (Acer rubrum L.) stem density also increased in the midstory of burned treatments, suggesting a legacy effect of decades of fire suppression and the concomitant mesophication that has occurred. We also examined the effects of continued fire exclusion on the fire-excluded reference treatment. Additional evidence of mesophication on this treatment was demonstrated by increased overstory (≥20 cm DBH) and subcanopy red maple stem density as well as midstory (2–10 cm DBH) eastern white pine (Pinus strobus L.) stem density, a prominent mesophyte on these sites. This study supports the idea that repeated prescribed burning followed by a 10-year fire-free interval can alter stand structure and lead to improved oak regeneration by increasing canopy openness. However, the results were variable across burned treatments (3x vs. 4x) and the ingrowth of red maple and other mesophytes after only 10 years of fire exclusion will require additional control measures. Successful maintenance of oak-dominated forests on upland sites in the Central Appalachian hardwoods region may be contingent on a subsequent canopy disturbance that further increases light availability followed by a fire-free interval. Importantly, in the absence of burning or other disturbance, red maple and other mesophytic species will continue to increase in relative stem density.

Hardwood Log Grading in the United States—Part III: An Assessment of the Current Status of Log Grading in the Hardwood Industry

Abstract This article documents how the hardwood industry, in the absence of a standardized, industry-wide log grading system, has gone about grading and scaling hardwood logs by surveying mills, primarily in the Appalachian region. In total, 135 surveys were completed by respondents and returned via mail, with only 110 of those surveys considered usable for further analysis, after a thorough review of the individual surveys. Survey responses were grouped around annual production level, with three defined levels; ≤2.5 million board feet (MMBF), &gt;2.5 and ≤8.0 MMBF, and &gt;8.0 MMBF. Responding mills used some variation of a log grading system based on the number of clear faces on the log and the small end diameter of the log. The most common log rule used by mills in this study was the Doyle log rule, with over 75 percent using Doyle for scaling logs. Nearly 90 percent of all mills sampled graded logs without rolling the log to examine all four sides/faces. Half of all the sawmills surveyed pay the same price per thousand board feet (MBF) for butt logs and uppers. When asked if they would support the development of a standard log grading system, about two-thirds of the respondents (66%) indicated they would indeed support a standardized system for Appalachian hardwoods. These findings can help guide the development of a set of log grading standards for buyers and sellers in the Appalachian region and other parts of the world where hardwood lumber is produced.

Nanofibrillated Cellulose from Appalachian Hardwoods Logging Residues as Template for Antimicrobial Copper

TEMPO nanofibrillated cellulose (TNFC) from two underutilized Appalachian hardwoods, Northern red oak (Quercus rubra) and yellow poplar (Liriodendron tulipifera), was prepared to determine its feasibility to be used as template for antimicrobial metallic copper particles. In addition, a comparison of the TNFC from the two species in terms of their morphological, chemical, thermal, and mechanical properties was also performed. The woody biomass was provided in the form of logging residue from Preston County, West Virginia. A traditional kraft process was used to produce the pulp followed by a five-stage bleaching. Bleached pulps were then subjected to a TEMPO oxidation process using the TEMPO/NaBr/NaClO system to facilitate the final mechanical fibrillation process and surface incorporation of metallic copper. The final TNFC diameters for red oak and yellow poplar presented similar dimensions, 3.8±0.74 nm and 3.6±0.85 nm, respectively. The TNFC films fabricated from both species exhibited no statistical differences in both Young’s modulus and the final strength properties. Likely, after the TEMPO oxidation process both species exhibited similar carboxyl group content, of approximately 0.8 mmol/g, and both species demonstrated excellent capability to incorporate antimicrobial copper on their surfaces.

Experimental investigation of char generated from co-pyrolysis of coal and Appalachian hardwoods

