Before learning about Southern Bioenergy, new users of this site might want to learn more about what an online encyclopedia consists of by checking out the Where to Begin page.

The forest ecosystems of the South serve many purposes including the production of bioenergy. This encyclopedia is a synthesis of the best available scientific knowledge regarding the state of bioenergy and bio-based products from Southern forest ecosystems. We are certainly not suggesting that all existing forests should be tapped for energy production. Forest biomass for energy and other bio-based products can and must be managed as simply one of a large number of goods and services that can be produced from the forests (IEA Bioenergy Task 31, 2000).

Bioenergy system

The Encyclopedia of Southern Bioenergy is divided into seven sub-sections:

• Understanding Bioenergy Resources:
• The Southern Bioenergy Resource:
• Forest Management:
• Harvesting:
  
• Utilization:
• Economics:
• Environmental Sustainability:

Biomass is the most important renewable energy source used in the world today. It is used mostly in solid form and, to a lesser extent, in the form of liquid fuels and gas. Despite many factors favoring bioenergy, the utilization of bioenergy has increased at only a modest rate in modern times. Large scale utilization of biomass for energy is still limited to a few countries. In the United States, the forest products industry is probably the largest user of forest biomass, using it to generate more than 70% of its energy needs. Climate change, forest health, wildfires, rural development, and energy security are problems facing the United States today. The increased utilization of forest biomass can help solve these problems. Energy, economic, and environmental benefits can be derived from the use of biomass for bioenergy and bio-based products.

Residues

This section of the Bioenergy Encyclopedia is designed to help the reader understand bioenergy resources both from a global perspective and then from a United States national perspective. Another section explains the Southern Bioenergy Resource.

• Global Utilization of Forest Biomass
• Current Status of Biomass in the US
• Environmental Benefits of Biomass
• Economic Benefits of Biomass
• Energy Benefits of Biomass
• Promoting Bioenergy

Sources of Nordic Biomass

On a global level, the forest biomass resource potentially available for bioenergy and bio-based product production is vast. Forestlands cover approximately 30 percent of the Earths surface or 9.6 billion acres (FAO 2001). These forests serve a variety of purposes including environmental protection and sustainability, timber production, wildlife habitat, and recreation areas. Globally, forests also serve as energy sources. According to the Food and Agricultural Organizations (FAO) State of the Worlds Forests report (2005), a majority of the total energy supply of many developing countries comes from fuelwood. Yet, black liquor, the lignin-rich residue generated during the papermaking process - used by the industry for process heat, steam, and electric power generation - is an important source of energy in some developed countries. Many European regions, especially Scandanavia, produce a significant percentage of their heat and electric power requirement from forest biomass. Approximately 25% of Swedens energy comes from forest biomass mainly in the form of heat. This biomass comes from a variety of sources including the forest sector, wood chips, black liquor, and recycled wood (above).

The potential for wood-based energy is not fully utilized in any industrialized country. But, signs of improvement are encouraging. In 1990, approximately 46% of harvested timber was used for fuelwood in the European Union (table below). Industrial residues accounted for approximately 50% of the biomass used, while conventional firewood comprised 44% (Hakkila and Parikka 2002). With increased research, education, and technological developments, the consumption of wood-based energy is predicted to increase globally.

(Table:Use of Wood-Based Energy in the 15 Countries of the European Union in 1990)

There is a convergence of factors favoring bioenergy use at a global level today. These factors include global climate change, the rising price and scarce supply of fossil fuels, and the economic, social, and environmental benefits related to bioenergy development (Silveira 2005).

This section provides more information related to the global utilization of biomass for bioenergy including:

• Availability of Biomass Across the Globe
• Utilization of Forest Biomass
• Organization for Economic Cooperation and Development (OECD) Countries
• European Union
• Future Scenarios

Regional Shares of Bioenergy Supply 2004

Significant regional differences exist with regard to the availability (at right) and use of biomass resources in the world. In Africa, most of the biomass used in the continent is harvested informally and only a small part is commercialized. Traditional technologies predominate. In many parts of Asia and Latin America, on the other hand, modern and commercial bioenergy options are readily available and significant. The Brazilian ethanol program, based largely on sugar cane, for example, is well-established and provides alternative fuel to the transportation sector at highly competitive prices.

In addition to woodfuels, other biomass fuels such as forest and crop residues, as well as animal waste, are common sources of bioenergy. Besides the amount of readily available biomass in the form of residues, and the potential for improved efficiency in technologies being presently applied, many countries still have land available for energy plantations. Integrating biomass harvesting for energy purposes with forestry and agricultural activities is another option. In most regions, the use of biomass still needs to become sustainable, this being true both where traditional and modern technologies are applied.

Biomass is the most important renewable energy source used in the world today. Although the use of renewable sources has increased constantly in the past three decades, their use has not kept pace with the use of fossil fuels, which has increased five times more in absolute terms.

Due to the fossil fuel dominance of past global trends, there is a tendency to conceptually link biomass use with poor countries at a low level of industrialization. However, many industrialized countries are also major users of biomass. In Sweden and Finland, for example, biomass accounts for approximately one-fourth of the energy used. In Brazil, 27% of the energy comes from biomass, almost half being sugarcane based. In these countries, biomass is being used to feed modern and efficient systems, providing essential energy services.

2004 Product Shares In
World Renewable Energy

Other renewable energy sources such as solar, wind, and tide comprise a very small fraction, corresponding to less than 0.1% of the world total energy supply; while biomass corresponds to 10.6% of the world total energy supply and 79.4% of the total renewable energy supply (at right) (IEA 2006).

In general, biomass is mostly used in solid form and, to a less extent, in the form of liquid fuels, renewable municipal solid waste and gas. However, recent trends show a faster increase in the use of liquid biomass and municipal waste than solid biomass. Notably, while the use of solid biomass increased by 1.8% per year in industrialized countries since 1990, liquid biomass has grown at an annual rate of 84%. In comparison, wind and solar energy have reached growth rates above 20%. These large growth rates have to be considered with caution as the starting points for renewables have been quite low, but they do indicate a positive trend towards more use of renewable energy sources. In fact, when compared with other renewables, solid biomass showed the slowest growth since 1990 (IEA 2006).

Thus some opportunities are being realized particularly as a result of efforts to find new alternatives to fossil fuels in the transportation sector and in waste management. Nevertheless, considering the resource base that is readily available, for example in the form of residues from forestry and agriculture, and the great potential to grow more biomass, there is much more that can be done to enhance the role of bioenergy. In addition, interest in assessing biomass potential in different parts of the world has increased in the past few years in face of the implied pressure that bioenergy utilization can put on natural resources such as land and water. We are likely to see more of these types of studies in the near future. New technologies, for example for gasification of wood materials or black liquor in the pulp and paper industry, are likely to further increase the efficiency of biomass utilization.

A better understanding of the utilization of biomass for bioenergy can be gained by looking at regional and country grouping examples including:

• Organization for Economic Cooperation and Development (OECD) Countries
• European Union (EU)

Biomass accounts for some 3% of the energy supply in OECD countries (http://www.oecd.org/). In fact, renewables as a whole correspond to only 5.7% of the total primary energy supply in OECD countries, of which about half is being used to generate electricity. The use of solid biomass has had a positive development in OECD countries, showing an annual increase of 1.8% since 1990 as opposed to 1.5% in non-OECD countries. The segments utilizing municipal solid waste and producing liquid biomass exhibit faster growth (IEA 2006).

