Global Supply of Biomass for Energy and Carbon Sequestration from Afforestation/Reforestation Activities

In this paper we provide an analytical framework to estimate the joint production of biomass and carbon sequestration from afforestation and reforestation activities. The analysis is based on geographical explicit information on a half-degree resolution. For each grid-cell the model estimates forest growth using a global vegetation model and chooses forest management rules. Land prices, cost of forest production and harvesting are determined as a function of grid specific site productivity, population density and estimates of economic wealth. The sensitivity of the results due to scenario storylines is assessed using different population and economic growth assumptions, which are consistent with B1 and A2 of the Intergovernmental Panel on Climate Change Special Report on Emission Scenarios (IPCC-SRES) marker scenarios. Considerable differences in the economic supply schedules are found. However, technical potentials seem to converge given constancy in other underlying assumptions of the model.     

Influence of Methodology and Assumptions on Reported National Carbon Flux Inventories: An Illustration from the Canadian Forest Sector

The Intergovernmental Panel on Climate Change (IPCC) has developed guidelines to standardize the international reporting of greenhouse gas emissions and removals by signatory nations of the UN Framework Convention on Climate Change. With regard to forest sector carbon fluxes, the IPCC guidelines require only that those fluxes directly associated with human activities (i.e., harvesting and land-use change) be reported. In Canada, the Carbon Budget Model of the Canadian Forest Sector (CBM-CFS2) has been used to assess carbon fluxes from the entire forest sector. This model accounts for carbon fluxes associated with both anthropogenic and natural disturbances, such as wild fires and insects. We combined model results for the period 1985 to 1989 with additional data to compile seven different national carbon flux inventories for the forest sector. These inventories incorporate different system components under a variety of seemingly plausible assumptions, some of which are encouraged refinements to the default flux inventory described in the IPCC guidelines. The resulting estimated net carbon fluxes varied from a net removal of 185,000 kt carbon per year of the inventory period to a netemission of 89,000 kt carbon per year. Following the default procedures in the IPCC guidelines, while using the best available national data, produced an inventory with a net removal of atmospheric carbon. Adding the effect of natural disturbances to that inventory reversed the sign of the net flux resulting in a substantial emission. Including the carbon fluxes associated with root biomass in the first inventory increased the magnitude of the estimated net removal. The variability of these results emphasizes the need for a systems approach in constructing a flux inventory. We argue that the choice of which fluxes to include in the inventory should be based on the importance of these fluxes to the overall carbon budget and not on the perceived ease with which flux estimates can be obtained. The results of this analysis also illustrate two specific points. Even those Canadian forests which are most free from direct human interactions—forests in which no commercial harvesting occurs—are not in equilibrium, and their contribution to national carbon fluxes should be included in the reported flux inventory. Moreover, those forest areas that are subject to direct management are still substantially impacted by natural disturbances. The critical effect of inventory methodology and assumptions on inventory results has important ramifications for efforts to “monitor” and “verify” programs aimed at mitigating global carbon emissions.     

Scenarios for the carbon balance of Finnish forests and wood products

The objective of this paper is to compare different scenarios for carbon (C) sequestration in the forest sector in Finland. Forest inventory data was used as input data to simulate the dynamics of C sequestration with a gap-type forest simulation model and a wood product model. In the baseline scenario, current forest management practices were applied. In another scenario, current recommendations for forest management were applied, which resulted in more intensive harvesting than in the baseline scenario. Both scenarios were also applied under changing climatic conditions to demonstrate the possible effect of climate change on C sequestration.This study demonstrates that C sequestration assessments should include not only C in the biomass of trees, but also C in the soil and in the wood products, as well as interactions between the respective pools. Partial assessments are likely to result in misleading estimates of the actual C sequestration. Forest management affects the distribution of C between the pools and the changing climate is likely to change this distribution. The Kyoto Protocol deals with only a limited part of the forestry and forest C cycle and C accounting accordingly can provide results that depart substantially from more complete accounting.     

