Culturally and Economically Important Nontimber Forest Products of Northern Maine

Welcome! 

For many people, a walk in the woods means more than fresh air. It is a chance to gather wild plants and mushrooms that can be used as food, medicine, crafts, and other uses. Plants and mushrooms that have such cultural and economic significance are called nontimber forest products. This website will introduce you to the cultural and ecological landscape of northern Maine and its Canadian neighbors through the nontimber forest products that grow there and the people who gather and depend on them. During a two-year study of plants and people in the St. John River Watershed, we spent time talking with gatherers and land managers and learning about the plants that are important to them. We hope you'll enjoy learning about this corner of the country, and please be in touch! 

We gratefully acknowledge the Northeastern States Research Cooperative's support in funding this project. Read about this project's contributors.

People, Plants and Gathering

• PROFILES OF GATHERERS in northern Maine


• PROFILES OF PLANTS that people use for food, medicine, and crafts


• LIST of plants and their uses 


• ROOTED DEEPLY, GROWING STRONG? Gathering in Northern Maine

Resources and Connections

• CURRICULUM resources for educators


• LINKS to websites about northern Maine, plants and plant uses, and natural resource conservation


• CONTACT US with stories, questions, or comments

Last Modified: 12/13/2010

For further information log on :
http://www.nrs.fs.fed.us/sustaining_forests/conserve_enhance/special_products/maine_ntfp/

Understanding family forest landowners’ interest in participating in carbon offset markets

Research Issue

Forests have the potential to be one of the largest-volume and lowest-cost means of sequestering carbon. Additional stored carbon can be quantified and sold in the market place as carbon credits to offset carbon emissions made elsewhere. The nation's family forest lands have the potential to be an important contributor to carbon sequestration efforts, but only if their owners are willing to manage for carbon and participate in markets that trade carbon credits. Yet little is known about how family forest landowners view programs that enable them to sell carbon credits generated from the growth of their forest, whether they would be interested in managing their lands to sequester additional carbon, or the compensation that would be required to encourage a meaningful level of participation. In the absence of this information, it is difficult to know how large of a role family forests may play in the carbon sequestration arena. 

Our Research

We conducted a study to identify and quantify family forest landowner interest in the Lake States in participating in a voluntary carbon market trading program. A mail survey was administered to 2,200 randomly selected family forest owners in Michigan, Wisconsin, and Minnesota. The questionnaire assessed landowner interest in participating in a hypothetical carbon credit trading program and sought information on landowner objectives and practices, their attitudes towards carbon credit programs, and characteristics about themselves and their forest land. From the survey data, a statistical model was developed to examine the factors affecting participation in a forest carbon offset project by family forest owners and estimate landowner participation probability. We also conducted six follow-up focus groups with a subset of the survey respondents to further probe some of the survey responses and to gain greater insight and clarity into family forest landowner attitudes towards forest carbon management and trading.  Focus group participants were purposefully selected to represent a cross-section of the earlier survey respondents, including landowners located across the three states and with a range of forest acreage, ownership objectives, management behaviors, and willingness to sell carbon credits.

Expected Outcomes

Results of our analysis suggest that Lake States family forest owners are very unfamiliar with forest carbon credits and markets, yet curious.  Our analysis found that, in general, landowners are more likely to be interested in selling carbon credits when payment amounts are higher and required contract lengths are shorter, which may be at odds with the need for longer participation to ensure the quality of carbon offsets.  Our modeling results suggest that a payment of approximately $18/acre/year would be required to generate a 50% participation rate among eligible Lake States family forest landowners.  This payment amount is higher than currently being offered for carbon credits through voluntary markets.  However, our model suggests that some portion of landowners would be interested in selling carbon credits within the range of payments currently offered, and further that a portion of owners might be willing to sell credits or manage for carbon without receiving any carbon credit compensation.  Our analysis suggests that landowners who require little or no payment for carbon management may place a high value on the co-benefits that can accrue from carbon sequestration efforts (e.g., improved water and soil quality, wildlife habitat, and aesthetic values) and believe that climate change is a problem of environmental concern that forests can help address.  These landowners may be more interested in simply managing for carbon sequestration rather than meeting the host of conditions required for formally selling carbon credits. More research is needed to identify and understand this segment of family forest landowners as they may hold the greatest potential among family forest landowners for contributing to forest carbon sequestration efforts.

Focus group findings underscored our survey results that family forest landowners generally prefer higher carbon credit payments and shorter contract lengths than those currently offered.  However, our focus group discussions uncovered additional factors that may influence a landowner’s interest in participating in a carbon offset project.  Specifically, some landowners expressed a willingness to participate for little to no compensation if a carbon offset program provided them with forestry assistance that helped them achieve other ownership goals.  We also found that landowners appear to be most interested in the personal benefits they can attain through carbon management (e.g., improved wildlife habitat) rather than the less tangible societal benefits (e.g., the role of their forests in contributing to global carbon levels).  Further, we found that landowners who either felt their land was in a poor condition or not meeting their desired forest ownership objectives were more receptive to the idea of participating in a forest carbon market program. In essence, many viewed carbon market participation as a vehicle by which other personal forest ownership goals could be achieved.  Finally, our research revealed that some landowners would be more amenable to participating in a carbon storage program structured as a property tax relief program as opposed to a carbon market trading program.  The feasibility of such an approach to enhance forest carbon storage would need to be explored.  Finally, additional research is needed to increase our understanding of how or whether participation in existing forest landowner assistance programs like the Forest Stewardship Program could allow landowners to meet carbon co-benefit land management goals.

