Small-diameter Trees Research Articles

Distribución potencial de barrenadores, defoliadores, descortezadores y muérdagos en bosques de coníferas de México

La distribución de plagas forestales en México es incierta, pues existe información escasa sobre áreas potenciales de bosques por ser afectados mediante algún tipo de plaga, o información sobre sus preferencias climáticas y ecológicas. El objetivo del presente estudio consistió en modelar la distribución potencial de insectos barrenadores (B), defoliadores (d), descortezadores (D) y muérdagos (M) mediante variables climáticas y dasométricas a través de MaxEnt (Máxima Entropía). Los registros de plagas forestales se obtuvieron durante el desarrollo del Inventario Nacional Forestal y de Suelos (2009-2014) y fueron proporcionados por la Comisión Nacional Forestal. Los modelos se probaron y validaron con el paquete dismo de R. Los generados mostraron ajustes aceptables (AUC > 0.85). La superficie potencial estimada por modelo, acorde al umbral mínimo de presencia conocida (> 0.1), fue alrededor de 270 (B), 307 (D), 315 (d) y 308 mil km2 (M). La mayor área potencial para los cuatro tipos de plaga se predijo en Chihuahua, Durango y Oaxaca, así como la probabilidad de ocurrencia más alta (> 0.90). Las variables climáticas contribuyeron con el mayor porcentaje para D y d (75.1 y 71.9 %); mientras que, para B y M, las dasométricas (73.6 y 59.8 %). El análisis de parámetros dasométricos indica que los cuatro tipos de plaga tienen preferencia por bosques con árboles de diámetros pequeños y sitios con pocas especies hospederas. Los bosques con mayor susceptibilidad se ubican en Chihuahua (M) y Michoacán, Estado de México, Nuevo León, Jalisco y Chihuahua (D).

Splitting a planar graph of girth 5 into two forests with trees of small diameter

In 1985, Mihok and recently Axenovich, Ueckerdt, and Weiner asked about the minimum integer g∗>3 such that every planar graph with girth at least g∗ admits a 2-colouring of its vertices where the length of every monochromatic path is bounded from above by a constant. By results of Glebov and Zambalaeva and of Axenovich et al., it follows that 5≤g∗≤6. In this paper we establish that g∗=5. Moreover, we prove that every planar graph of girth at least 5 admits a 2-colouring of its vertices such that every monochromatic component is a tree of diameter at most 6. We also present the list version of our result.

Pre-outbreak forest conditions mediate the effects of spruce beetle outbreaks on fuels in subalpine forests of Colorado.

Over the past 30years, forest disturbances have increased in size, intensity, and frequency globally, and are predicted to continue increasing due to climate change, potentially relaxing the constraints of vegetation properties on disturbance regimes. However, the consequences of the potentially declining importance of vegetation in determining future disturbance regimes are not well understood. Historically, bark beetles preferentially attack older trees and stands in later stages of development. However, as climate warming intensifies outbreaks by promoting growth of beetle populations and compromising tree defenses, smaller diameter trees and stands in early stages of development now are being affected by outbreaks. To date, no study has considered how stand age and other pre-outbreak forest conditions mediate the effects of outbreaks on surface and aerial fuel arrangements. We collected fuels data across a chronosequence of post-outbreak sites affected by spruce beetle (SB) between the 1940s and the 2010s, stratified by young (<130yr) and old (>130yr) post-fire stands. Canopy and surface fuel loads were calculated for each tree and stand, and available crown fuel load, crown bulk density, and canopy bulk densities were estimated. Canopy bulk density and density of live canopy individuals were reduced in all stands affected by SB, though foliage loss was proportionally greater in old stands as compared to young stands. Fine surface fuel loads in young stands were three times greater shortly (<30yr) following outbreak as compared to young stands not affected by outbreak, after which the abundance of fine surface fuels decreased to below endemic (i.e., non-outbreak) levels. In both young and old stands, the net effect of SB outbreaks during the 20th and 21st centuries reduced total canopy fuels and increased stand-scale spatial heterogeneity of canopy fuels following outbreak. Importantly, the decrease in canopy fuels following outbreaks was greater in young post-fire stands than in older stands, suggesting that SB outbreaks may more substantially reduce risk of active crown fire when they affect stands in earlier stages of development. The current study shows that the effects of SB outbreaks on forest structure and on fuel profiles are strongly contingent on pre-outbreak conditions as determined by pre-outbreak disturbance history.