Although electricity demand is growing by more than 2% per year in OECD countries, electricity generation from renewables has only grown by 0.8% per year since 1990. The participation of renewables in the total supply of electricity has decreased in absolute terms in many regions of the OECD since the late 1990s, particularly in the US. The European Unions use of renewables, on the other hand, has experienced continuous growth since 1990, thanks to supportive policies, particularly those related to urban waste handling (IEA 2006).

Biomass only corresponds to 1% of the world electricity generation. More specifically, electricity generation from solid biomass has shown an average increase of 2.7% per year and some 20 TWh (terrawatt-hour) have been added to the supply base of OECD countries since 1990, denoting a slight increase in the share of biomass for electricity generation in OECD countries. In fact, renewable municipal waste and biogas are becoming increasingly important in OECD countries. Though both are still at an initial stage, significant growth in these segments can be expected in the years to come. Heat production from biomass has also increased substantially, both in plants that produce only heat and in combined heat and power plants (CHPs).

Among European countries, the bulk of biomass being used consists of fuelwood for individual domestic heating. The use of biomass for district heating is substantial in a few countries such as Austria, Finland, and Sweden, mainly fed by fuelwood and wood residues from the forestry and wood processing industry. In Denmark, straw is used to some extent. In comparison, the use of biomass in industry and for electricity generation is modest. In addition, biofuels in transportation applications represent a small fraction of the bioenergy use in all countries including Austria, France, Germany, Italy, and Sweden (Bauen 2005).

At present, markets for bioenergy exist for co-firing with coal, district and small-scale heating, combined heat and power, and blending of biofuels with petroleum transportation fuels. Long-term options could be biomass use for heat and power generation in integrated gasification combined-cycle plants and for the production of new fuels such as hydrogen.

Biomass offers the largest renewable energy potential in the European Union today, although it only currently supplies 3.5% of the energy in the region. However, the interest in bioenergy has increased rapidly in the region. Some EU countries have had outstanding performance in their national biomass programs, for example, the Netherlands, United Kingdom, and Denmark, all of which started from very low levels in the early 1990s. Also, countries previously outside the EU, such as the Czech Republic and Hungary, have been investing in bioenergy (IEA 2003). Meanwhile, traditional bioenergy users such as Sweden, Finland, and Austria continue to expand their bioenergy generation.

In the past few years, the EU has developed common guidelines and energy directives which are expected to have a significant impact on bioenergy use in the coming years. Provided the efforts being made to promote bioenergy succeed, the amount could increase from 45 million tons of oil equivalent (TOE) to 130 million TOE in the region by 2010-2015 (Bauen 2005).

Bioenergy provides a great opportunity to address problems other than energy in the EU, such as decreasing populations in rural areas, employment in peripheral regions, and restructuring of agricultural policies including new uses for idle croplands and reduction of subsidies. A recent Europe-wide study indicated that as many as 900,000 jobs could be created by 2020 from investments in renewables of which 500,000 jobs would be related to agriculture production of  biofuels (ALTENER 2001).

The International Institute for Applied Systems Analysis/World Energy Council (IIASA/WEC) led a comprehensive study to analyze possible future global energy scenarios. This study is important because it has been largely used as reference in various international negotiations, for example, on climate change. Six scenarios were analyzed based on three alternative views of the future. Case A is called high growth and presents very ambitious rates of economic growth, that is, 2% per year in industrialized countries and twice as much in developing countries. Case B is the middle course and is based on a more pragmatic path with more moderate growth. Case C is ecologically driven. It is the most challenging and also the more optimistic when it comes to technology development, international cooperation, environmental protection and equity. Despite significant differences among the scenarios, they are all challenging given increasing population and demand for energy services, as well as sustainability requirements.

Global Primary Energy Consumption.
Evolution from 1850-2100

The results include both descriptive and normative scenarios and build on the assumption that no major discontinuities and catastrophes will take place. Bioenergy has a role to play in all scenarios, though of varying magnitudes. In scenario A1, bioenergy only accounts for some 10% of the total energy supply, and fossil fuels remain the major energy source throughout the century. In the so-called rich and green scenario, or scenario C1, biomass could account for almost 30% of the total amount of world energy in 2100 (see diagram, Nakicenovic 1998).

It is important to point out that biomass utilization in the IIASA/WEC scenarios differ from present conditions especially when it comes to technologies. In particular, significant changes in the way biomass is being utilized in many developing countries today will have to be accomplished. We are basically talking about going from traditional to modern and efficient technologies that can provide high-quality energy services, many of which require access to electricity (see also Fischer and Schrattenholzer 2001).

It is also important to remember that scenarios are neither predictions nor forecasts but possible ways in which the future can unfold following a set of assumptions. An important message of this study is that, although we will have to rely on fossil fuels for a few decades more, we can decide what energy future we want to have as we build new infrastructure in the coming years. The choices will be much more restricted after 2020 once major new investments are already in place.

The United States is covered by approximately 595 million acres of forestlands. Using only trees that are currently considered to be pre-commercial, non-merchantable, and residues from timber harvesting operations and "healthy forest and fire hazard reduction" operations, these forestlands can produce a total of approximately 368 million dry tons of biomass annually (Perlack and others 2005). Approximately 36% (214 million acres) of the total forestland is located in the thirteen southern states. In the South, about 55 million tons of pre-commercial, non-merchantable, and residue forest biomass are potentially available annually for the production of bioenergy and other bio-based products. For specific information on the supply of biomass, refer to the Sources and Quantity of Supply section. When the demand for more wood energy and bio-product feedstocks increases, trees now being harvested for traditional products such as pulp and paper, can be used. This transition of using commercial trees for energy will be a logical change, since demand for roundwood pulpwood in the South has decreased significantly over the last decade.

Yet, even with such a large available resource in the United States, only 9% of our domestic energy production is in the form of renewable energy. Forty-seven percent of that energy is from biomass (EIA 2004). While wood-based biomass is not as highly publicized as other forms (corn, sugarcane, etc.), it accounts for 72% of the source material for biomass generated energy. Our consumption of renewable energy is even lower, with only 6% of our total consumption being from renewable sources. Biomass accounts for approximately 47% of the renewable energy consumed in the U.S. (see Energy Benefits of Biomass).

The forest products industry is probably the largest user of forest biomass, generating more than 50% of its energy in-house - most of which comes from by-products (black liquor from the papermaking process, bark, hogged fuel, and dirty chips) of its manufacturing process.

Current Flow of Forest Products

The process of merchandising wood products from the forest is a well-developed process. As trees are harvested they are accumulated at a central location and sorted into the highest value products. These products are then transported to manufacturing facilities for processing into the targeted products (at left). Primary products include lumber, paper, fiber board, oriented strand board, pulp, and other wood composites. Chips, bark, and other by-products created from these processes are used to produce boiler fuel for the manufacturing processes. "Clean" chips and wood flakes can be used to produce such commodities as paper, oriented strand board, particle board, etc. "Dirty" chips are used to produce energy for the facility, mulch, etc.

In some cases, residual logging debris, under-sized trees, and other woody biomass are converted into wood chips by an in-woods chipper. These residue materials can be used for the production of electricity, dyes, inks, adhesives, fuels, chemicals, and many other bio-based products. However, this material is most frequently left on site and unutilized because of handling and transportations costs as well as the lack of markets. Efficient systems for harvesting and transportation systems can increase the utilization of this biomass while protecting the productive potential of the forest site. See the Harvesting module for more detailed coverage of this topic.