Research Results

Miller, Kristell A.; Snyder, Stephanie A.; Kilgore, Michael A. 2015. State forestry agency perspectives on carbon management and carbon market assistance to family forest owners. Journal of Forestry. 113(4): 372-380. 

Miller, Kristell A., Snyder, Stephanie A., Kilgore, Michael A., Davenport, Mae A. 2014. Family forest landowners’ interest in forest carbon offset programs: Focus group findings from the Lake States, USA. Environmental Management, 54(6): 1399-1411.

Miller, Kristell A.; Snyder, Stephanie A.; Kilgore, Michael A. 2012. An assessment of forest landowner interest in selling forest carbon credits in the Lake States, USA.  Forest Policy and Economics. 25: 113-122.  

Research Participants

• Kristell A. Miller, Department of Forest Resources, University of Minnesota 
• Stephanie A. Snyder, Operations Research Analyst, US Forest Service, Northern Research Station
• Michael A. Kilgore, Department of Forest Resources, University of Minnesota
• Mae A. Davenport, Department of Forest Resources, University of Minnesota

For further information log on website :
http://www.nrs.fs.fed.us/sustaining_forests/conserve_enhance/special_products/carbon_offset/

Conserve and Enhance Special Forest Products

Non-timber or special forest products (SFP) are a relatively unknown aspect of forest management. Many SFP, such as various berries, mushrooms, ramps (wild onions), fern fiddleheads, and ginseng, are derived from the herbaceous component of forest understories. Other SFPs come from other parts of various tree species—such as birch (bark for basketry), maple (sap for syrup making), fir (boughs for Christmas decorations), and witch hazel (twigs for medicinal/cosmetic purposes). Even less information exists on the people who gather SFP, the methods they use, their reasons for gathering, and the actual uses of products. Although most Forest Service SFP research is concentrated in the Pacific Northwest and is largely biological in its focus, the NRS has been doing research on SFPs in the Northeast and Midwest and on the extensive informal ecological knowledge possessed by gatherers in these areas.

Research Studies

Understanding family forest landowners’ interest in participating in carbon offset markets
The nation's family forest lands have the potential to be an important contributor to carbon sequestration efforts, but only if their owners are willing to manager for carbon and participate in markets that trade carbon credits. Yet little is known about how family forest landowners view programs that enable them to sell carbon credits generated from the growth of their forest, whether they would be interested in managing their lands to sequester additional carbon, or the compensation that would be required to encourage a meaningful level of participation.  

 

Culturally and Economically Important Nontimber Forest Products of Northern Maine
This website will introduce you to the cultural and ecological landscape of northern Maine and its Canadian neighbors through the nontimber forest products that grow there and the people who gather and depend on them. During a two-year study of plants and people in the St. John River Watershed, we spent time talking with gatherers and land managers and learning about the plants that are important to them. 

 

Gathering of Nontimber Forest Products in Scotland
An estimated one-quarter of Scotland’s population collects nontimber forest products such as mushrooms and other edibles, medicinal plants, and craft items. We are studying the social, cultural, economic and environmental characteristics of nontimber forest products (NTFP) gatherers, their practices, and their perceptions.

 

Morel Mushroom Gathering at Two National Park Sites
This study focused on morel mushroom harvesting at two National Park sites near Washington, D.C.: Catoctin Mountain Park and the Chesapeake and Ohio Canal National Historical Park. We conducted interviews and collected oral histories from 41 harvesters with two main goals in mind: (1) explore and use local ecological knowledge to understand morels and morel harvesting in the mid-Atlantic region, and (2) develop practical suggestions for morel management.

 

Forest Certification and Global Competitiveness  
Our research focuses on understanding the unique characteristics of the Appalachian hardwood industry and how these characteristics affect landowners’ and producers’ decisions to pursue certification.  This knowledge will give certifying bodies much needed information on the unique dynamics of the hardwood industry. It also will give members of the hardwood industry information on current certification trends. This knowledge is necessary to enhance industry competitiveness and market opportunities for both the landowner and producer.

 

Biofuels, Bioenergy, and Bioproducts from Short Rotation Woody Crops  
We are testing the genetics, physiology, and silviculture of poplar crops. Specific areas of interest include quantitative genetic analyses of biomass, rooting, and other important traits from hundreds of genotypes grown throughout the North Central United States, as well as analyses of tree growth regulating mechanisms in the face of varying environments and changing climate. Our silviculture research includes a range of studies from vegetation management to yield trials.

 

Impacts of Disturbances and Climate on Carbon Sequestration and Biofuels 
Currently, U.S. forests and forest products offset about 20% of the nation’s fossil fuel emissions. However, recent findings cast doubt on the sustainability of this offset. First, the strength of the U.S. forest carbon offset may be weakening due to forest ageing, climate variability, and increasing natural disturbances. Second, climate change is expected to further increase frequencies of insect outbreaks and wildfire, and alter species composition in forest ecosystems, consequently influencing forest carbon pools in a significant way.  These current and projected forest carbon cycle dynamics need to be considered in strategic forest planning and management decisions in coming decades if the nation’s forests are to provide stable or even increasing ecosystem services.

 

Comprehensive Database of North American Poplar Research Published from 1989 to 2011
In addition to compiling the information into one interactive location, our objectives are to encourage publication in peer-reviewed journals and to enhance collaborations with partners outside the poplar community. The constraints of the database include: only peer-reviewed manuscripts that are focused on poplars, cottonwoods, aspens, and their hybrids grown as short rotation woody crops, research conducted in North America, and at least one topic area.

