The carbon sequestration potential of unmanaged forest stands in Finland under changing climatic conditions

Changes in stand-level carbon (C) storage and C flows in biomass, litter and soil organic matter in the humus layer were studied under current and changing climatic conditions in Finland with the help of a gan-type simulation model. The changing climate scenario assumed increases in mean annual temperature of 0.4°C per decade for the first one hundred years and 0.2°C per decade for the second hundred years. Warming was assumed to be larger during the winter than during the other seasons.

In southern Finland, the long term average (over 200 years) net forest ecosystem production (NEP) at the stand level was 0.4–1.0 Mg C/ha/a under the current climatic conditions, and 0.1–0.9 Mg C/ha/a under changing conditions, depending on the tree species. Under the climate change scenario, NEP decreased in Scots pine, Norway spruce and Pubescent birch stands, but increased in Pendula birch stands. During the first 25–50 years, however, NEP was found to be larger both in Scots pine and Pubescent birch stands. In northern Finland, the long term average NEP increaed, regardless of tree species, from 0.3–0.8 Mg C/ha/a to 0.4–1.0 Mg C/ha/a. The biggest changes took place in Norway spruce and Pendula birch stands.

During the early and late phases of stand development, the stands were C sources, since emissions from decaying litter and soil organic matter in the humus layer exceeded the growth of vegetation. Stands became C sources earlier under the changing climatic conditions than under the current conditions. In southern Finland, the long term average C storage was 107–201 Mg C/ha under the current climatic conditions, and 88–142 Mg C/ha under the changing conditions, depending on tree species. In northern Finland, the long term average C storage was 77–151 Mg C/ha under the current climatic conditions and 89–177 Mg C/ha under the changing conditions.     

Plantation forestry in Brazil: the potential impacts of climatic change

Most climatic changes predicted to occur in Brazil would reduce yields of silvicultural plantations, mainly through increased frequency and severity of droughts brought on by global warming and by reduction of water vapor sources in Amazonia caused by deforestation. Some additional negative effects could result from changes in temperature, and positive effects could result from CO₂ enrichment. The net effects would be negative, forcing the country to expand plantations onto less-productive land, requiring increased plantation area (and consequent economic losses) out of proportion to the climatic change itself. These impacts would affect carbon sequestration and storage consequences of any plans for subsidizing silviculture as a global warming mitigation option.Climate change can be expected to increase the area of plantations needed to supply projected internal demand for and exports of end products from Brazil. June–July–August (dry season) precipitation reductions indicated by simulations reported by the Intergovernmental Panel on Climate Change (IPCC) correspond to rainfall declines in this critical season of approximately 34% in Amazonia, 39% in Southern Brazil and 61% in the Northeast. As an example, if rainfall in Brazilian plantation areas (most of which are now in Southern Brazil) were to decline by 50%, the area needed in 2050 would expand by an estimated 38% over the constant climate case, bringing the total plantation area to 4.5 times the 1991 area. These large areas of additional plantations imply substantial social and environmental impacts. Further addition of plantation area as a global warming response option would augment these impacts, indicating the need for caution in evaluating carbon sequestration proposals.     

发挥森林在城市中的生态服务功能

叙述了通过提高人们对生态效益经济价值认识活跃碳汇市场,调动全社会参与城市森林建设的重要性和意义,从经济学的角度指出,森林具有的生态价值,利用经济手段发挥森林在城市中的碳汇功能,丰富中国城市森林建设的体系。     

To sink or burn? A discussion of the potential contributions of forests to greenhouse gas balances through storing carbon or providing biofuels