Variable density thinning promotes variable structural responses 14 years after treatment in the Pacific Northwest

Abstract Young stands are commonly assumed to require centuries to develop into late-successional forest habitat. This viewpoint reflects the fact that young stands often lack many of the structural features that define late-successional habitat, and that these features derive from complex stand dynamics that are difficult to mimic with forest management. Variable density thinning (VDT) is a silvicultural strategy designed to accelerate development of late-successional habitat by applying a variety of harvest intensities within a stand. Previous reports indicate that VDT has had initial success increasing growth and regeneration. However, few studies have examined the effects of VDT at longer time scales. Here, we report 14-year growth response of residual trees in the thinned and unthinned VDT sub-treatments in five young mixed-conifer stands located on the Olympic Peninsula in western Washington. Our objectives were to investigate whether thinning has accelerated the recruitment of large trees (>80 cm dbh), recruitment of shade-tolerant species into the mid-story (40–65 cm), or development of longer crowns relative to the unthinned sub-treatment. In addition, we investigated whether the basal area distribution in the combined VDT sub-treatments has become more diverse compared to the unthinned sub-treatment. The response to thinning varied consistently across the diameter size class gradient. Thinning was ineffective at stimulating growth of upper canopy trees (65–80 cm). In this size class neither diameter growth nor crown length increased significantly compared to trees in unthinned patches. Further, only one stand has reached the restoration benchmark for large tree density. In contrast, thinning significantly increased diameter growth and crown length among trees in the mid-story (40–65 cm) and shade-tolerant species in the future mid-story (20–40 cm). Higher rates of recruitment into the mid-story were also observed from shade tolerant species growing in the thinned (34%) compared to unthinned (19%) patches, with two stands reaching the restoration benchmark for shade-tolerant mid-story density. Clear trends in basal area diversity and evenness have yet to develop in either the combined or unthinned sub-treatments. Collectively, our results demonstrate that VDT has partially accomplished its objectives. Although thinning has not yet accelerated recruitment of large trees, it has accelerated the advancement of shade-tolerant species into the mid-story and the development of deeper crowns among trees in smaller size classes. In addition, differing rates of diameter growth among smaller diameter trees in the various VDT sub-treatments suggest that increases in structural diversity may be developing more quickly than in untreated stands.

Case Study: Economic viability of producing animal bedding from low quality and small diameter trees using a wood shaving machine

ABSTRACT This study explores the feasibility of producing animal bedding using a wood shaving machine fed with low quality and small diameter trees. An economic decision model was created, allowing individuals to input site and machine-specific parameters into the model. Model output provides data for 2 scenarios. Scenario 1 explores whether a farmer could support this venture by producing bedding for on-farm consumption only. Scenario 2 explores the profit an individual (farmer or nonfarmer) could gain if operating the wood shaving machine for 8 to 40 h/wk throughout the year. Model output for scenario 1 found that the average-sized organic and conventional dairy farm in New England would not be able to support this type of venture. Instead, the breakeven volume of bedding corresponded to farms with greater than 170 cows, indicating that larger farms, or a cooperative of locally clustered small farms using the machine collectively, would have a more favorable payback period. For scenario 2, the payback period was >15 yr if operating 8 h/wk to 561 d if operating 40 h/wk throughout the year. The 15-yr net present value was $159,884 to $1,777,435 and the discounted benefit-cost ratio was 0.8 to 9.3 when operating 8 to 40 h/wk throughout the year. However, if operating 40 h/wk, supply may outweigh demand, as enough bedding could be produced for 30 organic or 25 conventional dairies of average size in the New England region.