In recent years, there has been increased interest in the co-combustion and co-gasification of coal and biomass materials in many industrial applications. The primary driving force behind this interest lays in the fact that co-combustion and co-gasification of coal biomass material are viewed to be a more carbon-neutral approach to processes typically used for power generation, as well as generation of syngas and other coal-derived chemicals. With the addition of renewable biomass materials to the coal used in these processes, the net amount of carbon dioxide released to the atmosphere is effectively reduced due to the assumption that replenishment of the biomass via replanting will lead to carbon dioxide removal via photosynthesis.The current study investigates co-pyrolysis of coal and biomass feedstocks, a precursor to the co-combustion or co-gasification reactions when both materials are fed together into the combustor or gasifier. Experiments have been conducted in which different mixtures of typical West Virginia power plant blend coals and Appalachian hardwoods have undergone pyrolysis using a tube furnace. Measurements were made with samples that contained 100% coal, 100% biomass as well as a 50% coal/50% biomass mixture. In addition, two different particle size ranges were used in order to examine the effect of particle size on the resulting pyrolysis products. In each experiment, the coal and biomass mixtures were heated to 500°C in a nitrogen atmosphere. Samples of the resulting solid char were collected and analyzed via ultimate and proximate analysis, and Fourier transform infra-red spectrometry (FT-IR).Numerous authors have debated whether or not the addition of biomass material to coal generates a synergistic, non-linear effect upon the resulting pyrolysis products. The data obtained during the current study suggests that varying the biomass content in the initial feed stock shows linearity with respect to the proximate and ultimate (elemental) analysis results of the produced chars; however, non-linearities can be seen in the tar and char yields, and in the functional group structure of the chars, as revealed by FT-IR analysis of the solid char samples.

Ripping Improves Tree Survival and Growth on Unused Reclaimed Mined Lands

There is renewed interest in re-establishing trees on 0.6 million ha of mining-disturbed lands in the Appalachian mountains of Eastern United States. Many coal-mined lands reclaimed to meet requirements of US federal law have thick herbaceous vegetation and compacted soils which impede tree establishment. Mitigation practices were applied on three mine sites and evaluated for success in enabling planted trees to become established. Eastern white pine (Pinus strobus), hybrid poplar (Populus deltoids × Populus trichocarpa), and mixed Appalachian hardwoods were established using weed control only and weed control with subsoil ripping. Trees were measured in October of 2008 after 5 years of growth. Subsoil ripping increased mixed hardwood survival from 43 to 71%, hybrid poplar biomass index from 1.51 to 8.97 Mg ha(-1), and Eastern white pine biomass index from 0.10 to 0.32 Mg ha(-1). When restoring trees to unused mined sites, subsoil ripping can aid survival and growth to an extent that will result in a valuable forest.

Wiant's Appalachian Hardwood Weight Equations—Revised

Revised model formulations are presented using the original data of Wiant et al. (Tables and procedures for estimating weights of some Appalachian hardwoods, W.V. Agr. For. Exp. Sta. Bull. 659T, 1977). Model forms are presented as functions of dbh and total tree height (THT), dbh and merchantable tree height (MHT), and dbh alone as independent variables. Using the root mean prediction sum of squares statistic (PRESS) statistic, the root mean square residual, and residual plots as the criteria for evaluating prediction accuracy, models using dbh and THT generally out performed those using dbh and MHT as well as models based on dbh alone. In general, newly fit nonlinear models outperformed earlier linear functions and provided a set of new equations based on the field measurement of merchantable height to a 4-in. top rather than requiring the input of total tree height.

Affordable Home Builder Demand for Green and Certified Wood Products

ABSTRACT Annual new housing starts in the United States decreased dramatically between 2005 and 2012. Consequently, products that are heavily tied to new housing starts, such as flooring, cabinetry, and moulding produced from Appalachian hardwoods, have suffered a corresponding decrease in demand. There may be opportunities to increase demand for these products, however, as demand in the green building sector increases. The present study evaluated the demand for certified wood products (CWPs) and green-labeled wood products in the central Appalachian affordable housing sector in 2011. The study also identified price premiums that affordable home builders were willing to pay for CWPs and green-labeled wood products. Results indicated that 50 percent of affordable housing respondents were planning future CWP purchases. Results also indicated that 62 percent of affordable housing respondents followed some type of green building standard. Additionally, more than 70 percent of affordable housing respondents suggested a willingness to pay an additional percentage for CWPs and local wood products. The use of CWPs was found to result from a combination of builder and homeowner preference. Last, of the housing builders who looked to purchase CWPs locally in 2011, only 17 percent were not able to locate the materials for purchase. The low percentage of unsuccessful procurement suggests CWPs are well distributed in areas near affordable housing projects in central Appalachia.