For further information log on website :
http://www.nrs.fs.fed.us/sustaining_forests/conserve_enhance/special_products/

Conserve and Enhance Forest Resources

Harvesting timber and manufacturing lumber products are important to the economies of many rural communities in the Northeast and Midwest. Although the NRS region's forests account for only 11% of the nation's forest lands, they contain 20% of the nation's forest industry lands and hardwood growing stock. Other non-timber forest products and wildlife and fish are also important, though in a smaller scale, to these communities. Many wildland recreational activities such as hunting and fishing, vacationing, nature tourism, and viewing wildlife and fall leaf color bring millions of visitors to many upstate mountains and woodlands. Maintaining healthy forests means that we must sustain forests in all their varied types, age classes, and ecosystem classifications. Lastly, tree plantations (aka tree farming of quick growing trees) for biomass production could help to reduce our dependency of fossil fuels.

• Timber productivity and wood quality
• Special forest products
• Wildlife and fish
• Biodiversity and structural and functional complexity of forests
• Recreation, experience of natural places
• Feedstocks for bioenergy  

Last Modified: 10/01/2006

For further information log on website :
http://www.nrs.fs.fed.us/sustaining_forests/conserve_enhance/

Sustaining Forests

Our forests provide human society with many useful and important products and services, with the added benefit that these products and services are renewable if the resource is managed carefully. These include the obvious products made from timber (from lumber, particleboard, and millwork to paper, to woodchips for biofuel) and specialty products such as mushrooms, birch bark, and ginseng; and wildlands for recreational activities such as hiking, fishing, hunting, kayaking, photography, etc. In addition, there are less-obvious benefits such as clean water for towns and cities; open space; and habitat for animals from bears, deer, and bobcats to salamanders, butterflies, and trout. However, maintaining sustainability requires knowledge of how forest ecosystems work and how changing climate and human influences are affecting them. Studies by NRS scientists help us gain that knowledge. 

Science Topics

• Methods to conserve and enhance forest resources
  • Timber productivity and wood quality
  • Special forest products
  • Wildlife and fish
  • Biodiversity and structural and functional complexity of forests
  • Recreation, experience of natural places
  • Feedstocks for bioenergy
• Forest resource monitoring and assessment
• Globalization impacts 
• Science to support the National Fire and Fuels Strategy
• Understanding the ecological roles of natural disturbance 

Sustaining Forests e-Learning Webcast

The Northern Research Station recently launched the NRS Sustainable Forests Webcast Series, which presents monthly webinars on a variety of forest management and research initiatives.

What we know about northern white-cedar and why you should care: May 20, 2010, 11:00 AM (Eastern)

Dr. Laura S. Kenefic, Principal Silviculturist
Center for Research on Ecosystem Change
Northern Research Station
USDA Forest Service

More information and/or watch the archived webcast.

For further information log on website :
http://www.nrs.fs.fed.us/sustaining_forests/

A breeding index for improving the early growth of sugarcane

Author T. TERAUCHI, M. MATSUOKA, H. NAKAGAWA and H. NAKANO Key Words dry matter, early growth, net assimilation rate, specific leaf area, sugarcane ［Objectives］    Sugarcane (Saccharum sp.) yield remains low compared to its photosynthetic ability. The slow growth of sugarcane at the early stages is one of the primary reasons for this low productivity. A high percentage of sunlight is lost to the soil at this stage. In order to increase sunlight absorption, the rapid expansion of leaf area in sugarcane is considered highly necessary. The delayed expansion of leaf area is attributed to the slow growth of individual plants as well as low density planting in sugarcane crops. Analysis of sugarcane growth at the early stage should be conducted with regard to plant growth as well as crop growth. [Results]   The growth of sorghum (Sorghum bicolor) was compared to sugarcane during the early growth stages. The dry weight of the sorghum was five times greater 48 days after emergence (Fig. 1), and it was concluded that a higher increasing rate of leaf area enabled rapid growth in the sorghum. The net assimilation rate (NAR) implies the same photosynthetic ability in both species. The higher dry matter percentage of leaves suggests that dry matter partitioning to leaves is higher in sugarcane. Specific leaf area (SLA) is approximately double in sorghum. As relative growth rate correlates to SLA (Fig. 2), the smaller SLA is one of the main reasons for the slow growth of sugarcane at the early stage. Genetic diversity of SLA is observed as an aspect of sugarcane genetic resources (Fig. 3). Some native clones including S. sinense are considered suitable for the breeding of varieties having greater SLA values. Even when compared to one of the rapid-growing commercial varieties, a native variety "Oshima" with greater SLA shows more rapid leaf area expansion and growth (Fig. 4). SLA can be employed as an index for improving the early growth of sugarcane. Fig. 1. Comparison of dry weight, specific leaf area (SLA) and net assimilation rate (NAR) between sugarcane and sorghum 48 days after emergence. Fig. 2. Relationship between SLA and relative growth rate (RGR). Fig. 3. SLA variation among sugarcane genetic resources. Fig. 4. Comparison of dry weight, leaf area and SLA among sugarcane varieties 84 days after emergence. ［References］ T. Terauchi and M. Matsuoka (2001)：Analysis of the slow growth of sugarcane at the early stage. Proceedings of the International Society of Sugar Cane Technologists, 24,149-151.