Forests can affect net CO₂ emissions by increasing or decreasing the amount of stored carbon, or by supplying biofuels for power generation to substitute for fossil fuels. However, forests store the most carbon when they remain undisturbed and are allowed to grow to maturity, whereas using wood for bioenergy requires wood removal from forests, which reduces on-site carbon storage. Hence, it is difficult to manage a forest simultaneously for maximum carbon storage and supplying fuelwood.For developing optimal strategies for the use of vegetation sinks, it is necessary to consider the feedbacks via the inherent natural adjustments in the global carbon cycle. Increased atmospheric CO₂ currently provides a driving force for carbon uptake by natural carbon reservoirs, such as the world's oceans. When carbon is removed from the atmosphere and stored in biomass, it lowers the concentration gradient between the atmosphere and these other reservoirs. This reduces the subsequent inherent rate of CO₂ removal from the atmosphere. This means that transferring a quantity of CO₂ from the atmosphere to a biomass pool lowers the atmospheric concentration the most immediately after the initial removal, but subsequently, the atmospheric concentration trends back towards the values without biospheric removal.The optimal timing for the use of vegetation sinks therefore depends on a number of factors: the length of time over which forest growth can be maintained, whether biomass is used for energy generation and on the nature of the most detrimental aspects of climate-change impacts. Climate-change impacts related to the instantaneous effect of temperature are mitigated less by vegetation sinks than impacts that act via the cumulative effect of increased temperature. It also means that short-term carbon storage in temporary sinks is not generally beneficial in mitigating climate change.     

Decentralised carbon footprint analysis for opting climate change mitigation strategies in India

Carbon footprint (CF) refers to the total amount of carbon dioxide and its equivalents emitted due to various anthropogenic activities. Carbon emission and sequestration inventories have been reviewed sector-wise for all federal states in India to identify the sectors and regions responsible for carbon imbalances. This would help in implementing appropriate climate change mitigation and management strategies at disaggregated levels. Major sectors of carbon emissions in India are through electricity generation, transport, domestic energy consumption, industries and agriculture. A majority of carbon storage occurs in forest biomass and soil. This paper focuses on the statewise carbon emissions (CO₂, CO and CH₄), using region specific emission factors and statewise carbon sequestration capacity. The estimate shows that CO₂, CO and CH₄ emissions from India are 965.9, 22.5 and 16.9 Tg per year, respectively. Electricity generation contributes 35.5% of total CO₂ emission, which is followed by the contribution from transport. Vehicular transport exclusively contributes 25.5% of total emission. The analysis shows that Maharashtra emits higher CO₂, followed by Andhra Pradesh, Uttar Pradesh, Gujarat, Tamil Nadu and West Bengal. The carbon status, which is the ratio of annual carbon storage against carbon emission, for each federal state is computed. This shows that small states and union territories (UT) like Arunachal Pradesh, Mizoram and Andaman and Nicobar Islands, where carbon sequestration is higher due to good vegetation cover, have carbon status >1. Annually, 7.35% of total carbon emissions get stored either in forest biomass or soil, out of which 34% is in Arunachal Pradesh, Madhya Pradesh, Chhattisgarh and Orissa.     

Carbon dioxide (CO2) storage and sequestration of land cover in the Leyte Geothermal Reservation

This study estimated the existing stored carbon (C) and rate of sequestration by vegetation that can potentially serve as a sink for the carbon dioxide emitted from eight geothermal plants in Leyte Geothermal Reservation, Philippines. For the 20,438 ha watershed in the vicinity of the power project, the total C storage is 3.84 Mt C (14.10 Mt CO₂) while C sequestration based on biomass change was 47.35 kt C (173.77 kt CO₂). Relative to power plant emission, the C stored in the reserve is equivalent to more than 22 years of CO₂ emission. Annual C sequestration is 27% of CO₂ emission per year. For the next 25 years, two scenarios were projected. Under Scenario I (“Business as Usual”), the forest reserve will be able to store and sequester more than 32 years of CO₂ emission from the power plants. Under Scenario II (“Accelerated Reforestation”), the reserve will be able to store and sequester about 34 years of CO₂ emission.In addition, the rate of C sequestration based on biomass change in vegetation was recorded to assess the optimum land use that can absorb the carbon dioxide emitted by the power project. These are as follows: tree plantations (10.09 tC/ha/yr)>coconut (4.78 tC/ha/yr)>brushland (4.29 tC/ha/yr)>natural forest (0.92 tC/ha/yr).In terms of cost, the power project operator is spending P1.22 per t CO₂ (P4.4 or US$0.12 per tC) for every year of C storage and sequestration. For 25 years, the total cost is P30.40 per tCO₂ (P111.5 or US$2.94 per tC) which is comparable to the cost of C offset in other tropical countries.     

