WOOD GAS

Wood gas is a syngas fuel which can be used as a fuel for furnaces, stoves and vehicles in place of gasoline, diesel or other fuels. During the production process biomass or other carbon-containing materials are gasified within the oxygen-limited environment of a wood gas generator to produce hydrogen and carbon monoxide. These gases can then be burnt as a fuel within an oxygen rich environment to produce carbon dioxide, water and heat. In some gasifiers this process is preceded by pyrolysis where the biomass or coal is first converted to char,  releasing methane and tar rich in polycyclic aromatic hydrocarbons.

Woodgas flame from a vehicle gasifier unit

History

The first wood gasifier was apparently built by Gustav Bischov in 1839. The first vehicle powered by wood gas was built by Thomas Hugh Parker in 1901.  Around 1900, many cities delivered syngas (centrally produced, typically from coal) to residences. Natural gas began to be used only in 1930.

Wood gas vehicles were used during World War II, as a consequence of the rationing of fossil fuels. In Germany alone, around 500,000 " producer gas " vehicles were in use at the end of the war. Trucks, buses, tractors, motorcycles, ships and trains were equipped with a wood gasification unit. In 1942 (when wood gas had not yet reached the height of its popularity), there were about 73,000 wood gas vehicles in Sweden, 65,000 in France, 10,000 in Denmark, and almost 8,000 in Switzerland. In 1944, Finland had 43,000 "woodmobiles", of which 30,000 were buses and trucks, 7,000 private vehicles, 4,000 tractors and 600 boats. Although charcoal was prefer for cars in China during the oil shortages.

A wood gas truck in North Korea.

Wood gasifiers are still manufactured in China and Russia for automobiles and as power generators for industrial applications. Trucks retrofitted with wood gasifiers are used in North Korean rural areas, particularly on the roads of the east coast.

Internal Combustion Engine

Efficiency of the gasifier system is relatively high. The gasification stage converts about 75% of fuel energy content into a combustible gas that can be used as a fuel for internal combustion engines. Based on long-term practical experiments and over 100,000 km drive with a wood gas-powered car, the energy consumption has been 1.54 times higher compared to the energy demand of the same car on petrol (not including the energy needed to extract, transport and refine the oil from which petrol is derived, and not including the energy to harvest, process, and transport the wood to feed the gasifier). This means that 1000 kg of wood combustible matter has been found to substitute 365 litres of petrol during real transportation in similar driving conditions and with the same otherwise unmodified vehicle. This can be considered to be a good result, because no other refining of the fuel is required. This study also considers all possible losses of the wood gas system, like preheating of the system and carrying of the extra weight of the gas-generating system. In power generation reported demand of fuel is 1.1 kg wood combustible matter / kWh electricity.

Wood gasifier on a Ford truck converted into a tractor

Gasifiers have been built for remote Asian communities using rice husk, which in many cases has no other use. One installation in Burma uses an 80 kW modified diesel for about 500 people who are otherwise without power. The ash can be used as Biochar fertilizer, so this can be considered a renewable fuel.

Wood gasifier system

Exhaust gas emission from an internal combustion engine is significantly lower on wood gas than on petrol. Especially the HC emissions are low on wood gas. A normal catalytic converter works well with wood gas, but even without it, emission levels less than 20 ppm HC and 0.2% CO can be easily achieved by most automobile engines. Combustion of wood gas generates no particulates, and the gas renders thus very little carbon black amongst motor oil.

Stoves, Cooking and Furnaces

Certain stove designs are in effect a gasifier working on the updraft principle—the air passes up through the fuel, which can be a column of rice husks, and is combusted, then reduced to carbon monoxide by the residual char on the surface. The resulting gas is then burnt by heated secondary air coming up a concentric tube. Such a device behaves very much like a gas stove. This arrangement is also known as a Chinese burner.

Coaxial downdraft gasification stove

An alternative stove based on the downdraft principle and typically built with nested cylinders also provides high efficiency. Combustion from the top creates a gasification zone with the gas escaping downwards through ports located at the base of the burner chamber. The gas mixes with additional incoming air to provide a secondary burn. Most of the CO produced by gasification is oxidized to CO₂ in the secondary combustion cycle; therefore, gasification stoves carry lower health risks than conventional cooking fires.

