Small-diameter Wood Research Articles

Bioreducer use in Finnish blast furnace ironmaking – Analysis of CO2 emission reduction potential and mitigation cost

Bioreducer use in the blast furnace could be one of the measures to decrease the fossil CO2 emissions of steelmaking. This paper presents an environmental and economic evaluation of three bioreducers; charcoal, torrefied wood and wood-based synthetic natural gas (Bio-SNG), produced from logging residues, small-diameter wood and stumps. Additionally, the CO2 emission reduction potential of these bioreducers is calculated, using Ruukki, a Finnish steel producer as a reference. Finally, we present the CO2 mitigation cost for each bioreducer.The Carbon Footprint (CFP) of the bioreducers without fertilizer production, carbon stock change and by-product credits is 7.2, 8.7, 8.5, 9.0gCO2/MJ for charcoal, 4.9, 5.2, 5.6, 5.4gCO2/MJ for torrefied wood and 7.4, 8.3, 8.2, 8.5gCO2/MJ for Bio-SNG, produced from logging residues, small-diameter wood with 30% and 50% moisture content and stumps, respectively. The CFP becomes larger when carbon stock change is taken into account; 45–117gCO2/MJ for charcoal, 27–61.0gCO2/MJ for torrefied wood and 32–79gCO2/MJ, for Bio-SNG. By-product credits can turn CFP to negative from −36.3 to −25.0gCO2/MJ for charcoal and from −2.7 to 4.7gCO2/MJ for Bio-SNG without carbon stock change and fertilizer use. Energy Return on Investment (EROI) of all the bioreducers is well above one, which means that production is energetically feasible.Based on the Finnish example, the global CO2 reduction potential could be up to 0.99–1.01Mtons without and 1.29–1.39Mtons with by-product credits annually. The CO2 mitigation costs without by-product credits are 33–69€/tCO2, 22–53€/tCO2 and 112–150€/tCO2 and with by-product credits 26–54€/tCO2, 22–53€/tCO2 and 107–143€/tCO2 for charcoal, torrefied wood and Bio-SNG, respectively. Even though the CO2 mitigation cost of bioreducers is considerably high in current cost structures, they provide a flexible alternative to CO2 emission reduction in the steel industry.

基于Voronoi图的林分空间模型及分布格局研究

PDF HTML阅读 XML下载 导出引用 引用提醒 基于Voronoi图的林分空间模型及分布格局研究 DOI: 10.5846/stxb201210131416 作者: 作者单位: 中南林业科技大学,中南林业科技大学,湖南省科学技术厅,中南林业科技大学,中南林业科技大学,中南林业科技大学 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金（31070568）；湖南省自然科学基金重点项目（10JJ2022）；湖南省教育厅重点科研项目（11A128） The stand spatial model and pattern based on voronoi diagram Author: Affiliation: Central South University of Forestry and Technology,Central South University of Forestry and Technology,China Hunan Provincial Science,Central South University of Forestry and Technology,Central South University of Forestry and Technology,Central South University of Forestry and Technology Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:以南洞庭湖龙虎山次生林为研究对象，建立林分Voronoi图模型，通过该模型表示林分空间结构特征，提取林木空间量化信息。在此基础上，引入变异系数量化Voronoi多边形面积的变化率，将林木空间格局分析转化为计算Voronoi图变异系数，并将计算结果与角尺度作相关性比较。结果表明：林分Voronoi图模型能准确表达林木邻接关系、相邻木距离及角度、空间密度等重要空间信息；大尺度取样时（76m以上），变异系数趋于稳定，林分整体空间格局呈接近随机分布的轻度聚集；Voronoi图变异系数和角尺度存在显著的正相关关系，进一步说明本研究格局分析方法的可行性和有效性；受多种因素影响，乔木层主要树种在不同发育阶段的空间格局表现出强烈的时间和空间动态特性，且小径木多为聚集分布，大径木呈轻度聚集或随机分布。基于Voronoi图的林分空间模型及格局分析方法，从空间上表征林木的生长繁育特性、种内种间关系、资源及环境分布特征，为计算几何方法应用于林分空间经营提供了新的思路。 Abstract:The secondary forest of Mt.Longhu in the south Dongting Lake is chosen as the research object in this paper which tries to establish a stand model based on Voronoi diagram. This diagarm is applied here to illustrates the stand spatial structure and extract forest spatial quantitative information. Based on this, coefficient of variation (CV) is used to quantify the change rate of Voronoi polygon area, transferring the analytic results of stand spatial pattern to the calculation of the CV based on Voronoi diagram, and comparing the calculation results with uniform angle index. The result shows that the stand model of Voronoi diagram can accurately display some important spatial information, such as the correlation, distance and angle between adjacent trees as well as spatial density, etc. When sampling large scale(above 76m), CV tends to remain stable, and the overall stand spatial pattern shows mild aggregation which is close to random distribution. The CV of Voronoi diagram and uniform angle index have notable positive correlation, which further proves the feasibility and effectiveness of the analytical methods applied in this paper.The spatial pattern of main tree species of abor layer in different development stages shows a distinct temporal and spatial dynamic characteristics due to many factors. The small-diameter wood belongs to aggregated distribution, while the large-diameter belongs to mild aggregation or random distribution. The stand spatial model and its pattern analytical method, both based on Voronoi diagram, charaterize the tree growth feature, intraspecific and interspecific relationship, characteristics of resources and enviornment distribution from the perspective of spatial structure, providing a new way of thinking for stand spatial management by applying computational geometry method. 参考文献 相似文献 引证文献

