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Abstract

In the current debate over the CO2 emissions implications of switching from fossil fuel energy sources to include a substantial amount of woody biomass energy, many scientists and policy makers hold the view that emissions from the two sources should not be equated. Their rationale is that the combustion or decay of woody biomass is simply part of the global cycle of biogenic carbon and does not increase the amount of carbon in circulation. This view is frequently presented as justification to implement policies that encourage the substitution of fossil fuel energy sources with biomass. We present the opinion that this is an inappropriate conceptual basis to assess the atmospheric greenhouse gas (GHG) accounting of woody biomass energy generation. While there are many other environmental, social, and economic reasons to move to woody biomass energy, we argue that the inferred benefits of biogenic emissions over fossil fuel emissions should be reconsidered.

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... Some have assumed that bioenergy is 'carbon-neutral' because harvested C, which is combusted and emitted as CO 2 , is later sequestered through forest regrowth (Kroetz & Friedland, 2008). However, a developing literature has questioned many of the fundamental assumptions in this argument (Johnson, 2009;Searchinger et al., 2009;Mckechnie et al., 2011;Zanchi et al., 2011;Gunn et al., 2012;Schulze et al., 2012). Important uncertainties remain regarding the temporal dynamics of C fluxes associated with bioenergy use. ...
... Another key consideration is how these dynamics will play out at landscape scales as a function of harvests scheduled or staggered across time and space (Gunn et al., 2012). There may be compensatory effects at landscape scales, possibly equilibrating C emissions and C uptake across multiple stands harvested at different time schedules (Ryan et al., 2010). ...
... An on-going debate has focused on whether bioenergy harvesting will result in lower landscape C storage with an associated increased C flux to the atmosphere, with some scientists arguing this as likely (Fargione et al., 2008;Gunn et al., 2012) and others arguing it as not (Malmsheimer et al., 2011). Our study suggests the answer may depend on a variety of factors. ...
Article
With growing interest in wood bioenergy there is uncertainty over greenhouse gas emissions associated with offsetting fossil fuels. Although quantifying postharvest carbon (C) fluxes will require accurate data, relatively few studies have evaluated these using field data from actual bioenergy harvests. We assessed C reductions and net fluxes immediately postharvest from whole‐tree harvests (WTH), bioenergy harvests without WTH, and nonbioenergy harvests at 35 sites across the northeastern United States. We compared the aboveground forest C in harvested with paired unharvested sites, and analyzed the C transferred to wood products and C emissions from energy generation from harvested sites, including indirect emissions from harvesting, transporting, and processing. All harvests reduced live tree C; however, only bioenergy harvests using WTH significantly reduced C stored in snags (P 0.01). On average, WTH sites also decreased downed coarse woody debris C while the other harvest types showed increases, although these results were not statistically significant. Bioenergy harvests using WTH generated fewer wood products and resulted in more emissions released from bioenergy than the other two types of harvests, which resulted in a greater net flux of C (P 0.01). A Classification and Regression Tree analysis determined that it was not the type of harvest or amount of bioenergy generated, but rather the type of skidding machinery and specifics of silvicultural treatment that had the largest impact on net C flux. Although additional research is needed to determine the impact of bioenergy harvesting over multiple rotations and at landscape scales, we conclude that operational factors often associated with WTH may result in an overall intensification of C fluxes. The intensification of bioenergy harvests, and subsequent C emissions, that result from these operational factors could be reduced if operators select smaller equipment and leave a portion of tree tops on site.
... The new hypothesis that is now taking hold is that bioenergy is not always "carbon neutral," and erroneous accounting may inappropriately stimulate the use of forest resources, taking the wood away from alternative uses having a lesser impacts on climate change [3,5]. It has been observed that the combustion of biomass replaces fossil emissions with its own emissions, which can also be higher per unit of energy [3]; that greenhouse physics is indifferent to the origin of the pollutant, and once a molecule of CO 2 enters the atmosphere its warming capacity is the same, irrespective of its origin [5]; that the different time scales with which the fossil and biogenic carbon interact with the carbon cycle must be taken into consideration [6]; that the shift from fossil fuels to energy from wood biomass could lead to an increase of the levels of greenhouse gases in the atmosphere for at least a number of decades [7e9]. ...
... The new hypothesis that is now taking hold is that bioenergy is not always "carbon neutral," and erroneous accounting may inappropriately stimulate the use of forest resources, taking the wood away from alternative uses having a lesser impacts on climate change [3,5]. It has been observed that the combustion of biomass replaces fossil emissions with its own emissions, which can also be higher per unit of energy [3]; that greenhouse physics is indifferent to the origin of the pollutant, and once a molecule of CO 2 enters the atmosphere its warming capacity is the same, irrespective of its origin [5]; that the different time scales with which the fossil and biogenic carbon interact with the carbon cycle must be taken into consideration [6]; that the shift from fossil fuels to energy from wood biomass could lead to an increase of the levels of greenhouse gases in the atmosphere for at least a number of decades [7e9]. The challenge to the principle of carbon neutrality of biomass is obviously a crucial issue for supportive policies and incentives for bioenergy and will require the development of new greenhouse gas accounting models [6]. ...
... Firewood harvested with traditional skidding system and processed in 1-m pieces (aþbþgþh*0.3þi*0.7þlþm*0.50þn*0.50þo)* 534 6. 5 *The letters in parentheses refer to the stages contributing to the production of each wood fuel considered -see Table 1 for correspondence with letters. Source: direct interviews with expert witnesses of the main logging companies ...
Article
Abstract The aim of this study is to conduct an economic and environmental assessment of forest biomass for heating, in particular two types of firewood and three types of wood chips were analyzed. Regarding economic aspects, an analysis was made of production costs and revenues (per tonne of biomass), considering all the stages involved “from the woods to the mouth of the boiler.” For the environmental analysis, conducted using life cycle assessment, the stages taken into account went from “the woods to the heat produced”. The wood biomasses were compared to each other and to fuel oil and natural gas. The economic analysis showed that at current market prices it is more profitable to produce firewood rather than wood chips. As concerns the environmental aspects, the results of the LCA showed that, for the same heat output, forest wood-based fuel has an environmental impact lower than fuel oil, but still higher than natural gas. There are no big differences in the impact of various wood fuels. In the conclusion, some ways for improvement have been proposed, in terms of both the economic competitiveness of the agro-energy supply chains considered and the reducing of their environmental impact.
... Interest in forest bioenergy fuel is increasing in the northeastern United States and beyond. Yet the question of how to harvest woody biomass in an ecologically sustainable manner continues to frame policy debates regarding expanded use of bioenergy (Buccholz et al. 2009, Lattimore et al. 2009, Gunn et al. 2012. The perceived benefits of this energy resource (e.g., local availability, renewable energy independence) must be evaluated against the potential for elevated harvest-induced stress on forest ecosystems, particularly if harvesting intensity increases with associated impacts on ecologically important elements of stand structure (Van Hook et al. 1982, Lattimore et al. 2009, Janowiak and Webster 2010. ...
... Potential ecological impacts of bioenergy harvesting have been of concern for several decades (e.g., Van Hook et al. 1982, Chadwick et al. 1986, Lattimore et al. 2009). Minimizing potential negative consequences is a major focus of policy discussions and academic research (Janowiak and Webster 2010, Manomet Center for Conservation Sciences 2010, Gunn et al. 2012. While previous research has tended to downplay the variability evident in harvesting practices-for instance, by strictly categorizing harvests as either bioenergy or nonbioenergy, or whole-tree vs. non-whole tree (e.g., Mann et al. 1988, Yanai 1998, Briedis et al. 2011)-our research highlights the importance of considering bio-energy as a continuous variable in the context of multiple harvest objectives. ...
Article
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Demand for forest bioenergy fuel is increasing in the northern forest region of eastern North America and beyond, but ecological impacts, particularly on habitat, of bioenergy harvesting remain poorly explored in the peer-reviewed literature. Here, we evaluated the impacts of bioenergy harvests on stand structure, including several characteristics considered important for biodiversity and habitat functions. We collected stand structure data from 35 recent harvests in northern hardwood-conifer forests, pairing harvested areas with unharvested reference areas. Biometrics generated from field data were analyzed using a multi-tiered nonparametric uni- and multivariate statistical approach. In analyses comparing harvested to reference areas, sites that had been whole-tree harvested demonstrated significant differences (relative negative contrasts, P < 0.05) in snag density, large live-tree density, well-decayed downed coarse woody debris volume, and structural diversity index (H) values, while sites that had not been whole-tree harvested did not exhibit significant differences. Classification and regression tree (CART) analyses suggested that the strongest predictors of structural retention, as indicated by downed woody debris volumes and H index, were silvicultural treatment and equipment type rather than the percentage of harvested volume allocated to bioenergy uses. In general, bioenergy harvesting impacts were highly variable across the study sites, suggesting a need for harvesting guidelines aimed at encouraging retention of ecologically important structural attributes.
... In a vast number of studies it is implicitly assumed that the BC e of biodegradable materials (e.g. organic waste contained in food and garden waste, paper and cardboard) released in the atmosphere after combustion, is in equilibrium to that absorbed by the biogenic pool (i.e. during the growth of plants); hence it is purported that it should not be accounted for as contributing to the global warming effect Giugliano et al., 2011;Gunn et al., 2012;Smith et al., 2001). Contrariwise, other studies suggest that BC e released from activities such as permanent deforestation, burning of a tropical forest or combustion of forest biomass for energy, is not entirely absorbed by biomass systems (Gunn et al., 2012;Rabl et al., 2007). ...