Nordic operations

Dirty chips (at right) are another by-product used to generate energy for the forest products industry. According to the U. S. Department of Energys Energy Efficiency and Renewable Energy Office (2004), the U. S. forest products industry is among the top 10 manufacturing industries in 46 states. It is also among the nine most energy intensive industries in the U. S., ranking third behind petroleum and chemical industries. Energy accounts for 15-25% of the operating expense of the forest products industry.

Small scale power generation

Across the nation, projects utilizing wood-based biomass are beginning to gain a foothold. Many of these projects are in the Northeast and West. A 25 MW plant in St. Paul, MN, uses urban tree waste to produce electricity (LeVan-Green 2005). Wood chips are used as heating fuel in Montana and Vermont. In Colorado, small modular gasifiers (at left) are being used to generate electricity. And in Arizona, wood from forest fuel treatments is being used to generate electricity.

The South has relatively few wood-based biomass energy projects. Santee Cooper in South Carolina announced in August 2005 that they would begin co-firing wood with coal in one of their facilities. Wood for the facility would be from fuel treatments and thinnings from the forests of the USDA Forest Service National Forest System (Stock 2005). According to company news releases and conference presentations, Southern Company has done limited studies, with varying degrees of success, of co-firing wood with coal, and switchgrass with coal at its Gadsden, Alabama coal fired plant.

Yet, for a number of reasons logging residues and small diameter trees do not comprise a significant component of energy production. Approximately 16% (by weight) of softwood and 26% of hardwood volume harvested is left in the forest as residue (Smith and others 2004) because it is currently not economical to utilize this material. Continued research in harvesting, utilization, and efficiency along with education will help move the industry forward into the future. When demand for energy, bio-fuels such as cellulosic ethanol, and bio-chemicals requires it, the value for these uses exceeds the value from traditional markets such as wood pulp, and conversion technologies are in commercial use, the United States, particularly the South, can produce enormous volumes of energy and bio-chemical feedstocks that are renewable, sustainable, and expandable to meet the countrys needs. This can be done without compromising air or water quality, wildlife habitat, or recreational opportunities on the land producing the wood feedstocks. One way to accomplish this is to integrate an energy/bio-chemical harvest in the silvicultural practices for forests located within an economical distance from energy and bio-chemical markets.

Global Climate Change

The global climate change agenda is a promising new platform whereby renewable technologies can receive support to gain new markets. Images of the Arctic Sea (at right) show that the ice boundary has shrunk significantly since 1979. In this context, bioenergy is an attractive alternative to help reduce fossil fuel use (Kaltschmitt and Bauen 1999). The need for renewable energy alternatives to mitigate climate change, the possibility to produce biomass resources on a sustainable basis, the opportunity to address rural socio-economic problems by promoting bioenergy, and the restructuring of energy markets favoring small-scale decentralized generation are some of the factors that make bioenergy options particularly interesting in many countries. Besides being renewable, bioenergy can bring about other environmental benefits including the recovery of degraded land, reduction of soil erosion, and protection of watersheds.

Carbon Cycle

Carbon sequestration, the removal of carbon dioxide from the atmosphere into long-lived carbon pools, and the mitigation of greenhouse gases are of prime importance in reducing global climate change. Carbon sequestration pools associated with forests can include above-ground living biomass (trees and shrubs), living biomass in soils (roots, soil organic matter, etc.), and products created from biomass (lumber, paper, etc.) (CSiTE 2002). Forests utilize carbon dioxide in photosynthesis and emit less carbon dioxide than fossil fuels when burned. The carbon cycle (left) is basically a closed cycle when using forest biomass to produce bioenergy and the process of burning forest biomass is essentially a carbon neutral process.

Wildfire

A primary reason for the recent high incidence of wildfires is the over abundance of available fuel wood. At the forest level, the use of biomass for bio-based products may help decrease the risk of wildfires. Creating a healthier forest by removing brush, small diameter trees, damaged trees, and other fuel sources can lessen the possibility of large, high intensity wildfires as well as mortality caused by insects and disease (See the Healthy Forests Initiative). A healthier forest can also support a larger diversity of wildlife. The use of sustainable forest biomass for bioenergy and bio-based products will benefit forests, wildlife, and humanity.

Environmental considerations related to bioenergy and bio-based products are discussed in detail in the section entitled Environmental Sustainability.

During the recent past, Southern forest landowners have been faced with decling pulpwood markets which utilize small diameter and low value trees (below). Removal of these trees is necessary to provide growing space and other resources for the production of larger, higher-value products. Additional markets need to be developed to replace this market for small diameter trees. In addition, a significant portion of harvested timber is left on site in the form of logging residues. Finding or developing markets for this material can provide additional income for landowners.

Hardwood Stumpage Trends

Pine Stumpage Trends

Rural Development

For communities dependent on timber, market changes can have dramatic impacts on employment, stability, and viability. Diboll (right), located in East Texas, was founded by Thomas Temple as a sawmill settlement in 1894. The Southern Pine Lumber Company, under Temple family direction, provided homes, a commissary, medical services, and infrastructure to the community. In 1962, the town was incorporated but remains strongly tied to the forest products industry. Diboll is currently the home of many Temple-Inland Forest Products, Inc. manufacturing facilities. Diboll is only one example of a community throughout the South dependent upon timber products for their livelihood.

Many of these rural communities need additional, high value markets in which to trade timber products. Sustainable forestry for bioenergy and bio-based products can provide one solution to the problems faced by timber dependent communities in the South. Harvesting logging residues, building processing facilities, and utilizing the products created can bolster economic conditions in Southern rural communities. More information on the economic impacts of bioenergy and bio-based products is included in the section on Economics.

U. S. Energy Production

Biomass has been a major source of energy since the beginning of civilization. It has also been important in the early stages of industrialization in several countries. Since the Industrial Revolution, however, fossil fuels gained increasing importance because they offered the scale, efficiency, and reliability needed to change production systems radically.

The world as a whole and the United States, in particular, is facing an increasingly worrisome energy future. The United States uses more energy from fossil fuels and less from renewable energy sources than the world-wide average. On a world-wide basis, roughly 80% of the total energy supply comes from fossil fuel sources, 13% from renewable energy sources, and 7% from nuclear power (IEA 2003). In the United States, 86% of the total energy consumed comes from fossil fuels, 6% from renewable energy sources, and 8% from nuclear power (EIA 2004) (below).

U. S. Energy Consumption

A rapidly industrializing world, with China, Brazil and India in the lead, is significantly increasing the global demand for fossil fuel energy supplies. In contrast, estimated recoverable reserves of coal, oil, and natural gas have only remained stable due to improved extraction technology. Most of the largest oil fields in the world were discovered and brought into production decades ago and are facing serious, near-term declines in oil output. Price increases for oil and natural gas are believed to be all but inevitable (Eriksson and others 2002).

In the last 50 years, the consumption of energy in the United States has drastically increased. Approximately 100 quadrillion BTUs of energy were used by Americans in 2004 (EIA 2005). As consumption increases (right), renewable fuel sources can play a larger role in meeting the demands of consumers.

Oil Supply in the United States

The United States is particularly vulnerable to oil supply disruptions or price increases since it imports over 50% of its crude oil consumption. Crude oil is imported from Canada, Mexico, and Venezuela in addition to the Middle East (left). More efficient and effective utilization of biomass will increase the amount of renewable energy sources used and help to lessen the dependence on fossil fuels and foreign supplies of fossil fuels.

