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Woody biomass is an important feedstock for renewable energy production in the United States. Residues are produced by forest harvests, and some operations utilize this material for energywood. Energywood requires additional processing and is often the lowest value product generated. Additional research quantifying the productivity and costs of energywood operations could allow stakeholders to evaluate the efficiency of those operations and identify areas for improvement. This study evaluated five energywood harvesting operations in the Lower Mid-Atlantic region of the United States (two Appalachian Mountain harvests and three Coastal Plain harvests). Each harvesting operation was observed for 4–7 days, and productivity data were collected on each harvesting function using time study and activity sampling methods. Productivity and costs of each operation were estimated, and equipment mixes and harvesting methods were evaluated to determine efficiency. Interviews were also conducted with each logging contractor to understand operating strategies and decision making. Cut and haul costs averaged (USD) $32.07/tonne and ranged from $26.19 to $38.28/tonne. Hauling consistently comprised the largest function cost at an average of $12.24/tonne. Machines handling energywood were less productive than those harvesting roundwood because of the large effect average stem size had on productivity levels. Harvesting system analysis also highlighted the importance of ensuring a balanced equipment mix to lower costs and ensure efficiency. This research provides stakeholders with a valuable comparison of energywood harvesting operations in the Lower Mid-Atlantic region of the United States that can be used to make better-informed decisions regarding the efficient and economical harvest of energywood. [ABSTRACT FROM AUTHOR]

Whole-tree harvesting is an increasingly common harvesting method due to the high demand for fuel chips. In whole-tree harvesting, nutrient removal from the site is substantially higher than in cut-to-length harvesting, in which nutrient-rich branches and unmerchantable top sections of trees are left in the cutting area. There is a concern that whole-tree harvesting impairs site productivity, especially on mires drained for forestry. We employed six field experiments to study the effects of the harvesting method used on the amount of logging residues left on the site in the thinning of Scots pine (Pinus sylvestris L.) stands. The four harvesting treatments varied in their intensity of biomass removal from conventional stem-only harvesting (CTL), where tree tops and branches were left on the site to whole-tree harvesting (WTH) complemented by the manual collection of residues. Logging residues left on the sites were weighed and sampled to determine their moisture content. After CTL, the amount of logging residues left on the site was 7780-15340 kg ha-1(dry mass), depending on the experiment. In (WTH) the amount of logging residues left on the site was 32-66% of that of CTL. After the manual collection of residues in WTH, 4-16% of the residues still remained on the sites. The residues left at site following WTH had a larger share of small-diameter material than after CTL. [ABSTRACT FROM AUTHOR]

The review gives an overview of the increased utilization of forest biomass for energy. The emphasis is on Nordic countries, especially on Sweden and Finland with large biomass potentials and a high share of renewable energy in gross final energy consumption. The utilization and potential of forest chip sources such as logging residues, small-size tree stems and stumps that are normally not harvested in conventional harvesting are described. Environmental potential and impacts that may reduce the utilization of forest biomass are discussed based on recent publications. Finally, the review summarizes the future developments based on their relationship to policies, certifications and guidelines and forest owners' decisions. [ABSTRACT FROM AUTHOR]

Abstract: Forest logging residues are systematically left after exploitation. In Romania, logging residues were traditionally used by population for fuel but have not been considered at large scale for industrialization. The estimation of the resource needed a more accurate assessment and the development of devoted biomass models for large-scale applications. Our study aims at estimating the amount of logging residues based on direct biomass measurements for the two main species of Romanian Carpathian forests: Norway spruce and beech. A country-scale field measurement campaign resulted in the sampling of 100 Norway spruce and 74 beech trees. Models of logging residues biomass were developed for both species. The amount of potential logging residues per tree was greater in beech than in Norway spruce. The models developed, nonlinear by essence, showed that diameter-based equations enable the evaluation of individual logging residues potential. Using tree height as an additional independent variable did not improve the models. The models fitted were applied to yield tables in order to estimate the resource potential in spruce and beech stands for each productivity class, and its dynamic during the production cycle. The calculations proved that the potential amount of logging residue is larger in spruce stands. The amount in beech is very sensitive to the productivity class, unlike in spruce stands. The potential biomass produced during early thinnings is however greater in beech stands than in spruce ones. A more systematic and organized collecting of residues could offer a fast answer to the need of increasing renewable energy share. [Copyright &y& Elsevier]

