Respiration of wood ant nest material affected by material and forest stand characteristics

We studied differences in respiration of materials from different parts of wood ant nest (top, bottom, and rim) and from the nest surroundings (humus layer and mineral soil). Samples were taken from 8 wood ant (Formica aquilonia) nests in each of the two types of forest (birch and pine) in eastern Finland. The differences were related to material and forest stand characteristics (i.e., moisture, pH, carbon content, and C:N ratio). As a result, the highest respiration per g DW was measured at the top of ant nests in the birch forest. However, respiration did not significantly differ between the parts of ant nests in the pine forest. Respiration of the humus layers in both forest stands was on average higher, whereas respiration of the mineral soils in both forest stands was lower in comparison with respiration of the nest materials. The respiration per g C did not show any significant differences between different parts of nests and surrounding soil. The most important factors influencing respiration of the materials appeared to be moisture, carbon content, and pH. In conclusion, respiration of wood ant nest material is affected by the specific material and forest stand characteristics.     

Traits mediate drought effects on wood carbon fluxes

CO₂ fluxes from wood decomposition represent an important source of carbon from forest ecosystems to the atmosphere, which are determined by both wood traits and climate influencing the metabolic rates of decomposers. Previous studies have quantified the effects of moisture and temperature on wood decomposition, but these effects were not separated from the potential influence of wood traits. Indeed, it is not well understood how traits and climate interact to influence wood CO₂ fluxes. Here, we examined the responses of CO₂ fluxes from dead wood with different traits (angiosperm and gymnosperm) to 0%, 35%, and 70% rainfall reduction across seasonal temperature gradients. Our results showed that drought significantly decreased wood CO₂ fluxes, but its effects varied with both taxonomical group and drought intensity. Drought‐induced reduction in wood CO₂ fluxes was larger in angiosperms than gymnosperms for the 35% rainfall reduction treatment, but there was no significant difference between these groups for the 70% reduction treatment. This is because wood nitrogen density and carbon quality were significantly higher in angiosperms than gymnosperms, yielding a higher moisture sensitivity of wood decomposition. These findings were demonstrated by a significant positive interaction effect between wood nitrogen and moisture on CO₂ fluxes in a structural equation model. Additionally, we ascertained that a constant temperature sensitivity of CO₂ fluxes was independent of wood traits and consistent with previous estimates for extracellular enzyme kinetics. Our results highlight the key role of wood traits in regulating drought responses of wood carbon fluxes. Given that both climate and forest management might extensively modify taxonomic compositions in the future, it is critical for carbon cycle models to account for such interactions between wood traits and climate in driving dynamics of wood decomposition.     

Old and stable soil organic matter is not necessarily chemically recalcitrant: implications for modeling concepts and temperature sensitivity

Soil carbon turnover models generally divide soil carbon into pools with varying intrinsic decomposition rates. Although these decomposition rates are modified by factors such as temperature, texture, and moisture, they are rationalized by assuming chemical structure is a primary controller of decomposition. In the current work, we use near edge X‐ray absorption fine structure (NEXAFS) spectroscopy in combination with differential scanning calorimetry (DSC) and alkaline cupric oxide (CuO) oxidation to explore this assumption. Specifically, we examined material from the 2.3–2.6 kg L^?1 density fraction of three soils of different type (Oxisol, Alfisol, Inceptisol). The density fraction with the youngest ¹⁴C age (Oxisol, 107 years) showed the highest relative abundance of aromatic groups and the lowest O‐alkyl C/aromatic C ratio as determined by NEXAFS. Conversely, the fraction with the oldest C (Inceptisol, 680 years) had the lowest relative abundance of aromatic groups and highest O‐alkyl C/aromatic C ratio. This sample also had the highest proportion of thermally labile materials as measured by DSC, and the highest ratio of substituted fatty acids to lignin phenols as indicated by CuO oxidation. Therefore, the organic matter of the Inceptisol sample, with a ¹⁴C age associated with ‘passive’ pools of carbon (680 years), had the largest proportion of easily metabolizable organic molecules with low thermodynamic stability, whereas the organic matter of the much younger Oxisol sample (107 years) had the highest proportion of supposedly stable organic structures considered more difficult to metabolize. Our results demonstrate that C age is not necessarily related to molecular structure or thermodynamic stability, and we suggest that soil carbon models would benefit from viewing turnover rate as codetermined by the interaction between substrates, microbial actors, and abiotic driving variables. Furthermore, assuming that old carbon is composed of complex or ‘recalcitrant’ compounds will erroneously attribute a greater temperature sensitivity to those materials than they may actually possess.     