Another application is the use of producer gas to displace LDO (light density fuel oil) in industrial furnaces.

Production

A wood gasifier takes wood chips, sawdust, charcoal, coal, rubber or similar materials as fuel and burns these incompletely in a fire box, producing solid ashes and soot (which have to be removed periodically from the gasifier) and wood gas. The wood gas can then be filtered for tars and soot/ash particles, cooled and directed to an engine or fuel cell. Most of these engines have strict purity requirements of the wood gas, so the gas often has to pass through extensive gas cleaning in order to remove or convert (i.e. to " crack " ) tars and particles. The removal of tar is often accomplished by using a water scrubber. Running wood gas in an unmodified gasoline-burning internal combustion engine may lead to problematic build-up of unburned compounds.

Fluidized bed gasifier in Güssing, Austria, operated on wood chips

The quality of the gas from different gasifiers varies a great deal. Staged gasifiers, where pyrolysis and gasification occur separately (instead of in the same reaction zone as was the case in e.g. the WWII gasifiers), can be engineered to produce essentially tar-free gas (less than 1 mg/m³), while single-reactor fluid-bed gasifiers may exceed 50,000 mg/m³ tar. The fluid bed reactors have the advantage of being much more compact (more capacity per volume and price). Depending on the intended use of the gas, tar can be beneficial as well by increasing the heating value of the gas.

The heat of combustion of producer gas (a term used in the U.S. meaning wood gas produced for use in a combustion engine) is rather low compared to other fuels. Taylor reports that "producer gas" has a lower heating value of 5.7 MJ/kg versus 55.9 MJ/kg for natural gas and 44.1 MJ/kg for gasoline. The heating value of wood is typically 15-18 MJ/kg. Presumably, these values can vary somewhat from sample to sample. The same source reports the following chemical composition by volume which most likely is also variable:

A charcoal gas producer at the Nambassa alternative festival in New Zealand in 1981

• Nitrogen N₂: 50.9%
• Carbon monoxide CO: 27.0%
• Hydrogen H₂: 14.0%
• Carbon dioxide CO₂: 4.5%
• Methane CH₄: 3.0%
• Oxygen O₂: 0.6%.

It is pointed out, that the gas composition is strongly dependent on the gasification process, the gasification medium (air, oxygen or steam) and the fuel moisture. Steam-gasification processes typically yield high hydrogen contents, downdraft fixed bed gasifiers yield high nitrogen concentrations and low tar loads, while updraft fixed bed gasifiers yield high tar loads.

- Wikipedia 

BARKDUST

In agriculture, gardening and landscaping, barkdust (also bark dust, bark chips, bark mulch, or beauty bark) is a form of mulch produced out of chipped or shredded tree bark. Coarser forms of barkdust may be known as bark nuggets. Trees typically used in the production of barkdust include the Douglas fir and the Western hemlock.

Barkdust

Production and Types of Barkdust

Barkdust is commonly produced from several tree species. The Douglas fir and the Western Hemlock are the most common sources of barkdust, with cedar bark also being used. Barkdust may be a byproduct of lumber production, of yard debris reycling processes, or it may be produced in its own right. Barkdust is typically categorized by the source plant, as well as by the coarseness of the resulting material. Fine barkdusts are used as mulch with coarser forms being used for weed control, as a playground surface, or for decorative purposes.

According to voluntary guidelines published by the Mulch and Soil Council a trade group of mulch and soil producers, a material with "bark" in the name should consist of "the corky exterior covering of trees, with a maximum wood content (interior xylem of 15%)". Products with greater than 15% wood content may be labelled as "wood mulch", but should not be called "bark", according to the group's guidelines.

Fresh fir bark is reddish-brown in color. The bark from cedar or hemlock is more tan in color, as the processes which produce these types of barkdust may leave a greater percentage of wood (as opposed to bark) in the resulting material. Shredded fir bark is known for lots of slivers, those who handle it with bare hands or walk on it with bare feet are likely to get splinters. Bark produced from hemlock or cedar is far less likely to produce splinters, and is commonly used as a covering for children's play areas.

Properties and Uses

Like many other types of mulch barkdust is used in gardening and landscaping for its properties in affecting soil pH regulating the temperature of the underlying soil, and preventing water loss and erosion.