Fitting diameter distribution models to data from forest inventories with concentric plot design

Aim: Several national forest inventories use a complex plot design based on multiple concentric subplots where smaller diameter trees are inventoried when lying in the smaller-radius subplots and ignored otherwise. Data from these plots are truncated with threshold (truncation) diameters varying according to the distance from the plot centre. In this paper we designed a maximum likelihood method to fit the Weibull diameter distribution to data from concentric plots.Material and methods: Our method (M1) was based on multiple truncated probability density functions to build the likelihood. In addition, we used an alternative method (M2) presented recently. We used methods M1 and M2 as well as two other reference methods to estimate the Weibull parameters in 40000 simulated plots. The spatial tree pattern of the simulated plots was generated using four models of spatial point patterns. Two error indices were used to assess the relative performance of M1 and M2 in estimating relevant stand-level variables. In addition, we estimated the Quadratic Mean plot Diameter (QMD) using Expansion Factors (EFs).Main results: Methods M1 and M2 produced comparable estimation errors in random and cluster tree spatial patterns. Method M2 produced biased parameter estimates in plots with inhomogeneous Poisson patterns. Estimation of QMD using EFs produced biased results in plots within inhomogeneous intensity Poisson patterns.Research highlights:We designed a new method to fit the Weibull distribution to forest inventory data from concentric plots that achieves high accuracy and precision in parameter estimates regardless of the within-plot spatial tree pattern.

Walnut Twig Beetle (Coleoptera: Curculionidae: Scolytinae) Colonization of Eastern Black Walnut Nursery Trees.

Thousand cankers disease, caused by the invasive bark beetle Pityophthorus juglandis Blackman and an associated fungal pathogen Geosmithia morbida M.Kolařík, E. Freeland, C. Utley, N. Tisserat, currently threatens the health of eastern black walnut (Juglans nigra L.) in North America. Both the beetle and pathogen have expanded beyond their native range via transport of infested walnut wood. Geosmithia morbida can develop in seedlings following inoculation, but the ability of P. juglandis to colonize young, small diameter trees has not been investigated. This study assessed the beetle’s colonization behavior on J. nigra nursery trees. Beetles were caged directly onto the stems of walnut seedlings from five nursery sources representing a range of basal stem diameter classes. Seedlings were also exposed to P. juglandis in a limited choice, field-based experiment comparing pheromone-baited and unbaited stems. When beetles were caged directly onto stems, they probed and attempted to colonize seedlings across the range of diameters and across sources tested, including stems as small as 0.5 cm in diameter. In the field experiment, beetles only attempted to colonize seedlings that were baited with a pheromone lure and appeared to prefer (though not statistically significant) the larger diameter trees. Despite several successful penetrations into the phloem, there was no evidence of successful progeny development within the young trees in either experiment. Further investigation is recommended to better elucidate the risk nursery stock poses as a pathway for thousand cankers disease causal organisms.

Implications of land-use change on forest carbon stocks in the eastern United States

Given the substantial role that forests play in removing CO2 from the atmosphere, there has been a growing need to evaluate the carbon (C) implications of various forest management and land-use decisions. Although assessment of land-use change is central to national-level greenhouse gas monitoring guidelines, it is rarely incorporated into forest stand-level evaluations of C dynamics and trajectories. To better inform the assessment of forest stand C dynamics in the context of potential land-use change, we used a region-wide repeated forest inventory (n = 71 444 plots) across the eastern United States to assess forest land-use conversion and associated changes in forest C stocks. Specifically, the probability of forest area reduction between 2002–2006 and 2007–2012 on these plots was related to key driving factors such as proportion of the landscape in forest land use, distance to roads, and initial forest C. Additional factors influencing the actual reduction in forest area were then used to assess the risk of forest land-use conversion to agriculture, settlement, and water. Plots in forests along the Great Plains had the highest periodic (approximately 5 years) probability of land-use change (0.160 ± 0.075; mean ± SD) with forest conversion to agricultural uses accounting for 70.5% of the observed land-use change. Aboveground forest C stock change for plots with a reduction in forest area was −4.2 ± 17.7 Mg ha−1 (mean ± SD). The finding that poorly stocked stands and/or those with small diameter trees had the highest probability of conversion to non-forest land uses suggests that forest management strategies can maintain the US terrestrial C sink not only in terms of increased net forest growth but also retention of forest area to avoid conversion. This study highlights the importance of considering land-use change in planning and policy decisions that seek to maintain or enhance regional C sinks.