For further information log on website :
http://www.jircas.affrc.go.jp/kankoubutsu/highlight/highlights2001/2001_20.html

The function of tomato mitochondrial small heat shock protein under heat stress conditions

Author

M. SHONO and J. LIU

Key Words

MT-sHSP, tomato (Lycopersicon esculentum Mill.), molecular chaperone

［Objectives］

   Heat stress is one of the most significant constraints on crop production. Under heat stress, synthesis of most proteins is repressed and some proteins, which are called heat shock proteins (HSPs), begin to be synthesized. Accumulation of sHSP in mitochondria (MT-sHSP) under heat stress has recently been reported in a number of plant species, but little is known about the cellular functions of MT-sHSP in the heat tolerance of plants.

   The aim of this study was to clone MT-sHSP cDNA from tomato (Lycopersicon esculentum Mill.) leaves, evaluate the transcription of the MT-sHSP gene at various temperatures, and assay the molecular chaperone activity of MT-sHSP in vitro.

[Results]

   A full-length cDNA (LeHSP23.8: accession number AB017134) encoding the precursor of the MT-sHSP in tomato was successfully cloned. The deduced protein precursor, had a calculated molecular weight of 23.8 kDa.

   A single copy of LeHSP23.8 was found in tomato genomic DNA through Southern-blot analysis.

   Northern blot analysis revealed the heat-inducible character of LeHSP23.8 mRNA. The threshold temperature was approximately 36 , and it was accumulated abundantly at 40 in tomato leaves (Fig. 1). Among the MT-, ER-, Class I and Class II-sHSP genes, MT-sHSP mRNA responded most quickly at 40°C in tomato flowers (Fig. 2).

   The molecular chaperone function of LeHSP23.8 was demonstrated in vitro. When the recombinant LeHSP23.8 was mixed with CS denatured by guanidine hydrochloride, 40% of the native CS activity was recovered after one hour of incubation (Fig. 3A). In another experiment, recombinant LeHSP23.8 protected CS from thermal inactivation and also promoted the renaturation of thermally inactivated CS. The loss of CS activity was relatively slow when CS was incubated with recombinant LeHSP23.8 at 38 . Furthermore, when the incubation temperature was shifted to 22 , rapid renaturation of thermal-denatured CS was observed within 10 minutes, and 90% of CS activity was recovered (Fig. 3B).

Fig. 1. Northern-blot analysis of temperature-dependent LeHSP23.8 mRNA accumulation in tomato leaves. Tomato plants were grown in greenhouse conditions at 25 and treated at 28 , 32 , 36 or 40 for two hours.

Fig. 2. Northern-blot analysis of heat-induction time course for sHSP genes in tomato flowers. Tomato plants grown under greenhouse conditions were transferred to the growth chamber on the day of flowering, and then incubated at 25 or 40 . The flowers were collected 0 min to 48 hours after the incubation. Panels MT, ER, Class I and Class II show the expression of the genes for MT-, ER-, Class I- and Class II-sHSP, respectively.

Fig. 3. (A) Effects of LeHSP23.8 protein on the renaturation of chemically denatured citrate synthase (CS). CS (15μM) was denatured in 6 M guanidine hydrochloride for 120 minutes and then diluted 100-fold into a solution supplemented with 150 nM lysozyme (  ) or with 1.8 μm recombinant LeHSP23.8 (  ). (B) Effects of recombinant LeHSP23.8 on the thermal inactivation of CS. CS (150 nM) was incubated in the presence of 150 nM lysozyme (  ) or 1.8 μm recombinant LeHSP23.8 (  ) at 38 for 60 minutes and then at 22 .

［References］

• J. Liu and M. Shono (1999)：Characterization of mitochondria-located small heat shock protein from tomato (Lycopersicon esculentum). Plant and Cell Physiology, 40, 1297-1304.

For further information log on website :
http://www.jircas.affrc.go.jp/kankoubutsu/highlight/highlights2001/2001_19.html

Community managed forests and forest protected areas: An assessment of their conservation effectiveness across the tropics

Published Date
15 March 2012, Vol.268:6–17, doi:10.1016/j.foreco.2011.05.034
Multiple Use of Tropical Forests: From Concept to Reality

Author 

Luciana Porter-Bolland ^a,,

Edward A. Ellis ^b

Manuel R. Guariguata ^c

Isabel Ruiz-Mallén ^d

Simoneta Negrete-Yankelevich ^a

Victoria Reyes-García ^e

• aInstituto de Ecología, A.C., Veracruz, Mexico
• bCentro de Investigaciones Tropicales, Universidad Veracruzana, Veracruz, Mexico
• cCenter for International Forestry Research (CIFOR), Bogor, Indonesia
• dInstitut de Ciència i Tecnologia Ambientals, Universitat Autònoma de Barcelona, Spain
• eICREA and Institut de Ciència i Tecnologia Ambientals, Universitat Autònoma de Barcelona, Spain

Available online 20 June 2011.

Abstract

This paper assesses the role of protected and community managed forests for the long term maintenance of forest cover in the tropics. Through a meta-analysis of published case-studies, we compare land use/cover change data for these two broad types of forest management and assess their performance in maintaining forest cover. Case studies included 40 protected areas and 33 community managed forests from the peer reviewed literature. A statistical comparison of annual deforestation rates and a Qualitative Comparative Analysis were conducted. We found that as a whole, community managed forests presented lower and less variable annual deforestation rates than protected forests. We consider that a more resilient and robust forest conservation strategy should encompass a regional vision with different land use types in which social and economic needs of local inhabitants, as well as tenure rights and local capacities, are recognized. Further research for understanding institutional arrangements that derive from local governance in favor of tropical forest conservation is recommended.