Barkdust increases soil acidity, and the decomposition of barkdust consumes nitrogen especially when fine bark mulch is mixed in with soil; coarser barkdust laid on top of soil will extract nitrogen at a much slower rate. Barkdust is also effective at absorbing water and preventing water loss due to evaporation.

Barkdust is commonly used in landscaping around trees or shrubs. It is especially common in the Pacific Northwest where the tree species used to produce it are native. Barkdust is valued for its effectiveness at suppressing weeds; many plants considered to be weeds do not tolerate the soil conditions brought upon by barkdust. On the other hand, the same is true for many flowering plants such as .

In addition, many consider barkdust to be visually appealing.

As barkdust is less dense than other types of soil or mulch, and doesn't compress a great deal, it is often considerably softer than bare earth. As a result, it also finds applications as a playground surface. For playground applications, hemlock or cedar bark is most commonly used, as fir bark frequently produces splinters when handled by or trod upon with bare skin.

Commerce in Barkdust

Barkdust is typically sold by the unit, with one unit of barkdust being equal to 200 cubic feet (7.41 cubic yards, or 5.66 m³); such large quantities of barkdust are typically delivered by truck to a jobsite. Barkdust is often spread with a bark blower, a machine consisting of a supply of barkdust, a blower, and a long flexible tube which "sprays" the barkdust over the intended area. Use of a bark blower often results in a more consistent application of barkdust than spreading it by hand, as well as being much faster.

Smaller quantities of barkdust, typically 2–3 cubic feet, are sold prepackaged in home improvement and gardening retailers.

For landscaping applications, a layer of 2"–3" (5 cm–7.5 cm) is generally recommended. For use in playgrounds, a 12" (30 cm) layer is often recommended.

- Wikipedia 

WOODCHIPS

Woodchips are a medium-sized solid material made by cutting, or chipping, larger pieces of wood.

Woodchips may be used as a biomass solid fuel and are raw material for producing wood pulp. They may also be used as an organic mulch in gardening, landscaping, restoration ecology, bioreactors for denitrification and mushroom cultivation. According to the different chemical and mechanical properties of the masses, the wood logs are mostly peeled, and the bark chips and the wood chips are processed in different processes. The process of making wood chips is called woodchipping and is done with a woodchipper.

Raw Materials

The raw materials of wood chips can be pulpwood, wood plantations, waste wood and residuals from construction, agriculture, landscaping, logging, and sawmills and locally grown and harvested fuel crops.

Woodchips waiting to be loaded at Albany Port in Western Australia

Production

A woodchipper is a machine used for reducing wood to smaller pieces. There are several types of woodchippers depending of the further processing of the woodchips. For industrial use, the woodchippers are large, stationary installations.

Pulp and Paper Industry

Wood chips used for chemical pulp must be relatively uniform in size and free of bark. The optimum size varies with the wood species. It is important to avoid damage to the wood fibres as this is important for the pulp properties. For roundwood it is most common to use disk chippers. A typical size of the disk is 2.0 - 3.5 m in diameter, 10 – 25 cm in thickness and weight is up to 30 tons. The disk is fitted with 4 to 16 knives and driven with motors of ½ - 2 MW. Drum chippers are normally used for wood residuals from saw mills or other wood industry.

Methods of Conveyance

There are four potential methods to move woodchips: pneumatic, conveyor belt hopper with direct chute, batch system (manual conveyance).

Applications

Woodchips are used primarily as a raw material for technical wood processing. In industry, processing of bark chips is often separated after peeling the logs due to different chemical properties.

Wood Pulp

Only the heartwood and sapwood are useful for making pulp. Bark contains relatively few useful fibres and is removed and used as fuel to provide steam for use in the pulp mill. Most pulping processes require that the wood be chipped and screened to provide uniform sized chips.

Mulch

Woodchipping is also used to produce landscape and garden woodchips mulch. It is used for water conservation weed control, reducing and preventing soil erosion and for supporting germination of native seeds and acorns in habitat revegetation-ecological restoration projects. As the ramial chipped wood decomposes it improves the soil structure, permeability, bioactivity, and nutrient availability. Woodchips when used as a mulch are at least three inches thick.