A multi-stem feller-buncher cycle-time model for partial harvest of small-diameter wood stands

Due to the increased partial harvest of small-diameter stems and the lack of feller-buncher time-consumption information in Maine, it was necessary to develop new cycle-time equations. Data were collected from seven different sites in Maine with six different operators to capture the variability in site and stand conditions as well as operator experience and proficiency. The results showed that over 55% of the trees harvested were cut in accumulations of two or more trees. Significant variables in the final model included sum of dbh and stem count per accumulation. An approach to simulate a list of accumulations with the required variables is described based on a tree list with dbh classes. Treating the combination of operator, machine, and site conditions as a random effect in a linear mixed-effects model resulted in an adjusted R 2 of 0.40 for fixed and random effects. The combination of operator, machine, and site conditions explained 32% of the variance caused by random effects. The results of this study can be incorporated into existing harvest cost prediction programs to improve estimates for this region.

Towards More Sustainable Ironmaking—An Analysis of Energy Wood Availability in Finland and the Economics of Charcoal Production

Replacement of fossil carbon by renewable biomass-based carbon is an effective measure to mitigate CO2 emission intensity in the blast furnace ironmaking process. Depending on the substitution rate of fossil fuels, the required amount of biomass can be substantial. This raises questions about the availability of biomass for multiple uses. At the same time, the economic competitiveness of biomass-based fuels in ironmaking applications should also be a key consideration. In this assessment, availability of energy wood, i.e., logging residues, small-diameter wood and stumps, in Finland is discussed. Since biomass must be submitted to a thermochemical process before use in a blast furnace, the paper describes the production chain, from biomass to charcoal, and economics related to each processing step. The economics of biomass-based reducing agents is compared to fossil-based ones by taking into account the effect of European Union Emissions Trading System (EU ETS). The assessment reveals that there would be sufficient amounts of energy wood available for current users as well as for ironmaking. At present, the economics of biomass-based reducing agents in ironmaking applications is unfavorable. High CO2 emission allowance prices would be required to make such a scheme competitive against fossil-based reducing agents at current fuel prices.