In this context, biomass emerges as an attractive modern energy source provided it can be economically utilized. All types of energy services can and are being provided today using biomass, with the reliability, safety, and efficiency required by the modern economy and society. Geopolitical considerations also have come to play an important role in energy security. As a result, many countries have realized the need to improve the efficiency of energy generation, distribution, and consumption, and to harness local resources as a way to increase the security of the energy supply, reverse fossil fuel dependency, and improve trade balance.

Despite many factors favoring bioenergy today, the utilization of bioenergy has increased at a modest rate. Large-scale utilization of biomass for energy purposes is still limited to a few countries.

Bioenergy needs to be considered from a systems perspective (Silveira 2005). Like the fuel chain, energy systems are composed of a variety of technologies for energy generation, distribution, and use which tend to cause significant environmental impacts. Even if individual technologies can sometimes be simple, the internal logistics of energy systems can be quite intricate. Single technological solutions are seldom sufficient to create an efficient energy delivery chain that is competitive with conventional solutions. It is at the systems level, in which various specific technologies are included, industrial processes integrated, and resources well managed that bioenergy can become a mainstream alternative.

Three fundamental questions related to the development of bioenergy are: (1) what biomass conversion technologies and end-uses present the most favorable economic and environmental options in the energy mix; (2) what amount of biomass resources will these options require; and (3) can long-term, high productivity feedstock be economically and sustainably produced? Options range from heat and power production to liquid fuel substitutes and blending agents, but opinions vary widely on their potential contribution to future energy mixes and with regard to the appropriate resources, technologies, and scales to be applied.

Where do opportunities lie for establishing markets for bioenergy systems and biofuels in the near future? How does short-term development fit with the potential long-term role envisaged for biomass in the energy mix?

These questions will be answered in the following sections:

• Market Formation
• Bioenergy Systems
• Biofuels
• Challenges in Bioenergy

Markets need to be created for new, economically feasible alternatives which are considered desirable by society but which will not easily become successful unless a policy framework is established to promote them. International Energy Agency (IEA) talks about three perspectives through which we analyze market formation. These are:

1. Research, development, and deployment perspective which focuses on innovation and industrial strategies.
2. Market barriers perspective which is the economists perspective and focuses on decisions made by investors and users.
3. Market transformation perspective which looks into the whole chain from production to use.

IEA concludes that the three perspectives are complementary and they are all needed to help define good policies than can transform energy systems visions into practice through the discipline of markets (IEA 2003). In addition, the IEA Bioenergy Agreement has recognized the growing importance of international biotrade and the necessity to ensure it is sustainable, and for this reason established the Sustainable International Bioenergy Trade (IEA Task 40) to address these issues (please see http://www.bioenergytrade.org).

The context of new energy markets is conducive to the introduction of renewable energy options and the inclusion of users as important actors in the operation and development of energy systems. We have broadened the considerations on resource availability, technology choice, and reliability and are now asking questions about acceptability, cost return, and profitability. More attention to the users is necessary in a competitive market thus hopefully also resulting in better service provision. In addition, legislation and policy incentives that encourage developing bioenergy markets are important.

Biofuels have traditionally been used in the same geographic region in which they are produced. This has been changing rapidly in the past years. For example, in Northern Europe solid biofuels trade has grown steadily for a decade. High taxes on fossil fuels, a well-developed burning capacity for solid fuels and new restrictions in waste legislation in Europe have created the base for biofuel markets (Hillring and others 2001). More recently, liquid biofuels for transportation have contributed to create global biofuel markets.

Pellets and Briquettes Production
in Lithuania, 1994-2003

The low-cost production of green chips and densified fuels (e.g. pellets and briquettes) in the Baltic states has also favored a solid biofuel trade in Northern Europe. The graph at right illustrates the production trends of briquettes and pellets in Lithuania. Most of the production is exported to Germany, Sweden, Denmark, and Norway. Imports from North America to district heating plants in Sweden have also increased lately. Danish and English coal power plants are now adding biomass to their fuel mix to reduce carbon emissions and have become major buyers of solid biomass.

While the possibility of using local and regional potential for bioenergy is a great advantage, the transformation of biofuels into commodities and the formation of international markets shall determine the extent to which bioenergy will become a major modern energy source in the coming decades. The formation of biofuel markets is likely to benefit developing countries which, in general, have favorable conditions for growing biomass.

The next ten years will be decisive for turning biomass into a modern and reliable energy supply source. The on-going development of bioenergy technologies and know-how, related to increasing international trade with biofuels, and policies to restrict carbon emissions are likely to create favorable conditions for a larger utilization of bioenergy. Equally important is the review of agricultural policies to guarantee increasing biomass supply on a sustainable basis (Silveira 2005).

Four major challenges in the development of bioenergy are:

1. Biofuel Supply and Market Development: Increasing internationalization of commodity markets for biofuels requires standardization and regulations that are still under development. Policy makers need to find ways of balancing local supply with imported fuels in order to retain the positive community impacts of biomass production and guarantee energy security. Transnational bioenergy companies are emerging.
2. Integration: A more rapid and effective development of bioenergy, with the reliability and cost efficiency commercially required, demands integration and coordination. In logistical terms, bio-based industrial clusters may emerge to promote the desired synergies. This poses challenges also in terms of designing multi-sectoral policies.
3. Competitiveness and Mainstreaming: In the near future, bioenergy will benefit from the formation of carbon markets and incentives being provided to increase the use of renewables. But as bioenergy becomes a mainstream alternative, it will have to deal with decreasing incentives and increasing cost competitiveness. Conditions for designing strategies for the segment are changing significantly.
4. Sustainability: As biofuel markets grow and bioenergy evolves from a peripheral to mainstream alternative in the energy sector, close monitoring of the impacts of large-scale biomass utilization is necessary to guarantee the environmental sustainability of bioenergy systems.

Other challenges related to bioenergy development include:

• Creating Synergies
• Managing Competition and Bottlenecks

When a country is contemplating the utilization of bioenergy, there are considerations related to the type of biomass available or to be produced, and to the potential for integrating biomass utilization with other industrial activities, end-uses and services. Bioenergy is intrinsically multi-sectoral and, therefore, cannot be considered within the realm of the energy sector alone. Actually, bioenergy is better stimulated when integrated with other business sectors and industrial processes.

Bioenergy system

The biomass resource chain, for example, is closely linked with the forest and agriculture sectors. There is also potential for integration with sectors such as waste management and rural development, which conventionally belong to other departments. The graphic to the right depicts the relationship between biomass production, sustainable operations, transportation, energy, consumer demand, sustainability, and rural development (Richardson and others 2002). Such integration requires a coordination of policies, planning and development, and strategies for marketing bioenergy. It requires coordination of public and private actors from different business spheres to go from policy to concrete projects (see examples from the European Commission 2002). The potential to contribute to environmental benefits, new business opportunities and regional development while providing efficient energy services can be crucial to assure continued support for bioenergy and further progress in this area.

This section delves into the possible synergies to be created among entities including:

• Integrating Forest Biomass and the Energy Sector
• Agriculture

There are a number of cost efficient measures to assist biofuels and bioenergy integration into the forest industry. Recent studies show that, by using the best technology commercially available, the pulp and paper industry can make a great amount of biofuel available to the market, if only energy efficiency is given high priority (STFI 2000). Gasification of black liquor alone has the potential to double power generation in the sector once it reaches a stage of commercial breakthrough.