... organic waste contained in food and garden waste, paper and cardboard) released in the atmosphere after combustion, is in equilibrium to that absorbed by the biogenic pool (i.e. during the growth of plants); hence it is purported that it should not be accounted for as contributing to the global warming effect Giugliano et al., 2011;Gunn et al., 2012;Smith et al., 2001). Contrariwise, other studies suggest that BC e released from activities such as permanent deforestation, burning of a tropical forest or combustion of forest biomass for energy, is not entirely absorbed by biomass systems (Gunn et al., 2012;Rabl et al., 2007). The basis of their argument is that the lower heating value (LHV) (or net calorific value) of carbon is the same regardless of its source, and as such BC e that is released in the atmosphere can also contribute to the global warming effect, measured using a unit-based index called GWP bio or CO 2biogenic emissions (Blengini, 2008a;Cherubini et al., 2011;Christensen et al., 2009;Gentil et al., 2009;Parkes et al., 2015). ...
Article
Full-text available
Established assessment methods focusing on resource recovery from waste within a circular economy context consider few or even a single domain/s of value, i.e. environmental, economic, social and technical domains. This partial approach often delivers misleading messages for policy and decision-makers. It fails to accurately represent systems complexity, and obscures impacts, trade-offs and problem shifting that resource recovery processes or systems intended to promote circular economy may cause. Here, we challenge such partial approaches by critically reviewing the existing suite of environmental, economic, social and technical metrics that have been regularly observed and used in waste management and resource recovery systems' assessment studies, upstream and downstream of the point where waste is generated. We assess the potential of those metrics to evaluate ‘complex value’ of materials, components and products, i.e., the holistic sum of their environmental, economic, social and technical benefits and impacts across the system. Findings suggest that the way resource recovery systems are assessed and evaluated require simplicity, yet must retain a suitable minimum level of detail across all domains of value, which is pivotal for enabling sound decision-making processes. Criteria for defining a suitable set of metrics for assessing resource recovery from waste require them to be simple, transparent and easy to measure, and be both system- and stakeholder-specific. Future developments must focus on providing a framework for the selection of metrics that accurately describe (or at least reliably proxy for) benefits and impacts across all domains of value, enabling effective and transparent analysis of resource recovery form waste in circular economy systems.
... The long-term C impacts of bioenergy harvests are particularly complex because the kind of energy generated (e.g., electricity vs. heat) and type of fossil fuel replaced all impact the net C outcomes (Harmon & Marks, 2002;Eriksson et al., 2007;Routa et al., 2011;Zanchi et al., 2012;Mika & Keeton, 2013). A poorly explored though critical consideration is how bioenergy harvest at landscape scales and over multiple rotations affect net C flux (see Table 1 for definition of terms; Gunn et al., 2012). ...
... Mika and W. Keeton, unpublished data). If bioenergy harvests result in increased removals of live biomass or residues (Zanchi et al., 2012), this may reduce average landscape C storage and increase atmospheric CO 2 , even with fossil fuel offsets (McKechnie et al., 2011;Gunn et al., 2012). Despite the potential for greater net C emissions associated with intensified harvesting, some bioenergy harvesting practices, such as stand improvement cuttings, removing low grade material, have the potential to improve stand stocking and residual tree quality (Hoover & Stout, 2007). ...
Article
The long-term greenhouse gas emissions implications of wood biomass (‘bioenergy’) harvests are highly uncertain yet of great significance for climate change mitigation and renewable energy policies. Particularly uncertain are the net carbon (C) effects of multiple harvests staggered spatially and temporally across landscapes where bioenergy is only one of many products. We used field data to formulate bioenergy harvest scenarios, applied them to 362 sites from the Forest Inventory and Analysis database, and projected growth and harvests over 160 years using the Forest Vegetation Simulator. We compared the net cumulative C fluxes, relative to a non-bioenergy baseline, between scenarios when various proportions of the landscape are harvested for bioenergy: 0% (non-bioenergy); 25% (BIO25); 50% (BIO50); or 100% (BIO100), with three levels of intensification. We accounted for C stored in aboveground forest pools and wood products, direct and indirect emissions from wood products and bioenergy, and avoided direct and indirect emissions from fossil fuels. At the end of the simulation period, although 82% of stands were projected to maintain net positive C benefit, net flux remained negative (i.e., net emissions) compared to non-bioenergy harvests for the entire 160-year simulation period. BIO25, BIO50, and BIO100 scenarios resulted in average annual emissions of 2.47, 5.02, and 9.83 Mg C ha−1, respectively. Using bioenergy for heating decreased the emissions relative to electricity generation as did removing additional slash from thinnings between regeneration harvests. However, all bioenergy scenarios resulted in increased net emissions compared to the non-bioenergy harvests. Stands with high initial aboveground live biomass may have higher net emissions from bioenergy harvest. Silvicultural practices such as increasing rotation length and structural retention may result in lower C fluxes from bioenergy harvests. Finally, since passive management resulted in the greatest net C storage, we recommend designation of unharvested reserves to offset emissions from harvested stands.
... Not only is the choice complicated by the non-permanent carbon storage both in soil and wood products (Aalde et al., 2006), but the whole scientific basis of substitution benefits is under debate (e.g. Fargione et al., 2008;Searchinger et al., 2008;Melillo et al., 2009;Wise et al., 2009;Schlesinger et al., 2010;Lippke et al., 2010;Gunn et al., 2012;Miner et al., 2014) The suggested solutions to the problem vary from fixing flawed carbon accounting conventions (Searchinger et al., 2009;Haberl et al., 2012) to an assessment of benefits and costs of substitution through life-cycle analysis (Cherubini et al., 2011;Helin et al., 2013). Thus, there seems to be no agreement on this globally important question. ...
... Tax may be paid by the forest owner harvesting the stand (IPCC convention) or by the agent causing the emission (PCO convention). Thus, our results are in line with the view by Gunn et al. (2012) that 'the physics of the greenhouse effect is indifferent as to the origin of the pollutant.' This results from decoupling of climate benefits of biomass growth from the costs of emissions, i.e. ...
Article
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First-best optimal forest sector carbon policy is examined. Using a forest and energy sector model with a carbon cycle module we show that the renewability and carbon neutrality arguments do not warrant emission free status of wood use. As a general optimality principle, the release of carbon is penalized by a tax and carbon capture is subsidized. However, under the biomass stock change carbon accounting convention, the land owners pay for the roundwood emissions and, to avoid double counting, the use of roundwood is treated as emission free. Yet, the carbon accounting convention followed does not affect the equilibrium outcome. The bioenergy from harvest residues is not emission free either. Furthermore, we show that an optimal policy subsidizes the production of wood products for their carbon sequestration. Correspondingly, carbon removals by biomass growth are subsidized and the harvest residue generation taxed. Numerical solution of the model shows that, although the use of wood is not emission free, it is optimal to increase the use of wood, possibly also in the energy sector. Before the wood use can be increased, the forest biomass will be increased. This carbon sink decreases the net emissions until the forest resources reach a new equilibrium. © 2016 Department of Forest Economics, Swedish University of Agricultural Sciences, Umeå
... The structure of accounting frameworks themselves can contribute to a lack of transparency in countries' GHG inventories and accounts, obscuring the actual quantity of global GHG emissions associated with bioenergy (Gunn et al., 2012;IPCC, 2019;Norton et al., 2019). Since the 1990s, countries have followed IPCC guidelines (IPCC, 1996) that recommended reporting and accounting for emissions from the combustion of harvested biomass feedstocks in the land use, land-use change, and forestry (LULUCF) sector, rather than counting such emissions in the energy sector. ...
Article
Full-text available
Development of the bioenergy sector is being actively pursued in many countries as a means to reduce climate change and fulfill international climate agreements such as the Paris Agreement. Although biomass for energy production (especially wood pellets) can replace carbon-intensive fossil fuels, its net greenhouse gas impact varies, and the production of wood pellets can also lead to intensification in forest harvests and reduction of forest carbon stocks. Additionally, under specific conditions, emissions associated with imported biomass feedstocks may be omitted from national accounts, due to incompatibilities in accounting approaches. We assessed the risks and potential scale of emissions omitted from accounts (EOA) among key trading regions, focusing on the demand for wood pellets under different levels of climate mitigation targets. Our results suggest that the global production of wood pellets would grow from 38.9 to 120 Mton/year between 2019 and 2050 in a scenario that limits global mean temperature increase to 1.5°C above pre-industrial levels. A large portion of this occurs in North America (36.8 Mton/year by 2050), Europe (47.6 Mton/year by 2050), and Asia (23.3 Mton/year by 2050). We estimate that in a 1.5°C scenario, global EOA associated with international trade of wood pellets has the potential to reach 23.81 MtCO2eq/year by 2030 and 69.52 MtCO2eq/year in 2050. Emissions resulting from European biomass energy production, based on wood pellet imports from the United States, may reach 11.68 MtCO2eq/year by 2030 and 33.57 MtCO2eq/year in 2050. The production of wood pellet feedstocks may also present a substantial carbon price arbitrage opportunity for bioenergy producers through a conjunction of two distinct GHG accounting rules. If this opportunity is realized, it could accelerate the growth of the bioenergy industry to levels that harm forests’ function as a carbon sink and omit actual emissions in national and global accounting frameworks.
... Contrary to being termed ''dead,'' DWM may affect most biotic processes in forest ecosystems (Harmon et al., 1986;Stokland et al., 2012). With the recent emergence of C/bioenergy economies, the attributes of DWM and associated roles in forest C/biomass cycles are facing even greater scrutiny (MCCS, 2010;Lippke et al., 2011;Gunn et al., 2012). The role of DWM in contemporary forest management is dichotomous (Hagan and Grove, 1999). ...
... In a critical examination of these propositions Gunn et al. (2012) evaluated the premise of the latter letter that carbon emissions from regional forests need not be related to global carbon cycles. When wood burning for heating purposes in temperate climate boosts regional CO 2 emissions, they occur in seasons with minimum photosynthesis and add to hemispheric peaks of CO2. ...