Forest energy procurement: state of the art in Finland and Sweden

AbstractThe EU should produce 20% of their energy from renewable sources, including bioenergy, by 2020. Each member state has their own target, for example, Finland should produce 38% and Sweden 49% of their energy from renewable sources by 2020. In this context, the development of forest energy utilization and more effective and economic supply systems plays an important role in both countries. The Nordic countries are the world leaders in the utilization of forest biomass for energy production. This paper provides a short overview of the driving forces behind the current technical solutions of forest energy procurement systems in Finland and Sweden and some perspectives on possible future developments. At the moment, the by‐products from forest industries (e.g., sawdust, black liquor) have a high degree of utilization in both countries. Additional raw materials for energy production include logging residues, stump and root wood, small diameter wood, and other wood not in demand by the traditional forest industries. Forest energy supply chains may be characterized based on the location of comminution into roadside comminution, terminal comminution, or comminution at a plant. The productivity of the generally highly sophisticated and costly procurement machinery is, to a large extent, dependent on the operator's skills and thus new technological solutions should be developed to improve their usability and consequently efficiency.This article is categorized under: Bioenergy > Economics and Policy

Effects of subsidies on the profitability of energy wood production of wood chips from early thinnings in Finland

To increase the production of wood chips for energy from small-diameter (d 1.3 < 10 cm) stems in thinnings from young forest stands, Finland's Ministry of Agriculture and Forestry provides financial incentives for the production of wood chips through the Sustainable Silviculture Foundation Law (Kemera). As of Autumn 2010, the Kemera incentive system provides subsidies for wood chips derived from small-sized stems of young stands, 16–19 €/m 3 (8.0–9.5 €/MWh) maximum in typical harvesting conditions (average stem size of removal 30–60 dm 3, and whole-tree chip removal 40–70 m 3/ha). Total production costs of small-diameter thinning of wood chips with and without the Kemera subsidies were researched. The effects of the Kemera incentives on the profitability of whole-tree chip production were presented and discussed. Results gave a clear indication that wood chips from small-diameter stems cannot currently be produced without the Kemera subsidies from young stands with typical harvesting conditions at the current price level of small-diameter wood chips (17–18 €/MWh). If operating without the Kemera subsidies at a higher price level of small-diameter wood chips, such as 20 €/MWh, the average stem size of whole trees harvested must be greater than 60–70 dm 3 with short road transportation distances between 20 and 40 km to be economically profitable in Finland.

Productivity of whole-tree bundler in energy wood and pulpwood harvesting from early thinnings

First thinnings have been neglected to great extent in Finland because of high harvesting costs. The whole-tree bundler (Fixteri) was developed in order to rationalize the integrated harvesting of small-diameter energy wood and pulpwood and to reduce transportation costs through load compaction. The operation of the whole-tree bundler is composed of cutting and compaction processes. In the present study, the productivity level and the performance characteristics of the second version of the whole-tree bundler (Fixteri II) in integrated energy wood and pulpwood harvesting from first thinnings were defined on the basis of a time study. When the mean volume of removed whole trees averaged 20 dm3 at the stand, the productivity of Fixteri II per effective working (E0 excluding delays) hour was 3.4 m3/(E0) and with an average removal of 75 dm3, it was 6.1 m3/(E0). When compared with the first prototype of the whole-tree bundler (Fixteri I), the productivity of Fixteri II was 38–77% higher, depending on the stand density and mean tree volume of the removal. The higher performance level of Fixteri II stemmed mainly from the increase in multi-tree cutting and from the introduction of grapple feeding of the bunches. Furthermore, the better hydraulic capacity of the base machine enabled a higher level of simultaneous working processes.

Development of a Gasification System for Utilizing Fish Processing Waste and Coastal Small Diameter Wood in Rural Areas

Many small rural communities lack the infrastructure and demands of urban areas and find themselves constrained by fuel and energy limitations. Researching gasification processes that can be used by these communities can play a significant role in making them sustainable by reducing their environmental and economic impact through the use of locally available resources. This research focuses on developing a methodology and process to gasify a unique waste stream composed of salmon fishery wastes and small diameter alder, by taking a low-cost practical approach to create a system that could be locally sustainable and support existing infrastructure and heating needs. The waste stream was successfully processed and then gasified in a small-scale downdraft gasifier. Various combinations of feedstock mixtures and gasification conditions were determined using a response surface model and then trialed. The results showed a distinct set of optimal conditions and suggested that utilization of salmon processing waste in a downdraft fixed bed gasifier is feasible and could potentially generate a new function for this waste.