Playground Surfacing

Wood chips can be reprocessed into an extremely effective playground surfacing material, or impact-attenuation surface. When used as playground surfacing (soft fall, cushion fall, or play chip, as it is sometimes known), woodchips can be very effective in lessening the impact of falls from playground equipment. When spread to depths of one foot (30 centimeters) playground wood chips can be effective at reducing impacts in falls up to 11 feet (3 meters). Playground woodchip is also an environmentally friendly alternative to rubber type playground surface

Bioreactor

Woodchip piles at the edge of a field can inhibit nitrates from running off into water tiles. They are a simple measure for farmers to reduce nitrate pollution of the watershed without them having to change their land management practice. A 2011 study showed that most of the nitrate removal was due to heterotrophic denitrification. A 2013 experiment from Ireland showed that after 70 days of startup, a woodchip pile loaded with liquid pig manure at 5 L/m²/day removed an average of 90% of nitrate in the form of ammonium after one month. A January 2015 study from Ohio State University showed very low nitrogen gas, i.e. greenhouse gas emissions from nitrate transformation under the anaerobic conditions of the wood chip bioreactor. Scientists constructed a model for water flow and nitrate removal kinetics which can be used to design denitrification beds. It is unknown if other nutrients like phosphorus or pathogens are affected by the bioreactor as well.

Fuel

Woodchips have been traditionally used as solid fuel for space heating or in energy plants to generate electric power from renewable energy. The main source of forest chips in Europe and in most of the countries have been logging residues. It is expected that the shares of stumps and roundwood will increase in the future. As of 2013 in the EU, the estimates for biomass potential for energy, available under current conditions including sustainable use of the forest as well as providing wood to the traditional forest sectors, are: 277 million m³, for above ground biomass and 585 million m³ for total biomass.

The newer fuel systems for heating use either woodchips or wood pellets. The advantage of woodchips is cost, the advantage of wood pellets is the controlled fuel value. The use of woodchips in automated heating systems, is based on a robust technology.

The size of the woodchips is particularly important when burning woodchip in small plants. Unfortunately there are not many standards to decide the fractions of woodchip. One standard is the GF60 which is commonly used in smaller plants, including small industries, villas, and apartment buildings. "GF60" is known as "Fine, dry, small chips". The requirements for GF60 are that the moisture is between 10–30% and the fractions of the woodchips are distributed as follows: 0–3.5mm: <8%, 3.5–30mm: <7%, 30–60mm: 80–100%, 60–100mm: <3%, 100–120mm: <2%.

The energy content in one cubic metre is normally higher than in one cubic metre wood logs, but can vary greatly depending on moisture. The moisture is decided by the handling of the raw material. If the trees is taken down in the winter and is left to dry under the summer, with tears in the bark and covered so rain can't reach to them and then is chipped in the fall the woodchip will get an moisture of approx. 20–25%. The energy content is then approx 3.5–4.5kWh/kg (~150–250 kg/cubic metre).

Coal power plants have been converted to run on woodchips, which is fairly straightforward to do, since they both use an identical steam turbine heat engine  and the cost of woodchip fuel is comparable to coal.

Solid biomass is an attractive fuel for addressing the concerns of the energy crisis and climate change since the fuel is affordable, widely available, close to carbon neutral and thus climate-neutral in terms of carbon dioxide (CO2), since in the ideal case only the carbondioxide which was drawn in during the tree’s growth and stored in the wood is released into the atmosphere again. It is sustainable as long as crops are allowed to regrow; In most cases, biomass is not carbon neutral as wood is not regrown and the efficiency of biomass operations produce more pollutants than the processes they replace.

Waste and Emission

Compared to the solid waste disposal problems of coal and nuclear fuels, woodchip fuel's waste disposal problems are less grave; in a study from 2001 fly ash from wood chip combustion had 28.6 mg cadmium/kg dry matter. Compared to fly ash from burning of straw, cadmium was bound more heavily, with only small amounts of cadmium leached. It was speciated as a form of cadmium oxide, cadmium silicate (CdSiO₃); authors noted that adding it to agricultural or forest soils in the long-term could cause a problem with accumulation of cadmium.

Like coal, wood combustion is a known source of mercury emissions, particularly in northern climates during winter. The mercury is both gaseous as elemental mercury (especially when wood pellets are burned) or mercury oxide, and solid PM2.5 particulate matter when untreated wood is used.