Recycle,Bury, or Burn Wood Waste Biomass?: LCA Answer Depends on Carbon Accounting,Emissions Controls,Displaced Fuels,and Impact Costs

This study extends existing life cycle assessment (LCA) literature by assessing seven environmental burdens and an overall monetized environmental score for eight recycle, bury, or burn options to manage clean wood wastes generated at construction and demolition activity sites. The study assesses direct environmental impacts along with substitution effects from displacing fossil fuels and managed forest wood sourcing activities. Follow‐on effects on forest carbon stocks, land use, and fuel markets are not assessed. Sensitivity analysis addresses landfill carbon storage and biodegradation rates, atmospheric emissions controls, displaced fuel types, and two alternative carbon accounting methods commonly used for waste management LCAs. Base‐case carbon accounting considers emissions and uptakes of all biogenic and fossil carbon compounds, including biogenic carbon dioxide. Base‐case results show that recycling options (recycling into reconstituted wood products or into wood pulp for papermaking) rank better than all burning or burying options for overall monetized score as well as for climate impacts, except that wood substitution for coal in industrial boilers is slightly better than recycling for the climate. Wood substitution for natural gas boiler fuel has the highest environmental impacts. Sensitivity analysis shows the overall monetized score rankings for recycling options to be robust except for the carbon accounting method, for which all options are highly sensitive. Under one of the alternative methods, wood substitution for coal boiler fuel and landfill options with high methane capture efficiency are the best for the overall score; recycling options are next to the worst. Under the other accounting alternative, wood substitution for coal and waste‐to‐energy are the best, followed by recycling options.     

Thermal behavior of biodegraded lime wood

The effects of the soft-rot fungus Trichoderma viride Pers., on the thermal behavior of lime wood (Tillia cordata Mill.) were investigated. The lime wood pieces were inoculated with the fungus over a 12-week period. At pre-established time intervals two samples were withdrawn from the medium and analyzed by thermogravimetry and differential calorimetry, and the results were correlated with mass loss. Fungal activity was indicated by continuous decrease of sample mass.Modification of the wood because of the presence of the fungus was evidenced by structural changes that affected its thermal properties, both in respect to the hydrophilicity of the wood (evidenced mainly in desorption process) and in its decomposition behavior. The shape of DTG curves depends on the exposure time of wood to the action of microorganisms. The peak temperature assigned to the decomposition of wood components increases, while the global kinetic parameters for the main peak decrease with increasing exposure time of the wood to the attack by microorganisms.The increased characteristic temperatures of water desorption and cellulose decomposition processes and lower thermal stability could be explained by newly formed structures, mainly the oxidized ones.     

Preliminary investigation on Mgbede-20 oil-polluted site in Niger Delta, Nigeria

Soil physicochemical properties (pH, electrical conductivity (EC), % moisture, total organic carbon (TOC), total organic matter (TOM)), total extractable hydrocarbon content (THC), and micronutrient (Mn, Fe, Cu, Zn) levels of the Mgbede-20 oil-impacted site in Niger Delta, Nigeria, were investigated. Both oil-impacted and their background control soils were found to be acidic especially at surface depth. A slightly higher EC value of 107.4+/-15.0 microS cm(-1) was obtained for the subsurface-polluted soils. Of the micronutrients investigated, only Fe exceeded its acceptable limit (>100 mg/kg). The observed increase in moisture content resulting from the oil's aggregation of soil particles may lower soil porosity, and increase resistance to penetration and hydrophobicity. Soil pH can be adjusted by aeration to complete the microbially mediated oxidation of the organic acids, followed by the addition of agricultural lime to provide some buffering capacity to the soil.     