Bioenergy plantations or long-term carbon sinks? – A model based analysis

In order to mitigate climate change bio-productive land may be used mainly in two ways: afforestation with long-rotation forests with the primary aim to act as carbon sinks, and short-rotation forests that are used for energy purposes and thereby replace fossil fuels. Under an ambitious climate target, land that may be used for both bioenergy plantations and long-rotation forests, are likely to be scarce, and thereby competition between long-rotation forests and bioenergy plantations can be expected. The goal of the study is to analyze the cost-effectiveness of bioenergy plantations versus long-rotations forests aimed at capturing and storing carbon. The study is performed by solving and analyzing a linear optimization model that links the energy system, an afforestation sector and the pulp and timber market. Many earlier studies tend to suggest that long-rotation forests offer lower costs per ton of CO₂ avoided. Our study, however, shows that long-rotation forests for the purpose of carbon sequestration will not be cost-effective in the long run under a stringent climate policy. Thus, economic efficiency considerations tend to support short-rotation plantations for high carbon prices. The reason for this is that scarcity of land increases the opportunity cost of land, a feature which is generally not captured in static near-term analysis, but it is captured in a dynamic model like ours. For less stringent carbon targets long-rotation forests, that are harvested and sold as timber are cost-effective during a transient phase.     

Effects of climate change on biomass production and substitution in north-central Sweden

In this study we estimate the effects of climate change on forest production in north-central Sweden, as well as the potential climate change mitigation feedback effects of the resulting increased carbon stock and forest product use. Our results show that an average regional temperature rise of 4 °C over the next 100 years may increase annual forest production by 33% and potential annual harvest by 32%, compared to a reference case without climate change. This increased biomass production, if used to substitute fossil fuels and energy-intensive materials, can result in a significant net carbon emission reduction. We find that carbon stock in forest biomass, forest soils, and wood products also increase, but this effect is less significant than biomass substitution. A total net reduction in carbon emissions of up to 104 Tg of carbon can occur over 100 years, depending on harvest level and reference fossil fuel.     

A modeling approach for investigating climate change impacts on renewable energy utilization

In this study, an integrated community‐scale energy model (ICEM) was developed for supporting renewable energy management (REM) systems planning with the consideration of changing climatic conditions. Through quantitatively reflecting interactive relationships among various renewable energy resources under climate change, not only the impacts of climate change on each individual renewable energy but also the combined effects on power‐generation sector from renewable energy resources could be incorporated within a general modeling framework. Also, discrete probability levels associated with various climate change impacts on the REM system could be generated. Moreover, the ICEM could facilitate capacity–expansion planning for energy‐production facilities within a multi‐period and multi‐option context in order to reduce energy‐shortage risks under a number of climate change scenarios. The generated solutions can be used for examining various decision options that are associated with different probability levels when availabilities of renewable energy resources are affected by the changing climatic conditions. A series of probability levels of hydropower‐, wind‐ and solar‐energy availabilities can be integrated into the optimization process. The developed method has been applied to a case of long‐term REM planning for three communities. The generated solutions can provide desired energy resource/service allocation and capacity–expansion plans with a minimized system cost, a maximized system reliability and a maximized energy security. Tradeoffs between system costs, renewable energy availabilities and energy‐shortage risks can also be tackled with the consideration of climate change, which would have both positive and negative impacts on the system cost, energy supply and greenhouse‐gas emission. Copyright © 2011 John Wiley & Sons, Ltd.     