Forest Management for Mitigation of CO2 Emissions: How Much Mitigation and Who Gets the Credits?

Forestry projects can mitigate the net flux of carbon (C) to the atmosphere in four ways: (1) C is stored in forest biomass—trees, litter and soil, (2) C is stored in durable wood products, (3) biomass fuels displace consumption of fossil fuels, and (4) wood products often require less fossil-fuel energy for their production and use than do alternate products that provide the same service. We use a mathematical model of C stocks and flows (GORCAM) to illustrate the inter-relationships among these impacts on the C cycle and the changing C balance over time. The model suggests that sustainable management for the harvest of forest products will yield more net C offset than will forest protection when forest productivity is high, forest products are produced and used efficiently, and longer time periods are considered. Yet it is very difficult to attribute all of the C offsets to the forestry projects. It is, at least in concept, straightforward to measure, verify, and attribute the C stored in the forests and in wood products. It is more challenging to measure the amount of fossil fuel saved directly because of the use of biomass fuels and to give proper attribution to a mitigation project. The amount of fossil fuel saved indirectly because biomass provides materials and services that are used in place of other materials and services may be very difficult to estimate and impossible to allocate to any project. Nonetheless, over the long run, these two aspects of fossil fuel saved may be the largest impacts of forestry projects on the global C cycle.     

Role of Bio-Energy Plantations for Carbon-Dioxide Mitigation with Special Reference to India

Fuelwood plays an important role in the rural economy of the developing countries of Asia and Africa. Optimizing energy fixation in forest trees through high density energy plantations (HDEP), gasification of wood, and conversion of forest tree biomass, are some of the potential areas whereby additional research and development input for efficient management of atmospheric carbon in our energy system can be incorporated. For example, the photosynthetic efficiency of forest trees is rarely above 0.5%, which on the basis of theoretical considerations can be increased by up to 6.6%. Thus there is an ample scope to improve the efficiency up to 1%, which amounts to doubling of the productivity of the forests. Recent policy changes and experiences with wood-based bio-energy programmes in several countries indicate that woodfuels may become increasingly attractive as industrial energy sources. Use of biodiesel and the formulation of a project for undertaking 13.4 million ha of Jatropha plantations in India highlight the seriousness with which the Government of India is promoting carbon neutral energy plantations. The cost of establishment of plantations primarily for fuel production and its conversion to energy are major deterrents in this pursuit. Some of the issues in developing countries, like low productivity on marginal lands, degraded forest lands, and unorganized units for biomass energy conversion, result in cost escalation as compared to other energy sources. This paper revisits the scope for raising energy plantations, a comparison of the direct and indirect mitigation potential uses of plantations as an adaptation strategy through reforestation and afforestation projects for climate change mitigation and socio-economic issues to make this venture feasible in developing countries.     

An assessment of uncertainty in forest carbon budget projections

Estimates of uncertainty are presented for projections of forest carbon inventory and average annual net carbon flux on private timberland in the US using the model FORCARB. Uncertainty in carbon inventory was approximately ±9% (2000 million metric tons) of the estimated median in the year 2000, rising to 11% (2800 million metric tons) in projection year 2040, with this range covering 95% of the distribution. Relative uncertainties about net flux were higher and more variable than relative uncertainty estimates of carbon inventory. Results indicated that relatively high correlations among projected carbon budgets for the regional forest types led to greater total uncertainty than under assumptions of independence among types, indicating that an accurate portrayal of correlations is important. Uncertainty in soil carbon, closely followed by uncertainty in tree carbon, were most influential in estimating uncertainty in carbon inventory, but uncertainties in projections of volume growth and volume removals were most important in estimating uncertainty in carbon flux. This implies the most effective ways of reducing uncertainty in carbon flux are different from those required to reduce uncertainties in carbon inventory. Analyses as presented here are necessary prerequisites to identify and reduce uncertainty in a systematic and iterative way.     