Upgraded solid biofuels such as pellets are mainly produced from by-products of saw mills. The largest portion of the by-products is used either to meet the industries internal energy demand, or as raw material in the pulp industry. Only a fraction is upgraded to biofuels. In the long run, however, depending on how the price relation among various products evolves, it is realistic to expect that saw mills will use solid biofuels of lower quality to meet internal energy needs, and their own by-products to produce other fuels, i.e. pellets, thereby better exploiting the value and economy of the by-product.

Bioenergy generation companies need vertical integration of the fuel chain to guarantee quality biofuels derived from waste handling and forestry activities. The sector also needs to advance integration in consumer markets in order to exploit the full potential and qualities of bioenergy. But there are barriers to such integration. For example, biofuel and bioenergy production are at the margin of core activities of most forest companies. Other non-technical barriers include issues related to the distribution of business ownership, as well as the sharing of responsibility for management and risks.

In the long run, cost-efficient bioenergy production could be integrated into forest fiber production and wood-using industries, and become an important component of the forest industries, particularly in temperate zones. In this context, effective ways of sharing the costs for guaranteeing the long-term production capacity of the forestland, for example the application of ash resulting from the bioenergy process to enhance forest stands site productivity, need to be developed (Ling and Silveira 2005).

Agricultural policy reforms are needed in many countries today due to the high costs of subsidies. This is the case in Europe and North America. In addition, developing countries are pushing for more open markets for agricultural products as an important part of increasing free trade. In Europe, pending reforms may impact the development of energy crops. The EU Common Agricultural Policy (CAP) reforms have two goals: an increasing market orientation of the sector, and the reinforcement of structural, environmental, and rural development aspects of sustainable agriculture (European Commission 2002). Aspects that could favor bioenergy, such as the multi-functionality of agriculture, are among the principles driving agricultural policy in the EU today. Although there are no specific non-food policies, a number of measures related to agri-environment and structural measures in particular, provide opportunities for the development of non-food crops (Bauen 2005).

For the European forest industry, co-production of bioenergy is an attractive opportunity. The pulp and paper industry has the best potential to increase its use of bioenergy in Europe and this is already happening. At present, the regional capacity is only limited by competitive prices for solid biomass fuels. Thus policies and tax incentives are still needed.

The emissions trading scheme will tend to increase the market price for electricity. On the other hand, the scheme will impove the competitiveness of renewable energy sources in all European countries. The use of the other Kyoto mechanisms, Clean Development Mechanism and Joint Implementation, widen the possibility of emission reduction investments also including developing countries (Silveira 2005).

Energy-intensive industries in Europe have been particularly concerned about the impacts of higher electricity prices on their competitiveness. However, the various energy-intensive industries are in different relative positions with regard to their electricity supply, their access to alternative energy sources, and amounts of initial emission permits received in emissions trading schemes. For example, in Finland, the metal industry relies almost completely on electricity bought from the market, whereas the pulp and paper industry owns most of their electricity and heat supply, either directly or through shareholdings in power production companies.

The EU goals for bioenergy use are so ambitious that the availability and the price of biomass resources will be limiting factors for growth in the future. All the main biomass sources will be needed: forest resources, agricultural biomass, and biodegradable urban wastes. Several studies on biomass resources in Europe have been published but many questions remain concerning the biomass potentials, and the dynamics and sustainability that the bioenergy segment can achieve. 

Majestic trees, abundant wildlife, camping, wildfires, and timber production: all of these terms invoke thoughts of forestlands. Biomass, organic matter available on a renewable basis, is not one of the first things that comes to mind when forests are mentioned. Yet, the forests of the Southern United States provide a large renewable supply of biomass in the form of logging residues, small diameter trees, mill residues, and even short rotation woody crops.

The Southern Forest

While some of the material typically classified as "non-commercial" or not "merchantable" is currently being utilized, a large portion of this renewable natural resource is not utilized. Residues from the forest products manufacturing process are commonly used to create energy for the forest products industry.

Logging residues from commercial harvesting operations are typically left at the harvest site. Small diameter trees from thinning operations have traditionally entered into the pulpwood supply chain, but declining markets have limited this practice. As a result, these trees are either not harvested or necessary silvicultural thinnings are delayed, frequently resulting in overcrowded stands susceptible to fire, insects, and disease.

Why should we care about this excess biomass? Forest biomass can be used for generating electricity, producing biofuels, and producing biochemicals. Rising fuel costs, uneasiness about energy supplies, and dependence on foreign energy sources make renewable natural energy alternatives more attractive. Increased utilization of forest biomass can reduce dependence on non-renewable energy feedstocks while also reducing wildfire potential, slowing climate change, mitigating declining pulpwood markets, and improving forest health and sustainability. Forest biomass resources can also be used to create bio-based products. These are industrial products, other than feed or food, that utilize biological products, forestry materials, or renewable domestic agricultural (marine, plant, and animal) materials (USDA-ARS-BBCC 2003). These products include adhesives, solvents, plastics, inks, and lubricants.

Worldwide summary data from 1997 show that about 85% of global bioenergy consumption is in the form of firewood and charcoal to address heating and cooking needs. Most of the remaining 15% is black liquor, a by-product of the pulp and paper manufacturing process. This black liquor is used by the forest products industry to produce heat, steam, and electricity for a variety of purposes (IEA Bioenergy Task 31 2000). A startling difference exists between developing and developed countries. In Latin America, Africa, and Asia the prevalent use of bioenergy is for firewood and charcoal. In North America, Europe, and Japan bioenergy is primarily used for industrial purposes.

The following sections provide a background and understanding of biomass in the Southern United States. These sections include:

• The Southern United States and Potential for Bioenergy
• The Southern Forest

The Southern US

Stretching from the Atlantic Coast to the deserts of Texas and covering 834,937 square miles, the southern United States is a land of contrast and beauty. Sparkling beaches, majestic mountain ranges, fertile valleys, desert sands, pine forests, and hardwood forests can all be found in the South. The 13 southern states include Alabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, and Virginia (at right).

In 2003, estimates indicated that over 95 million people resided in the South, of which about one quarter live in rural areas (below left). These rural areas include over 60% of the counties and parishes in the southern states (Economic Research Service 2004).

Socioeconomic Conditions in the
Southern US

The South tends to lag behind the rest of the United States in terms of income and education. According to U. S. Census Bureau data (1999), the median household income in the South was approximately $5000 less than the U. S. average. Unemployment rates and the poverty rate tend to be above the national average. While a large percentage of the population are high school graduates, the average education level is still less than the national average. Approximately 21% of the population has a college degree, again slightly lower than the national average. On a positive note, the rate of home ownership in the South is higher than the national average. Regional and national socioeconomic averages are shown in the graphic below right.

Population Dispersal

The economy of the southern states is as varied as the people. Yet, natural resources serve as the economic base for many of the southern rural communities. These natural resources include the Southern forests. In 1997, the value of the Southern forest industry was calculated at $83 billion in total industry output (Abt and others 2002). The South provides over 60% of the U. S. timber supply and is home to over 1/3 of the wood products jobs in the United States. Wood products jobs make up 6% of the workforce in the South. The graph at right shows the percentage of manufacturing and wood products jobs in the South.

The Southern forest can serve as a source of unutilized woody biomass for the production of bioenergy and other bio-based products. This includes biomass from harvesting and logging residues, thinning, and wood processing residues. The quantities of these biomass sources are summarized in Table 1. This table was constructed by the Southeast SunGrant Center using Forest Inventory Analysis data and state forestry data. State biomass fact sheets are also available at Forest Bioenergy.