Carbon sequestration by forestation across China: Past, present, and future

Plantation forests are the most effective and ecologically friendly way of absorbing CO₂ and increasing carbon sinks in terrestrial ecosystems; mitigating global warming and beginning ecological restoration. China's forestation rate is the highest in the world, and contributes significantly to the nation's carbon sequestration. We have applied empirical growth curves, scale transformations, field sampling plots, and forest inventory data, to our carbon estimation model, to analyze the carbon sequestration in living biomass and soil organic carbon pools in past and current plantations. Furthermore, the potential carbon sinks of future plantations, 2010-2050, have been simulated. From 1950 to the present, plantations in China sequestered 1.686 Pg C by net uptake into biomass and emissions of soil organic carbon. The carbon stock of China's present plantations was 7.894 Pg C, including 21.4% of the total sequestration as forest biomass and 78.6% as SOC. We project that China's forestation activities will continue to net sequester carbon to a level of 3.169 Pg C by 2050, and that carbon stock in plantations will amount to 10.395 Pg C. Spatial patterns of carbon sequestration were dissimilar to those of planting area. On the basis of area, carbon sequestrations were highest in North China, while changes were generally greatest in the Northeast and Southwest regions.     

Australia: Approaching an energy crossroads

This paper considers energy policy in Australia in the context of its considerable energy resources, climate change and a recent change in government. It examines the possible paths that future energy use and policy in Australia could take, including published projections based largely on a “business as usual” approach and projections based on a dramatic shift towards more efficient use of energy and renewable energy technologies. It also considers the various factors affecting future policy direction, including energy security, the advocacy in Australia for establishing nuclear electricity generation and other parts of the nuclear fuel-cycle, responses to climate change, and carbon sequestration. It concludes that while the Australian Government is currently reluctant to move away from a dependence on coal, and unlikely to adopt nuclear energy generation, a low-emissions future without waiting for the deployment of carbon capture and storage and without resorting to nuclear power is within reach. However, in the face of strong pressure from interest groups associated with energy intensive industry, making the necessary innovations will require further growth of community concern about climate change, and the development of greater understanding of the feasibility of employing low carbon-emissions options.     

Modeling the role of forests in a regional carbon mitigation plan

Biomass from the forest sector can be an important source of renewable energy and can contribute to climate change mitigation and bioenergy development. However, the removal of biomass from forests has significant impacts on the forest ecosystem. For instance, it modifies soil litter which is particularly important to preserve soil characteristics and to sustain a diversity of organisms. Our aim is to analyze alternatives of sustainable forest management and compare how they perform in terms of carbon savings in order to assess the role of the sector in a regional emission reduction plan. The analysis is performed applying CO2FIX, a well-known carbon accounting model to the forests of the Italian region of Emilia-Romagna. The behavior of the most important forest macro-categories is investigated under common management alternatives: no harvest activities, maintenance of a constant stock, different rotation lengths, and maximization of harvested biomass. We evaluate their impact at landscape level on the regional carbon budget, thus estimating the maximum potential contribution from the forest sector.     

Climate mitigation comparison of woody biomass systems with the inclusion of land-use in the reference fossil system

While issues of land-use have been considered in many direct analyses of biomass systems, little attention has heretofore been paid to land-use in reference fossil systems. Here we address this limitation by comparing forest biomass systems to reference fossil systems with explicit consideration of land-use in both systems. We estimate and compare the time profiles of greenhouse gas (GHG) emission and cumulative radiative forcing (CRF) of woody biomass systems and reference fossil systems. A life cycle perspective is used that includes all significant elements of both systems, including GHG emissions along the full material and energy chains. We consider the growth dynamics of forests under different management regimes, as well as energy and material substitution effects of harvested biomass. We determine the annual net emissions of CO₂, N₂O and CH₄ for each system over a 240-year period, and then calculate time profiles of CRF as a proxy measurement of climate change impact. The results show greatest potential for climate change mitigation when intensive forest management is applied in the woody biomass system. This methodological framework provides a tool to help determine optimal strategies for managing forests so as to minimize climate change impacts. The inclusion of land-use in the reference system improves the accuracy of quantitative projections of climate benefits of biomass-based systems.     