Land Use,Land-Use Change,Forestry, and Agricultural Activities in the Clean Development Mechanism: Estimates of Greenhouse Gas Offset Potential

Activities involving land use, land-use change,forestry, and agriculture (LUCF) can help reducegreenhouse gas (GHG) concentrations in the atmosphereby increasing biotic carbon storage, by decreasing GHGemissions, and by producing biomass as a substitutefor fossil fuels. Potential activities includereducing rates of deforestation, increasing landdevoted to forest plantations, regenerating secondaryforest, agroforestry, improving the management offorests and agricultural areas; and producing energycrops.Policymakers debating the inclusion of a variety ofLUCF activities in the Clean Development Mechanism(CDM) of the Kyoto Protocol need to consider themagnitude of the carbon contribution these activitiescould make. Existing estimates of the cumulative GHGoffset potential of LUCF activities often take aglobal or regional approach. In contrast, land-usedecisions are usually made at the local level anddepend on many factors including productive capacityof the land, financial considerations of thelandowner, and environmental concerns. Estimates ofGHG offset potential made at a local, or at mostcountry, level that incorporate these factors may belower, as well as more useful for policy analyses,than global or large regional estimates. Whilecountry-level estimates exist for forestry activities,similar estimates utilizing local information need tobe generated for agricultural activities and biofuels,as well as for the cumulative potential of all LUCFactivities in a particular location.     

Afforestation opportunities when stand productivity is driven by a high risk of natural disturbance: a review of the open lichen woodland in the eastern boreal forest of Canada

Afforestation has the potential to offset the increased emission of atmospheric carbon dioxide and has therefore been proposed as a strategy to mitigate climate change. Here we review the opportunities for carbon (C) offsets through open lichen woodland afforestation in the boreal forest of eastern Canada as a case study, while considering the reversal risks (low productivity, fires, insect outbreaks, changes in land use and the effects of future climate on growth potential as well as on the disturbances regime). Our results suggest that : (1) relatively low growth rate may act as a limiting factor in afforestation projects in which the time available to increase C is driven by natural disturbances; (2) with ongoing climate change, a global increase in natural disturbance rates, mainly fire and spruce budworm outbreaks, may offset any increases in net primary production at the landscape level; (3) the reduction of the albedo versus increase in biomass may negatively affect the net climate forcing; (4) the impermanence of C stock linked to the reversal risks makes this scenario not necessarily cost attractive. More research, notably on the link between fire risk and site productivity, is needed before afforestation can be incorporated into forest management planning to assist climate change mitigation efforts. Therefore, we suggest that conceivable mitigation strategies in the boreal forest will likely have to be directed activities that can reduce emissions and can increase C sinks while minimizing the reversal impacts. Implementation of policies to reduce Greenhouse Gases (GHG) in the boreal forest should consider the biophysical interactions, the different spatial and temporal scales of their benefits, the costs (investment and benefits) and how all these factors are influenced by the site history.     