Article
Full-text available
Basically, the combustion of woody biomass in high temperature processes results in a long lasting addition of carbon dioxide to the atmosphere. When harvesting large extra amounts of stem tree for energetic use, a global as well as secular time frame is needed to assess overall conse-quences if due attention is to be given to biosphere processes, including the complex productivity of whole ecosystems. Analytically, a time dependent variable of carbon neutralization can be traced by a simple carbon neutrality or CN factor. Using the (forgotten) Marland approach, project manag-ers should document how a pay-back of the whole carbon debt incurred by their projects proceeds over time. As recommended by the European Parliament in May 2011, this methodology should be applied consistently in climate and energy policies when revising the failures of the 'instant carbon neutrality' approach for smokestack emissions that was propagated within the Kyoto process, the first phase of which is ending in 2012. Otherwise, we allow that the substitution of wood pellets for coal or other fossil fuels creates long lasting extra emissions of carbon dioxide. This is a climate policy mistake which carbon trading systems such as that of the EU ETS do not compensate for, but instead amplify by giving extra credits for further pollution. This contradicts the very purpose of the UNFCCC, namely to prevent environmental degradation.
... Forest biomass energy systems are characterized by CO 2 fluxes distributed over long time scales, from combustion and decomposition of dead organic materials left in the forest to time-distributed CO 2 sequestration in re-growing biomass. Net CO 2 emissions of the bioenergy systems are sometimes directly compared to those from fossil energy systems, with the latter subtracted to the former [44][45][46][47][48]. If the net result is positive, the bioenergy system releases more CO 2 than the fossil system, so resulting in the so-called up-front C debt (here expressed as CO 2 debt), if negative it is the opposite. ...
Article
Full-text available
Environmental impact studies of forest bioenergy systems usually account for CO2 emissions and removals and identify the so-called carbon debt of bioenergy through comparison with a reference system. This approach is based on a simple sum of fluxes and does not consider any direct physical impact or climate system response. Other recent applications go one step further and elaborate impulse response functions (IRFs) and subsequent metrics for biogenic CO2 emissions that are compatible with the life-cycle assessment (LCA) methodology. However, a thorough discussion about the role of the different metrics in the interpretation of the climate impacts of forest bioenergy systems is still missing. In this work, we assess a single LCA dataset of selected bioenergy systems using different emission metrics based on cumulative CO2 emissions, radiative forcing and global surface temperature. We consider both absolute and normalized metrics for single pulses and sustained emissions. The key challenges are the choice of end point (emissions, concentration, radiative forcing, change in temperature, etc), the type of measure (instantaneous or time-integrated) and the treatment of time. Bioenergy systems usually perform better than fossil counterparts if assessed with instantaneous metrics, including global surface temperature change, and in some cases can give a net global cooling effect in the short term. The analysis of sustained, or continuous emissions, also shows that impacts from bioenergy systems are generally reversible, while those from fossil fuels are permanent. As shown in this study, the metric choice can have a large influence on the results. The dominant role traditionally assigned to cumulative metrics in LCA studies and climate impact accounting schemes should therefore be reconsidered, because such metrics can fail to capture important time dependences unique to the biomass system under analysis (to which instantaneous metrics are well suited).
... fluxes), energy conversion efficiency, and a well-defined fossil energy source for comparison, among others (Walker et al., 2013;Mika & Keeton, 2014). Much of the research to date has focused on the appropriate choice of baseline (Gunn et al., 2012;Lamers & Junginger, 2013;Walker et al., 2013) or leakage (Gan & McCarl, 2007). ...
Article
The potential greenhouse gas benefits of displacing fossil energy with biofuels are driving policy development in the absence of complete information. The potential carbon neutrality of forest biomass is a source of considerable scientific debate because of the complexity of dynamic forest ecosystems, varied feedstock types, and multiple energy production pathways. The lack of scientific consensus leaves decision makers struggling with contradicting technical advice. Analyzing previously published studies, our goal was to identify and prioritize those attributes of bioenergy greenhouse gas (GHG) emissions analysis that are most influential on length of carbon payback period. We investigated outcomes of 59 previously published forest biomass greenhouse gas emissions research studies published between 1991 and 2014. We identified attributes for each study and classified study cases by attributes. Using Classification and Regression Tree analysis, we identified those attributes that are strong predictors of carbon payback period (e.g. the time required by the forest to recover through sequestration the carbon dioxide from biomass combusted for energy). The inclusion of wildfire dynamics proved to be the most influential in determining carbon payback period length compared to other factors such as feedstock type, baseline choice, and the incorporation of leakage calculations. Additionally we demonstrate that evaluation criteria consistency is required to facilitate equitable comparison between projects. For carbon payback period calculations to provide operational insights to decision makers, future research should focus on creating common accounting principles for the most influential factors including temporal scale, natural disturbances, system boundaries, GHG emission metrics, and baselines.
... In line with the United Nations Framework Convention on Climate Change (UNFCCC), countries are advised to report emission inventories of their greenhouse gases (GHGs) from various sectors of their economy including forestry ( Gupta et al., 2007). Increasing intensity of wood harvest to meet wood energy demand can depress the carbon stocks on the landscape to a lower equilibrium storage condition thereby increasing the overall atmospheric CO 2 ( Harmon et al., 1990;Smithwick et al., 2006;McKechnie et al., 2011;Gunn et al., 2012). Forest degradation and deforestation are responsible for the emissions of approximately 1.5e2.2 ...
Article
Excessive wood consumption for energy and over-dependence on fossil fuel-based energy are fundamental issues of importance regarding the destruction of environmental sanity. In this respect, international communities are seeking to explore opportunities on how to encourage aggressive deployment of technologies for clean and sustainable development and possibly renewable. The Kyoto protocol on climate change meeting in 1997 with about 160 countries in attendance has been used as one of the platform of discourse on carbon emissions reduction strategies. Advocated strategies agreed include increase in renewable energy consumption via modern techniques. Massive deployment of renewable energy systems on a global scale will ensure a reasonable displacement of oil based energy production which is the main source of anthropogenic Greenhouse Gases. In sub-Saharan Africa, limited access to modern energy in the region has stepped-up reliance on bioenergy consumption in form of wood fuel and charcoal resulting to attendant effects on human health, environment and the biodiversity in general. In view of the foregoing, this study presents a review on the current situations of unconstructive effects in the overuse of fuel wood and its charcoal derivative for energy consumption in three selected sub-Saharan African countries; Nigeria, Ghana and Uganda. In conclusion, suggestions on how to confront the challenges associated with the over-exploitation conditions of fuel wood in the region are put forward. The suggestions could be part of the pursuit to increase electricity availability, reliability and security with lower level of emissions in the region.
... Most LCA practitioners consider forest products to be climate neutral because the emitted and sequestered carbon dioxide flows are equal, and part of the natural carbon cycle (Vogtländer et al., 2014; Garcia and Freire, 2014; Sjølie and Solberg, 2011). However, some claim that biogenic emissions should have the same value as fossil emissions because they have the same effect in the atmosphere (Gunn et al., 2012). Sjølie and Solberg (2011) argue that due to their slow growth, the equilibrium between biogenic carbon sequestration and emissions is more problematic for boreal forests. ...
... In a critical examination of these propositions Gunn et al. (2012) evaluated the premise of the latter letter that carbon emissions from regional forests need not be related to global carbon cycles. When wood burning for heating purposes in temperate climate boosts regional CO 2 emissions, they occur in seasons with minimum photosynthesis and add to hemispheric peaks of CO2. ...
... A special case is whether or not the net carbon balance is considered in determining which CO 2 emissions should be included in the inventory. It has been common to include only CO 2 from nonbiogenic sources (thus excluding emissions from biogenic sources) with the motivation that the long-term carbon balance will not be affected by these as the emissions can be assumed to soon be involved in new biomass generation, but this approach is often criticised today (Gunn et al., 2012;Johnson, 2009). The dynamics of the carbon balance are affected by the soil carbon content, land management practices, crop selection, harvesting and regrowth rates and many other parameters. ...
Chapter
Climate change is a key environmental challenge of our time. Carbon footprinting is a key environmental accounting tool for business managers, policy makers and non-governmental organisations attempting to identify mitigation measures that reduce the threat of climate change. The textile industry is increasingly engaged in carbon footprinting as a part of policy development and product design. As is the case for any accounting tool, there are a number of methodological issues that need to be handled by analysts producing carbon footprint calculations, and by the consumers of such information, in order to ensure that the information is meaningful in its particular context. This chapter describes these key challenges, the standardisation processes that have arisen to meet them, the outcomes of practical carbon footprint calculations for textile manufacturing facilities and textile products, and recent work on carbon labelling of products. It also attempts to describe current trends and attempts to qualitatively extrapolate future developments in this field.
... burning of firewood and charcoal) have not been computed in this study. The issue of equating biogenic emissions to fossil-fuel emissions is one that is still very much debated [25]. Indeed, this study relies on the IPCC methodology for computing emissions [32] which does not attribute biogenic emissions to the energy sector. ...
Article
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As Ghana's economy grows, the choice of future energy paths and policies in the coming years will have a significant influence on its energy security. A Renewable Energy Act approved in 2011 seeks to encourage the influx of renewable energy sources in Ghana's energy mix. The new legal framework combined with increasing demand for energy has created an opportunity for dramatic changes in the way energy is generated in Ghana. However, the impending changes and their implication remain uncertain. This paper examines the extent to which future energy scenarios in Ghana could rely on energy from biomass sources, through the production of biogas, liquid biofuels and electricity. Analysis was based on moderate and high use of bioenergy for transportation, electricity generation and residential fuel using the LEAP (Long-range Energy Alternatives Planning) model. Results obtained indicate that introducing bioenergy to the energy mix could reduce GHG (greenhouse gas) emissions by about 6 million tonnes CO2e by 2030, equivalent to a 14% reduction in a business-as-usual scenario. This paper advocates the use of second generation ethanol for transport, to the extent that it is economically exploitable. Resorting tofirst generation ethanol would require the allocation of over 580,000 ha of agricultural land for ethanol production.