Recovery of forest structure and composition to harvesting in different strata of mixed even-aged central Appalachian hardwoods

Implementing nature-based silviculture requires understanding the structural and compositional changes that occur in forested stands under known disturbance types and intensities. The objectives were to assess the (a) resistance of hardwood forests to change, (b) their trajectory of recovery following disturbance, and (c) how closely resulting forests resemble original forests. We characterized tree structure and composition at three points in time (pre-disturbance, 1-year post-disturbance, and ∼15 years following disturbance) along a harvesting disturbance gradient created by removing trees in different forest canopy strata. Significant differences to pre-disturbance conditions were noted immediately post-harvest for tree basal area, density, species richness, and tree species composition; treatment differences were observed for all parameters except diversity. Plots exposed to the least extreme harvesting disturbances (cutting small and intermediate trees) had returned to pre-disturbance conditions for most parameters after 15 years, while the most extreme harvesting disturbance (cutting large trees) had not yet recovered. Although not initially resistant, Central Appalachian eastern hardwoods are fairly resilient to the removal of trees in the subcanopy or a mixture of the subcanopy and canopy; only the removal of solely canopy trees (i.e., high grading) and complete removal (i.e., clearcutting) appear to impose harvesting disturbances to which these forests may not be resilient.

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China Buys American

Soil properties associated with net nitrification following watershed conversion from Appalachian hardwoods to Norway spruce

Nitrate (NO3-N) in soil solution and streamwater can be an important vector of nitrogen (N) loss from forested watersheds, and nitrification is associated with negative consequences of soil acidi- fication and eutrophication of aquatic ecosystems. The purpose of this study was to identify vegetation- mediated soil properties that may control potential net nitrification dynamics and to determine if net nitrifi- cation is a function of abiotic retention or biotic inhibition. We performed a soil inoculation and incubation study and analyzed a suite of soil chemical and biological properties in soils from a 40-year-old Appalachian hardwood forest and an adjacent 37-year-old Norway spruce forest converted from Appalachian hardwoods. Our results indicate that net NO3-N production was nine times higher in hardwood soil (mean = 183.51 mg N/kg/28 days) than in the spruce soil (mean = 18.97 mg N/kg/28 days) and differences in net NO3-N production were attributed to differences in soil substrate quality. Soil properties that were most strongly correlated with NO3-N production across vegetation types included total soil N, soil C:N ratio, oxalate concentration, and sulfate concentration.Establishmentofasprucemonoculturein the central Appalachian hardwood ecoregion signifi- cantly altered N cycling, likely depleted soil N stores, increased soil acidity, and altered soil organic matter dynamics, thus leading to low net nitrification rates.

Roost Selection by Male Indiana Myotis Following Forest Fires in Central Appalachian Hardwoods Forests

AbstractDespite the potential for prescribed fire and natural wildfire to increase snag abundance in hardwood forests, few studies have investigated effects of fire on bat roosting habitat, particularly that of the endangered Indiana myotis Myotis sodalis. From 2001 to 2009, we examined roost selection of Indiana myotis in burned and unburned forests in Tucker County, West Virginia. We radiotracked 15 male Indiana myotis to 50 roost trees; 16 in burned stands and 34 in unburned stands. Indiana myotis roosted in stands that had initially been burned 1–3 y prior to our observations. In burned stands, Indiana myotis roosted exclusively in fire-killed maples (Acer spp.). In unburned stands, they roosted in live trees, predominately hickories (Carya spp.), oaks (Quercus spp.), and maples. Roost trees in burned stands were surrounded by less basal area and by trees in advanced stages of decay, creating larger canopy gaps than at random trees in burned stands or actual roost trees located in unburned stands. Compared to random trees in unburned stands, roost trees in unburned stands were less decayed, had higher percent bark coverage, and were surrounded by less basal area, also resulting in larger canopy gaps. Roost-switching frequency and distances moved by Indiana myotis among roost trees were similar between burned and unburned stands. Our research indicates that use of fire for forest management purposes, at minimum provoked no response from Indiana myotis in terms of roost tree selection, and may create additional roost resources, depending on spatial context.

Crown Class Dynamics of Oaks, Yellow-Poplar, and Red Maple after Commercial Thinning in Appalachian Hardwoods: 20-Year Results

Abstract Silvicultural strategies are often planned to favor the growth and survival of desired species until they reach a competitive position in the upper canopy. Once desired species reach the upper canopy, they can persist and provide a variety of benefits for decades. Later, they can serveas a source of natural regeneration for sustaining species composition. Although information is available for promoting desired advance seedlings in the understory of mature stands and culturing desired saplings in the upper canopy of young stands, additional information is needed on promoting desired species at mid-rotation, when the stand first reaches commercial size classes. Crown class transition rates for a total of 2,668 white and chestnut oaks, northern red oak, scarlet and black oaks, yellow-poplar, red maple, blackgum, and black birch were observed for 20 years in a 53-year-old central Appalachian mixed-hardwood stand. Treatments included three residual stand densities after commercial thinning and an unthinned control. In general, the thinning treatments reduced mortality, increased crown class retention rates of codominant trees, and increased the ascension rates of trees in the intermediate crown class. After thinning, codominant trees exhibited the crown class stability of dominant trees, and intermediate trees exhibited greater survival and ascension to the upper canopy compared with unthinned controls. Very few suppressed trees improved canopyposition in thinning treatments; however, thinning did tend to reduce mortality of these trees. Crown class transition rates are presented to help forest managers understand how commercial thinning treatments can affect the composition of the upper canopy in the latter stages of stand development.