Pyrolysis biochar systems,balance between bioenergy and carbon sequestration

This study aimed to investigate the extent to which it is possible to marry the two seemingly opposing concepts of heat and/or power production from biomass with carbon sequestration in the form of biochar. To do this, we investigated the effects of feedstock, highest heating temperature (HTT), residence time at HTT and carrier gas flow rate on the distribution of pyrolysis co‐products and their energy content, as well as the carbon sequestration potential of biochar. Biochar was produced from wood pellets (WP) and straw pellets (SP) at two temperatures (350 and 650 °C), with three residence times (10, 20 and 40 min) and three carrier gas flow rates (0, 0.33 and 0.66 l min^?1). The energy balance of the system was determined experimentally by quantifying the energy contained within pyrolysis co‐products. Biochar was also analysed for physicochemical and soil functional properties, namely environmentally stable‐C and labile‐C content. Residence time showed no considerable effect on any of the measured properties. Increased HTT resulted in higher concentrations of fixed C, total C and stable‐C in biochar, as well as higher heating value (HHV) due to the increased release of volatile compounds. Increased carrier gas flow rate resulted in decreased biochar yields and reduced biochar stable‐C and labile‐C content. Pyrolysis at 650 °C showed an increased stable‐C yield as well as a decreased proportion of energy stored in the biochar fraction but increased stored energy in the liquid and gas co‐products. Carrier gas flow rate was also seen to be influential in determining the proportion of energy stored in the gas phase. Understanding the influence of production conditions on long term biochar stability in addition to the energy content of the co‐products obtained from pyrolysis is critical for the development of specifically engineered biochar, be it for agricultural use, carbon storage, energy generation or combinations of the three.     

Gross Direct and Embodied Carbon Sinks for Urban Inventories

Cities and urban regions are undertaking efforts to quantify greenhouse (GHG) emissions from their jurisdictional boundaries. Although inventorying methodologies are beginning to standardize for GHG sources, carbon sequestration is generally not quantified. This article describes the methodology and quantification of gross urban carbon sinks. Sinks are categorized into direct and embodied sinks. Direct sinks generally incorporate natural process, such as humification in soils and photosynthetic biomass growth (in urban trees, perennial crops, and regional forests). Embodied sinks include activities associated with consumptive behavior that result in the import and/or storage of carbon, such as landfilling of waste, concrete construction, and utilization of durable wood products. Using methodologies based on the Intergovernmental Panel on Climate Change 2006 guidelines (for direct sinks) and peer‐reviewed literature (for embodied sinks), carbon sequestration for 2005 is calculated for the Greater Toronto Area. Direct sinks are found to be 317 kilotons of carbon (kt C), and are dominated by regional forest biomass. Embodied sinks are calculated to be 234 kt C based on one year's consumption, though a complete life cycle accounting of emissions would likely transform this sum from a carbon sink to a source. There is considerable uncertainty associated with the methodologies used, which could be addressed with city‐specific stock‐change measurements. Further options for enhancing carbon sink capacity within urban environments are explored, such as urban biomass growth and carbon capture and storage.     