Highlights

► Forest loss in protected (PA) and community managed forests (CMF) was compared by meta-analysis. ► Deforestation rates and driving factors of 40 Pantropical PAs and 33 CFMs were analyzed with QCA. ► Mean annual rates of forest loss in PAs was greater and more variant than in CMF. ► PAs are successful at conserving forest in isolated areas with little demographic pressure. ► Governance and legitimacy are suggested as key factors for conservation success in CFMs.

Keywords

Land use/cover change

Tropical deforestation

Meta-analysis

Qualitative Comparative Analysis

Community managed forests

Protected areas

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  Corresponding author. Present address: Carretera Antigua a Coatepec #351, El Haya, Coatepec, Veracruz 91070, Mexico. Tel.: +52 228 8421800x4317.

For further details log on website :
http://www.sciencedirect.com/science/article/pii/S0378112711003215

Integration of the first and second generation bioethanol processes and the importance of by-products

Published Date
August 2014, Vol.165:3–8, doi:10.1016/j.biortech.2014.01.127
Special Issue: CESE 2013 & Special Issue: ICABB 2013
Open Access, Creative Commons license

Author 

• Patrik R. Lennartsson ^a
• Per Erlandsson ^b
• Mohammad J. Taherzadeh ^a,,

• aSwedish Centre for Resource Recovery, University of Borås, SE 501 90 Borås, Sweden
• bLantmännen Energi, S:t Göransgatan 160A, Stockholm, Sweden

Received 14 December 2013. Revised 28 January 2014. Accepted 30 January 2014. Available online 8 February 2014. 

Highlights

• Investment in 2nd generation ethanol plants is expensive and high risk.
• •
  The 2nd generation ethanol can be integrated into 1st generation plants using fungi.
• •
  Animal feed is an important byproduct not be challenged in this integration.
• •
  There are ascomycetes and zygomycetes suitable for this purpose.

Abstract

Lignocellulosic ethanol has obstacles in the investment costs and uncertainties in the process. One solution is to integrate it with the running dry mills of ethanol from grains. However, the economy of these mills, which dominate the world market, are dependent on their by-products DDGS (Distiller’s Dried Grains and Solubles), sold as animal feed. The quality of DDGS therefore must not be negatively influenced by the integration. This puts restraints on the choice of pretreatment of lignocelluloses and utilizing the pentose sugars by food-grade microorganisms. The proposed solution is to use food related filamentous Zygomycetes and Ascomycetes fungi, and to produce fungal biomass as a high-grade animal feed from the residues after the distillation (stillage). This also has the potential to improve the first generation process by increasing the amount of the thin stillage directly sent back into the process, and by decreasing the evaporator based problems.

Graphical abstract

Keywords

• Bioethanol
• DDGS
• Filamentous fungi
• Integration
• Lignocellulose

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1 Introduction

From a human perspective, the world is dependent on fossil fuels for its primary energy supply. In 2010, we consumed 12.7 billion tons of oil equivalents (IEA, 2012) globally, including 32.4% oil, 27.3% coal and peat, and 21.4% natural gas, while biofuels and waste contributed with 10.0%. Amongst the oil consumers, the transport sector completely dominated with 61.5% of the total consumption. Consequently, renewable alternatives for the transportation fuel should be seriously considered, if the fossil fuels are to be replaced.

During the last decade(s), concerns regarding global warming, fossil fuel depletion, and energy security resulted in a wide interest in renewable and environmentally friendly fuels. The dominating biofuel for transportation is ethanol with the annual world production rising from 17.0 to 86.1 × 10⁶ m³ from 2000 to 2011 (REN21, 2012). It is followed by biodiesel with an annual world production of 21.4 × 10⁶ m³ in 2011. The largest ethanol producing countries are USA and Brazil, responsible for the production of 54 × 10⁶ and 21 × 10⁶ m³ in 2011, respectively (REN21, 2012). Currently, all industrial scale production of ethanol belongs to the first generation of biofuels. However, the technology to produce second generation ethanol does exist. One of the main obstacles for its implementation is the combination of high risk investments (including technological risks and political/policy risks) with low potential returns.

The aim of the present paper is to present an alternative to the direct implementation of an industrial scale second generation bioethanol process with the integration of the second generation into the existing first generation bioethanol processes, which aims to reduce the current barriers to process change/investments. The challenge of a pentose-rich substrate is also taken into account.

2 Bioethanol production

2.1 First generation bioethanol

The first generation ethanol plants utilize either sugars or starch. The sugar-based ethanol plants are predominantly produced in Brazil from sugarcanes. The starch-based ethanol is generally from corn but also from grains, and is dominated by the US followed by other major ethanol producing countries such as China, Canada, France, Germany, and Sweden. In the global market, ca. 21 million m³ ethanol is produced from sugarcane, while ca. 60 million m³ ethanol is produced from corn and grains (REN21, 2012). The starch-based process will be in focus here. There are more than 200 such plants in the US with an average capacity of about 260,000 m³/year ethanol producing from corn or sorghum (www.ethanolproducer.com).

The first step of the ethanol production from grains (Fig. 1) in the process called dry mills is the milling of the substrate and subsequent liquefaction of the starch. The liquefaction is followed by the hydrolysis or saccharification, which releases the sugar (glucose) monomers into the solution. During the subsequent, or simultaneous fermentation with yeast (Saccharomyces cerevisiae), the sugar monomers are converted into ethanol and carbon dioxide. Usually an ethanol concentration of ca. 10% (w/v) is obtained at the end of the fermentation. The fermentation liquid, or beer, is distilled to separate and purify the ethanol, which is then dehydrated to concentrations above 99.7% for fuel applications, according to the European standard EN 15376 (SIS, 2011). In the bottom of the distillation column, the stillage consisting of about 10% TS (total solids), including residual substrate, yeast, and fermentation by-products, is accumulated. Some of the solid particles are removed from the liquid via centrifugation by a decanter and the remaining thin stillage is sent to an evaporator. The centrifugation cake and the resulting syrup from the evaporation are normally mixed to produce Distillers Dried Grains and Solubles (DDGS). The DDGS, which is principally a protein source as animal feed, plays a crucial role in the overall process economy. More detailed descriptions can be found in the literature, e.g., a recent book chapter by Taherzadeh et al. (2013).