When wood burning is used for space heating, indoor emissions of 1,3-butadiene, benzene, formaldehyde and acetaldehyde, which are suspected or known carcinogenic compounds, are elevated. The cancer risk from these after exposure to wood smoke is estimated to be low in developed countries .

Certain techniques for burning woodchips result in the production of biochar - effectively charcoal - which can be either utilised as charcoal, or returned to the soil, since wood ash can be used as a mineral-rich plant fertilizer. The latter method can result in an effectively carbon-negative system, as well as acting as a very effective soil conditioner, enhancing water and nutrient retention in poor soils.

Automated Handling of Solid Fuel

Unlike the smooth, uniform shape of manufactured wood pellets, wood chip sizes vary and are often mixed with twigs and sawdust. This mixture has a higher probability of jamming in small feed mechanisms. Thus, sooner or later, one or more jams is likely to occur. This reduces the reliability of the system, as well as increasing maintenance costs. Despite what some pellet stove manufacturers may say, researchers who are experienced with woodchips, say they are not compatible with the 2 inch (5 cm) auger used in pellet stoves.

Micro Combined Heat and Power

Wood is occasionally used to power engines, such as steam engines, Stirling engines and Otto engines running on wood gas. As of 2008, these systems are rare, but as technology and the need for it develops, it is likely to be more common in the future. For the time being, wood can be increasingly used for heating applications. This will reduce the demand for heating oil, and thereby allow a greater percentage of fuel oil to be used for applications such as internal combustion engines, which are less compatible with wood based fuel and other solid biomass fuels. Heating applications generally do not require refined or processed fuels, which are almost always more expensive

Comparison to Other Fuels

Woodchips are similar to wood pellets, in that the movement and handling is more amenable to automation than cord wood, particularly for smaller systems. Woodchips are less expensive than wood pellets and are theoretically more energy efficient than pellets, because less energy is required for manufacturing, processing, and transportation; however, this assumes that they are consumed in an appropriately designed burner, and as of 2008, these are mostly only available in large systems designed for commercial or institutional use, which have been very successful in terms of performance, cost, reliability, and efficiency.

Woodchips are less expensive than cord wood because the harvesting is faster and more highly automated. Woodchips are of greater supply, partly because all parts of a tree can be chipped, whereas small limbs and branches can require much labor convert to cord wood. Cordwood generally needs to be "seasoned" or "dry" before it can be burned cleanly and efficiently. On the other hand, woodchip systems are typically designed to cleanly and efficiently burn "green chips" with very high moisture content of 43–47% (wet basis).

Environmental Aspects

If woodchips are harvested through sustainable forestry practices, then this is considered a source of renewable energy. On the other hand, harvesting practices, such as clearcutting large areas, are highly damaging to forest ecosystems.

Theoretically, whole-tree chip harvesting does not have as high a solar energy efficiency compared to short rotation coppice, however, it can be an energy-efficient and low-cost method of harvesting. In some cases, this practice may be controversial when whole-tree harvesting may often often be associated with clear cutting and perhaps other questionable forestry practices.

Waste Processing

Woodchips, and bark chips, can be used as bulking agents in industrial composting of municipal biodegradable waste, particularly biosolids.

Woodchip biomass does not have the waste disposal issues of coal and nuclear power, since wood ash can be used directly as a mineral-rich plant fertilizer.

Forest Fire Prevention

Woodchip harvesting can be used in concert with creating man made firebreaks, which are used as barriers to the spread of wildfire. Undergrowth coppice is ideal for chipping, and larger trees may be left in place to shade the forest floor and reduce the rate of fuel accumulation.

Market Products, Supply and Demand

Currently, domestic or residential sized systems are not available in products for sale on the general market. Homemade devices have been produced, that are small-scale, clean-burning, and efficient for woodchip fuels. Much of the research activity to date, has consisted of small budget projects that are self-funded. The majority of funding for energy research has been for liquid biofuels.

United States

"Wood chip costs usually depend on such factors as the distance from the point of delivery, the type of material (such as bark, sawmill residue or whole-tree chips), demand by other markets and how the wood fuel is transported. Chips delivered directly to the (powerplant) station by truck are less expensive than those delivered ... and shipped by railcar. The range of prices is typically between US$18 to US$30 per (wet)-ton delivered."

In 2006, prices were US$15 and US$30 per wet-ton in the northeast.