Percent of US Wood Products and
Manufacturing Jobs in the South

More information about the SunGrant Initiative and the regional centers can be found by visiting their websites: SunGrant Initiative, Southeast SunGrant Center, and the South Central SunGrant Center

If the trees and sawmill residues in the South now being used to produce wood pulp were instead converted to ethanol, approximately 6.5 billion gallons (162 million green tons [Johnson and Steppleton 2005] x 40 gallons per green ton) of transportation fuel would be added to the nations supply of transportation fuel. If only the difference in the Souths peak harvest rate of about 200 million green tons vs. its current harvesting rate of about 162 million green tons, roughly 1.5 billion gallons per year of ethanol would be available to meet the consumer demand of about 150 million gallons of gasoline per day. When forest residues are added, the volume of transportation fuel becomes even larger. Another incentive for using wood to produce cellulosic ethanol is that jobs are created in rural America, since that is where the wood is located. The countrys balance of payments is improved, since ethanol would replace imported oil, and the supply of ethanol is not affected by pipeline disruptions, since ethanol is not transported through pipelines.

Forest Cover in the United States

According to the Southern Forest Resource Assessment (Wear and Greis 2002), the Southern United States consists of more than 214 million acres of forest land. Approximately 13 million of these acres are classified as "reserved and other forest land," leaving 201 million acres in productive forest land. This number has remained relatively constant since the 1970s. Forest cover is depicted in green in the graphic of the United States, to the left. Timberland, defined as land capable of producing a commercial timber crop, makes up 93% of the Souths forest land. Over the past 20 years, increases in timberland, primarily from conversion of agriculture to timber, have occurred in Alabama, Arkansas, Mississippi, and Kentucky. Southern states losing timberland include Florida and Louisiana.

Change in Timberland

Forested acres for each state in 1982 and 1999 are presented in the graphic to the right.

Landowners controlling timberland in the South include a diverse group of nonindustrial private forest landowners, forest industry, government, and other public agencies. Government lands are classed as national forest and other public lands (Wear and Greis 2002). Other public lands include land administered by Native Americans, other federal agencies, state, county, and municipal agencies. Nonindustrial private forest landowners include corporations (not manufacturing wood products) and private individual owners. A recent addition to the nonindustrial forest landowner class includes timber investment management organizations (TIMOs). These organizations include banks, agribusiness, real estate investment and development firms, and insurance companies. TIMOs typicaly do not own timberland, but rather manage it for private landowners and investors. Forest industry land accounts for the most readily available source of raw material for the forest products industry.

Forest Ownership

According to the Forest Inventory Analysis (FIA) data, nonindustrial private individuals own 69% of the timberland in the South. Twenty percent of forest land is owned by forest industry. Approximately 11% is held as public timberland (at right). The public land is divided between 6% national forest and 5% other public lands. While each state differs in actual percentages, it is evident that most forest land is privately held.

Trends in the number of forest landowners indicate a 12% increase in landowners from 1978 to 1993. In 1993, there were 4.9 million forest landowners and a majority owned tracts smaller than 50 acres. Subsequently, there are more landowners owning smaller parcels of land in the South (Wear and Greis 2002).

The following sections describe the vast renewable resources that comprise the southern forest. Topics include:

• Forest Types
• Geographic Characteristics

The Forest Inventory Analysis (FIA) program of the USDA Forest Service recognizes five broad categories of forest types found in the South. Forest types are based on the species creating the majority of the live-tree stocking. Although the total acreage of timberlands has remained relatively stable, there has been a shift in forest types. The five forest types include planted pine, natural pine, mixed oak-pine, upland hardwood, and lowland hardwood.

Planted Pine

Planted Pine stands, or pine plantations, have been artificially regenerated by planting or direct seeding. These stands have at least 10% stocking and are classed as pine or other softwood forest type. Acreage in planted pine has been increasing steadily since 1950 and now stands at approximately 30 million acres (Wear and Greis 2002).

Natural Pine

Stands classed as pine or other softwood types that have not been artificially regenerated are considered Natural Pine stands. There must be at least a 10% stocking level. Natural pine stands have been decreasing steadily since 1950. These stands now account for approximately 34 million acres and continue to decrease (Wear and Greis 2002).

Mixed Oak-Pine Forest

The majority of the Mixed Oak-Pine stands consists of hardwoods, mainly upland oaks. Pines make up 25-50% of the stand stocking. Stocking will be at least 10%. Mixed oak-pine stands account for approximately 30 million acres in the Southern United States (Wear and Greis 2002).

Upland Hardwood Forest

Upland Hardwood forests are classified as oak-hickory or maple-beech-birch forest types. Stocking is at least 10%. These forests cover over 75 million acres in the South (Wear and Greis 2002).

Lowland Hardwood Forest

Forests classed as oak-gum-cypress, elm-ash-cottonwood, palm, or other tropical types are considered Lowland Hardwood forests. Again, the stocking rate is at least 10%. Approximately 30 million acres of the South are classified as lowland hardwood forests (Wear and Greis 2002).

Within the above timber types, there are approximately two million acres classified as non-stocked.

A Southern Hardwood Forest

The geography of a region can have a great impact on the regions productivity. Rocky mountains, mountain valleys, sandy shores, and dry plains all characterize areas in the Southern United States. Geographic characteristics play a role in the management decisions that are made at different sites. This section will describe three geographic characteristics affecting the management and productivity of the Southern forests. These characteristics include:

• Physiography
• Climate
• Soils

Physiography of the Southern United States

The forests of the South cover a vast range of territory ranging from the northern areas of Virginia and Kentucky to the forests of East Texas and Oklahoma. This area covers several different regions including mountains, coastal plains, and river valleys. The physiographic regions include:

• Coastal Plain
  • East Gulf Coastal Plain
  • West Gulf Coastal Plain
  • Lower Mississippi Alluvial Plain (Delta)
  • Florida Peninsula
  • Atlantic Coastal Plain
• Piedmont Province
• Blue Ridge Province
• Ridge and Valley Province
• Appalachian Plateaus
• Interior Low Plateaus
• Interior Highlands

For physiographic information on a specific state, click one of the following links: Alabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, and Virginia.

The Coastal Plain stretches from the Piney Woods of East Texas to the Atlantic shore. This area encompasses the West Gulf Coastal Plain, Lower Mississippi Alluvial Plain, East Gulf Coastal Plain, Florida Peninsula, and the Atlantic Coastal Plain (Walker and Oswald 2000).

Coastal Plain

The East Gulf Coastal Plain is characterized by terraces that run almost parallel to the Gulf of Mexico, while the West Gulf Coastal Plain includes low ridges and valleys runing parallel to the current coastline. These plains areas are home to the most productive pine forests in the South (Walker and Oswald 2000).

Interrupting these patterns are the Lower Mississippi Alluvial Plain and the Florida Peninsula. The Lower Mississippi Alluvial Plain, or Delta, runs north to south along the river and contains distinctive lowland hardwood forests. In contrast, the northern area of the Florida Peninsula rises abruptly from the sea floor. This area consists of marine terrace lowlands that are generally less than 100 feet in elevation. The central part of the peninsula, south of Tampa Bay, consists of broad plains less than 20 feet in elevation. At one time, this area was 80-85% swampland. Pines cover the higher areas of this part of the peninsula. The southern area of the peninsula consists mainly of non-forested lands (Walker and Oswald 2000).