Fig. 1. Process outline for a first generation ethanol process (top) and second generation ethanol process (bottom).

Considering the vast amount of accumulated knowledge gathered from decades of industrial production of the first generation ethanol process, there are very few uncertainties involved in the process, raw materials, and the markets. Thus, even if the process only provides a low rate of return, it comes with relatively low risk, which is mainly based on uncertainties regarding the cost of the feedstock and the price of the products: ethanol and animal feed (DDGS). However, the use of potential human food as feedstock for the process has led to considerable ethical discussions, normally referred to as the “food vs. fuel” debate, with widely diverse and strongly polarized views. The supply of the feedstock can also become a potential limiting factor compared with the potential demand. It is a complex issue that is discussed in its own forum, e.g., cf. Kaye-Blake (2010). This debate also results in propositions for new laws and regulations to push the ethanol plants to direct their expansion away from food-based feedstock, which causes some uncertainties regarding future plans.

2.2 Second generation bioethanol

Second generation ethanol utilizes different types of lignocellulosic materials as substrate. Currently, only negligible amounts of second generation bioethanol are produced in several demo plants around the world that work industrially, but are not yet commercially feasible. At the moment, Borregaard company located in Norway declares to be the largest producer of second generation ethanol with an annual production of 20,000 m³ (Rødsrud et al., 2012). The ethanol is produced from the sugar monomers released as a by-product during their sulfite process. Historically, more ethanol however has been produced from lignocellulosic feedstock. As an example, during the 1940s more than 30 sulfite mills were in operation in Sweden, all of which included ethanol production (Eklöf et al., 2012), and by the end of the 1980s Soviet sulfite mills had a production capacity of up to 190,000 m³/year (Rabinovich, 2010). Overall, the second generation bioethanol process will most likely be partly similar to the first generation process and current/past processes based on by-products from sulfite mills.

Second generation ethanol processes have technically no issues with feedstock supply, as 7–18 billion tons/year of lignocellulosic biomass is available for human exploitation (Lin and Tanaka, 2006). Instead, the process is currently limited by technical and by economic challenges (the cost of lignocellulosic feedstock, including its transportation, often compete unfavorably with the efficient supply chain of sugar or starch containing raw materials), which although connected can be divided into three groups (Cheng and Timilsina, 2011). The first technical challenge is caused by the recalcitrance of the biomass and thus the need for relatively harsh pretreatments of the feedstock. This harsh pretreatment, in turn, results in the formation of inhibitory compounds, which causes problems during the fermentation. Numerous reviews can be found on the topic, e.g., by Taherzadeh and Karimi (2008). The second challenge is in the production of efficient enzymes to hydrolyze the cellulose, at a cost competitive to the first generation enzymes hydrolyzing starch. Although major improvements have been accomplished by the enzyme manufacturers, reducing the cost of the enzyme to 0.13 USD/L ethanol (Geddes et al., 2011), improvements are still necessary. Thirdly, sufficiently high ethanol concentrations in the beer have to be reached in order to reduce the cost of distillation and wastewater treatment. A goal of 4–4.5% (w/v) is generally considered. This might appear to be a minor issue, but reaching it requires substrate loadings above 15% (Viikari et al., 2012) with subsequent mixing and inhibitor problems.

A number of lignocellulosic materials also release high amounts of pentose sugars during hydrolysis. Corn stover, wheat straw, and switch grass are examples of lignocellulosic materials with xylan contents above 20% on a dry weight basis; more than half of the glucan content in the corresponding materials (Mosier et al., 2005). Since the microorganism of choice, S. cerevisiae, is unable to utilize pentoses, this can become an issue. A plethora of examples of genetic manipulation to overcome this issue exists in the literature (Madhavan et al., 2012). However, although the results are promising, improvements are still necessary. Furthermore, legal issues and consumer opinions regarding the use of genetically modified organisms, especially in Europe, are often overlooked.

3 Process integration

A possible solution to use all the current dry mills for the second generation ethanol production and also decrease the high risk of investing in a new second generation ethanol process is to integrate lignocellulosic ethanol into the current dry mills. In principle, most of the dry mills have access to lignocelluloses produced together with the grains such as straw, corncob and bran with a relatively low transportation cost. An example of how this process integration could be carried out is depicted in Fig. 2with two different proposed solutions: (a) integration at the fermentation stage and (b) integration at the fungal cultivation stage (see Section 4). In both cases, the first generation process remains mostly unchanged, although not completely unaffected. A larger potential influence on the first generation ethanol process is carried out by the alternative (a), as the inhibitors from the second generation process could enter the fermentor(s). Considering the dilution effect, it is rather unlikely that these inhibitors would disrupt the fermentation. New residuals, such as mainly lignin and undigested cellulose, will also pass through the entire process. Nevertheless, bringing an unknown factor into the heart of the process is not usually popular for plant managers, which could prevent implementation of the integrated process. If the integration is performed in the later steps, i.e., at the new suggested step “fungal cultivation” (see Section 4), the heart of the first generation process would be untouched. This would also minimize the amount of sugar (pentose) rich process streams in use, and thus the risk of unwanted reactions and contamination.