... However, this topic continues to be subject of debate in the international scientific world. In fact, the new hypothesis which is becoming popular is that bio-energy is not always "carbon neutral" and inaccurate accountability may inappropriately stimulate the use of forestry resources, by subtracting the wood from alternative uses with less impact on climate changes [49] and [50]. However, the topic of carbon neutrality goes beyond the scope of this article, and for this reason it will not be discussed in this context. ...
Article
This work compares the different methods of transport used to import pellets, through a case study of pellets imported into Italy. The objective was to evaluate the economic and environmental sustainability of the different transport methods, the former via a cost analysis, and the latter via an LCA analysis. In particular, the method of transport by sea from Virginia (USA) was compared to overland transport from some European locations. Industrial pellet markets strictly depend on the import of wood pellets from outside the EU-27. The analysis of transport phase is therefore crucial, for inspecting the consequences of transporting such a commodity along considerable distances and allowing decision makers to make strategic decisions about trade planning, optimize international routes, and choose the most sustainable transport methods. The economic analysis showed that road transport cost ranged from 18 to 112 € t−1, while sea cost from 68 to 82 € t−1. Concerning the environmental evaluation, the impact categories most involved were Fossil Fuels, Respiratory Inorganics and Land Use, showing that the critical points in the transport phase are the oil consumption per km and the production of high quantities of SO2 and NOx. Basically, transport by sea appeared to be better, from the economic viewpoint, and for what concerns one of the major environmental impacts involved (fossil fuels) and primary energy consumption, compared to road transport from some of the European locations normally supplying the Italian market. On the contrary, road transport was preferred if transporting pellets from locations nearest to Italy.
... Methods are often in disagreement over the wood product Life Cycle Assessment (LCA) assumption of a priori carbon neutrality, where biogenic emissions from the combustion and decomposition of wood is ignored because the carbon released from wood is assumed to be replaced by subsequent tree growth in the following decades (EPA 2016). Despite a multitude of analyses that recognize that the assumption is fundamentally flawed (Harmon et al 1996, Gunn et al 2011, Schulze et al 2012, Buchholz et al 2016, Booth 2018, it continues to be used in mitigation analyses, particularly for wood bioenergy. ...
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Atmospheric greenhouse gases (GHGs) must be reduced to avoid an unsustainable climate. Because carbon dioxide is removed from the atmosphere and sequestered in forests and wood products, mitigation strategies to sustain and increase forest carbon sequestration are being developed. These strategies require full accounting of forest sector GHG budgets. Here, we describe a rigorous approach using over one million observations from forest inventory data and a regionally calibrated life-cycle assessment for calculating cradle-to-grave forest sector emissions and sequestration. We find that Western US forests are net sinks because there is a positive net balance of forest carbon uptake exceeding losses due to harvesting, wood product use, and combustion by wildfire. However, over 100 years of wood product usage is reducing the potential annual sink by an average of 21%, suggesting forest carbon storage can become more effective in climate mitigation through reduction in harvest, longer rotations, or more efficient wood product usage. Of the ∼10 700 million metric tonnes of carbon dioxide equivalents removed from west coast forests since 1900, 81% of it has been returned to the atmosphere or deposited in landfills. Moreover, state and federal reporting have erroneously excluded some product-related emissions, resulting in 25%–55% underestimation of state total CO 2 emissions. For states seeking to reach GHG reduction mandates by 2030, it is important that state CO 2 budgets are effectively determined or claimed reductions will be insufficient to mitigate climate change.
... The climate neutrality of biogenic carbon dioxide is based on the assumption that forest products (and other bio-based products) are carbon neutral, i.e. that there is a balance between carbon sequestration at the forest level and the re-emission of this carbon at the product's end of life (EoL). This assumption has been questioned by some authors as the fate of carbon dioxide molecules emitted into the atmosphere is indifferent to its source (Gunn et al., 2012) or because excessive biomass harvesting may reduce carbon stocks (McKechnie et al., 2011;Johnson, 2009). Furthermore, even in cases where the carbon neutrality assumption is valid, this does not automatically imply climate neutrality as a temporal shift between emitted and sequestered carbon may contribute to a temporary increase in radiative forcing (Helin et al., 2013;, just as an overlap of carbon stored in products and carbon sequestered at the forest level may reduce the radiative forcing (as discussed in the previous paragraph). ...
... A second key question when relating biodiversity benefits versus costs of bioenergy is whether forest bioenergy is likely to reduce the magnitude of future climate change. Interestingly, there has been substantial debate over whether forest bioenergy instead of fossil fuel energy development will reduce greenhouse gas emissions (Hudiburg et al. 2011, Law and Harmon 2011, Gunn et al. 2012, Lippke et al. 2012, Mitchell et al. 2012, Walker et al. 2013, Ter-Mikaelian et al. 2015. Some studies focus on established plantations or regulated natural forests where carbon neutrality is assumed because carbon is absorbed by forest regrowth as fast as it is harvested (Lippke et al. 2012). ...
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Demand for bioenergy is expected to triple by 2050 as a result of policies aimed to improve energy independence and mitigate global climate change. We review forest practices that generate biomass in mesic forests and show that they vary widely in intensity and potential magnitude of the effects on biodiversity. Although increased demand for bioenergy may incentivize maintaining forestland, increasing economic value of woody biomass will probably stimulate more intensive management practices, impacting many species, especially those associated with deadwood. The spatial extent of habitat modification and the type and degree of management will have an impact on populations of sensitive species. We propose preliminary management guidelines to minimize biodiversity impacts and introduce an initial research agenda to test the sensitivity of forest biodiversity to bioenergy practices at multiple scales.
... Given the complicated pathways of carbon (C) emissions/sequestration between the diverse components of forest ecosystems (e.g., pools such as live biomass and forest floor), there are substantial knowledge gaps regarding C implications of forest management activities (McKinley et al., 2011;Malmsheimer et al., 2011). In particular, fate of downed dead wood has emerged as a knowledge gap in bioenergy policy debates (MCCS, 2010;Lippke et al., 2011;Gunn et al., 2012). Coarse woody debris (CWD), one focus of bioenergy, can be defined as downed dead wood in forests that often exceeds a certain minimum size threshold (e.g., 10 cm diameter and 1 m length, Woodall et al., 2009). ...
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Emerging questions from bioenergy policy debates have highlighted knowledge gaps regarding the carbon and biomass dynamics of individual pieces of coarse woody debris (CWD) across the diverse forest ecosystems of the US. Although there is a lack of long-term measurements of CWD across the diverse forest ecosystems of the US, there is an abundance of line intersect sampling (LIS) transects used for monitoring efforts such as fuel loadings. In order to provide an objective method for monitoring the carbon/biomass dynamics of individual CWD pieces for use with LIS, this study developed and tested a CWD piece matching algorithm for inventory plots where LIS was used to sample CWD at two points in time across the eastern US. Results indicated that a CWD piece matching algorithm may be constructed using three steps: (1) matching the location of each piece, (2) matching individual piece metrics (e.g., large-end diameter), and (3) scoring an index of many CWD attributes with adjustment by decay and measurement error (i.e., quality control tolerances). For most forest types in the US, this study’s algorithm matched between 20% and 40% of CWD pieces over time (≈5 years). The algorithm performed poorly in forests potentially disturbed by floods and/or with relatively high mean annual temperatures and subsequent fast decay rates. Due to this influence of decay, the algorithm attained low match rates for highly decayed or small-sized CWD pieces. The algorithm should not be used to estimate changes in carbon/biomass within a stock change accounting framework. However, the algorithm may provide a method to aggregate a subset of paired LIS CWD observations over time to inform CWD dynamics research at large-scales.
... The methods for measuring, monitoring, and verifying GHG leakage need to be further developed and tested before their incorporation into certification programs. Also, carbon dynam-ics of biomass and bioenergy should be taken into account (Gunn et al. 2012). Another aspect that has not been included in bioenergy certification is energy efficiency and security. ...
Article
We review certification programs targeting sustainable bioenergy production and identify common features and differences with sustainable forest management (SFM) certification programs. SFM programs are compatible with bioenergy certification programs except for greenhouse gas (GHG) emissions, air quality, and food security requirements. Program commonalities call for coupling SFM and bioenergy certification to reduce costs and enhance program development and adoption. As integrated biorefineries using wood-based feedstocks come online, the coupling of certification programs seems inevitable and beneficial. In turn, bioenergy certification may improve forest management and operations as well as energy and land-use efficiencies. Coupled certification will thus help find the balance between biomass removals and long-term soil productivity on the one hand and sequestration of carbon in forest growing stock and wood-based products with bioenergy GHG emission offsets on the other.
... How to consider this temporal shift depends, for example, on whether one assumes that the carbon sequestration that is attributable to the studied product occurred before the harvest (e.g. based on the argument that the trees were planted with the purpose of harvesting) or after the harvest (e.g. based on the argument that replantation is a consequence of harvesting, as this is often required by legislation or forestry certification schemes). It has been shown that results of LCAs of forest products can depend strongly on whether or not biogenic carbon dioxide is considered climate neutral (Garcia & Freire 2014;Guest & Strømman 2014;Zanchi et al. 2012;Sjølie & Solberg 2011; also showed in Paper IV), and assuming climate neutrality by default has therefore been questioned (Ter-Mikaelian et al. 2015;Agostini et al. 2013;Gunn et al. 2012;Schulze et al. 2012;Johnson 2009;Searchinger et al. 2008). It should be noted that abandoning the climate neutrality assumption does not necessarily imply an increase in the calculated climate impact of forest products, as a well-managed forest can function as a net carbon sink and thus result in a negative (i.e. ...