The relative volume growth effects of thinning after whole-tree harvesting (WTH) compared to a conventional stem-only harvest (CH) in young stands of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) were analyzed, using a series of four pine and four spruce field experiments. The series was established in the years 1972–1977, and thinning was performed only once. Results are shown periodically and cumulatively. All sites were included for 20 (19) years in pine and 25years in spruce. The total experimental period varied between 19 and 35years for individual sites. Four models assuming additive or multiplicative effects gave only slightly varying results. The inclusion of standing volume after thinning as a covariate was effective in spruce independent of whether the covariate was treated as multiplicative or additive. A logarithmic model with a multiplicative effect of the covariate was preferred in further presentations. Results for pine stands after 20years indicated a nonsignificant loss of 5% with confidence limits (p =0.05) of ±6–7%, while the spruce stands showed a significant growth loss of 11% with confidence limits of ±4–5% after 25years. The difference between the species in relative growth effects was significant, and amounted to 8% for a cumulative 20-year period. No indications of trends in response were found during a 20-year period in pine and a 25-year period in spruce. An analysis of growth effects in the first years showed that basal area increment in spruce was significantly reduced already in the first growing season after thinning. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was to determine the amount of boron in three Norway spruce (Picea abies (L.) Karst) stands in eastern Finland, where boron deficiency is common. A further aim was to estimate the effects of logging-residue harvest on boron balance and the boron-to-nitrogen ratio on these sites. The data were obtained from a 30-year-old and a 62-year-old healthy spruce stand as well as from a 35-year-old spruce stand with boron deficiency and growth disorders. Altogether 2.1 and 2.4kgha−1 boron, respectively, were bound in trees+organic layer+0–10cm mineral soil layer in the two healthy stands, and 0.9kgha−1 in the boron deficient stand. For the amount of boron in the healthy stands the trees made up 43% and 49%, respectively, and in the boron deficient stand 38%. Stems contained 30% and 40%, respectively, of the boron in trees in the healthy stands and 37% in the boron-deficient stand. Only 11–13% of the tree boron was in the needles. The amount of nitrogen bound in the ecosystem studied was 2.1 and 2.5Mgha−1, respectively, in the two healthy stands and 3.0Mgha−1 in the boron deficient stand. In the ecosystem the trees contained 21–29% of the amount of nitrogen. Stems contained 14–24%, respectively, and needles 26–36%, respectively, of the nitrogen in the trees on the studied stands. In stem-only harvestings, relatively more boron than nitrogen would be removed from a site. In the boron-deficient stand, boron fertilisation for 3years nearly doubled the amount of boron in the ecosystem. Only 38% of the fertiliser boron (2kgha−1) was found in the ecosystem components studied. [Copyright &y& Elsevier]

Abstract: Regression models relating variables derived from airborne laser scanning to the amount of biomass of potential logging residues (PLR) were estimated for 147 sample plots (200 m2) measured in mature boreal forest. Logging residues were in this study defined as branches and tops of all trees. The base model explained 86% of the variation, and when the data were stratified into two strata according to site quality, the stratum-specific models accounted for 88% and 77% of the variation in PLR on poor sites and on good sites, respectively. Effect of tree species composition were assessed by including the proportion of Norway spruce as potential explanatory variable and this extended model explained 87% of the variability. The estimated models were validated using two datasets, one comprising 120 sample plots (200 m2), and the other consisting of 25 measured stands. The ground observations in the stand dataset were based on data collected by a harvester. The validation of the overall model gave an RMSE value of 27.6% and 22.2% of the mean value in the plot and stand data, respectively. The stratum-specific models gave RMSE values of 25.3 and 22.5% in the plot validation, and 24.3 and 17.6% in the stand validation. Including proportion of spruce in the model gave an RMSE of 23.2% in the plot validation and 21.3% in the stand validation. The study shows that PLR in a boreal forest can be estimated by airborne laser scanning with accuracy comparable to those obtained when estimating e.g. stand volume. [Copyright &y& Elsevier]