Carbon charges and natural gas use in China

Substitution of natural gas for coal in China's power sector could significantly reduce emissions of carbon dioxide, but gas-fired power is generally more costly than coal-fired power in China today. This paper explores how carbon charges and carbon sequestration technology might tip the balance in favour of gas. The costs of electricity from new coal-fired and gas-fired power plants in China are compared under various assumptions about fuel costs, exchange rates, carbon dioxide charges, and application of carbon sequestration technology. Under average cost conditions today, gas-fired power is roughly two-thirds more costly than coal-fired power. But with a charge of $20/tonne of carbon dioxide, the costs of gas- and coal-fired power would typically be about equal. Over the longer term, carbon sequestration technology could be economical with a carbon dioxide charge of $22/tonne or more under typical cost conditions, but gas with sequestration would not have a clear cost advantage over coal with sequestration unless the charge exceeded $35/tonne.     

Impact of row spacing, nitrogen rate, and time on carbon partitioning of switchgrass

Cultivation of switchgrass (Panicum virgatum L.) as an energy crop could lower atmospheric carbon dioxide (CO₂) levels by replacing fossil fuel and sequestering carbon (C). Information on the details of C partitioning within the switchgrass–soil system is important in order to quantify how much C is sequestered in switchgrass shoots, roots, and soil. No studies of C partitioning in a switchgrass–soil system under field conditions have been conducted. This study was aimed at determining the impact of agricultural management practices, such as row spacing and nitrogen (N) application rate, on C partitioning within the switchgrass–soil system; changes in C partitioning with time after switchgrass establishment were also considered. The results indicate that C storage in switchgrass shoots was higher with wide than narrow rows, and increased with N application rates. These responses were due to higher yields with wide than narrow rows and higher yields as N application rate increased. Carbon storage in shoots was 14.4% higher with 80-cm than 20-cm row spacing. Annual application of 224 kgNha⁻¹ increased C storage in shoots by 207% and 27% when compared with annual applications of 0 and 112 kgNha⁻¹, respectively. Carbon storage increased by 62% over time from 1995 to 1996 in newly established switchgrass on sandy loam soil in the coastal plain of Alabama. Rate of C increase in roots (72%) was higher than in shoots (49%) between 1995 and 1996. Carbon storage was in order of soil C > root C > shoot C in both 1995 and 1996. The root/shoot ratio of C storage was 2.2. It appears that C partitioning to roots plays an important role in C sequestration by switchgrass.     

Estimation of forest area near deserts — production of Global Bio-Methanol from solar energy

This paper proposes a new synthesis method for methanol as a future alternative fuel, by the combination of carbon supplied from wood and hydrogen supplied from the electrolysis of water using a solar power generation system in the desert. In the developed countries, more than half of the potential forest area has already been converted into other land uses, while existing forests are well organized and available for wood production. In the developing countries, potential forest sites are expected to be available for wood production, even though they are presently grasslands or secondary forests, while natural tropical forests will not be allowed to be converted into artificial forests. The area available for plantations within 500 km distant from deserts was estimated to be 65 Mha in the world, except for the mountain areas. Biomass production from these sites will be converted annually into 980 Mt methanol with hydrogen from the deserts. This amount is equal to 34% of the world's fuel consumption by vehicles.     

Time-dependent climate benefits of using forest residues to substitute fossil fuels

In this study we analyze and compare the climate impacts from the recovery, transport and combustion of forest residues (harvest slash and stumps), versus the climate impacts that would have occurred if the residues were left in the forest and fossil fuels used instead. We use cumulative radiative forcing (CRF) as an indicator of climate impacts, and we explicitly consider the temporal dynamics of atmospheric carbon dioxide and biomass decomposition. Over a 240-year period, we find that CRF is significantly reduced when forest residues are used instead of fossil fuels. The type of fossil fuel replaced is important, with coal replacement giving the greatest CRF reduction. Replacing oil and fossil gas also gives long-term CRF reduction, although CRF is positive during the first 10-25 years when these fuels are replaced. Biomass productivity is also important, with more productive forests giving greater CRF reduction per hectare. The decay rate for biomass left in the forest is found to be less significant. Fossil energy inputs for biomass recovery and transport have very little impact on CRF.     