English

It is well known that soil microbial communities reestablish following disturbance, but limited research has been done on how long this takes in eastern reclaimed coal mine soils. The objective of this study was to track the development of total microbial biomass in reclaimed mine soils following coal mining in southwestern Virginia. A chronosequence of sites was established based on locally documented shifts in vegetation species with succession (0-2, 5-7, 18-20, and 38-42 yr old) on reclaimed sites with undisturbed adjacent sites used as a reference. The 0-2 yr old sites were covered with annual and perennial grasses and forbs, the 5-7 yr sites by thick stands of Lespedeza cuneata, the 18-20 yr sites predominately with Festuca arundinaceae and patches of deciduous trees, and the 38-42 yr old sites with a mix of planted conifers and native Appalachian hardwoods with a grass understory. Undisturbed sites predominately supported mixed Appalachian hardwoods with a mixed forb/grass understory. Four samples were taken from each site age (3 replicates) at the 0-5 cm depth. Chloroform-fumigation- extraction was used to determine total organic carbon from lysed microbial cells as a proxy for microbial biomass. Microbial biomass carbon (MBC) did not vary significantly among any of the site ages sampled; however, a general trend of increasing MBC from a low level in the more recently reclaimed sites (131-138 g microbial C kg -1 soil) to a higher level of MBC in the 16-20 and 38-42 yr sites (280 and 244 g microbial C kg -1 soil, respectively) was observed. This indicated a recovery of soil microbial communities with time; possibly well within the 5-year vegetation liability release period mandated by the Surface Mining Control and Reclamation Act (SMCRA).

Diameter-Limit Harvesting: Effects of Residual Trees on Regeneration Dynamics in Appalachian Hardwoods

Abstract Ten-years after diameter-limit harvesting in an Appalachian hardwood stand, the height, dbh, and basal area of sapling regeneration was inversely related to the degree of “overtopping” of residual trees. Black cherry and red maple were the most abundant saplings with 416.5 ± 25.7 and 152.9 ± 16.8 stems per acre, respectively. Models of black cherry height and diameter showed significant negative relationships (P &lt; 0.05) with residual tree basal area. In addition, height, diameter, and basal area of dominant and codominant black cherry and black birch saplings were inversely related to residual tree basal area (P &lt; 0.05), as was the basal area of red maple saplings. Alternatively, red maple sapling diameter had a significant positive relationship (P &lt; 0.05) with residual basal area, and height was not significantly affected. Findings suggest that overall stand conditions were most favorable for the development of shade-tolerant red maple, with shade-intolerant species developing well in open areas. However, the long-term development of black cherry may be jeopardized by side shade and canopy cover. Removal of residual trees and subsequent cleaning operations are recommended to increase growth rates of shade-intolerant sapling regeneration.

A Three-Dimensional Bucking System for Optimal Bucking of Central Appalachian Hardwoods

An optimal tree stem bucking system was developed for central Appalachian hardwood species using three-dimensional (3D) modeling techniques. ActiveX Data Objects were implemented via MS Visual C++/OpenGL to manipulate tree data which were supported by a backend relational data model with five data entity types for stems, grades and prices, logs, defects, and stem shapes. A network analysis algorithm was employed to achieve the optimal bucking solution with four different alternative stage intervals under the bucking by value principle. A total of 264 tree stems were measured in the field including stem dimensions, defects, sweep, and the manual bucking solution of each stem. Results when using the 3D optimal bucking system suggest that compared to manual bucking the total log value and volume gain from each tree stem could be increased on average by 31 to 38 percent and 16 to 17 percent, respectively. Results also show the individual tree stem utilization rate could be increased by 10 to 11 percent. The optimal bucking system developed can be used as a training tool on desktop PCs and can also be installed on field PCs to aid field buckers and operators of sawbucks. The 3D bucking optimization system developed in this research should be valuable to operators in the central Appalachian region due to the variability in tree stems and species of hardwoods.