The southern Atlantic Coastal Plain begins at the Delaware River and runs south to the Georgia coastline. This area is marked by a series of fluvial step-like and marine terraces that run parallel to the ocean. The northern area of the Atlantic Coastal Plain begins in central North Carolina and covers the northern part of the southern forest. Bays and estuaries divide the area into a series of peninsula-like extensions (Walker and Oswald 2000).

More information about the Coastal Plain can be found at the Wikipedia Free Encylopedia site.

Piedmont Province

The Piedmont Province covers an area from north of the Potomac River south to Alabama. This area consists of the eastern foothills of the Appalachian Mountains. Elevations in this province range from 300 to 1200 feet above sea level. Granite rests underneath approximately 20% of the area creating uplands and rock formations. Rolling hills, isolated rock features, and valleys dot the landscape of the Piedmont Province (Walker and Oswald 2000). More in-depth information about the Piedmont Province can be found in the Southern Appalachian Encyclopedia.

Blue Ridge Province

The Blue Ridge Mountains, a belt 5-80 miles wide, extend from the southern Appalachians in Virginia southward to Georgia. The area ranges in elevation from 1000 to 4000 feet above sea level, making it the most rugged topography east of the Rocky Mountains. The province appears as a single ridge or flanked by lesser ridges in the north, while in the south closely spaced ridges form a rugged landscape with a prominent escarpment overlooking the Piedmont Province. The rugged area has discouraged many settlers but it is home for many craving the isolation provided by the land (Walker and Oswald 2000). More information about the Blue Ridge Province can be found in the Southern Appalachian Encyclopedia.

Ridge and Valley

Lying between the Blue Ridge Mountains and the Appalachian Plateaus, the Ridge and Valley Province is an area 50-75 miles in width. Even crested ridges, separated by narrow valleys, make up this area. The rock base consists of shale, sandstone, and limestone. American chestnut forests once covered much of this area. Because of the high soil fertility, agriculture now dominates the valleys. Power and flood control projects also dot the landscape (Walker and Oswald 2000). The Ridge and Valley Province is covered in more detail in the Southern Appalachian Encyclopedia.

Appalachian Plateaus

Geological uplifts within the Southern Appalachian Mountains are referred to as the Appalachian Plateaus. Eastern boundary elevations range from 500-1000 feet above sea level. The western landscape is cut into buttes and promontories by the many streams running through the area (Walker and Oswald 2000). More in-depth information regarding the Appalachian Plateaus can be found in the Southern Appalachian Encylopedia.

Interior Low Plateaus

To the west of the Appalachian Plateaus, lie the Interior Plateaus. The plateaus form a broad upwarp running parallel to the Appalachain Mountains. Erosion has eaten up much of the original soil to create basins such as those around Nashville and Lexington. These areas are now primarily farmland (Walker and Oswald 2000).

The U. S. Geological Survey website has more information related to the Interior Low Plateaus.

Consisting of the Ozark Plateaus and the Ouachita Province, the Interior Highlands of the southern forest are located in Oklahoma and Arkansas. To the north, the Ozark Plateaus rise 2200 feet above sea level. Regional streams dissect the plateaus creating flatland prairies between the rivers (Walker and Oswald 2000).

Interior Highlands

The Arkansas River separates the Ozark Plateaus from the Ouachita Province in the southern part of the Interior Highlands. The topography of the area is similar to the Ridge and Valley Province. Elevations range from below 1000 feet to 2600 feet near the Oklahoma border in the West (Walker and Oswald 2000).

The U. S. Geological Survey website has more information related to the Interior Highlands.

Climatic Regions of the U. S.

With such a large geographic region, it is only logical that the climate of the Southern forest would vary. Yet, the majority of the Southern forest is characterized as a humid subtropical climate. This climatic region is known for abundant precipitation and high temperatures. The exceptions to this rule are the mountains in the northern regions where the climate and forests can be like that of coastal Maine (Walker and Oswald 2000). Major climate regions of the United States are shown to the right.

Average US Temperatures - 2004

The southern growing season averages 180 days or more. In southern Florida, the season is about 320 days. High temperatures over the course of the growing season provide abundant energy for growth, making the South ideal for timber production.

Average Annual US Precipitation

Average U. S. temperatures are depicted in the figure to the left. Some species in the region may have six flushes of growth, in contrast to three or fewer flushes in other suitable growing regions.

Precipitation in the South is generally consistent throughout the region and annually averages 40-60 inches. Average annual precipitation is shown in the figure to the right. The southerly mountains may receive 80 inches, while the northerly mountainous areas may receive upwards of 120 inches of precipitation. Yet, the South is not immune to "dry spells." It is during these dry times that fire, disease, and pest damage can be extremely harmful to the forest (Walker and Oswald 2000).

Soils are an important component of the forest landscape. Soils perform several different functions in the forest landscape including habitat for soil organisms, recycling systems for nutrients and organic wastes, provisions of water supply and its purification, and as a medium for plant growth (Brady and Weil 1999). Different soil types perform these functions in different ways. Some soils may be better growing mediums while others provide better organism habitat. For example, sandy soil allows water and nutrients to flow through the soil, while clay soil creates an impenetrable soil surface. Clay soil is generally not a good soil for use as an engineering medium because of its tendency to shrink and swell based on the water content of the soil. Yet, chemicals and nutrients are not held by sandy soil in plant-available form as they are by a clay soil.

Soil Development and Weathering

With that in mind, it is important to differentiate between soil types. Soils are classified into six different taxonomic categories including 1) order, 2) suborder, 3) great group, 4) subgroup, 5) family, and 6) series.

We will limit our discussion to the top level classification or soil orders. Soil orders are differentiated by the presence or absence of diagnostic horizons or features that reflect major courses of development. There are twelve different soil orders. Order names provide a characteristic of the soil and end in sols (from the Latin solum, soil). Temperature and moisture are the climatic factors that most frequently affect the soils in the area. It should be noted that since soil orders are the most general level of soil classification, variation of soil characteristics within orders is quite large and, therefore, should be used accordingly. The diagram to the right shows the typical temperature and moisture factors related to each soil order. The table below can serve as a key reference to identifying soil orders. It provides major diagnostic features for each order.

Soil Diagnostic Features

Eight of the twelve soil orders are present in the forests of the Southern United States. Orders in small amounts include Histosols, Entisols, Mollisols, and Spodosols. The prominent soil orders, listed in order of productive capacity, in the South include:

• Alfisols
• Inceptisols
• Ultisols
• Vertisols

Photographs and distribution maps of dominant soil orders can be found on the Natural Resources Conservation website and at the University of Idaho website.

Soil surveys provide soil maps and interpretations needed in giving technical assistance to natural resource managers; in guiding decisions about soil selection, use, and management; and in planning research and disseminating the results of research. The surveys also are used in educational programs about soil use and conservation. County-level soil surveys can be found at the NRCS website. Additional assistance is available from USDA Service Centers. These centers are designed to be a single location where customers can access the services provided by the Farm Service Agency, Natural Resources Conservation Service, and the Rural Development agencies. Service centers for each state are shown on the USDA website. The site will provide the address of a USDA Service Center and other Agency offices serving your area along with information on how to contact them.

The conservation of forest soils is an important component of a sustainable bioenergy and bio-based products industry in the Southern United States. A more detailed discussion of forest soils and their role in the bioenergy and bio-based products value chain is contained in Soil Values in the Environmental Sustainability section.

Alfisol Soils in the United States

Alfisols occur in the western areas of the southern forest. These soils tend to be strongly weathered, well developed, and contain a subsurface horizon in which clays have accumulated. They typically develop under under native deciduous forests. Coloring tends to run from dark brown to a light gray horizon as the soil evolves. The combination of favorable climate and high native fertility allows Alfisols to be very productive soils for both agricultural and silvicultural uses (Brady and Weil 1999).