Fig. 2. An integrated first and second generation ethanol process. The integration could occur at the fermentation step (top) or at the proposed fungal cultivation step (bottom).

One of the major challenges of the lignocellulosic ethanol processes is obtaining sufficiently high sugar concentrations after the hydrolysis. To a large degree, this is solved by integrating the first and second generation processes, since sufficiently high concentrations are easily reached in the first generation. Thus, lower concentrations of the lignocellulosic feedstock are required, which considerably reduce the problems associated with mixing of the slurry. The lower concentrations will also lead to lower concentrations of inhibitors formed during the pretreatment, resolving the need for detoxification. Other than being less challenging, the pretreatment and hydrolysis will most likely be very similar to any second generation process. Thus, the pretreatment will most likely utilize acids or bases to open up the structure. However, care must be taken because the chemicals have to be chosen so that they do not negatively influence the quality of the animal feed product (DDGS) or produce large amounts of inhibitors. Considering that filamentous fungi have been grown on spent sulfite liquor, which is relatively rich in inhibitors, and used as fish feed without adverse effects to the fish (Bankefors et al., 2011), the latter is probably not an issue. On the other hand, the choice of chemicals for the pretreatment and even hydrolysis should also be considered. For example, sulfuric acid and dilute-acid processes could be an interesting option for the pretreatment. However, sulfur has limitation in animal feed and it might demand avoiding sulfuric acid in the pretreatment of the lignocelluloses. Furthermore, the hydrolysis will probably use enzymes and could either be carried out in a separate vessel or together with the fermentation, and would most likely not influence the quality of the DDGS. Following hydrolysis, the liberated hexoses will be converted into ethanol and CO₂ by the fermenting microorganism as usual.

A potential integration of the first and second generation ethanol processes, however, does not solve the problem of how to utilize the pentoses. A possible solution would be to use genetically modified strains of S. cerevisiae, especially for the European market legislations; however, negative public opinion may become an issue. Other microorganisms capable of fermenting pentoses into ethanol could also be employed, but they are generally quite sensitive to inhibitors (including ethanol). For instance Scheffersomyces stipites (formerly known as Pichia stipites) is sensitive to organic acids (Agbobo et al., 2007) and has been found to be inhibited when the ethanol concentration exceeded 30 g/L (Meyrial et al., 1997). This could become an issue, especially on the industrial scale. Co-fermentation of pentoses and hexoses are also yet to be solved. However, the pentoses could also be used for the production of compounds other than ethanol at later stages in the process.

The best opportunity for late utilization of pentoses is most likely after the separation of most of the solids from the stillage, i.e., the thin stillage (Fig. 2). However, a dedicated process step solely for pentose utilization in an integrated first/s generation process is not likely to be economically optimal due to the relatively low concentrations. Still, unfermented substrate (including carbohydrate polymers), dead yeast cells, and metabolites are likely to remain in relatively large quantities in the thin stillage as well. Therefore, a method to utilize both pentoses and the other residues is needed. Furthermore, since the animal feed product DDGS plays a crucial role in the process economy of existing first generation plants, its quality must not be compromised. This significantly reduces the number of potential solutions, as the microorganism essentially has to be food-grade to avoid damage to the environment or the animals eating the feed.

4 Fungal cultivation and pentose utilization

A proposed solution to the utilization of unfermented substrate without compromising the quality of the DDGS is to use food-related strains of Zygomycetes and Ascomycetes filamentous fungi. Potential strains include Rhizopus sp. isolated from tempe; Fusarium venenatum used for the production of Quorn; Aspergillus oryzaefrom e.g., sake fermentation; Neurospora intermedia isolated from oncom (fermented food based on left-overs in Indonesia); and Monascus purpureus used for the production of red rice. All of these strains have been confirmed to grow on mostly wheat-based thin stillage in aerobic conditions, resulting in the production of 11–19 g/L fungal biomass and 0.9–4.7 g/L ethanol (unpublished data). The fungal biomass can then easily be separated from the liquid due to its filamentous nature and dried. The ethanol will remain in the fermented broth, which is sent to the evaporators. The volatile ethanol will naturally join the outgoing steam, which is condensed and sent back into the process as is currently done in the first generation plants. Thus, no additional process steps will be required to separate the ethanol.

For pentose utilization and second generation processes, the focus among these filamentous fungi has been on the Zygomycetes. The research was initiated by Taherzadeh et al. (2003) with the use of sulphite liquor from the paper pulp industry as a substrate for Rhizopus, and has been ongoing since then. Noteworthy, publications for the use of food related Zygomycetes include the works by Millati et al., 2005 and Ferreira et al., 2012, and Wikandari et al. (2012). The general trend has been that while the ethanol yield from xylose is most often limited (ca. 0.2 g/g), the production of fungal biomass has been more promising (ca. 0.35 g/g). These ethanol yields from xylose can also be considered close to what is achievable, since all the evidence suggests that Zygomycetes follow the general fungal pathway (c.f. Chiang and Knight (1960)), resulting in an imbalance among the redox carriers. Without access to oxygen, it is not possible for the cells to correct this imbalance, which prevents anaerobic fermentation of xylose by these fungi. Thus, the need for aeration adds a natural limitation to produce ethanol, especially in industrial scale, which prevents the required micro-adjustments in the oxygen level for obtaining a high ethanol yield. The production of fungal biomass, which is the best in aerobic conditions, can probably still be optimized from pentoses by adjusting the process parameters and the feed composition. However, in general utilization of pentose sugars by fungi is a slower process than of hexose sugars and has not been reported at high hexose concentrations for these filamentous fungi.