English

There is a surging interest in restoring forests on surface mined lands in the Appalachians. Many lands reclaimed since the passage of the Surface Mining Control and Reclamation Act of 1977 (SMCRA) have dense ground covers and compacted soil materials, in some cases associated with unfavorable soil chemical properties. To address these concerns, three previously reclaimed mined sites were located in Lawrence County, OH; Nicholas County, WV; and Wise County, VA. At each site, Eastern white pine, hybrid poplar, and mixed Appalachian hardwoods were planted at three levels of silvicultural intensity (weed control only, weed control with soil ripping, and weed control with soil ripping and fertilization). Each combination of species and treatment was repeated three times in each of the three states for a total of 9 replications and 81 treatment plots. The OH sites were dominated by compacted siltstone backfill with a thin topsoil cap, the WV sites by shale fragments through the profile and the VA sites by mixed shale and sandstone fragments through the profile with a crushed sandstone cap. Trees were measured in October of 2007 after 4 years of growth. Across all treatments and species, Virginia had a higher survival rate, 70.7%, than West Virginia, 49.4%, and Ohio, 40.3%. West Virginia had a higher biomass index per tree, 5,673 cm 3 (cubic centimeters), than Ohio, 1,446 cm 3 Across all states and treatments, the survival rates of mixed hardwoods, 63.2%, and hybrid poplar, 55.1%, were greater than that of Eastern white pine, 42.1%. Total biomass index per tree for hybrid poplar, 10,024 cm 3 , was greater than that for Eastern white pine, 258 cm 3 , and mixed hardwoods, 138 cm 3 . Survival across all states and species was increased from 44% to 64% with ripping. Ripping plus weed control increased average biomass index from approximately 1,000 cm 3 per tree to 5,000 cm 3 per tree over weed control only. All species achieved their highest biomass values for this study on the West Virginia shale-based spoils and their highest survival rates on the Virginia sandstone-dominated spoils. When restoring forest vegetation to previously reclaimed mine sites with unfavorable soil and vegetation properties, the use of silvicultural treatments (weed control and soil ripping, with or without fertilization) can aid survival and growth.

Ecoregion-Based Local Volume Equations for Appalachian Hardwoods

Abstract Local merchantable board foot, cubic foot, and weight equations are developed for six economically important hardwood species in central Appalachia. Equations were based on a simple power function and were fit to volumes from the US Forest Service Forest Inventory Analysis data for West Virginia and parts of Ohio, Pennsylvania, Maryland, Virginia, and Kentucky. Five ecoregions were identified and the volume equations were tested to determine whether differences by ecoregion were statistically significant. Results varied by species, volume type, and ecoregion. Average bias between a single-species region-wide model and specific ecoregion forms ranged from −9.1 to 8.5% for gross board foot volume (International ¼ in.), −3.5 to 9.2% for gross merchantable cubic foot volume, and −9.5 to 16.7% for merchantable drybole weight (pounds).

A Comparison of the Arithmetic and Geometric Means in Estimating Stump Diameter, Basal Area, and Volume in Appalachian Hardwoods

Abstract The difference between the use of the arithmetic and geometric means for estimation of average stump diameter, stump cross-sectional area and estimated tree volume was investigated using measurements from 739 stumps from an Appalachian hardwood stand located in central West Virginia. Although average stump diameter, cross-sectional area, and tree volumes were statistically different between estimates based on the arithmetic and geometric mean diameter, these differences were of little practical significance. The difference in average stem diameter, cross-sectional area, tree cubic volume, and board foot volume were 0.05 in, 0.01 ft2, 0.45 ft3, and 2.41 bd ft, respectively.

A Simple Technique for Estimating Board Foot Volume Yields in Appalachian Hardwoods

Abstract A simple whole stand yield equation based solely on basal area per acre for sawtimber-sized trees and average dominant height was found to provide reasonably accurate estimates of board foot (International) yield in Appalachian hardwoods. Separate parameter estimates were obtained for mesophytic hardwood and mixed oak remeasurement plot data and the yield tables of Schnur (Schnur, G.L. 1937. Yield, stand and volume tables for even-aged upland oak forests. USDA Tech. Bull. 560). Estimates of board foot yield per acre for the remeasurement plot data were within 10% of observed values for stands over 30 years old and within 5% for stands over 45 years old. A separate model form based on the same two input variables was developed for Schnur’s yield table data for site index classes 50–80. Estimates of board foot yield were within 10% of tabular values for stands over 45 years old, regardless of site index class.