In the 20 years leading up to 2008, prices have fluctuated between US$60–70/oven-dry metric ton (odmt) in the southern states, and between US$60/odmt and US$160/odmt in the Northwest.

Europe

In several well wooded European countries (e.g. Austria, Finland, Germany, Sweden) wood chips are becoming an alternative fuel for family homes and larger buildings due to the abundant availability of wood chips, which result in low fuel costs. The European Union is promoting wood chips for energy production in the EU Forest action plan 2007-2011. The total long term potential of wood chips in the EU it is estimated to be 913 million m3.

Japan

After a long period of negative scores, the demand of wood chip for paper manufacturing started increasing again. Starting in the last quarter of 2013, orders for printing paper and card board increased before the consumption tax increase then by weakening yen, import of papers like copy paper decreases and export of paper increases, which stimulate paper production in Japan. Softwood chip prices from the United States increased by 12% compared to October 2013 and softwood chip prices from Australia increased by 7%.

- Wikipedia 

PULPWOOD

Pulpwood

Pulpwood refers to timber with the principal use of making wood pulp for paper production.

Harvesting a stand of eucalyptus pulpwood in Australia.

Applications

• Trees raised specifically for pulp production account for 16% of world pulp production, old growth forests 9% and second- and third- and more generation forests account for the balance. Reforestation is practiced in most areas, so trees are a renewable resource.
• Pulpwood is also used as the raw material for some wood products, such as oriented strand board (OSB).
• There is an increasing demand for pulpwood as a source of 'green energy' by the bio-energy sector.

Properties

The fiber length of the cellulose fiber is the most important parameter of the pulpwood and determines what it may be used for. The first separation is into softwood and hardwood, that have long and short fibers respectively. In paper production fiber from softwood give tensile strength and fibers from hardwood give opacity.

Logging

In the logging of mixed forest stands, the better trees are usually used for sawlogs for lumber production, while the inferior trees and components are harvested for pulpwood production. Pulpwood usually derives from four types of woody materials in a mixed logging operation:

• Open-grown trees, that are heavily branched low on the trunk, and so make poor sawlogs.
• Dead or diseased trees.
• Tops cut from trees harvested for sawlogs (branches are rarely used since they contain little usable wood after the bark has been removed).
• Small trees, too small to harvest for sawlogs.

Natural forest stands may also be harvested solely for pulpwood where, for various reasons, the value of the trees as sawlogs is low. This may be due to the predominant species in the forest stand (for example, some aspen forests in northern North America), or to the relative proximity of the nearest sawmill or pulp mill

Plantations

Pulpwood is also harvested from plantations/tree farms established for the specific purpose of growing pulpwood, with little or minimal sawlog production. Monocultures of species intended specifically for pulpwood include loblolly/slash pine in the southern USA; various species of eucalyptus (most commonly Eucalyptus globulus and Eucalyptus grandis) in Latin America, Iberian Peninsula, Australia, south-east Asia and southern Africa and acacia( most commonly Acacia mangium) in south-east Asia and southern Africa.

Salvage Cutting

Salvage cuts after forest fires, tornadoes,  hurricanes, or other natural disasters are often used for pulpwood. An alternative source of wood for use in kraft pulping is recovered lumber from demolition, industrial processing of wood and wooden pallets.

Wood Residuals

Saw residuals are used as pulp wood. The most important of these are the side cuttings from lumber edgers.  This gives wood with almost only sapwood and no heartwood. The sapwood is easier to pulp due to a more open structure and less content of extractives than the heartwood. The fibre length of sapwood is generally longer than the fibre length of heartwood. The sapwood is also normally lighter and that is an advantage when producing mechanical pulps as less bleaching is needed.

Earlier sawdust had some limited use in paper production. It gives very short fibres that are suitable as part of the furnish for paper tissues and writing papers. Saw blades have become thinner and with smaller teeth making the sawdust too small as fibre source.