Inceptisol Soils

Inceptisols are common in the eastern regions of Tennessee, North Carolina, Kentucky, and Virginia and occur under a wide range of ecological settings (Brady and Weil 1999). These soils are considered young and at the beginning of geological weathering and profile development, exhibiting minimal horizon development. They are often found on fairly steep slopes, young geomorphic surfaces, and on resistant parent materials. Productivity of these soils varies greatly. A sizeable percentage of Inceptisols are found in mountainous areas and are used for forestry, recreation, and watershed.

Ultisol Soils

Ultisols are the dominant soil type found in the southern forest. The "red clay" soils of the southeastern United States are examples of Ultisols. These soils are generally formed under forest canopy, explaining why they are the dominant forest soil in the south. Iron and aluminum are constantly being leached from the soil surface into the subsoil below often resulting in the lighter coloring at the soil surface and the strong yellowish or reddish colors at the lower horizons. Subsoils also tend to be stiffer due to the downward movement of iron in the soil (Walker and Oswald 2000). Ultisols are acidic in nature and quite productive under good management (Brady and Weil 1999). However, high acidity and relative low availability of calcium, magnesium, and potassium render these soils poorly suited for continuous agriculture without the use of fertilizer and lime.

Vertisol Soils

Vertisols are most commonly found in eastern Mississippi, western Alabama, and southeast, south, and central Texas. These are clay soils characterized by shrinking and swelling as moisture content varies. The clay content is generally present at 1 meter or more (Brady and Weil 1999). These soils are generally sticky during the wet season and hard in the dry season, so they require special management practices regardless of the type of equipment used. Shrink-swell processes in Vertisols are related to the total clay content, the content of fine clay, and mineralogy. They generally have high clay content (50-70%), with a relatively large proportion in the fine clay fraction.

Bioenergy products from southern forests are among a large number of goods and services that can be produced using sustainable forest management practices. Bioenergy products have historically come from woody materials that have not been economically usable for the manufacture of lumber, pulp, paper, and other timber products. Most of the bioenergy products are expected to come from residues harvested after cutting for stand regeneration and from trees cut during stand improvement, but with low market values for other purposes. Mill residues, which are currently widely used by the industry for energy, are not discussed here as they do not directly impact forest management.

This section of The Encylopedia of Southern Bioenergy synthesizes knowledge on the management of forest stands to provide biomass that can be used for bioenergy or bio-based products. In some management circumstances, bioenergy will be the only material harvested from the forest stand, but more typically, bioenergy will be an additional product produced during the traditional harvesting of timber or pulpwood. The emphasis is on how, when, and where bioenergy production can be integrated into silviculture, while ensuring the long-term sustainability of the forest ecosystem. An example of an integrated approach is given at Integrating Bioenergy Harvesting with Silviculture - A California Example.

Silviculture is the science and art of managing forest stands and woodlands for the desired needs and values of landowners and society on a sustainable basis (Helms 1998). These goals or objectives can include the production of timber products (of which biomass for bioenergy is one of several possibilities), soil and water conservation, amenity values, recreation, hunting and fishing, agroforestry or range, nature preservation, biodiversity, and providing lifestyle attributes. Often forest owners have multiple goals. Although alternative forest products are important to industrial forest owners, the primary focus is on the sustainable production of saleable timber and a financial return on their investments. In many national forests and often with non-industrial private forest (NIPF) owners, the main objectives are the production of a variety of forest resources, of which timber products may be a component. Clearly it is important to define the goals of management in order to develop silvicultural plans compatible with these goals. Nevertheless, even where the goal is not for industrial products, providing biomass for bioenergy can often assist the owner in achieving the major objectives, provided this can be done within economic and other constraints.

Because of their long-lived nature, forests should be managed through carefully written plans. Most national and industrial forests have such plans that detail management objectives, the characteristics of the forest, the flow of products from the forest, monitoring systems, etc. Forest management is described in detail elsewhere (Young and Giese 2002; Davis and others 2001). However, since many small NIPF owners often do not have management plans, a section on goal setting and management planning for their particular circumstances, including how to incorporate bioenergy production can be found in Forest Management Issues for Bioenergy Production by NIPFs.

The optimum silvicultural system for a particular situation is the integration of the owners objectives, the forest type and its current state, site characteristics, ecosystem processes, market opportunities, infrastructure, and other resource opportunities. In addition, economics, environmental sustainability, and social issues must also be considered. Most of these variables are discussed in this module although some, such as economics, social, and sustainability issues, are covered in more depth elsewhere.

The potential for the production of bioenergy from Southern forests is currently constrained by the lack of developed markets in many areas of the South. Biomass for bioenergy is a low value product compared to sawlogs, but given improvements in the relative economics could compete with pulpwood and other low value products. Unlike pulpwood, the inclusion of crown material and bark, which are generally left as harvest residue, is generally not a hindrance to its use as an energy source. Apart from short rotation crops grown primarily for energy, most of the bioenergy potential is from residues or currently unutilized biomass. The following main stand condition classes can be distinguished in relation to bioenergy potential:

• Naturally managed hardwood or softwood forests with high valued timber where harvesting residues and and low-value trees are possible sources of bioenergy.
• Stands where biomass harvesting can assist other goals such as timber stand improvement, reduction of hazard and risk from fire, insects, or disease, improving amenity, or wildlife habitat.
• Degraded, low-value forests that could be utilized for bioenergy as part of the process of improving the stands or replacing them with plantations.
• Industrial plantations grown for timber or fiber and where harvesting residues and thinned trees, currently left in the woods to rot, are utilized for bioenergy.
• Short-rotation hardwoods or combinations of trees with other bioenergy-specific crops that are grown primarily as a source of energy.

Despite the largely secondary nature of biomass for bioenergy it can be integrated into silviculture and harvesting practices to obtain overall benefits to the forest owner and wider community. However, in doing so it is important to ensure sustainability and that other forest values are not compromised. More in-depth discussion of the production of biomass for bioenergy can be found at:

• Favorable Stand Attributes for Bioenergy Production
• Forest Management and Silviculture for Bioenergy Production

Not all forest stands will have biomass readily available in sufficient quantity for immediate utilization. An undocumented but widely used rule of thumb is that at least 6-7 dry tons per acre are required. Furthermore, topography and other physical factors are likely to constrain the economic utilization of forest biomass. Despite this, many forest stands can be potential sources of biomass for bioenergy at some point in the management cycle and its integration into silviculture can assist in meeting management goals.

Several major sources of residue-biomass are available from forests. Logging residues, thinned trees, under-utilized tree species, and other stand improvement measures are the major sources likely to be available from forests (see Biomass Harvesting). Catastrophic events such as hurricanes, fires, or major insect outbreaks also can result in sources of biomass. Short-rotation tree bioenergy crops could also be grown by landowners. Municipal wastes and secondary residues from forest industries and manufacturers will not directly influence forest management and are not included in this discussion.

Site attributues in terms of land-use, forest type, species composition, historical management, and site characteristics have a direct bearing on the potential for forest bioenergy production. In general:

• Logging residues usually come from clearcutting stands on relatively flat topography, with easy access to roads that are suitable for large chip vans. The maximum slope for tracked machines is about 40% and for rubber-tired machines is about 20%. Soil factors may also influence harvesting operations and on very wet or infertile