Chapter
This chapter provides an extensive walkthrough of the important challenges encountered when carrying out life cycle assessment (LCA) of forest products, and proposes some solutions to these challenges, with examples from the scientific literature and technical reports. The topics include: modelling future and/or uncertain product systems, handling multi-functionality (i.e., allocation problems), inventory analysis and impact assessment (carbon flow modelling, assessing climate impact, biodiversity loss, water cycle disturbances and energy use), managing trade-offs and connecting the LCA work to global environmental challenges, and integrating LCA work in the R&D of new products.
... How to consider this temporal shift depends, for example, on whether one assumes that the carbon sequestration that is attributable to the studied product occurred before the harvest (e.g. based on the argument that the trees were planted with the purpose of harvesting) or after the harvest (e.g. based on the argument that replantation is a consequence of harvesting, as this is often required by legislation or forestry certification schemes). It has been shown that results of LCAs of forest products can depend strongly on whether or not biogenic carbon dioxide is considered climate neutral (Garcia & Freire 2014;Guest & Strømman 2014;Zanchi et al. 2012;Sjølie & Solberg 2011; also showed in Paper IV), and assuming climate neutrality by default has therefore been questioned (Ter-Mikaelian et al. 2015;Agostini et al. 2013;Gunn et al. 2012;Schulze et al. 2012;Johnson 2009;Searchinger et al. 2008). It should be noted that abandoning the climate neutrality assumption does not necessarily imply an increase in the calculated climate impact of forest products, as a well-managed forest can function as a net carbon sink and thus result in a negative (i.e. ...
Chapter
This chapter introduces some of the strengths and weaknesses of forest products, for example relating to renewability, biodegradability, climate change, biodiversity loss and water cycle disturbances, indirect land use and land use change. It is explained how the complexities surrounding these topics are key reasons for why environmental assessments are needed to ensure that forest products replacing non-forest products actually reduce environmental impact.
... How to consider this temporal shift depends, for example, on whether one assumes that the carbon sequestration that is attributable to the studied product occurred before the harvest (e.g. based on the argument that the trees were planted with the purpose of harvesting) or after the harvest (e.g. based on the argument that replantation is a consequence of harvesting, as this is often required by legislation or forestry certification schemes). It has been shown that results of LCAs of forest products can depend strongly on whether or not biogenic carbon dioxide is considered climate neutral (Garcia & Freire 2014;Guest & Strømman 2014;Zanchi et al. 2012;Sjølie & Solberg 2011; also showed in Paper IV), and assuming climate neutrality by default has therefore been questioned (Ter-Mikaelian et al. 2015;Agostini et al. 2013;Gunn et al. 2012;Schulze et al. 2012;Johnson 2009;Searchinger et al. 2008). It should be noted that abandoning the climate neutrality assumption does not necessarily imply an increase in the calculated climate impact of forest products, as a well-managed forest can function as a net carbon sink and thus result in a negative (i.e. ...
Book
This brief contains information on the reduction of environmental impact and explains how it is a key driver for the R&D of new forest products. The authors, experts in the field, describe how Life Cycle Assessment (LCA) is used to assess the environmental impact of such products, e.g. in order to guide R&D or attract investments. The authors describe the main challenges of carrying out LCAs on forest products, make recommendations for managing these challenges, and discuss future research needs. LCA case studies are used to illustrate the challenges, covering a variety of forest products: building components, biofuels, industrial chemicals, textile fibres and clothing. Described challenges include the planning of LCA studies (e.g.how can one use LCA in R&D?), the modelling of product systems (how can one handle multi-functionality and uncertainties related to waste handling and geographical location of future production?) and environmental impact (how can one assess water and land use impact, and the climate impact of biomass?).
... How to consider this temporal shift depends, for example, on whether one assumes that the carbon sequestration that is attributable to the studied product occurred before the harvest (e.g. based on the argument that the trees were planted with the purpose of harvesting) or after the harvest (e.g. based on the argument that replantation is a consequence of harvesting, as this is often required by legislation or forestry certification schemes). It has been shown that results of LCAs of forest products can depend strongly on whether or not biogenic carbon dioxide is considered climate neutral (Garcia & Freire 2014;Guest & Strømman 2014;Zanchi et al. 2012;Sjølie & Solberg 2011; also showed in Paper IV), and assuming climate neutrality by default has therefore been questioned (Ter-Mikaelian et al. 2015;Agostini et al. 2013;Gunn et al. 2012;Schulze et al. 2012;Johnson 2009;Searchinger et al. 2008). It should be noted that abandoning the climate neutrality assumption does not necessarily imply an increase in the calculated climate impact of forest products, as a well-managed forest can function as a net carbon sink and thus result in a negative (i.e. ...
Chapter
This chapter contains some concluding remarks related to the content of previous chapters, for example stressing the need for context-aligned methods and practices in life cycle assessment (LCA) of forest products.
... Table 4 shows the PEFs and CO 2 emission factors of fuels used in various scenarios taken from (E. y T. Ministerio de Industria 2014).These values were assumed to be unchanged for the future years in all scenarios. It should be mentioned here that the low specific emission factors for biogas and biomass might be considered controversial (Gunn et al. 2012). Even though combustion of biofuels emits carbon that is part of the biogenic carbon cycle, studies and analysis do not always take into account how long does it take for this carbon to return to the biogenic pool from the atmosphere. ...
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This paper presents the technical, environmental, and economic evaluation of integrating various combinations of renewable energy sources-based systems in the expansion of a district heating and cooling network of a Technology Park near Barcelona in Spain. At present, a combined heat and power plant running on fossil fuels serves the heating, cooling, and electricity demand of the Park. However, this energy demand is expected to increase substantially in the coming years. EnergyPRO software was used to model the energy demand growth till 2030. Validation of the software application was done by making a base model using real plant data from the year 2014. The software was then used to project the energy supply based on three 15-year scenarios, having different combinations of renewable energy technologies, from 2016 until 2030. Primary energy consumption, CO2 emissions, and the net present value obtained in each scenario were used to decide the best combinations of renewable energy sources. The results of the study showed that presently, biomass boilers combined with absorption chillers and supported with solar thermal cooling are the most competitive technologies in comparison to ground source heat pumps for large DHC networks. This is mainly because of the lower primary energy consumption (624,380 MWh/year in 2030 vs. 665,367 MWh/year), higher net present value (NPV) (222 million € vs. 178 million €), and lower CO2 emissions (107,753 tons/year in 2030 vs. 111,166 tons/year) obtained as a result of the simulations.
... On the contrary, emissions from fossil sources contribute to the atmospheric pool by releasing carbon from the geologic pool and are therefore new emissions to the atmosphere (Breton et al. 2018). In this respect, Gunn et al. (2012) affirmed that biogenic emissions are less harmful than fossil emissions. Thus, regarding GHG emission, this is also an advantage of the pasture-based system compared with the semi-confinement system. ...
Article
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Milk production has been estimated to contribute 3–4% of anthropogenic greenhouse gas (GHG) emissions. However, the carbon footprint associated with raw milk can vary, depending on a variety of factors, such as the geographical area, species of cow and production system. In this study, a global overview of research published on the carbon footprint (CF) of raw cow milk is provided. Additionally, two different dairy systems (semi-confinement and pasture-based) have been analysed by life-cycle assessment (LCA) in order to determine their effect on the CF of the milk produced. Inventory data were obtained directly from these facilities, and the main factors involved in milk production were included (co-products, livestock food, water, electricity, diesel, cleaning elements, transport, manure and slurry management, gas emissions to air etc.). In agreement with reviewed literature, it was found that the carbon footprint of milk was basically determined by the cattle feeding system and gas emissions from the cows. The values of milk CF found in the systems under study were within the range for cow milk production worldwide (0.9–4.7 kgCO2eq kgFPCM⁻¹). Specifically, in the semi-confinement and the pasture-based dairy farms, 1.22 and 0.99 kgCO2eq kgFPCM⁻¹ were obtained, respectively. The environmental benefits obtained with the pasture grazing system are not only mainly due to the lower use of purchased fodder but also to the allocation between milk and meat that was found to be a determining methodological factor in CF calculation. Finally, data from the evaluated dairy systems have been employed to analyse the influence of raw milk production on cheese manufacturing. With this aim, the CF of a small-scale cheese factory has also been obtained. The main subsystems involved (raw materials, water, electricity, energy, cleaning products, packaging materials, transport, wastes and gas emissions) were included in the inventory of the cheese factory. CF values were 16.6 and 14.7 kgCO2eq kg⁻¹ of cheese for milk produced in semi-confinement and pasture-based systems, respectively. The production of raw milk represented more than 60% of CO2eq emissions associated with cheese, so the primary production is the critical factor in reducing the GHG emissions due to cheese making.
... Wood bioenergy production is interpreted as being carbonneutral by assuming that trees regrow to replace those that burned. However, this does not account for reduced forest carbon stocks that took decades to centuries to sequester, degraded productive capacity, emissions from transportation and the production process, and biogenic/direct emissions at the facility (35). Increased harvest through proposed thinning practices in the region has been shown to elevate emissions for decades to centuries regardless of product end use (36). ...
Article
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Strategies to mitigate carbon dioxide emissions through forestry activities have been proposed, but ecosystem process-based integration of climate change, enhanced CO2, disturbance from fire, and management actions at regional scales are extremely limited. Here, we examine the relative merits of afforestation, reforestation, management changes, and harvest residue bioenergy use in the Pacific Northwest. This region represents some of the highest carbon density forests in the world, which can store carbon in trees for 800 y or more. Oregon's net ecosystem carbon balance (NECB) was equivalent to 72% of total emissions in 2011-2015. By 2100, simulations show increased net carbon uptake with little change in wildfires. Reforestation, afforestation, lengthened harvest cycles on private lands, and restricting harvest on public lands increase NECB 56% by 2100, with the latter two actions contributing the most. Resultant cobenefits included water availability and biodiversity, primarily from increased forest area, age, and species diversity. Converting 127,000 ha of irrigated grass crops to native forests could decrease irrigation demand by 233 billion m3⋅y-1Utilizing harvest residues for bioenergy production instead of leaving them in forests to decompose increased emissions in the short-term (50 y), reducing mitigation effectiveness. Increasing forest carbon on public lands reduced emissions compared with storage in wood products because the residence time is more than twice that of wood products. Hence, temperate forests with high carbon densities and lower vulnerability to mortality have substantial potential for reducing forest sector emissions. Our analysis framework provides a template for assessments in other temperate regions.