Changes in the Chemical Composition and Decay Resistance of Thermally-Modified Hevea brasiliensis Wood

In this study the effect of thermal treatment on the equilibrium moisture content, chemical composition and biological resistance to decay fungi of juvenile and mature Hevea brasiliensis wood (rubber wood) was evaluated. Samples were taken from a 53-year-old rubber wood plantation located in Tabapuã, Sao Paulo, Brazil. The samples were thermally-modified at 180°C, 200°C and 220°C. Results indicate that the thermal modification caused: (1) a significant increase in the extractive content and proportional increase in the lignin content at 220°C; (2) a significant decrease in the equilibrium moisture content, holocelluloses, arabinose, galactose and xylose content, but no change in glucose content; and (3) a significant increase in wood decay resistance against both Pycnoporus sanguineus (L.) Murrill and Gloeophyllum trabeum (Pers.) Murrill decay fungi. The greatest decay resistance was achieved from treatment at 220°C which resulted in a change in wood decay resistance class from moderately resistant to resistant. Finally, this study also demonstrated that the influence of thermal treatment in mature wood was lower than in juvenile wood.     

Short‐term lime pretreatment of poplar wood

Short‐term lime pretreatment uses lime and high‐pressure oxygen to significantly increase the digestibility of poplar wood. When the treated poplar wood was enzymatically hydrolyzed, glucan and xylan were converted to glucose and xylose, respectively. To calculate product yields from raw biomass, these sugars were expressed as equivalent glucan and xylan. To recommend pretreatment conditions, the single criterion was the maximum overall glucan and xylan yields using a cellulase loading of 15 FPU/g glucan in raw biomass. On this basis, the recommended conditions for short‐term lime pretreatment of poplar wood follow: (1) 2 h, 140°C, 21.7 bar absolute and (2) 2 h, 160°C, and 14.8 bar absolute. In these two cases, the reactivity was nearly identical, thus the selected condition depends on the economic trade off between pressure and temperature. Considering glucose and xylose and their oligomers produced during 72 h of enzymatic hydrolysis, the overall yields attained under these recommended conditions follow: (1) 95.5 g glucan/100 g of glucan in raw biomass and 73.1 g xylan/100 g xylan in raw biomass and (2) 94.2 g glucan/100 g glucan in raw biomass and 73.2 g xylan/100 g xylan in raw biomass. The yields improved by increasing the enzyme loading. An optimal enzyme cocktail was identified as 67% cellulase, 12% β‐glucosidase, and 24% xylanase (mass of protein basis) with cellulase activity of 15 FPU/g glucan in raw biomass and total enzyme loading of 51 mg protein/g glucan in raw biomass. Ball milling the lime‐treated poplar wood allowed for 100% conversion of glucan in 120 h with a cellulase loading of only 10 FPU/g glucan in raw biomass. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009     

High‐Performance Solar Steam Device with Layered Channels: Artificial Tree with a Reversed Design

Solar steam generation, combining the most abundant resources of solar energy and unpurified water, has been regarded as one of the most promising techniques for water purification. Here, an artificial tree with a reverse‐tree design is demonstrated as a cost‐effective, scalable yet highly efficient steam‐generation device. The reverse‐tree design implies that the wood is placed on the water with the tree‐growth direction parallel to the water surface; accordingly, water is transported in a direction perpendicular to what occurs in natural tree. The artificial tree is fabricated by cutting the natural tree along the longitudinal direction followed by surface carbonization (called as C‐L‐Wood). The nature‐made 3D interconnected micro‐/nanochannels enable efficient water transpiration, while the layered channels block the heat effectively. A much lower thermal conductivity (0.11 W m^?1 K^?1) thus can be achieved, only 1/3 of that of the horizontally cut wood. Meanwhile, the carbonized surface can absorb almost all the incident light. The simultaneous optimizations of water transpiration, thermal management, and light absorption results in a high efficiency of 89% at 10 kW m^?2, among the highest values in literature. Such wood‐based high‐performance, cost‐effective, scalable steam‐generation device can provide an attractive solution to the pressing global clean water shortage problem.     