Carbon storage and sequestration potential of selected tree species in India

A dynamic growth model (CO2FIX) was used for estimating the carbon sequestration potential of sal (Shorea Robusta Gaertn. f.), Eucalyptus (Eucalyptus Tereticornis Sm.), poplar (Populus Deltoides Marsh), and teak (Tectona Grandis Linn. f.) forests in India. The results indicate that long-term total carbon storage ranges from 101 to 156 Mg C?ha^?1, with the largest carbon stock in the living biomass of long rotation sal forests (82 Mg C?ha^?1). The net annual carbon sequestration rates were achieved for fast growing short rotation poplar (8 Mg C?ha^?1?yr^?1) and Eucalyptus (6 Mg C?ha^?1?yr^?1) plantations followed by moderate growing teak forests (2 Mg C?ha^?1?yr^?1) and slow growing long rotation sal forests (1 Mg C?ha^?1?yr^?1). Due to fast growth rate and adaptability to a range of environments, short rotation plantations, in addition to carbon storage rapidly produce biomass for energy and contribute to reduced greenhouse gas emissions. We also used the model to evaluate the effect of changing rotation length and thinning regime on carbon stocks of forest ecosystem (trees?+?soil) and wood products, respectively for sal and teak forests. The carbon stock in soil and products was less sensitive than carbon stock of trees to the change in rotation length. Extending rotation length from the recommended 120 to 150 years increased the average carbon stock of forest ecosystem (trees?+?soil) by 12%. The net primary productivity was highest (3.7 Mg ha^?1?yr^?1) when a 60-year rotation length was applied but decreased with increasing rotation length (e.g., 1.7 Mg ha^?1?yr^?1) at 150 years. Goal of maximum carbon storage and production of more valuable saw logs can be achieved from longer rotation lengths. ‘No thinning’ has the largest biomass, but from an economical perspective, there will be no wood available from thinning operations to replace fossil fuel for bioenergy and to the pulp industry and such patches have high risks of forest fires, insects etc. Extended rotation lengths and reduced thinning intensity could enhance the long-term capacity of forest ecosystems to sequester carbon. While accounting for effects of climate change, a combination of bioenergy and carbon sequestration will be best to mitigation of CO₂ emission in the long term.     

中国森林植被生物量空间网格化估计

森林是陆地生态系统的重要碳库之一,在全球碳循环中发挥着巨大作用。森林生物量是核算森林碳储量的主要因子,其数量及空间分布是评估森林生态系统碳汇潜力的重要参数。论文以中国第8次森林资源清查资料为基础,以影响森林生物量空间分布的气候（气温、降水）、地形（高程、坡度）和植被因子（NDVI）为辅助,利用降尺度方法估算了1 km×1 km格网分辨率下的中国森林生物量,并从不同空间尺度对研究结果进行了验证。结果表明：1）中国森林生物量总量约为13.56 Pg,平均生物量密度为65.3 t/hm²,各省森林生物量总量差异较大,总量较高省份主要集中于西南和东北内蒙古地区,其中西南地区（西藏、四川、云南）最高,为4.5 Pg,占总量的33%;东北内蒙古地区（黑龙江、吉林、辽宁、内蒙古）次之,为3.58 Pg,占总量的26%;2）在省级尺度构建的森林生物量与相关影响因子的回归关系可用于栅格尺度下森林生物量的降尺度估算,多尺度验证分析表明网格化估算结果基本合理;3）中国森林生物量空间格局区域分异规律明显,大致以东北至西南为界,与水热条件空间分布格局基本一致,生物量高值区主要集中于东北地区（大小兴安岭、长白山地区）、西南地区（横断山脉）、新疆山区（阿尔泰山、天山、昆仑山）、秦岭和东南武夷山等地区。     