Industrial supply chains and production machinery of forest chips in Finland

Abstract Metsateho Oy surveyed the industrial supply chains used in the production of forest chips in 2006 in Finland. The Metsateho study also conducted a survey of the production machinery of forest chips used by energy plants in 2007, and provided an estimate of industrial supply chains and future machinery requirements for forest chip production in Finland. The majority of the logging residue chips and chips from small-sized thinning wood were produced using the roadside chipping supply chain in 2006. The chipping at plant supply chain was also significant in the production of logging residue chips. The majority of all stump wood chips consumed were comminuted at the plant, and with only around one fifth comminuted at terminals. The role of the terminal chipping supply chain was also significant in the production of chips from logging residues and small-sized wood chips. It was predicted that the roles of both terminal chipping of logging residues and chipping at the plant will increase by the year 2010. Regarding the production of chips from small-diameter wood, it was estimated that the role of chipping at the plant will also increase in coming years. The proportion of roadside chipping in the production of small-sized wood chips and logging residue chips is expected to decrease. The study estimated that a total of 1100 machine and truck units were employed in the production of forest chips for energy plants in 2007. Increasing forest chip consumption will create considerable demand for additional forest chip production resources in the future.

Potential of utilization of the residues from poplar plantation for particleboard production in Iran

The composite board industry in Iran is obliged to use residues from forest operation as well as wood industry for competing with paper industry because of shortage of wood. In the present study we investigated the residues from poplar plantation used for particleboard production. Three kinds of wood materials, poplar branches, small diameter poplar wood (3–8 cm) and beech wood, were used in the experiment of particleboard production. The results demonstrated that the characteristic of particleboard made from poplar branches and small diameter wood is comparable to that made from mature beech wood. To avoid too much residual acid in the final board, the properties of boards produced with 1.5% hardener at 175°C press temperature are acceptable, although the properties of particleboard produced with 2% hardener were higher than were higher than that of the board produced with lower hardener (1% or 1.5%).. The MOR, MOE and IB of particleboard made from branches were measured as 14.57, 2015, and 1.32 MPa, respectively, while The MOR, MOE and IB of particleboard produced from small diameter poplar wood were 19.90, 2199, and 1.86 MPa, respectively. The thickness swelling of boards made from branches after 2 and 24 h immersion in water was 20.14% and 31.26%. The utilization of branches and very small diameter wood of poplar is recommended for the survival and developments of particleboard industry in Iran.

Reuse of Wood Wastes for Energy Generation

Forests are principal global economic as well as ecological resource. Wood biomass involves trees with commercial structure and forest residues not being used in the traditional forest products industries. Available forest residues may appear to be an attractive fuel source. Forest residues are parts of trees such as branches, small-diameter wood, stumps and dead wood as well as undergrowth and low-value species. Principal sources of waste wood are two waste streams: municipal solid waste and construction and demolition waste. The most limiting factors for using of wood waste as fuel for power generation are transportation costs and its energy content.

Producing chopped firewood with firewood processors

Abstract The TTS Institute's research and development project studied both the productivity of new, chopped firewood processors (cross-cutting and splitting machines) suitable for professional and independent small-scale production, and the costs of the chopped firewood produced. Seven chopped firewood processors were tested in the research, six of which were sawing processors and one shearing processor. The chopping work was carried out using wood feeding racks and a wood lifter. The work was also carried out without any feeding appliances. Altogether 132.5 solid m 3 of wood were chopped in the time studies. The firewood processor used had the most significant impact on chopping work productivity. In addition to the firewood processor, the stem mid-diameter, the length of the raw material, and of the firewood were also found to affect productivity. The wood feeding systems also affected productivity. If there is a feeding rack and hydraulic grapple loader available for use in chopping firewood, then it is worth using the wood feeding rack. A wood lifter is only worth using with the largest stems (over 20 cm mid-diameter) if a feeding rack cannot be used. When producing chopped firewood from small-diameter wood, i.e. with a mid-diameter less than 10 cm, the costs of chopping work were over 10 € solid m −3 with sawing firewood processors. The shearing firewood processor with a guillotine blade achieved a cost level of 5 € solid m −3 when the mid-diameter of the chopped stem was 10 cm. In addition to the raw material, the cost-efficient chopping work also requires several hundred annual operating hours with a firewood processor, which is difficult for individual firewood entrepreneurs to achieve. The operating hours of firewood processors can be increased to the required level by the joint use of the processors by a number of firewood entrepreneurs.