... On the other hand, sources of energy can also be classified based on the sources of carbon emission as the part of sawmilling procedures. For example, the energy produced as a result of the burning of wood biomass is called a biogenic energy, whereas energy derived from fossil fuel is called as the anthropogenic emission source (Gunn et al. 2012). ...
Article
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As awareness of climate and environment issues increases and consumption habits change, new opportunities are opening up for the forest industry and wood construction to develop functional green solutions to meet consumers’ needs. Wood is a versatile raw material and the only renewable construction material. The manufacture of wood products and structures consumes little energy in comparison to similar products and structures made of other materials. Unlike other materials, most of the energy needed to manufacture wood products is derived from renewable energy sources. The global timber sector currently faces the dual challenges of meeting the growing demand of quality timber products and minimising possible adverse impacts on the environment and human health. Major sources of environmental impacts occur throughout the wood supply chain from sawmills to final products. The major objective of this paper is to explore ways to reduce the environmental impacts of timber products, from sawmills to final products. The specific objectives include the identification of major sources and mechanisms of environmental impacts from timber products, the assessment of the status of energy consumption and GHG emission in wood products during timber processing and manufacturing as well as identifying the potential ways to minimize these environmental impacts.
... In carbon dynamic studies, where cumulative CO 2 fluxes in bioenergy systems are compared with a fossil reference system, a "carbon debt" for the first decades of the assessment period is usually identified, especially when bioenergy is grown from slow growing forests (Fargione et al., 2008;Schlamadinger, 1995, 1997;Schlamadinger and Marland, 1996a;Schlamadinger and Marland, 1996b;McKechnie et al., 2011;Manomet, 2010). The default assumption of climate neutrality is recently questioned by an increasing number of papers within the LCA or carbon accounting/reporting community Johnson, 2009;Searchinger, 2010;Searchinger et al., 2009Searchinger et al., , 2010aBright et al., 2012b;Cherubini et al., 2011b;Gunn et al., 2012). ...
Article
Analyses of global warming impacts from forest bioenergy systems are usually conducted either at a single stand level or at a landscape level, yielding findings that are sometimes interpreted as contrasting. In this paper, we investigate and reconcile the scales at which environmental impact analyses of forest bioenergy systems are undertaken. Focusing on the changes caused in atmospheric CO2 concentration of forest bioenergy systems characterized by different initial states of the forest, we show the features of the analyses at different scales and depict the connections between them. Impacts on atmospheric CO2 concentration at a single stand level are computed through impulse response functions (IRF). Results at a landscape level are elaborated through direct application of IRFs to the emission profile, so to account for the fluxes from all the stands across time and space. Impacts from fossil CO2 emissions are used as a benchmark. At a landscape level, forest bioenergy causes an increase in atmospheric CO2 concentration for the first decades that is similar to the impact from fossil CO2, but then the dynamics clearly diverge because while the impact from fossil CO2 continues to rise that from bioenergy stabilizes at a certain level. These results perfectly align with those obtained at a single stand for which characterization factors have been developed. In the hypothetical case of a sudden cessation of emissions, the change caused in atmospheric CO2 concentration from biogenic CO2 emissions reverses within a couple of decades, while that caused by fossil CO2 emissions remains considerably higher for centuries. When counterfactual aspects like the additional sequestration that would have occurred in the forest if not harvested and the theoretical displacement of fossil CO2 are included in the analysis, results can widely differ, as the CO2 debt at a landscape level ranges from a few years to several centuries (depending on the underlying assumptions considered).
... The study has shown that vegetal-based material have a negative environmental impact. This is due to the contribution of the plant to the decrease of the atmospheric CO2 concentration [32]. More than cork and cellulose, the wood fiber insulation system appears the best solution among the vegetal materials, achieving the lowest total impact. ...
... FIA's inventory serves as perhaps the largest publicly available DDW dataset across a continental scale, with plots in nearly every US state, and with cumulative sample transects spanning a distance nearly equivalent to the distance across the coterminous United States (Fig. 1). Describing these data, as well as the continuous monitoring program and recent modifications, is paramount to not only forest C science 25 , but also to emerging bioenergy efforts [26][27][28] . ...
Article
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The quantity and condition of downed dead wood (DDW) is emerging as a major factor governing forest ecosystem processes such as carbon cycling, fire behavior, and tree regeneration. Despite this, systematic inventories of DDW are sparse if not absent across major forest biomes. The Forest Inventory and Analysis program of the United States (US) Forest Service has conducted an annual DDW inventory on all coterminous US forest land since 2002 (~1 plot per 38,850 ha), with a sample intensification occurring since 2012 (~1 plot per 19,425 ha). The data are organized according to DDW components and by sampling information which can all be linked to a multitude of auxiliary information in the national database. As the sampling of DDW is conducted using field efficient line-intersect approaches, several assumptions are adopted during population estimation that serve to identify critical knowledge gaps. The plot- and population-level DDW datasets and estimates provide the first insights into an understudied but critical ecosystem component of temperate forests of North America with global application.
... Subsequent biogenic emissions and decay rates (Gunn et al., 2012) will be contingent on a range of factors including standing versus down, snag fragmentation rates, climatic setting, material size and wood density, and biotic agents of decay. Suspended, aerial dead wood (dead trees, portions of trees) decays more slowly (lower annual emissions) than downed wood on the forest floor in contact with the soil that experiences greater moisture content and decomposition rates (Harmon et al., 2011). ...
Article
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Prolonged drought and intense heat‐related events trigger sudden forest die‐off events and have now been reported from all forested continents. Such die‐offs are concerning given that drought and heatwave events are forecast to increase in severity and duration as climate change progresses. Quantifying consequences to carbon dynamics and storage from die‐off events is critical for determining the current and future mitigation potential of forests. We took stand measurements five times over 2+ years from affected and unaffected plots across the Northern Jarrah Forest, southwestern Australia, following an acute drought/heatwave in 2011. We found a significant loss of live standing carbon (49.3 t ha⁻¹), and subsequently a significant increase in the dead standing carbon pool by six months post die‐off. Of the persisting live trees, 38% experienced partial mortality contributing to rapid regrowth and replenishment (82‐88%) of labile carbon pools (foliage, twigs, branch) within 26 months. Such regrowth was not substantial in terms of net carbon changes within the timeframe of the study but does reflect the resprouting resilience of this forest type. Dead carbon generated by the die‐off may persist for centuries given low fragmentation and decay rates resulting in low biogenic emission rates relative to other forest types. However, future fire may threaten persistence of both dead and live pools via combustion and mortality of live tissue and impaired regrowth capacity. Resprouting forests are commonly regarded as resilient systems, however a changing climate could see vulnerable portions of forests become carbon sources rather than carbon sinks. This article is protected by copyright. All rights reserved.
... Thus, no environmental impact is due to the production stage of such design solutions. This is due to the contribution of plants to the decrease of atmospheric CO 2 concentration, thanks to the carbon sequestrated during their growth [61]. Wood fiber insulation system achieves the lowest production impact in terms of Ecopoints. ...
Article
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Historic buildings are defining elements of city centres but also responsible for a large share of greenhouse gas emissions. In order to reduce their energy demand, it is important to improve envelopes’ thermal transmittance without damaging the historic integrity of their façades by applying interior insulation. Thus, a detailed planning is needed to guarantee that case-specific variables are well considered. In this study, a holistic performance-based evaluation method is developed. Firstly, the hygrothermal risks are investigated through dynamic hygrothermal simulation. Secondly, an energy assessment is performed, followed by a life-cycle assessment to investigate the environmental impact of the intervention. The developed method is applied in the framework of a conservation and rehabilitation case of a residential building, to evaluate six natural-based insulation systems: perlite filled bricks, wood fibre, cellulose, cork, mineral foam, and calcium silicate. Results show that vegetal-based materials have the lowest initial environmental impact. In any case, retrofit interventions proved to be crucial to reduce the overall environmental impact associated with the use of historic buildings. The developed method, proving to be suitable for application to internally insulated historic buildings, supports a clear identification of the design solution with the lowest environmental impact by using a unique indicator.
... This regards the complexities of terrestrial ecosystem developments as part of the interactions between man and environment and its societal determinants. Regarding CO 2 -outputs from chimneys and tale-pipes it is clear, that also biogenic emissions (Gunn et al. 2011) are drivers of a rising CO 2 concentration in the atmosphere and not only fossil fuel. Comprehensive action for decarbonization is needed to also reduce these emissions. ...
Chapter
The search for sustainable energy alternatives has been increasingly important, not only because the depletion of fossil fuels, but also due to the necessary reduction in the emission of greenhouse gases. The use of renewable energy has contributed to the mitigation of this problem, but this doesn’t always adapt to the requirements of energy demand. The energy of biomass, in particular by the combustion of vegetal biomass, is a form already in use and with broad application, from domestic heating equipment to thermoelectric power plants. An alternative energy source is the refuse derived fuels, RDF, which offer a double benefit, given they provide an energy resource and avoid the occupation of landfill space. However, the use of biomass or RDF has limitations, due to the fuel quality. As received, it presents low heating value, low adiabatic flame temperature and low density. The improvement of the properties of these fuels may be obtained by torrefaction. This is a low-temperature pyrolysis process, where the heating gradient, top temperature and process duration must be controlled. In this study, an experimental prototype was developed for torrefaction trials. During the torrefaction experiments the heating rate and maximum temperature were controlled, and were measured sample temperatures, mass decay and also the composition of the gases released. Later, the higher heating value, density and hydrophilicity of biomass and RDF samples, as received and with various stages of torrefaction, were measured, confirming the advantage of applying this thermal process in the improvement of the biomass and RDF fuel properties.