Pulpwoods
Economically Important Pulpwoods

• Hardwoods

Acacia

Aspen

Birch

Eucalyptus

Maple

Pacific Albus

• Softwoods

Pine

Spruce

Chemical composition of some pulpwoodsEdit

Chemical composition of pulpwood (%)
Wood	Cellulose	Lignin	Mannan	Araban	Xylan
Aspen	56.5	16.3	2.3	0.4	16.0
Paper Birch	44.5	18.9	1.5	0.5	24.6
Red maple	44.8	24	3.5	0.5	17.3
Balsam fir	47.7	29.4	12.4	0.5	4.8
Jack pine	45.0	28.6	10.8	1.4	7.1
White spruce	48.5	27.1	11.6	1.6	6.8

- Wikipedia

NON TIMBER FOREST PRODUCT

Non-timber Forest Products

Non-timber forest products (NTFPs), also special, non-wood, minor, alternative and secondary forest products, are useful substances, materials and/or commodities obtained from forests which do not require harvesting (logging) trees. They include game animals, fur-bearers, nuts, seeds, berries, mushrooms, oils, foliage, medicinal plants, peat, fuelwood and forage.

Mahua seeds

Research on NTFPs have focused on their commodifiability for rural incomes and markets, as an expression of traditional knowledge or as a livelihood option for rural household needs, and, as a key component of sustainable forest management and conservation strategies. All research promote forest products as valuable commodities and tools that can promote the conservation of forest

Definitions

There is a wide variety of NTFPs, including mushrooms, huckleberries, ferns, transplants, seed cones, piñon seeds, tree nuts,, moss, maple syrup,  cork, cinnamon, rubber, tree oils and resins,  and ginseng.  The United Kingdom's Forestry Commission defines NTFPs as "any biological resources found in woodlands except timber," and Forest Harvest, part of the Reforesting Scotland project, defines them as "materials supplied by woodlands - except the conventional harvest of timber". These definitions include wild and managed game, fish and insects. NTFPs are commonly grouped into categories such as floral greens, decoratives, medicinal plants, foods, flavors and fragrances, fibers, and saps and resins.

Tendu patta (leaf) collection

Other terms similar to NTFPs include special, non-wood, minor, alternative and secondary forest products. NTFPs in particular highlight forest products which are of value to local people and communities but have been overlooked in the wake of forest management priorities (for example, timber production and animal forage). In recent decades, interest has grown in using NTFPs as alternatives or supplements to forest management practices. In some forest types, under the right political and social conditions, forests can be managed to increase NTFP diversity and, consequently, to increase biodiversity and potentially economic diversity.

Uses

The harvest of NTFPs remains widespread throughout the world. People from a wide range of socio-economic, geographical and cultural contexts harvest NTFPs for a number of purposes, including but not limited to: household subsistence, maintenance of cultural and familial traditions, spiritual fulfillment as well as physical and emotional well-being scientific learning and income. Other terms synonymous with harvesting include wild-crafting, gathering, collecting and foraging. NTFPs also serve as raw materials for industries ranging from large-scale floral greens suppliers and pharmaceutical companies to micro-enterprises centred upon a wide variety of activities (such as basket-making, woodcarving and the harvest and processing of various medicinal plants).

Economic Importance

It is difficult to estimate the contribution of NTFPs to national or regional economies as there is a lack of broad-based systems for tracking the combined value of the hundreds of products that make up various NTFP industries. One exception to this is the maple syrup industry, which in 2002 in the US alone yielded 1.4 million US gallons (5,300 m³) worth USD $38.3 million. In temperate forests such as in the US, wild edible mushrooms such as matsutake, medicinal plants such as ginseng, and floral greens such as salal land sword fernare multimillion-dollar industries. While these high-value species may attract the most attention, a diversity of NTFPs can be found in  most forests of the world.

In tropical forests, for example, NTFPs can be an important source of income that can supplement farming and/or other activities. A value-analysis of the Amazon rainforest in Peru found that exploitation of NTFPs could yield higher net revenue per hectare than would timber harvest of the same area, while still conserving vital ecological services. Their economic, cultural and ecological value, when considered in aggregate, makes managing NTFPs an important component of sustainable forest management and the conservation of biological and cultural diversity.

Research

Research on NTFPs have focused on three perspectives: NTFPs as a commodity with a focus on rural incomes and markets, as an expression of traditional knowledge or as a livelihood option for rural household needs, and, finally, as a key component of sustainable forest management and conservation strategies. These perspectives promote forest products as valuable commodities and important tools that can promote the conservation of forests. In some contexts, the gathering and use of NTFPs can be a mechanism for poverty alleviation and local development.

- Wikipedia