Relative roles of termites and saprotrophic microbes as drivers of wood decay: A wood block test

Deadwood in tropical ecosystems represents an important but poorly studied carbon (C) pool. Biologically mediated decay of this pool occurs by both saprotrophic microbes and macro‐invertebrates, such as termites. The activity of these decay agents is influenced by abiotic conditions, especially water availability in tropical systems. While saprotrophic microbial activity is directly controlled by moisture, termites employ various morphological and behavioural modifications that should allow for continued activity in dry conditions. We therefore hypothesized that the relative role of termites would be enhanced in the dry season and a dry compared to a wet site. We deployed a novel wood bait (Pinus radiata) at two sites (rainforest and savanna), with or without access holes cut into termite‐excluding mesh. Mass loss from wood baits was measured after a dry season and after a full dry/wet annual cycle. Mass loss was higher at the rainforest site, demonstrating the overall role of moisture in driving wood decay. Counter to expectations, we found no evidence that the relative role of termites was higher at the dry site, nor during the dry season. However, the prevalence of termites was higher in the savanna compared to the rainforest. While termites clearly impact wood decay, these findings indicate that the relative importance of termites in the fate of deadwood may not reflect their mere presence within and across ecosystems. If moisture availability shifts under climate change, our results suggest similar functional responses between termites and saprotrophic microbes in driving C loss from deadwood.     

Carbon flux from decomposing wood and its dependency on temperature,wood N2 fixation rate,moisture and fungal composition in a Norway spruce forest

Globally 40–70 Pg of carbon (C) are stored in coarse woody debris on the forest floor. Climate change may reduce the function of this stock as a C sink in the future due to increasing temperature. However, current knowledge on the drivers of wood decomposition is inadequate for detailed predictions. To define the factors that control wood respiration rate of Norway spruce and to produce a model that adequately describes the decomposition process of this species as a function of time, we used an unprecedentedly diverse analytical approach, which included measurements of respiration, fungal community sequencing, N₂ fixation rate, nifH copy number, ¹⁴C‐dating as well as N%, δ¹³C and C% values of wood. Our results suggest that climate change will accelerate C flux from deadwood in boreal conditions, due to the observed strong temperature dependency of deadwood respiration. At the research site, the annual C flux from deadwood would increase by 27% from the current 117 g C/kg wood with the projected climate warming (RCP4.5). The second most important control on respiration rate was the stage of wood decomposition; at early stages of decomposition low nitrogen content and low wood moisture limited fungal activity while reduced wood resource quality decreased the respiration rate at the final stages of decomposition. Wood decomposition process was best described by a Sigmoidal model, where after 116 years of wood decomposition mass loss of 95% was reached. Our results on deadwood decomposition are important for C budget calculations in ecosystem and climate change models. We observed for the first time that the temperature dependency of N₂ fixation, which has a major role at providing N for wood‐inhabiting fungi, was not constant but varied between wood density classes due to source supply and wood quality. This has significant consequences on projecting N₂ fixation rates for deadwood in changing climate.     

Flowering of allergenically important plant species in relation to the North Atlantic Oscillation system and thermal time in the Czech Republic

This paper analyses long-term (1960–2015) onset of flowering in 16 native terrestrial plants (11 of them produce important allergens) recorded in different parts of the Czech Republic (southern, central and northern part) in relation to the North Atlantic Oscillation (NAO) index of the preceding winter and thermal data—growing degree-days (GDD) and soil temperature. Flowering occurred significantly earlier following positive winter NAO phases (causing spring to be warmer than normal in Central Europe) in nearly all early-flowering (February, March, April) species; high Pearson correlation values were recorded in, e.g. wood anemone, common snowdrop, goat willow, common hazel and common alder. There was found a difference between the southern and northern part of the country, e.g. in silver birch and pedunculate oak. Out of the later-flowering (May–July) plant species, black elder and meadow foxtail also significantly correlated with the winter NAO index, lime tree correlated less markedly. The best results of a threshold for calculation of GDD to onset of beginning of flowering were found in lime tree—it was 5 °C at all three stations. Results of other taxa were more variable (e.g. 4–7 °C in goat willow; 6–10 °C in silver birch). Pearson correlation coefficients between NAO index and GDD were negative in lime tree at all thresholds (5, 6, 7, 8, 9, 10 °C), while goat willow and silver birch were not so uniform (both positive and negative values). Correlation coefficients between phenophase onset and soil temperature (10 cm depth) had the highest values in silver birch, European larch and wood anemone. Stations situated at higher elevation showed negative correlation coefficient with soil temperature in common snowdrop, pedunculate oak, meadow foxtail and lime tree; other values were positive.     