Article
This article examines policy approaches impacting the adoption of alternative energy technology. Researchers investigated the factors affecting the transition to automated wood pellet heating (AWPH) in northeastern US as an example of the early stages of an energy transition in small-scale heating. The research team applied diffusion of innovation theory and the multi-level perspective on sociotechnical transitions to develop a system-wide analysis of the AWPH transition, incorporating multiple actor groups and policy strategies. Sixty interviews were conducted across four northeastern states with adopters and informed non-adopters of AWPH, and with industry, policy, and community representatives. Using interview results and theory, surveys were developed and distributed state-wide to both adopters and non-adopters with 690 useable responses (38% response rate). Qualitative and quantitative data analysis found differences in the factors impacting AWPH adoption between those within the Model Neighborhood Project (MNP), a privately-run program aimed at accelerating the diffusion of AWPH, and those who had access to state-run programs alone. These differences and the success of the MNP suggest that policy aimed at supporting early-stage energy transitions should incorporate not only consumer financial incentives, but also build a local network of supply-side actors through community-based outreach and technical support.
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The European Community has long recognized the need to further promote renewable energy. Under the overall objective to support and enhance sustainable management, the promotion of the use of forest biomass could help to mitigate climate change by substituting fossil fuel, increasing carbon stock in wood products and improve energy self-sufficiency enhancing security of supply and providing job opportunities in rural areas. To what extent Italian forests can satisfy an increased wood demand, without compromising the others Ecosystem Services (ESs) remains an open question. Our aim was to assess the potential supply of woody biomass from the network of protected areas in Italy considering the felling constraints. We estimated the theoretical annual potential increment from forest inventory data performing a correlation with the Corine Land Cover 2006 at the IV level with a 1:100,000 resolution elaborated in a GIS (Geographic Information System) environment. The average annual potential increment at national level available for felling was 4.4 m 3 ha -1 . Within the network of protected areas (EUAP and Natura 2000), the average annual increment, available to felling, was 0.98 m 3 ha -1 , respectively 0.81 m 3 ha -1 from coppice and 1.14 m 3 ha -1 from non-coppice forests. Based on data obtained from this study, the availability of wood materials could be increased of almost 20 % at national level by pursuing an active management within the network of protected areas. In Italy, the actual level of resource utilization is rather low; increasing felling together with the implementation of an active management within protected areas could allow satisfying, theoretically, the Italian wood consumption.
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Excerpt Reducing concentrations of carbon dioxide (CO2) and other greenhouse gases (GHG) in Earth's atmosphere is identified as one of the most pressing modern-day environmental issues (IPCC 2007). As a signatory country to the United Nations Framework Convention on Climate Change (UNFCCC), the United States is actively engaged in a critical international effort to find solutions to the problems posed by climate change. Agriculture, in addition to being affected by the climate, contributes to climate change through its exchanges of GHG with the atmosphere. Thus, the management of agricultural systems to sequester atmospheric CO2 as soil organic carbon (SOC) and to minimize GHG emissions has been proposed as a partial solution to the climate change problem. In this paper, we discuss the potential role of agriculture in the United States to mitigate climate change through sequestration of carbon (C). We also identify critical knowledge gaps where further research is needed. Carbon enters terrestrial ecosystems, including agriculture, through photosynthesis by green plants that assimilate CO2 and fix it into organic forms (figure 1). Some C eventually enters the soil, where its subsequent cycling and storage among SOC and soil inorganic carbon (SIC) pools determine its residence time and ultimately its return back…
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Paleoclimate data show that climate sensitivity is ~3 deg-C for doubled CO2, including only fast feedback processes. Equilibrium sensitivity, including slower surface albedo feedbacks, is ~6 deg-C for doubled CO2 for the range of climate states between glacial conditions and ice-free Antarctica. Decreasing CO2 was the main cause of a cooling trend that began 50 million years ago, large scale glaciation occurring when CO2 fell to 450 +/- 100 ppm, a level that will be exceeded within decades, barring prompt policy changes. If humanity wishes to preserve a planet similar to that on which civilization developed and to which life on Earth is adapted, paleoclimate evidence and ongoing climate change suggest that CO2 will need to be reduced from its current 385 ppm to at most 350 ppm. The largest uncertainty in the target arises from possible changes of non-CO2 forcings. An initial 350 ppm CO2 target may be achievable by phasing out coal use except where CO2 is captured and adopting agricultural and forestry practices that sequester carbon. If the present overshoot of this target CO2 is not brief, there is a possibility of seeding irreversible catastrophic effects.
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Simulations of carbon storage suggest that conversion of old-growth forests to young fast-growing forests will not decrease atmospheric carbon dioxide (CO2) in general, as has been suggested recently. During simulated timber harvest, on-site carbon storage is reduced considerably and does not approach old-growth storage capacity for at least 200 years. Even when sequestration of carbon in wooden buildings is included in the models, timber harvest results in a net flux of CO2 to the atmosphere. To offset this effect, the production of lumber and other long-term wood products, as well as the life-span of buildings, would have to increase markedly. Mass balance calculations indicate that the conversion of 5 × 106 hectares of old-growth forests to younger plantations in western Oregon and Washington in the last 100 years has added 1.5 × 109 to 1.8 × 109 megagrams of carbon to the atmosphere.
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The impact of forest management activities on the ability of forest ecosystems to sequester and store atmospheric carbon is of increasing scientific and social concern. The nature of these impacts varies among forest ecosystems, and spatially and temporally explicit ecosystem models are useful for quantifying the impacts of a number of alternative management regimes for the same forest landscape. The LANDIS-II forest dynamics simulation model is used to quantify changes to the live overstory and coarse woody debris pools under several forest management scenarios in a high-latitude South American forest landscape dominated by two species of southern beech, Nothofagus betuloides and N. pumilio. Both harvest type (clearcutting vs. partial overstory retention) and rotation length (100 years vs. 200 years) were significant predictors of carbon storage in the simulation models. The prompt regeneration of harvest units greatly enhanced carbon storage in clearcutting scenarios. The woody debris pool was particularly sensitive to both harvest type and rotation length, with large decreases noted under short rotation clearcutting. The roles of extended rotations and partial overstory retention are noted for enhancing net carbon storage on the forest landscape.
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2006 IPCC Guidelines for preparation of National Greenhouse Gas Inventories -- guidelines for Petrochemical and Carbon Black Production (Principal Author) https://www.ipcc-nggip.iges.or.jp/public/2006gl/vol3.html
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Temperate forests are an important carbon sink, yet there is debate regarding the net effect of forest management practices on carbon storage. Few studies have investigated the effects of different silvicultural systems on forest carbon stocks, and the relative strength of in situ forest carbon versus wood products pools remains in question. Our research describes (1) the impact of harvesting frequency and proportion of post-harvest structural retention on carbon storage in northern hardwood-conifer forests, and (2) tests the significance of including harvested wood products in carbon accounting at the stand scale. We stratified Forest Inventory and Analysis (FIA) plots to control for environmental, forest structural and compositional variables, resulting in 32 FIA plots distributed throughout the northeastern U.S. We used the USDA Forest Service's Forest Vegetation Simulator to project stand development over a 160 year period under nine different forest management scenarios. Simulated treatments represented a gradient of increasing structural retention and decreasing harvesting frequencies, including a “no harvest” scenario. The simulations incorporated carbon flux between aboveground forest biomass (dead and live pools) and harvested wood products. Mean carbon storage over the simulation period was calculated for each silvicultural scenario. We investigated tradeoffs among scenarios using a factorial treatment design and two-way ANOVA. Mean carbon sequestration was significantly (α = 0.05) greater for “no management” compared to any of the active management scenarios. Of the harvest treatments, those favoring high levels of structural retention and decreased harvesting frequency stored the greatest amounts of carbon. Classification and regression tree analysis showed that management scenario was the strongest predictor of total carbon storage, though site-specific variables were important secondary predictors. In order to isolate the effect of in situ forest carbon storage and harvested wood products, we did not include the emissions benefits associated with substituting wood fiber for other construction materials or energy sources. Modeling results from this study show that harvesting frequency and structural retention significantly affect mean carbon storage. Our results illustrate the importance of both post-harvest forest structure and harvesting frequency in carbon storage, and are valuable to land owners interested in managing forests for carbon sequestration.
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Numerous studies have analyzed the carbon sequestration potential of forests and forest management. However, most studies either focused on national and supra-national scales or on the project level in the context of the flexible mechanisms of the Kyoto Protocol. Few studies are available which analyze the effects of alternative silvicultural strategies on carbon sequestration, timber production and other forest services and functions at the operational level of the forest management unit (FMU). The present study investigates effects of three alternative management strategies for secondary Norway spruce forests (Picea abies (L.) Karst.) (Norway spruce age class forestry; continuous cover forestry; conversion to mixed broadleaved forests) and an unmanaged control variant on C sequestration in situ, in wood products and through bioenergy production at the level of a private FMU in Austria, and analyses the interrelationships with timber production and key indicators of biodiversity. The hybrid patch model PICUS v1.4 and a wood products model are employed to simulate forest ecosystem development, timber production, carbon storage in the forest and in wood product pools. Results show that in situ C sequestration is sensitive to forest management with the highest amount of carbon stored in the unmanaged strategy, followed by the continuous cover regime. All three management strategies store substantial quantities of C in the wood products pool. Considering alternative biomass utilization focused on bioenergy production, substantial C offsets could be generated from potential substitution of fossil fuels. Opportunity cost estimates for C sequestration reveal that C sequestration through forest management can be a cost efficient way to reduce atmospheric CO2, but the achievable quantities are limited due to biological limitations and societal constraints. The study emphasizes the importance of developing sustainable forest management strategies that serve the multiple demands on forests in the future.