The costs and profitability of using granulated wood ash as a forest fertilizer in drained peatland forests

Increasing and more intensive energy wood harvesting from forests necessitate efforts to ensure that adequate amounts of nutrients are recycled back onto the site. Recycling nutrients back to the forest in the form of wood ash is a natural means to correct the nutrient imbalance and acidity of forest soils that can occur from intensive management, as well as to solve the problem of disposing of wood combustion wastes. Methods of refining and spreading have been developed to improve the logistics and cost competitiveness of recycling wood ash back into the forest as fertilizer. In this study, the costs of spreading granulated wood ash in the forest were calculated under Finnish conditions. The profitability of recycling wood ash to drained peatland forests as a fertilizer was also analyzed, from the forest owner’s point of view. For this analysis, wood ash was compared with chemical fertilizer in terms of effect, cost and profitability. Wood ash fertilization using the ground-based forwarder system was two to three times cheaper than using the aerial helicopter-loader system. From the forest owner’s point of view, the fertilization of peatland forest with wood ash proved to be a very profitable silvicultural investment (IRR 3-12 percent). To improve the economics of wood ash recycling to forests, ground-based spreading of granulated ash should be emphasized. Furthermore, in order to create large enough operational units for the cost-efficient spreading of ash, there needs to be comprehensive planning of spreading sites.     

A review of climate change, mitigation and adaptation

Global climate change is a change in the long-term weather patterns that characterize the regions of the world. Scientists state unequivocally that the earth is warming. Natural climate variability alone cannot explain this trend. Human activities, especially the burning of coal and oil, have warmed the earth by dramatically increasing the concentrations of heat-trapping gases in the atmosphere. The more of these gases humans put into the atmosphere, the more the earth will warm in the decades and centuries ahead. The impacts of warming can already be observed in many places, from rising sea levels to melting snow and ice to changing weather patterns. Climate change is already affecting ecosystems, freshwater supplies, and human health. Although climate change cannot be avoided entirely, the most severe impacts of climate change can be avoided by substantially reducing the amount of heat-trapping gases released into the atmosphere. However, the time available for beginning serious action to avoid severe global consequences is growing short. This paper reviews assessing of such climate change impacts on various components of the ecosystem such as air, water, plants, animals and human beings, with special emphasis on economy. The most daunting problem of global warming is also discussed. This paper, further reviews the mitigation measures, with a special focus on carbon sequestration and clean development mechanism (CDM). The importance of synergy between climate change mitigation and adaptation has been discussed. An overview of the relationship between economy and emissions, including Carbon Tax and Emission Trading and the policies are also presented.     

Feasibility of the Nordic forest energy harvesting technology in Poland and Scotland

Finland and Sweden have been forerunners in the development of wood harvesting machinery and methods. In both countries, small- and large-scale supply systems for wood chips have been in operation for several decades. More recently, the production and use of forest chips from logging residues and small diameter trees has been growing rapidly.The European Union (EU) has set ambitious targets for the use of renewable energy to mitigate climate change and to increase domestic energy security and self-sufficiency. The largest unutilised source for renewable energy in the EU is forest biomass. European forests could fulfill one third of the goal set for biomass-based energy production in the EU’s Biomass Action Plan. In addition, member countries have started national programmes to promote the use of biomass for energy.As a result, interest in Nordic forest energy technology has been increasing rapidly in other parts of the EU. The Finnish Forest Research Institute and its collaborators have been running a technology transfer project in ten European countries, with the goal of tailoring and adapting Nordic forest technology to local conditions through analysing the applicability, costs and overall competitiveness of selected feedstock supply technologies.This paper summarizes the findings of feasibility studies carried out in Poland and Scotland and gives an overview of the current situation and development trends of forest energy in the European Union.