A pantropical analysis of the impacts of forest degradation and conversion on local temperature

Temperature is a core component of a species' fundamental niche. At the fine scale over which most organisms experience climate (mm to ha), temperature depends upon the amount of radiation reaching the Earth's surface, which is principally governed by vegetation. Tropical regions have undergone widespread and extreme changes to vegetation, particularly through the degradation and conversion of rainforests. As most terrestrial biodiversity is in the tropics, and many of these species possess narrow thermal limits, it is important to identify local thermal impacts of rainforest degradation and conversion. We collected pantropical, site‐level (<1 ha) temperature data from the literature to quantify impacts of land‐use change on local temperatures, and to examine whether this relationship differed aboveground relative to belowground and between wet and dry seasons. We found that local temperature in our sample sites was higher than primary forest in all human‐impacted land‐use types (N = 113,894 daytime temperature measurements from 25 studies). Warming was pronounced following conversion of forest to agricultural land (minimum +1.6°C, maximum +13.6°C), but minimal and nonsignificant when compared to forest degradation (e.g., by selective logging; minimum +1°C, maximum +1.1°C). The effect was buffered belowground (minimum buffering 0°C, maximum buffering 11.4°C), whereas seasonality had minimal impact (maximum buffering 1.9°C). We conclude that forest‐dependent species that persist following conversion of rainforest have experienced substantial local warming. Deforestation pushes these species closer to their thermal limits, making it more likely that compounding effects of future perturbations, such as severe droughts and global warming, will exceed species' tolerances. By contrast, degraded forests and belowground habitats may provide important refugia for thermally restricted species in landscapes dominated by agricultural land.     

Life Cycle Impacts and Benefits of Wood along the Value Chain: The Case of Switzerland

Sustainable use of wood may contribute to coping with energy and material resource challenges. The goal of this study is to increase knowledge of the environmental effects of wood use by analyzing the complete value chain of all wooden goods produced or consumed in Switzerland. We start from a material flow analysis of current wood use in Switzerland. Environmental impacts related to the material flows are evaluated using life cycle assessment–based environmental indicators. Regarding climate change, we find an overall average benefit of 0.5 tonnes carbon dioxide equivalent per cubic meter of wood used. High environmental benefits are often achieved when replacing conventional heat production and energy‐consuming materials in construction and furniture. The environmental performance of wood is, however, highly dependent on its use and environmental indicators. To exploit the mitigation potential of wood, we recommend to (1) apply its use where there are high substitution benefits like the replacement of fossil fuels for energy or energy‐intensive building materials, (2) take appropriate measures to minimize negative effects like particulate matter emissions, and (3) keep a systems perspective to weigh effects like substitution and cascading against each other in a comprehensive manner. The results can provide guidance for further in‐depth studies and prospective analyses of wood‐use scenarios.     

Effects of harvesting on spatial and temporal diversity of carbon stocks in a boreal forest landscape

Carbon stocks in managed forests of Ontario, Canada, and in harvested wood products originated from these forests were estimated for 2010–2100. Simulations included four future forest harvesting scenarios based on historical harvesting levels (low, average, high, and maximum available) and a no‐harvest scenario. In four harvesting scenarios, forest carbon stocks in Ontario's managed forest were estimated to range from 6202 to 6227 Mt C (millions of tons of carbon) in 2010, and from 6121 to 6428 Mt C by 2100. Inclusion of carbon stored in harvested wood products in use and in landfills changed the projected range in 2100 to 6710–6742 Mt C. For the no‐harvest scenario, forest carbon stocks were projected to change from 6246 Mt C in 2010 to 6680 Mt C in 2100. Spatial variation in projected forest carbon stocks was strongly related to changes in forest age (r = 0.603), but had weak correlation with harvesting rates. For all managed forests in Ontario combined, projected carbon stocks in combined forest and harvested wood products converged to within 2% difference by 2100. The results suggest that harvesting in the boreal forest, if applied within limits of sustainable forest management, will eventually have a relatively small effect on long‐term combined forest and wood products carbon stocks. However, there was a large time lag to approach carbon equality, with more than 90 years with a net reduction in stored carbon in harvested forests plus wood products compared to nonharvested boreal forest which also has low rates of natural disturbance. The eventual near equivalency of carbon stocks in nonharvested forest and forest that is harvested and protected from natural disturbance reflects both the accumulation of carbon in harvested wood products and the relatively young age at which boreal forest stands undergo natural succession in the absence of disturbance.     

