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The first aim of the study was to present the methodology applied by the model WOody biomass and Carbon ASsessment to compute the past potentially available residues (RA; branches and tops only; t·yr−1 of dry matter, DM), potentially generated heat and electricity (TE, EE, respectively; GJ·yr−1) and potentially avoided CO2 emissions into the atmosphere (EM; t·yr−1 CO2) for the final combustion process. The available residues are computed at the forest stand level through a recovery rate based on six technical parameters. The methodology was applied to the public stands of Valle Camonica district (Italy) (total area: 3.67·104 ha; period: 1984–2016). The mass of residues calculated for that period was used to estimate the current supply, i.e. 2.15·103 ± 6.04·102 t·yr−1 DM. By assuming that this mass was used in an Organic Rankine Cycle (ORC) unit of a local centralized heating plant, TE = 2.06·104 ÷ 2.41·104 GJ·yr−1 and EE = 5.08·103 ÷ 5.95·103 GJ·yr−1. By assuming that: (i) heat generated by the ORC replaced heat produced by conventional natural gas-based plants; (ii) electricity generated by the ORC replaced electricity generated by Italian natural gas-based plants-mix (combined heat and electricity production) EM = 1.85·103 ÷ 2.17·103 t·yr−1 CO2. [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]

Availability of solid by-products from wood harvesting and mechanical wood processing was estimated as sources for energy production based on recent actual harvesting, sawmill, and plywood production in Northwest Russia at 30 million m3. Nearly 70% of the energy wood, 20 million m3, was from harvesting, consisting of non-industrial round wood, unused branches and tops, defective wood resulting from logging, and spruce stumps removed after final felling. Over 30%, 10 million m3, of the available volume was from sawmills and plywood mills, i.e. wood chips, sawdust, and bark. Due to current low utilization of energy wood for bioenergy in Northwest Russia, delivery cost of energy wood to the potential border-crossing points in Finland was analyzed for three means of transport: railways, roadways, and waterways. Nearly 28 million m3of the energy wood could be transported by railways and 2 million m3by roadways and waterways. The costs were lowest by roadways from the nearby border areas (10–15 €/m3for wood processing by-products and 16–22 €/m3for forest chips). The costs by railways varied from 12 to 27 €/m3on shorter distances to 47–58 €/m3on longer distances. Waterway transportation was the most expensive, about 28–48 €/m3. It should be emphasized that we have estimated availability and delivery costs of energy wood, not prices which are defined by the market based on supply and demand. [ABSTRACT FROM AUTHOR]

In this case study, forest fuel procurement chains of stumps and logging residues were evaluated using a Life Cycle Assessment perspective. Direct emissions from combustion were not included, but soil organic carbon change was included as changes in carbon stocks in litter and soil. The results showed that primary forest biomass for energy has a climate impact which is time dependent. However, in long-time perspectives, there are large greenhouse gas (GHG) savings. In a short-term (20 years), there were no GHG savings when natural gas or coal was replaced. This is due to the fact that the harvest lead to decreased input of organic matter to the soil which is compared to a reference where biomass are left to decompose. The reduction in soil organic carbon may have been underestimated in the stump harvest systems studied, as the effect of soil disturbance per se was not included. Important factors when assessing GHG balance of forest fuels, besides the time horizon used, were site productivity, geographical position and forest fuel resource (stumps or logging residues). When assessing the greenhouse gas savings, efficiency of the end-use, allocation method between heat and power and type of fossil fuel replaced were also important. [ABSTRACT FROM AUTHOR]

To achieve optimal utilisation of logging residues for energy, it is important to know how different handling and storage methods affect fuel properties. The aim of this study was to model how the moisture content and dry matter losses of logging residues develop during storage. Logging residues were collected from five different stands of spruce and pine during different seasons of the year and stored in the same location. The logging residues were stored in covered piles of bundled residues and loose residues. Only minor differences were found in the moisture content profiles between piles of bundles and loose residues. Logging residues located in the centre of both types of piles had considerably lower moisture content than the outer parts. The moisture content significantly affected dry matter loss, with the highest dry matter losses being found in the samples with the least favourable drying conditions. The dry matter losses varied between 1 and 3% per month. Significantly higher dry matter losses were found in the spruce bundles than in the pine bundles. Seasoned logging residues had the lowest dry matter loss, while the logging residues harvested and piled in the autumn had the highest loss. [ABSTRACT FROM AUTHOR]

In Nordic countries, the harvesting of slash and stumps from regeneration areas for energy purposes has rapidly increased, and will increase further in the future. This development has unknown technoeconomic effects on soil scarification. This study investigated three spot mounding methods and factors affecting their quality, productivity and costs in regeneration areas after slash and stump removal. The methods were integrated stump lifting and spot mounding (INTE), separate excavator-based spot mounding (BLADE), and separate spot mounding by a continuously working mounding unit (CONT). The average quality of work was worst in INTE, while CONT was the most sensitive to stoniness. Average work times per spot mound were 4.1 and 3.1 times higher in INTE and BLADE, respectively, than in CONT. Altogether, the cost-quality ratio of CONT was better than that of the other methods, except in very small areas. [ABSTRACT FROM AUTHOR]

Biodiversity management in broadleaved forests includes partial cutting to improve conditions for species that benefit from semi-open stand structure. The harvested wood is usually used as fuel and, therefore, it is stockpiled in situ for months before further processing. If such forest fuel piles attract saproxylic insects, they are likely to be ecological traps, because the settling cost for insects is death as the wood is chipped and used for energy. This study investigated beetle species composition in piles of oak wood in southern Sweden. Species density and frequency of occurrence were compared in wood with different diameters and at the top, middle and bottom parts of piles. A total of 39 species (six red-listed) and 3528 individual beetles emerged. The highest density of both individuals and species was in the top layer. No species was significantly more frequent in the middle or bottom layers. Diameter had only a limited effect on species density and individual species reproduced in both coarse and fine wood. In conclusion, forest fuel piles can be ecological traps for several uncommon and red-listed saproxylic beetles. The negative effects can be mitigated by removing the piles before the insects colonize them. If this is not possible, then the top layer should be retained. [ABSTRACT FROM AUTHOR]

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]

Knowledge of the canopy lichen flora of managed forests is poor, but needs more focus since, for example, slash (tops, branches and twigs) harvest for biofuel may pose a threat to epiphytic lichen diversity. This study compared lichen species richness, density and composition between stems, tops, branches and twigs of mature Norway spruce (Picea abies) and aspen (Populus tremula) in managed boreonemoral forests in south-central Sweden. The stems were also compared with the slash fractions pooled together. All comparisons were made separately for each tree species. In total, 30 lichen species were found on Norway spruce and 46 on aspen. No significant differences in species richness or species density between fractions were found for Norway spruce, whereas aspen tops were significantly less species rich and species dense than the other fractions. Moreover, aspen slash was significantly more species dense than the stem. The lichen species composition of the stems clearly differed from that of the tops, branches and twigs in both tree species. Thus, lichen communities other than those removed with stems by conventional forestry are removed from the stands owing to slash harvest. However, these species are rather common and widespread in Sweden. The impact of slash harvest on the epiphytic lichen flora may therefore be of minor importance in forests established after clear-cutting or on former arable land. [ABSTRACT FROM AUTHOR]