Methodology to assess the potential for energy wood procurement in Russia is described in this article and applied to the Leningrad region. Wood from thinnings, logging residues, non-industrial roundwood and residues from sawmilling are considered as sources for energy production. Energy wood available in the region, based on the 2004 actual cut, is approximately 4 million m3. Nearly 86% of this is non-industrial roundwood and felling residues, and 14% is by-products from sawmilling. Almost two-thirds of the non-industrial roundwood and felling residues are in cutting areas and one-third is in central processing yards. Deciduous tree species (birch and aspen) dominate in energy wood, representing about 65% of the total amount of felling residues and non-industrial wood. It is possible to intensify utilization of forest resources and thereby also to increase the use of wood in energy production. The total amount could be 54% higher if the allowable cut was fully utilized and 124% higher if thinnings were also utilized completely. There are, however, significant intraregional differences, as the current rate of utilization of forest resources varies in the region. [ABSTRACT FROM AUTHOR]

1. Slash harvesting from forests to provide bioenergy reduces the amount of woody debris in the managed forest landscape and changes the physical and chemical environment in clear-cuts. We examined previously unstudied effects of commercial (i.e. non-experimental) slash harvest on species composition and richness of liverworts, mosses and vascular plants. The results call for modification of commercial slash harvest practices. 2. Differences between conventionally harvested (i.e. slash left) and slash-harvested stands were investigated 5–10 years after clear-cutting through analysis of 28 paired stands, with one 0·1-ha plot divided into five 0·02-ha subplots in each stand. 3. The species composition of mosses and liverworts in 0·1-ha plots was significantly affected by slash harvest, whereas the composition of vascular plant species was not. 4. The species richness of liverworts was significantly reduced by slash harvest in plots of both sizes, whereas moss richness was reduced only in 0·02-ha plots. The loss of liverwort species was largest, with approximately one-third of the species disappearing. The species richness of vascular plants was not significantly affected by slash harvest in either plot size. 5. Slash harvest reduced species richness of forest bryophytes and of bryophytes typically growing on organic substrates in open habitats. Species richness of non-forest bryophytes on inorganic substrates remained unchanged. 6. Synthesis and applications. Our results show that slash harvest reduces shelter and woody substrates, which changes species composition and reduces species richness of liverworts and mosses in clear-cuts. Increased mechanical disturbance that removes remnant vegetation and exposes mineral soil may also play a role. In order to conserve bryophytes, we advocate mitigation of adverse ecological effects through enhanced environmental care within slash-harvested stands. Leaving more tree clusters, and creating and protecting large woody debris would be especially important in these stands, and would also improve the habitat for other organisms. [ABSTRACT FROM AUTHOR]

Abstract: Renewable energy sources have been identified to play an important role in mitigating climate change. The main reason is that carbon dioxide emission is avoided when fossil fuels are replaced. This paper presents a study focusing on direct and indirect greenhouse gas emissions from fuel chip production in Finland. The fuel chips studied were produced from logging residue at final harvest. Five different fuel production chains were considered. The calculations showed that fuel chip production from the residues of final harvest is very efficient from the viewpoint of energy use during collection, chipping and transportation. Only an input of 2–3% of the produced energy is needed, which means that roughly 30 to 50 units of bioenergy is produced for every unit of (fossil) energy consumed. The emissions from collecting, chipping and transporting the residues were evaluated to be about 4–7kg depending on harvesting and chipping methods and transportation distance. Emissions of greenhouse gases (other than ) from burning forest residues in a modern CHP-plant were evaluated to be small, about 2kg . If nitrogen losses are compensated for with fertilisation, the additional greenhouse gas emissions were calculated to be about . The calculations showed that in a favourable situation as much as 97–98% of the greenhouse gas emissions could be avoided by substituting a fossil fuel with wood fuel, but even in an unfavourable situation the amount avoided should be higher than 75%. [Copyright &y& Elsevier]

Abstract: The integration of logging residue extraction, along with the establishment of a new stand and soil preparation is a new idea. A dual-purpose machine has been developed in Finland. It can be used as both a scarifier and a slash forwarder without the need for time-consuming conversion work. According to research results, the machine has proved to be rather competitive. In average conditions, the integration decreases the cost of scarification and residue recovery by about 10%, when compared to separate operations with two machines. Slash forwarder–scarifier is ideally suited for use in small regeneration areas, where the costs of moving two separate machines between sites would constitute a large share of the total costs. By the slash forwarder–scarifier operators exposure to the whole body vibration during the work decreases due to slower driving speed, the machine''s greater weight and the position of scarifying plates in the middle of the machine body. [Copyright &y& Elsevier]