Sequential augmentation reveals life history and suitable conditions for colonization of the rare mahogany mistletoe in South Florida

AbstractSuccessfully reintroducing rare plant populations to recover historical community composition may require multiple efforts and greater lengths of time than is typically devoted by researchers. To improve the probability of successful colonization and to learn about the life history of the regionally endangered mahogany mistletoe (Phoradendron rubrum) in the Florida Keys, United States, we conducted sequential augmentations for 10 years across two host tree sizes, two seed sources, and six recipient sites. Long‐term monitoring for 13 years revealed that sowing fresh seeds in dry periods from introduced versus wild plants onto small diameter trees (&lt;20 cm diameter at breast height [dbh]) that had branch diameters 15–20 mm resulted in the greatest colonization success. An average of 38.7% of seeds germinated and 23.8% survived to 2015. Plant development was quite slow. Seeds required over 100 days to germinate, 1.6 years for cotyledon emergence, and over 4.7 years to produce fruit. We detected first recruitment nearly 8 years after installation. Population growth improved following multiple attempts and expanded spatial extent as is predicted by theory. Portions of the life cycle are undetectable and thus could give false indications of reintroduction success or failure. Achieving and documenting unequivocal success of this reintroduction has required over a decade.

Responses of a Federally Endangered Songbird to Understory Thinning in Oak-Juniper Woodlands.

Wildlife conservation and management on military lands must be accomplished in the context of military readiness, which often includes ground-based training that is perceived to conflict with wildlife needs and environmental regulations. From 2008‒2012, we examined territory density, pairing success, and fledging success of the federally endangered golden-cheeked warbler (Setophaga chrysoparia; hereafter warbler) in relation to removal of small-diameter trees from the understory of mature oak-juniper (Quercus-Juniperus) woodland at the 87,890 ha Fort Hood Military Reservation in central Texas. Understory thinning created troop maneuver lanes, but left canopy vegetation intact. Warbler density, pairing success, and fledging success were similar across thinned and control sites. We found that warbler pairing and fledging success were best predicted by Ecological site (hereafter Ecosite), an indicator of hardwood tree species composition. Warbler pairing and fledging success were about 1.5 and 1.6 times higher, respectively, for territories dominated by the Low Stony Hill Ecosite than territories dominated by the Redlands Ecosite. Our results indicate that understory thinning for military training purposes did not have a negative effect on warblers at Fort Hood in the manner tested, and suggest that removal of smaller trees from the understory in a way that replicates historic conditions may elicit neutral responses from this forest-dependent songbird. Quantifying wildlife responses to military activities provides the Department of Defense and US Fish and Wildlife Service with data to guide conservation of threatened and endangered species on Department of Defense facilities while maintaining the military mission, and supports wildlife management efforts on other public and private lands.

Regional GIS-based evaluation of the potential and supply costs of forest biomass in Sweden

The potential for harvestable forest fuel (logging residues and stumps from regeneration fellings and small diameter trees from early thinnings) in Sweden, divided in five regions, is provided. Marginal cost curves for logging residues and stumps are calculated through a GIS-based method based on forest inventory plots and locations of selected terminals, and heat and combined heat and power facilities. Four supply chains for logging residues and two for stumpwood were compared. Fixed and variable costs of harvesting equipment and transport vehicles were used for determining the costs of each of the supply systems under consideration. A list with the GPS coordinates of all facilities and terminals was made based on their geographical location. The distance from the center of each forest inventory plot to the nearest receiving point within the region, either facility or terminal, was estimated. There were large differences in the estimated potential of harvestable forest fuel between the regions. The overall annual potential for each of the five regions ranged from 0.97 to 2.73 million oven dry tonnes and the total potential amounted to 9.39 Mt (oven dry). One of the northernmost regions (R1) had the steepest slope in its marginal cost curve. For the other regions, the slope of their cost curves was less dramatic. Information on the economic availability of logging residues and stumps in each region is important for forest fuel suppliers and receiving facilities.