Potential carbon sequestration in China’s forests

Forests are believed to be a major sink for atmospheric carbon dioxide. There are 158.94 million hectares (Mha) of forests in China, accounting for 16.5% of its land area. These extensive forests may play a vital role in the global carbon (C) cycle as well as making a large contribution to the country’s economic and environmental well-being. Currently there is a trend towards increased development in the forests. Hence, accounting for the role and potential of the forests in the global carbon budget is very important.In this paper, we attempt to estimate the carbon emissions and sequestration by Chinese forests in 1990 and make projections for the following 60 years based on three scenarios, i.e. “baseline”, “trend” and “planning”. A computer model F-CARBON 1.0, which takes into account the different biomass density and growth rates for the forests in different age classes, the life time for biomass oxidation and decomposition, and the change in soil carbon between harvesting and reforestation, was developed by the authors and used to make the calculations and projections. Climate change is not modelled in this exercise.We calculate that forests in China annually accumulate 118.1 Mt C in growth of trees and 18.4 Mt in forest soils, and release 38.9 Mt, resulting in a net sequestration of 97.6 Mt C, corresponding to 16.8% of the national CO₂ emissions in 1990. From 1990 to 2050, soil carbon accumulation was projected to increase slightly while carbon emissions increases by 73, 77 and 84%, and net carbon sequestration increases by −21, 52 and 90% for baseline, trend and planning scenarios, respectively. Carbon sequestration by China’s forests under the planning scenario in 2000, 2010, 2030 and 2050 is approximately 20, 48, 111 and 142% higher than projected by the baseline scenario, and 8, 18, 34 and 26% higher than by the trend scenario, respectively. Over 9 Gt C is projected to accumulate in China’s forests from 1990 to 2050 under the planning scenario, and this is 73 and 23% larger than projected for the baseline and trend scenarios, respectively. During the period 2008–2012, Chinese forests are likely to have a net uptake of 667, 565 and 452 Mt C, respectively, for the planning, trend and baseline scenarios. We conclude that China’s forests have a large potential for carbon sequestration through forest development. Sensitivity analysis showed that the biggest uncertainty in the projection by the F-CARBON model came from the release coefficient of soil carbon between periods after harvesting and before reforestation.     

燕山北部山地人工林和天然次生林的生物碳贮量

为了了解人工林与天然次生林碳汇功能的差异,以燕山北部山地华北落叶松人工林和杨桦天然次生林为研究对象,对不同年龄阶段的两种林分的生物碳贮量进行了研究。结果表明:13、18、28 a生杨桦天然次生林总生物碳贮量分别为27.33、35.77、46.13 t/hm²,9、13、30 a华北落叶松人工林分别为21.97、34.14、55.62 t/hm²; 0~13 a,14~18 a,19~28 a杨桦林生物总碳贮量的年碳积累速率分别为2.10、1.69、1.04 t/hm², 0~9 a,10~13 a,14~30 a落叶松林分别为2.44、3.04、1.34 t/hm²;华北落叶松单木生物量增长速率明显高于白桦和山杨,在10~25 a的年龄段,落叶松生长速度是白桦、山杨的1.63~5.83、2.26~7.87倍;华北落叶松的BCEF(生物量转化和扩展因子)和BEF(生物量扩展因子)随年龄和胸径的增长有逐渐降低的趋势,而白桦和山杨的两个参数则有逐渐增加的趋势。由此得出结论,在燕山北部山地,与杨桦天然次生林相比,华北落叶松人工林表现出更强的碳吸存能力,该地区大面积的华北落叶松幼、中龄林具有巨大的碳汇潜力;同时,使用生物量碳计量参数时应考虑树种、林龄和胸径的差异。     

Forest biomass extraction for livestock feed and associated carbon analysis in lower Himalayas,India

Accounting the changes in the net carbon (C) sink-source balance is an important component for greenhouse gas emissions (GHG) inventories. However, carbon emission due to the vegetation biomass extraction for household purposes is generally not accounted in forest carbon budget analysis due to miniscule volume and non-availability of data. However, if vegetation remains in the forests, then vegetation biomass decomposes after natural death and decay and fixes some carbon to soil and releases some directly to the atmosphere. The study attempts to quantify the carbon removal against the biomass extraction for livestock feed by collecting primary data on feed from 316 randomly selected households engaged in livestock rearing in the lower Himalayas, Uttarakhand, India and carbon flow components due to livestock production. The analysis results that average daily forest fodder consumption was 13 kg per Adult Cattle Unit (ACU) and total of 20.31 Million tonnes (Mt) consumption of forest biomass by total livestock of Uttarakhand. This results into absolute annual carbon removal of 3.25 Mt from Uttarakhand forests against the livestock fodder. However, overall carbon flow including the enteric fermentation and manure management system of livestock estimated as per IPCC guidelines, results into emissions of 9.42 Mt CO₂ eq. Therefore, biomass extraction for household purposes should be accounted in regional carbon flow analysis and properly addressed in the GHG inventories of the forests and livestock sector. Suitable measures should be taken for emissions reduction generated due to forest based livestock production.     