Considering that utilization of xylose for biomass production requires aerobic conditions, aeration has to be considered an important factor. This is also true for the Ascomycetes strains. Aeration is also a crucial factor to decompose carbohydrate polymers in the thin stillage; metabolites from the fermentation and infections such as glycerol, lactic acid, and acetic acid; low concentrations of unfermented sugars such as xylose; and yeast cells lysis products. All of these compounds either require oxygen to be utilized by the fungi or the utilization is considerably enhanced by oxygen. Many of the compounds also need to be degraded enzymatically in order to be accessible to the fungi. Zygomycetes, however, are known to be able to produce e.g., amylases, cellulases, proteases, and lipases and can thus utilize most substrates (Ferreira et al., 2013). Similar enzyme production by different Ascomycetes is also very well known, including enzymes for more uncommon reactions (Zelinski and Hauer, 2002). Since the production of enzymes increases the energy expenditure of the cells, good access to ATP generating processes is required. This further increases the importance of aeration.

Cultivation of filamentous fungi is not without challenges. Mixing can particularly become an issue due to the broth viscosity caused by the filamentous nature of the cells (Gibbs et al., 2000). The fungi may also attach to the equipment inside the reactor such as baffles and impellers (Byrne and Ward, 1989). There are two possible ways to counteract this phenomenon. One is to adjust the process conditions and try to control the growth morphology. For instance, pellets (small beads consisting of intertwined hyphae) can be formed if the conditions are controlled (Nyman et al., 2013) to reduce the broth viscosity. However, growth in the form of pellets instead of free mycelia/clumps has been shown to both increase and decrease the metabolite yields, depending on the strain and the metabolite. Thus, growth in the form of pellets is not always beneficial. The other way to solve the problem is to adjust the cultivation vessel to fit the growth of the filamentous fungi. For instance, air-lift and bubble-column type reactors have been performing well for fungal cultivations on the thin stillage in aerobic conditions (unpublished data). The common factor between these two types of reactors is that they lack internal moving parts, and the mixing is achieved via the aeration process. This also has the benefit of a relatively low energy demand for the mixing.

5 Benefits of biomass production

Although the first generation ethanol production is a well-known process with few uncertainties, it is still very dependent on the raw material cost and the selling price of ethanol and DDGS. Even though the market values of both the raw material and the ethanol have a strong correlation with the price of fossil fuel, individual fluctuations still occur (cf. The World Bank (2013) and Alternative fuels data center (2013)). Since the profit margins are relatively small, these fluctuations represent a considerable risk to the process economy.

One way to decrease the impact of substrate/production price fluctuations is to follow the biorefinery concept and produce more than one product. Edible Zygomycetes or Ascomycetes fungal biomass have the potential to fulfill this role as an additional product. The fungal biomass could either be used to improve the quality of the DDGS, or be sold separately. The first alternative has the advantage of being relatively easy to implement. The second alternative has the potential advantage of providing the highest price. This can mainly be attributed to the high protein content (>50%), which makes it potentially useful as a fish feed component. The fungal biomass would then replace part of the fishmeal (Bankefors et al., 2011) or be added as an extract (Bhandari et al., 2002). In both cases the fish consumed the feed and grew well. Alternatives to fishmeal is of particular interest since it has more than quadrupled in price from January 2000 to April 2013, ending with an average price of 1849 USD/ton (The World Bank, 2013). The demand is also likely to remain high, as more and more fish are produced in aquacultures. Production of fungal biomass is also advantageous since it will utilize substrate that is challenging to use for bioethanol production (Section 4).

Fungal biomass could also find other uses. Some strains are known to produce valuable lipids (Bellou et al., 2012), which could be extracted from the biomass and sold as e.g., dietary supplements. The lipid contents are also high, close to 30% have been observed for some species (Kavadia et al., 2001). Low-grade fatty acids could instead be used for e.g., biodiesel production. If Zygomycetes are cultivated, the cell wall fraction of the biomass could be used as a source of chitosan, or be used to produce a bio-based superabsorbent (Zamani, 2010). However, all these applications require additional process steps after the harvesting and their economic benefit is unknown.

Cultivation of filamentous fungi provides benefits other than an additional product; there are also process related advantages such as easy separation of the produced mycelium. A major potential advantage can be found in the evaporators, which have the challenging task of removing as much water from the thin stillage as possible. Fouling, in particular, and the viscosity of the liquid can be major obstacles in the process. By reducing the total amount of suspended solids and organic compounds in the liquid, the severity of these obstacles could be decreased. This could allow more water to be removed in the evaporators and less in the driers. It could also allow more of the thin stillage to be sent back into the process as back-set, which would directly decrease the load on the evaporators and the driers.

6 Conclusion

Integration of second and already existing first generation ethanol processes is an attractive way to reduce the investment costs and risks compared to a standalone second generation processes. However, since most of today’s ethanol production is based on starch and thus dependent on by-products sold as e.g., animal feed to be economically feasible, the integration cannot adversely affect these by-products. This severely limits the possible ways to utilize the pentose sugars released from the lignocellulosic feedstock. The proposed solution is to use edible Zygomycetes and Ascomycetes filamentous fungi, which are naturally capable of utilizing pentoses, but also other unfermented substrates left after distillation.

Acknowledgement

The authors would like to extend their gratitude to the Swedish Energy Agency for their financial support for this project.

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