Ecological Characteristics of Sub-Alpine Coniferous Forest on Banyabong in Mt. Jiri

This study was conducted to elucidate the ecological characteristics of sub-alpine coniferous forest on Banyabong, Mt. Jiri. Soil pH was 4.20. The contents of organic matter, total N, available P and CEC were 14.15%, 0.43%, 10.1 ppm and 17.17 cmolSUP+/SUP/kg, respectively. Sub-alpine coniferous forest had a relatively soil moisture content with 22.9%. According to the results of importance value analysis, Picea jezoensis (42.7) and Abies koreana (34.0) for tree layer, Rhododendron schlippenbachii (25.5) for subtree layer and Tripterygium regelii (18.4) and Rhododendron mucronulatum (16.6) for shrub layer were high, respectively. Shannon’s diversity ranged from 0.3560 to 1.050. Evenness and dominance ranged from 0.398 to 0.733 and 0.267 to 0.601, respectively. A. koreana population had a reverse J-shaped DBH distribution, while P. jezoensis population had a normal DBH distribution. Height growth according to DBH of A. koreana was higher than that of P. jezoensis, which indicate than A. koreana have more effective water use efficiency than P. jezoensis. Annual mean tree ring growth of P. jezoensis and A. koreana showed up 1.792, 1.652, 1.389 mm/yr and 2.081, 1.921, 1.576 mm/yr for small, middle and large diameter tree, respectively.

Mulching fuels treatments promote understory plant communities in three Colorado, USA, coniferous forest types

Mulching fuels treatments have been increasingly implemented by forest managers in the western USA to reduce crown fire hazard. These treatments use heavy machinery to masticate or chip unwanted shrubs and small-diameter trees and broadcast the mulched material on the ground. Because mulching treatments are relatively novel and have no natural analog, their ecological impacts are poorly understood. We initiated a study in 2007 to examine the effects of mulching on vascular understory plant communities and other ecological properties and processes. We established 15 study areas in Colorado, USA, distributed across three broadly-defined coniferous forest types: pinyon pine – juniper (Pinus edulis – Juniperus spp.); ponderosa pine (P. ponderosa) and ponderosa pine – Douglas-fir (Pseudotsuga menziesii); and lodgepole pine (P. contorta) and mixed conifer (lodgepole pine, limber pine (P. flexilis), and other conifers). Measurements were conducted along 50-m transects 2–4years post-treatment (2007 or 2008), and again 6–9years post-treatment (2012), in three mulched and three untreated stands per study area. Mulching dramatically reduced overstory basal area (i.e., basal area of trees >1.4m tall) and increased forest floor biomass (i.e., the biomass of litter, duff, and woody material <2.5cm in diameter) for all three forest types, as evidenced by previous measurements conducted in our mulched and untreated stands 2–4years post-treatment. The total richness and cover of understory plant species in mulched stands 2–4years post-treatment were either similar to, or greater than, the richness and cover in untreated stands for the three forest types; however, by 6–9years post-treatment, total understory plant richness and cover in mulched stands were always greater. The stimulatory effect of mulching on understory plants was largely driven by the response of graminoids and forbs; mulching had little effect on shrub richness or cover. The increases in total understory plant richness and cover in mulched stands 6–9years post-treatment occurred despite the fact that understory plants tended to be heavily suppressed in localized areas where the forest floor layer was deep, because such areas were rare. Exotic plant richness and cover were commonly higher in mulched than untreated stands in both sampling periods, but nonetheless understory plant communities remained highly native-dominated. Taken as a whole, our findings suggest that mulching treatments promoted denser and more diverse native understory plant communities in these three Colorado coniferous forest types, particularly over the longer-term.

The potential rural development impacts of utilizing non-merchantable forest biomass

The development of a market for currently non-merchantable forest material, such as harvest residues or small diameter trees, has been suggested as a possible win-win solution that could: (i) provide a material that can be processed in rural communities reeling from changes in the forest products industry and policy environment; (ii) capture more value from timber management activities; and (iii) provide a financial incentive for treatments to reduce wildfire risk or restore forest stands. Modeling the supply of this material with spatially-explicit potential demand locations allows for a realistic analysis of the feasibility of such a market to stimulate rural development. We model multiple scenarios for the utilization of harvest residues within the current forest products market in western Oregon. Sensitivity analysis explored the effects of cost of the depots on feasibility, including policy designed to support depot establishment through subsidies. Scenarios were also used to assess the effects of increases in federal harvest activities. Results suggest that with relatively high biomass prices, there is some potential for investment in depots to aid rural communities in western Oregon, but there is little change in either the overall feasibility or the location of depot establishment under scenarios of increased federal harvest.