Prospects for carbon-neutral housing: the influence of greater wood use on the carbon footprint of a single-family residence

This paper examines the energy and carbon balance of two residential house alternatives; a typical wood frame home using more conventional materials (brick cladding, vinyl windows, asphalt shingles, and fibreglass insulation) and a similar wood frame house that also maximizes wood use throughout (cedar shingles and siding, wood windows, and cellulose insulation) in place of the more typical materials used – a wood-intensive house. Carbon emission and fossil fuel consumption balances were established for the two homes based on the cumulative total of three subsystems: (1) forest harvesting and regeneration; (2) cradle-to-gate product manufacturing, construction, and replacement effects over a 100-year service life; and (3) end-of-life effects – landfilling with methane capture and combustion or recovery of biomass for energy production.The net carbon balance of the wood-intensive house showed a complete offset of the manufacturing emissions by the credit given to the system for forest re-growth. Including landfill methane emissions, the wood-intensive life cycle yielded 20 tons of CO₂e emissions compared to 72 tons for the typical house. The wood-intensive home's life cycle also consumed only 45% of the fossil fuels used in the typical house.Diverting wood materials from the landfill at the end of life improved the life cycle balances of both the typical and wood-intensive houses. The carbon balance of the wood-intensive house was 5.2 tons of CO₂e permanently removed from the atmosphere (a net carbon sink) as compared to 63.4 of total CO₂e emissions for the typical house. Substitution of wood fuel for natural gas and coal in electricity production led to a net energy balance of the wood-intensive house that was nearly neutral, 87.1 GJ energy use, 88% lower than the scenario in which the materials were landfilled.Allocating biomass generation and carbon sequestration in the forest on an economic basis as opposed to a mass basis significantly improves the life cycle balances of both houses. Employing an economic allocation method to the forest leads to 3–5 times greater carbon sequestration and fossil fuel substitution attributable to the house, which is doubled in forestry regimes that remove stumps and slash as fuel. Thus, wood use has the potential to create a significantly negative carbon footprint for a house up to the point of occupancy and even offset a portion of heating and cooling energy use and carbon emissions; the wood-intensive house is energy and carbon neutral for 34–68 years in Ottawa and has the potential to be a net carbon sink and energy producer in a more temperate climate like San Francisco.     

长白山不同生态系统地下部分生物量及地下C贮量的调查

论文在收集已有资料的基础上,补充调查了长白山自然保护区中沿不同海拔高度形成的不同森林生态系统的细根生物量和一些森林类型的根系总生物量,并且对自然环境因子对根系生物量的影响进行了相关分析。研究表明,由高海拔到低海拔(岳桦林、苔藓岳桦暗针叶林、暗针叶林过渡带、苔藓红松暗针叶林、红松针阔混交林)树木细根(<2mm)生物量分别是458.92gm^-2、537.42gm^-2、390.35gm^-2、397.25gm^-2和660.21gm^-2;根系总生物量分别是2578.00gm^-2、2794.00gm^-2、2680.00gm^-2、3459.25gm^-2和5155.00gm^-2。分别对细根生物量和根系总生物量与降水量和活动积温之间进行相关性分析时,发现细根生物量与不同海拔高度的活动积温和降水量没有明显的相关性;而根系生物量与这些因子存在着指数相关关系。该研究同时对不同海拔高度根系中的C、N含量和土壤中有机质的含量进行了分析和测定。结合已有的倒木和凋落物的资料,估算了长白山自然保护区中沿不同海拔高度形成的不同森林生态系统地下C的贮量。在长白山自然保护区内,由高海拔到低海拔,林地C贮量分别是15493.88gm^-2、21005.74gm^-2、19819.24gm^-2、14232.51gm^-2和7344.02gm^-2。     