Socioeconomic Barriers and the Role of Biomass Utilization in Southwestern Ponderosa Pine Restoration

There is general consensus that ecological restoration of southwestern ponderosa pine systems is necessary and there exists ample ecological science suggesting that it is physically attainable. However, the pace of restoration has been noticeably slow and is far from approaching the landscape level. We conducted a review of published journal articles, book chapters, and proceedings on the restoration of ponderosa pine forests in the Southwest in order to identify and examine the primary socioeconomic barriers that are impeding the progress of ecological restoration in the region. The role of small-diameter wood utilization in the southwestern United States is highlighted as an example of broader, divergent socioeconomic contexts needing reconciliation if restoration is to expand to the ecosystem scale. A synthesis of opportunities for overcoming barriers and furthering the progress of forest restoration is provided.

Comparison of methods for sampling saproxylic beetles in fine wood

Three methods for extracting saproxylic beetles from wood samples were compared. The aim with the samples was to collect substrate-specific data on the beetle fauna in different types of small diameter wood. The methods were: (1) sifting – peeling bark from the wood, sifting it and extracting beetles in Tullgren funnels, (2) box-rearing – storing wood in dark wooden boxes and using light to attract emerging beetles; and (3) sack-rearing – hanging the wood in white cotton sacks with a collection vial at the bottom. Rearing sacks gave the species richest samples. Box-rearing gave similar results, but some small beetle species, especially Staphylinidae, were less frequent. Sifting was not useful for species occurring as larvae in the wood, but gave results similar to the two rearing methods for most species that occurred as adults, and was the most efficient method for the Staphylinidae. The two rearing methods were somewhat more labour intensive than sifting, but produced more beetles per sample. Sack-rearing was somewhat more efficient than box-rearing.

Wood CO2 efflux in a primary tropical rain forest

AbstractThe balance between photosynthesis and plant respiration in tropical forests may substantially affect the global carbon cycle. Woody tissue CO2 efflux is a major component of total plant respiration, but estimates of ecosystem‐scale rates are uncertain because of poor sampling in the upper canopy and across landscapes. To overcome these problems, we used a portable scaffolding tower to measure woody tissue CO2 efflux from ground level to the canopy top across a range of sites of varying slope and soil phosphorus content in a primary tropical rain forest in Costa Rica. The objectives of this study were to: (1) determine whether to use surface area, volume, or biomass for modeling and extrapolating wood CO2 efflux, (2) determine if wood CO2 efflux varied seasonally, (3) identify if wood CO2 efflux varied by functional group, height in canopy, soil fertility, or slope, and (4) extrapolate wood CO2 efflux to the forest. CO2 efflux from small diameter woody tissue (&lt;10 cm) was related to surface area, while CO2 efflux from stems &gt;10 cm was related to both surface area and volume. Wood CO2 efflux showed no evidence of seasonality over 2 years. CO2 efflux per unit wood surface area at 25° (FA) was highest for the N‐fixing dominant tree species Pentaclethra macroloba, followed by other tree species, lianas, then palms. Small diameter FA increased steeply with increasing height, and large diameter FA increased with diameter. Soil phosphorus and slope had slight, but complex effects on FA. Wood CO2 efflux per unit ground area was 1.34±0.36 μmol m−2 s−1, or 508±135 g C m−2 yr−1. Small diameter wood, only 15% of total woody biomass, accounted for 70% of total woody tissue CO2 efflux from the forest; while lianas, only 3% of total woody biomass, contributed one‐fourth of the total wood CO2 efflux.