Sapling harvest: A predominant factor affecting future composition of tropical dry forests

Degradation of tropical forests is of global concern and studies of the ecosystem processes concerned with the regeneration of trees have a great value for reforestation management. We analysed the structure of a tropical dry forest (TDF) in India in terms of the composition of small-diameter trees (saplings) at five distinct sites located along a gradient of soil moisture, and investigated the effects of biotic and abiotic disturbances on the diversity, aboveground biomass (AGB), AGB-accumulation, annual recruitment index (ARI) and annual mortality index (AMI) of saplings. Aim of the study was to analyse the relative impact of important disturbing factors on the species composition of saplings in the TDF. Study questions were: (1) how is the TDF structured in terms of tree saplings and their AGB? (2) what are the levels of biotic and abiotic disturbances which affect sapling population, forest regeneration and future composition of the community? (3) what is the relationship between species mortality and recruitment in the sites having different disturbance intensities? and (4) what is the relative importance of individual disturbing factors for the recruitment, mortality and structure of sapling community? Step-wise multiple regressions were performed for predicting species richness, stem density, mean AGB, AGB-accumulation, ARI and AMI from mean values of soil moisture content (SMC), harvest index, browse index, drought index and fire index. Results showed 80, 15, 4.5 and 0.5%, mortality through harvest, browse, drought, and fire, respectively. Floristic composition of the sapling population was different compared to that of the mature trees. Selective harvesting of the saplings of large canopy trees such as Terminalia tomentosa and Shorea robusta indicated the possiblity of change in floristic composition of the TDF in future. Tree saplings in our TDF are mainly damaged by illegal harvesting. Compared to browsing and natural mortality on account of drought and fire, damage to saplings due to harvesting was substantially higher at most of the study sites. In this study, the site which had the lowest level of SMC throughout the year, contained the lowest number of species and sapling stems and also had the greatest level of disturbance in terms of damaged saplings. In order to protect and improve the diversity and recruitment of tree saplings, we suggest to restrict the illegal (unauthorized) harvesting and to control browsing in the forest. Particularly the saplings of the dominant canopy trees and those with high biomass accumulation potential need to be protected.

Interaction network of vascular epiphytes and trees in a subtropical forest

The commensalistic interaction between vascular epiphytes and host trees is a type of biotic interaction that has been recently analysed with a network approach. This approach is useful to describe the network structure with metrics such as nestedness, specialization and interaction evenness, which can be compared with other vascular epiphyte-host tree networks from different forests of the world. However, in several cases these comparisons showed different and inconsistent patterns between these networks, and their possible ecological and evolutionary determinants have been scarcely studied. In this study, the interactions between vascular epiphytes and host trees of a subtropical forest of sierra de San Javier (Tucuman, Argentina) were analysed with a network approach. We calculated metrics to characterize the network and we analysed factors such as the abundance of species, tree size, tree bark texture, and tree wood density in order to predict interaction frequencies and network structure. The interaction network analysed exhibited a nested structure, an even distribution of interactions, and low specialization, properties shared with other obligated vascular epiphyte-host tree networks with a different assemblage structure. Interaction frequencies were predicted by the abundance of species, tree size and tree bark texture. Species abundance and tree size also predicted nestedness. Abundance indicated that abundant species interact more frequently; and tree size was an important predictor, since larger-diameter trees hosted more vascular epiphyte species than small-diameter trees. This is one of the first studies analyzing interactions between vascular epiphytes and host trees using a network approach in a subtropical forest, and taking the whole vascular epiphyte assemblage of the sampled community into account.

Quality and productivity in comminution of small-diameter tree bundles

ABSTRACTBundling small-diameter trees from thinnings has become a viable technology with the development of the Fixteri harvester-bundler. Several studies have measured the productivity of the machine, however, bundling also influences the whole supply chain. A study was conducted to investigate the quality of chips and productivity of five different conventional chippers and one grinder when comminuting bundles produced of small-diameter trees. The productivity based on dry mass was on average 44.8 tonne per effective working hour (E0 H−1), and varied considerably between the machines; 1:2.3 being the observed relation between lowest and highest performance of machines. Productivity when comminuting bundles was 1.5–3.2 times higher than normally found in the literature for unbundled (loose) material. The quality of the produced fuel chips varied between machines in dry weight share of particle sizes <3.15 mm from around 5 to 35%. The average size of the chips varied between 5 and 20 mm. The study indicated that productivity and quality of fuel chips are dependent on machine type and the raw material processed. Further investigations should examine different machine systems in designed experiments where e.g. several assortments and operational environments are included.