Benefits of tropical forest management under the new climate change agreement—a case study in Cambodia

Promoting sustainable forest management as part of the reduced emissions from deforestation and degradation in developing countries (REDD)-plus mechanism in the Copenhagen Accord of December 2009 implies that tropical forests will no longer be ignored in the new climate change agreement. As new financial incentives are pledged, costs and revenues on a 1-ha tract of tropical forestland being managed or cleared for other land use options need to be assessed so that appropriate compensation measures can be proposed. Cambodia's highly stocked evergreen forest, which has experienced rapid degradation and deforestation, will be the first priority forest to be managed if financial incentives through a carbon payment scheme are available. By analyzing forest inventory data, we assessed the revenues and costs for managing a hypothetical 1 ha of forestland against six land use options: business-as-usual timber harvesting (BAU-timber), forest management under the REDD-plus mechanism, forest-to-teak plantation, forest-to-acacia plantation, forest-to-rubber plantation, and forest-to-oil palm plantation. We determined annual equivalent values for each option, and the BAU-timber and REDD-plus management options were the highest, with both options influenced by logging costs and timber price. Financial incentives should be provided at a level that would allow continuation of sustainable logging and be attractive to REDD-plus project developers.     

Carbon Budget Implications of the Transition from Natural to Managed Disturbance Regimes in Forest Landscapes

Land-use change from an unmanaged to a managed forested landscape in northern forests is associated with a reduction of the area annually affected by natural disturbances (wildfires and forest insects) and the introduction of harvesting as a new disturbance. This study examined the impacts of changes in the disturbance regime-the frequency and type of disturbance-on landscape-level carbon (C) content and fluxes. The Carbon Budget Model of the Canadian Forest Sector was used to assess these impacts in six representative landscapes (100,000 ha each) with a range of disturbance regimes that are characteristic of conditions in coastal British Columbia, the interior of British Columbia, and the eastern boreal forest in Canada. The model was used to simulate ecosystem C fluxes during a period of natural disturbances, a 50-year transition period during which harvesting replaced natural disturbances, followed by 150 years of harvesting. The initial landscape-level biomass C content under natural disturbance regimes in the six example landscapes was 22 to 75% of their potential maximum content which is often used as the reference or baseline case. After 200 years of forest management, the C stored in the landscape plus the C retained in forest products manufactured from harvested biomass was between 58 and 101% of the landscape C content prior to the onset of harvesting. Landscape-level ecosystem C content was found to be affected by changes in the disturbance frequency, the age-dependence of the disturbance probabilities, and the disturbance-specific impacts on ecosystem C content. The results indicate that using the potential maximum C content of a landscape as the baseline always overestimates the actual C release due to land use change. A more meaningful procedure would be to assess the actual differences in landscape-level C content between the natural and the managed disturbance regime.     

Carbon Budget Implications of the Transition from Natural to Managed Disturbance Regimes in Forest Landscapes

Land-use change from an unmanaged to a managed forested landscape in northern forests is associated with a reduction of the area annually affected by natural disturbances (wildfires and forest insects) and the introduction of harvesting as a new disturbance. This study examined the impacts of changes in the disturbance regime-the frequency and type of disturbance-on landscape-level carbon (C) content and fluxes. The Carbon Budget Model of the Canadian Forest Sector was used to assess these impacts in six representative landscapes (100,000 ha each) with a range of disturbance regimes that are characteristic of conditions in coastal British Columbia, the interior of British Columbia, and the eastern boreal forest in Canada. The model was used to simulate ecosystem C fluxes during a period of natural disturbances, a 50-year transition period during which harvesting replaced natural disturbances, followed by 150 years of harvesting. The initial landscape-level biomass C content under natural disturbance regimes in the six example landscapes was 22 to 75% of their potential maximum content which is often used as the reference or baseline case. After 200 years of forest management, the C stored in the landscape plus the C retained in forest products manufactured from harvested biomass was between 58 and 101% of the landscape C content prior to the onset of harvesting. Landscape-level ecosystem C content was found to be affected by changes in the disturbance frequency, the age-dependence of the disturbance probabilities, and the disturbance-specific impacts on ecosystem C content. The results indicate that using the potential maximum C content of a landscape as the baseline always overestimates the actual C release due to land use change. A more meaningful procedure would be to assess the actual differences in landscape-level C content between the natural and the managed disturbance regime.     