Drivers behind the development of forest energy in Sweden

The use of forest fuels has more than doubled in Sweden over the last 25–30 years. Almost a fifth of the utilized energy is now based on forest biomass. Concurrently, real prices of bioenergy have decreased to less than a third of what they were 25 years ago. Some principal driving forces behind this development are identified and discussed in this paper. The origin of this development was equally the result of a foreseen shortage of fibre and a reaction to this vulnerable position, made obvious through the ‘oil crises’. Although Sweden has a long tradition of large-scale use of forest energy, 35 years ago she was almost totally dependent on imported oil. Forest mechanisation provided rational solutions to handling small diameter wood and stumps in conventional industrial processes, but also enabled the economical use of such wood for energy. During 3 decades of development, drivers and obstacles have shifted. What started to reduce dependence on fossil fuels was later driven by increased general environmental awareness. An emerging ‘green’ lobby blocked the development of nuclear power and expanded harnessing of hydropower which were alternative means of self-sufficiency. In the last 10–15 years, focus has changed again. Global concern for climatic change due to emissions of greenhouse gases is a powerful driver, endorsing increased use of CO 2 -neutral energy sources. Sustainability, resource cycling and the welfare of future generations are seen as goals for continued development. Ideals and policies do not, however, automatically induce change in regular operations. A set of drivers is identified, that has played the decisive role in practice. These include the direct technical–operational drivers, as well as indirect drivers through market development, taxation and other legislation.

Does size matter?: On the importance of various dead wood fractions for fungal diversity in Danish beech forests

The importance of different fractions of coarse wood debris (cwd) for species diversity of wood-inhabiting fungi was investigated in near-natural Danish beech stands. Species number per tree increased significantly with increasing tree size, pointing out large trees to be most valuable for fungal diversity if single samples are compared. Rarefaction curves, evaluating the importance of different cwd fractions in a cumulative space, revealed a different and more complex picture. Rarefaction curves based on wood volume showed small trees and branches to host more species per volume unit than larger trees and logs, respectively, while snags were the most species-poor fraction. Surface-based curves showed species density to be rather similar among cwd types, though species density still decreased slightly with tree size. These results are interpreted to reflect a combination of two factors: firstly, small diameter cwd represent a larger surface area per volume and hence more space for fungal sporocarps, than large diameter cwd. This ‘surface area factor’ explains the high degree of similarity of the surface-based rarefaction curves. Secondly, a collection of small diameter cwd involves more separate units than an equal volume of large diameter cwd, and represents thereby more individual cases of fungal infection and, most likely, more variation in environmental conditions. The effect of this ‘number of item factor’ is reflected in the slightly increasing species density per surface area with decreasing tree size. Richness patterns of red-listed and non-red-listed species were found to be strikingly similar across cwd types, and a general preference for large logs among red-listed species was hence absent. An individual look at the most frequent encountered red-listed species revealed substrate preference patterns to occur in three of six species, of which one, the heart-rot agent Ischnoderma resinosum, preferred large logs. Based on these results, it would be obvious to conclude that local fungal species diversity is most efficiently increased in managed forests if small diameter cwd is prioritised for natural decay. However, small diameter wood appear to be unable to support heart-rot agents and other species depending on a long and diverse infection history and thus the integrity of saproxylic communities may be seriously undermined if only small diameter cwd is left for decay. Therefore, we strongly recommend that whole, naturally dead trees, representing the full range of cwd habitats, are prioritised for natural decay in managed forests whenever possible.

Does size matter?On the importance of various dead wood fractions for fungal diversity in Danish beech forests