Composition, diversity, and structure of tidal “Várzea” and “Igapó” floodplain forests in eastern Amazonia, Brazil

The objective of this study was to evaluate the composition, diversity, and structure of tidal “Varzea” and “Igapo” forests in eastern Amazonia, Amapa, Brazil. All live tree individuals with diameter at breast height (dbh) ≥10 cm were registered. A total of 130 plots measuring 10 × 100 m were inventoried, distributed among 13 ha in each of the two forest typologies. A total of 10,575 trees were reported, belonging to 343 species, 172 genera, and 49 families. For all 26 ha sampled, mean tree density was 406 ± 61.27 trees ha−1 and mean basal area was 27.2 ± 11.13 m2 ha−1. Fabaceae, Arecaceae, Malvaceae, Meliaceae, and Rubiaceae were the most important families in tidal “Varzea”, together accounting for 74.76 % of the family importance value index (FIVI %). In “Igapo”, the most important families were Lecythidaceae, Euphorbiaceae, Malvaceae, and Arecaceae, which together accounted for 57.05 % of the family important value index (FIVI %). Smaller diameter trees measuring between 10 and 30 cm dbh dominated the landscape, accounting for 75.52 % of all individuals sampled. In general, 80 % (8285) individuals were under 24 m in height, while only 1.32 % of trees (140) reached heights above 34 m. There was evidence for statistically significant mean differences among tidal “Varzea” and “Igapo” with regard to the number of individuals, species, diversity, and tree height. However, no mean differences were detected for equitability, dbh, dominance, and basal area. Compositional patterns showed low similarity between the evaluated areas, indicating the existence of phytogeographic pattern based on species distribution.

Processing and sorting forest residues: Cost, productivity and managerial impacts

Feedstocks generated from processing forest residues have traditionally been considered as a low value product. The economic potential of these materials can be enhanced by emerging biomass conversion technologies, such as torrefaction, briquetting, and gasification; however, these systems require higher quality feedstock. The objective of this study was to determine the cost of processing and sorting forest residues to produce feedstock, so that the best comminution machines (i.e. chipper vs. grinder) could be used to better control feedstock size distribution. The tree tops left from sawlog processing and small-diameter trees were delimbed and separated from the slash pile. Three harvest units were selected and each unit was divided into three sub-treatment units (no-, moderate, and intensive sorting). Results showed that the cost of operations were higher for the sorted sub-units when compared to the non-sorted. The total cost of operation (felling to loading) for sawlogs was lowest at 40.81 $ m−3 in the nosorting treatment unit, followed by moderate (42.25 $ m−3) and intensive treatment unit (44.75 $ m−3). For biomass harvesting, the cost of operation (felling to delimbing and sorting) ranged from 27 to 29 $ oven dry metric ton−1. The most expensive operational phase was primary transportation; therefore, cost of treating the forest residues had less impact on the overall cost. The cost increase (1150 $ ha−1) of sorting forest residues could offset cost savings from avoided site preparation expenses (1100 $ ha−1), provided that the forest residues were utilized.

A Survey of Bioenergy Research in Forest Service Research and Development

Forest biomass represents 25–30 % of the annual biomass available in the USA for conversion into bio-based fuels, bio-based chemicals, and bioproducts in general. The USDA Forest Service Research and Development (R&D) has been focused on producing products from forest biomass since its inception in 1905, with direct combustion, solid sawn lumber, pulp and paper, ethanol as fuel, and silvichemicals all among the mission areas of product research and development. The renewed national interest in biomass conversion to fuels and chemicals is supportive of the most critical need of USDA Forest Service R&D, uses for small-diameter trees and other forest biomass that needs to be removed in the fuel mitigation–fire suppression and forest restoration work of the USDA Forest Service. This paper will summarize the recent USDA Forest Service research on direct combustion, fuel pellets, and conversion of forest biomass to ethanol, both as stand-alone biorefinery processes and as an addition to the traditional wood pulping process.