LCA of environmental and socio-economic impacts related to wood energy production in alpine conditions: Valle di Fiemme (Italy)

An extended Life Cycle Assessment (LCA) is performed for evaluating the impacts of a woody biomass supply chain for heating plants in the alpine region. Three main aspects of sustainability are assessed: greenhouse gas emissions, represented by global warming potential (GWP) impact category, costs and direct employment potential. We investigate a whole tree system (innovative logging system) where the harvest of logging residues is integrated into the harvest of conventional wood products. The case study is performed in Valle di Fiemme in Trentino region (North Italy) and includes theoretical and practical elements. The system boundary is the alpine forest fuel system, from logging operations at the forest stand to combustion of woody biofuels at the heating plant. The functional unit is 1 m³ solid over bark of woody biomass, delivered to the district heating plant in Cavalese (Trento). The relative sustainability of traditional and innovative systems is compared and energy use is estimated. Results show that the overall GWP and costs are about 13 kg CO_2equivalent and 42 euro per functional unit respectively for the innovative system. Along the product supply chain, chipping contributes the greatest share of GWP and energy use, while extraction by yarder has the highest financial costs. The GWP is reduced by 2.3 ton CO_2equivalent when bioenergy substitutes fuel oil and 1.7 ton CO_2equivalent when it substitutes natural gas. The sensitivity analysis illustrates that variations in fuel consumption and hourly rates of costs have a great influence on chipping operation and extraction by cable yarder concerning GWP and financial analysis, respectively. This is confirmed by sensitivity analysis. Better technologies, the use of biofuels along the product supply chain and more efficient systems might reduce these impacts. Replacing the traditional system with the innovative one reduces emissions and costs. A low energy input ratio is required for harvesting logging residues. The direct employment potential is a conflicting aspect and needs further investigations.     

A Simulation of Temporal and Spatial Variations in Carbon at Landscape Level: A Case Study for Lake Abitibi Model Forest in Ontario,Canada

Using a case study of the Lake Abitibi Model Forest (LAMF), this study aims to assess the temporal and spatial variability in carbon storage during 1990–2000, and to present a comprehensive estimation of the carbon budget for LAMF's ecosystems. As well, it provided the information needed by local forest managers to develop ecological and carbon-based indicators and monitor the sustainability of forest ecosystems. Temporal and spatial carbon dynamics were simulated at the landscape level using ecosystem model TRIPLEX1.0 and Geographical Information System (GIS). The simulated net primary productivity (NPP) and carbon storage in forest biomass and soil were compared with field data and results from other studies for Canada's boreal forests. The results show that simulated NPP ranged from 3.26 to 3.34 tC ha⁻¹ yr⁻¹ in the 1990s and was consistent with the range measured during the Boreal Ecosystem-Atmosphere Studies (BOREAS) in central Canada. Modeled NPP was also compared with the estimation from remote sensing data. The density of total above-and belowground biomass was 125.3, 111.8, and 106.5 tC ha⁻¹ for black spruce, trembling aspen, and jack pine in the LAMF ecosystem, respectively. The total carbon density of forested land was estimated at 154.4 tC ha⁻¹ with the proportion of 4:6 for total biomass and soil. The analysis of net carbon balance of ecosystem suggested that the LAMF forest ecosystem was acting as a carbon sink with an allowable harvest in the 1990s.