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The potential of forest-based bioenergy to reduce greenhouse gas (GHG) emissions when displacing fossil-based energy must be balanced with forest carbon implications related to biomass harvest. We integrate life cycle assessment (LCA) and forest carbon analysis to assess total GHG emissions of forest bioenergy over time. Application of the method to case studies of wood pellet and ethanol production from forest biomass reveals a substantial reduction in forest carbon due to bioenergy production. For all cases, harvest-related forest carbon reductions and associated GHG emissions initially exceed avoided fossil fuel-related emissions, temporarily increasing overall emissions. In the long term, electricity generation from pellets reduces overall emissions relative to coal, although forest carbon losses delay net GHG mitigation by 16-38 years, depending on biomass source (harvest residues/standing trees). Ethanol produced from standing trees increases overall emissions throughout 100 years of continuous production: ethanol from residues achieves reductions after a 74 year delay. Forest carbon more significantly affects bioenergy emissions when biomass is sourced from standing trees compared to residues and when less GHG-intensive fuels are displaced. In all cases, forest carbon dynamics are significant. Although study results are not generalizable to all forests, we suggest the integrated LCA/forest carbon approach be undertaken for bioenergy studies.
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A globally consistent methodology using satellite imagery was implemented to quantify gross forest cover loss (GFCL) from 2000 to 2005 and to compare GFCL among biomes, continents, and countries. GFCL is defined as the area of forest cover removed because of any disturbance, including both natural and human-induced causes. GFCL was estimated to be 1,011,000 km(2) from 2000 to 2005, representing 3.1% (0.6% per year) of the year 2000 estimated total forest area of 32,688,000 km(2). The boreal biome experienced the largest area of GFCL, followed by the humid tropical, dry tropical, and temperate biomes. GFCL expressed as the proportion of year 2000 forest cover was highest in the boreal biome and lowest in the humid tropics. Among continents, North America had the largest total area and largest proportion of year 2000 GFCL. At national scales, Brazil experienced the largest area of GFCL over the study period, 165,000 km(2), followed by Canada at 160,000 km(2). Of the countries with >1,000,000 km(2) of forest cover, the United States exhibited the greatest proportional GFCL and the Democratic Republic of Congo the least. Our results illustrate a pervasive global GFCL dynamic. However, GFCL represents only one component of net change, and the processes driving GFCL and rates of recovery from GFCL differ regionally. For example, the majority of estimated GFCL for the boreal biome is due to a naturally induced fire dynamic. To fully characterize global forest change dynamics, remote sensing efforts must extend beyond estimating GFCL to identify proximate causes of forest cover loss and to estimate recovery rates from GFCL.
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We used a new model, STANDCARB, to examine effects of various treatments on carbon (C) pools in the Pacific Northwest forest sector. Simulation experiments, with five replicates of each treatment, were used to investigate the effects of initial conditions, tree establishment rates, rotation length, tree utilization level, and slash burning on ecosystem and forest products C stores. The forest examined was typical of the Cascades of Oregon and dominated by Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and western hemlock (Tsuga heterophylla (Raf.) Sarg). Simulations were run until a C steady state was reached at the landscape level, and results were rescaled relative to the potential maximum C stored in a landscape. Simulation experiments indicated agricultural fields stored the least (15% of the maximum) and forests protected from fire stored the greatest amount (93% of the maximum) of landscape-level C. Conversion of old-growth forests to any other management or disturbance regime resulted in a net loss of C, whereas conversion of agricultural systems to forest systems had the opposite effect. The three factors, in order of increasing importance, most crucial in developing an optimum C storage system were (i) rotation length, (ii) amount of live mass harvested, and (iii) amount of detritus removed by slash burning. Carbon stores increased as rotation length increased but decreased as fraction of trees harvested and detritus removed increased. Simulations indicate partial harvest and minimal fire use may provide as many forest products as the traditional clearcut – broadcast-burn system while increasing C stores. Therefore, an adequate supply of wood products may not be incompatible with a system that increases C stores.
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Depending on management, forests can be an important sink or source of carbon that if released as CO2 could contribute to global warming. Many forests in the western United States are being treated to reduce fuels, yet the effects of these treatments on forest carbon are not well understood. We compared the immediate effects of fuels treatments on carbon stocks and releases in replicated plots before and after treatment, and against a reconstruction of active-fire stand conditions for the same forest in 1865. Total live-tree carbon was substantially lower in modern fire-suppressed conditions (and all of the treatments) than the same forest under an active-fire regime. Although fire suppression has increased stem density, current forests have fewer very large trees, reducing total live-tree carbon stocks and shifting a higher proportion of those stocks into small-diameter, fire-sensitive trees. Prescribed burning released 14.8 Mg C/ha, with pre-burn thinning increasing the average release by 70% and contributing 21.9-37.5 Mg C/ha in milling waste. Fire suppression may have incurred a double carbon penalty by reducing stocks and contributing to emissions with fuels-treatment activities or inevitable wildfire combustion. All treatments reduced fuels and increased fire resistance, but most of the gains were achieved with understory thinning, with only modest increases in the much heavier overstory thinning. We suggest modifying current treatments to focus on reducing surface fuels, actively thinning the majority of small trees, and removing only fire-sensitive species in the merchantable, intermediate size class. These changes would retain most of the current carbon-pool levels, reduce prescribed burn and potential future wildfire emissions, and favor stand development of large, fire-resistant trees that can better stabilize carbon stocks.
Article
Two forest management objectives being debated in the context of federally managed landscapes in the U.S. Pacific Northwest involve a perceived trade-off between fire restoration and carbon sequestration. The former strategy would reduce fuel (and therefore C) that has accumulated through a century of fire suppression and exclusion which has led to extreme fire risk in some areas. The latter strategy would manage forests for enhanced C sequestration as a method of reducing atmospheric CO2 and associated threats from global climate change. We explored the trade-off between these two strategies by employing a forest ecosystem simulation model, STANDCARB, to examine the effects of fuel reduction on fire severity and the resulting long-term C dynamics among three Pacific Northwest ecosystems: the east Cascades ponderosa pine forests, the west Cascades western hemlock-Douglas-fir forests, and the Coast Range western hemlock-Sitka spruce forests. Our simulations indicate that fuel reduction treatments in these ecosystems consistently reduced fire severity. However, reducing the fraction by which C is lost in a wildfire requires the removal of a much greater amount of C, since most of the C stored in forest biomass (stem wood, branches, coarse woody debris) remains unconsumed even by high-severity wildfires. For this reason, all of the fuel reduction treatments simulated for the west Cascades and Coast Range ecosystems as well as most of the treatments simulated for the east Cascades resulted in a reduced mean stand C storage. One suggested method of compensating for such losses in C storage is to utilize C harvested in fuel reduction treatments as biofuels. Our analysis indicates that this will not be an effective strategy in the west Cascades and Coast Range over the next 100 years. We suggest that forest management plans aimed solely at ameliorating increases in atmospheric CO2 should forgo fuel reduction treatments in these ecosystems, with the possible exception of some east Cascades ponderosa pine stands with uncharacteristic levels of understory fuel accumulation. Balancing a demand for maximal landscape C storage with the demand for reduced wildfire severity will likely require treatments to be applied strategically throughout the landscape rather than indiscriminately treating all stands.
Article
This paper reviews the effects of past forest management on carbon stocks in the United States, and the challenges for managing forest carbon resources in the 21st century. Forests in the United States were in approximate carbon balance with the atmosphere from 1600-1800. Utilization and land clearing caused a large pulse of forest carbon emissions during the 19th century, followed by regrowth and net forest carbon sequestration in the 20th century. Recent data and knowledge of the general behavior of forests after disturbance suggest that the rate of forest carbon sequestration is declining. A goal of an additional 100 to 200 Tg C/yr of forest carbon sequestration is achievable, but would require investment in inventory and monitoring, development of technology and practices, and assistance for land managers.
Article
Simulations of carbon storage suggest that conversion of old-growth forests to young fast-growing forests will not decrease atmospheric carbon dioxide (CO2) in general, as has been suggested recently. During simulated timber harvest, on-site carbon storage is reduced considerably and does not approach old-growth storage capacity for at least 200 years. Even when sequestration of carbon in wooden buildings is included in the models, timber harvest results in a net flux of CO2 to the atmosphere. To offset this effect, the production of lumber and other long-term wood products, as well as the life-span of buildings, would have to increase markedly. Mass balance calculations indicate that the conversion of 5 x 109 to 1.8 x 109 megagrams of carbon to the atmosphere.
Article
Forests currently absorb billions of tons of CO2 globally every year, an economic subsidy worth hundreds of billions of dollars if an equivalent sink had to be created in other ways. Concerns about the permanency of forest carbon stocks, difficulties in quantifying stock changes, and the threat of environmental and socioeconomic impacts of large-scale reforestation programs have limited the uptake of forestry activities in climate policies. With political will and the involvement of tropical regions, forests can contribute to climate change protection through carbon sequestration as well as offering economic, environmental, and sociocultural benefits. A key opportunity in tropical regions is the reduction of carbon emissions from deforestation and degradation.
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Maine Voices: Tale of the Tree Turns a New Leaf Available at: http://www.pressherald. com/opinion/tale-of-the-tree-turns-a-new-leaf_2010-09-05.html
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Carbon Neutrality and Bioenergy: A Zero-Sum Game? Resources for the Future Discussion Paper DP 11-15 Available at: http://www.rff.org
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