The importance of different fractions of coarse wood debris (cwd) for species diversity of wood-inhabiting fungi was investigated in near-natural Danish beech stands. Species number per tree increased significantly with increasing tree size, pointing out large trees to be most valuable for fungal diversity if single samples are compared. Rarefaction curves, evaluating the importance of different cwd fractions in a cumulative space, revealed a different and more complex picture. Rarefaction curves based on wood volume showed small trees and branches to host more species per volume unit than larger trees and logs, respectively, while snags were the most species-poor fraction. Surface-based curves showed species density to be rather similar among cwd types, though species density still decreased slightly with tree size. These results are interpreted to reflect a combination of two factors: firstly, small diameter cwd represent a larger surface area per volume and hence more space for fungal sporocarps, than large diameter cwd. This ‘surface area factor’ explains the high degree of similarity of the surface-based rarefaction curves. Secondly, a collection of small diameter cwd involves more separate units than an equal volume of large diameter cwd, and represents thereby more individual cases of fungal infection and, most likely, more variation in environmental conditions. The effect of this ‘number of item factor’ is reflected in the slightly increasing species density per surface area with decreasing tree size. Richness patterns of red-listed and non-red-listed species were found to be strikingly similar across cwd types, and a general preference for large logs among red-listed species was hence absent. An individual look at the most frequent encountered red-listed species revealed substrate preference patterns to occur in three of six species, of which one, the heart-rot agent Ischnoderma resinosum , preferred large logs. Based on these results, it would be obvious to conclude that local fungal species diversity is most efficiently increased in managed forests if small diameter cwd is prioritised for natural decay. However, small diameter wood appear to be unable to support heart-rot agents and other species depending on a long and diverse infection history and thus the integrity of saproxylic communities may be seriously undermined if only small diameter cwd is left for decay. Therefore, we strongly recommend that whole, naturally dead trees, representing the full range of cwd habitats, are prioritised for natural decay in managed forests whenever possible.

The suitability of five Western Australian mallee eucalypt species for wood–cement composites

There are currently around 10 000 ha of mallee eucalypt plantations in Western Australia that have been established primarily for the production of eucalypt leaf oils. Planting rates are projected to increase dramatically in future. The financial viability of these plantations is dependent upon finding a commercial outlet for the small diameter wood and bark residues, which may constitute up to half of the harvested material. The potential for such residues to be utilised in cement-bonded wood composite panels was investigated here. The woody residues of five species of mallee eucalypts, as expected, inhibited the hydration reaction of Portland cement, but not to such an extent as to make the wood unsuitable for cement composites. The bark of one of the species, E. loxophleba ssp. lissophloia, inhibited the setting of Portland cement to such an extent that the residue of this species (with bark present) was unsuitable for use in wood–cement composites. Three out of the five mallee eucalypt species retained relatively good compatibility with cement even when bark was present in the residues. The flexural properties (MOR and MOE) of cement-bonded panels manufactured from chipped mallee eucalypt residues were low in comparison to similar boards made from radiata pine, probably because of the smaller particle size and lower aspect ratio of the eucalypt wood residues. Boards made from E. polybractea, E. horistes and E. kochii ssp. plenissima were stronger and more resistant to water than those made from E. angustissima and E. loxophleba ssp. lissophloia. On the basis of our findings, opportunities and challenges for the commercial utilisation of mallee eucalypt wood for wood–cement composites are discussed.

Carbon Particles in Dated Sediments from Lake Michigan, Green Bay, and Tributaries

Carbon particle analysis is carried out on four sediment cores from Lake Michigan (CLM-I), Green Bay (GB-D), and the Fox (FR-C) and Kinnickinnic Rivers (KK-6) to explore the inputs of pollution from incomplete combustion of fossil fuels. Elemental carbon content is determined by CHN analyzer, and carbon particle type (from burning of coal, wood, and petroleum), abundance, and size are determined through scanning electron microscopy. Carbon contents are between 0 and 1.0% except for core KK-6, where high values (3-33%) appear to be linked to a now defunct coke and coal gasification plant. Maxima are found in the 1950s (CLM-I) or during 1940-1962 (FR-C). The abundance of coal particles is between 40 and 95% in all four cores. The wood fraction is between 0 and 40% with the highest value in the central Lake Michigan core (CLM-I), indicating long-range transport of small diameter (18-22 micron m) wood particles with a minimum during 1960-1970 in agreement with the US consumption record. The fraction of oil particles increases in the top layers of KK-6, FR-C, and CLM-I, reflecting increasing emissions from automobile traffic since 1920-1940. Core GB-D shows the opposite trend since 1953, demonstrating reduced significance of Green Bay as a commercial port. PAH data for these areas, obtained by others, generally support the results. (A)