Response of feather moss associated N2 fixation and litter decomposition to variations in simulated rainfall intensity and frequency

Feather mosses in boreal forests form a dense ground‐cover that is an important driver of both nutrient and carbon cycling. While moss growth is highly sensitive to moisture availability, little is known about how moss effects on nutrient and carbon cycling are affected by the dynamics of moisture input to the ecosystem. We experimentally investigated how rainfall regimes affected ecosystem processes driven by the dominant boreal feather moss Pleurozium schreberi by manipulating total moisture amount, frequency of moisture addition and moss presence/absence. Moisture treatments represented the range of rainfall conditions that occur in Swedish boreal forests as well as shifts in rainfall expected through climate change. We found that nitrogen (N) fixation by cyanobacteria in feather mosses (the main biological N input to boreal forests) was strongly influenced by both moisture amount and frequency, and their interaction; increased frequency had greater effects when amounts were higher. Within a given moisture amount, N fixation varied up to seven‐fold depending on how that amount was distributed temporally. We also found that mosses promoted vascular litter decomposition rates, concentrations of litter nutrients, and active soil microbial biomass, and reduced N release into soil solution. These effects were usually strongest under low moisture amount and/or frequency, and revealed a buffering effect of mosses on the decomposer subsystem under moisture limitation. These results highlight that both the amount and temporal distribution of rainfall, determine the effect of feather mosses on ecosystem N input and the decomposer subsystem. They also emphasize the role of feather mosses in mediating moisture effects on decomposer processes. Finally, our results suggest that projected shifts in precipitation in the Swedish boreal forest through climate change will result in increased moss growth and N₂ fixation but a reduced dependency of the decomposer subsystem on feather moss cover for moisture retention.     

Environmental Assessment of Wood‐Based Biofuel Production and Consumption Scenarios in Norway

In Norway, the boreal forest offers a considerable resource base, and emerging technologies may soon make it commercially viable to convert these resources into low‐carbon biofuels. Decision makers are required to make informed decisions about the environmental implications of wood biofuels today that will affect the medium‐ and long‐term development of a wood‐based biofuels industry in Norway. We first assess the national forest‐derived resource base for use in biofuel production. A set of biomass conversion technologies is then chosen and evaluated for scenarios addressing biofuel production and consumption by select industry sectors. We then apply an environmentally extended, mixed‐unit, two‐region input?output model to quantify the global warming mitigation and fossil fuel displacement potentials of two biofuel production and consumption scenarios in Norway up to 2050. We find that a growing resource base, when used to produce advanced biofuels, results in cumulative global warming mitigation potentials of between 58 and 83 megatonnes of carbon dioxide equivalents avoided (Mt‐CO₂‐eq.‐avoided) in Norway, depending on the biofuel scenario. In recent years, however, the domestic pulp and paper industry—due to increasing exposure to international competition, capacity reductions, and increasing production costs—has been in decline. In the face of a declining domestic pulp and paper industry, imported pulp and paper products are required to maintain the demand for these goods and thus the greenhouse gas (GHG) emissions of the exporting region embodied in Norway's pulp and paper imports reduce the systemwide benefit in terms of avoided greenhouse gas emissions by 27%.