3. Planting for woodfuel

3.1 Woodfuel production trends
3.2 Planting systems
3.3 Species for energy
3.4 Silvicultural aspects
3.5 Social and environmental aspects

3.1 Woodfuel production trends

FAO (2000) modelled three scenarios to study future trends in woodfuel plantations and a summary of these results, to 2020, is presented here (Table 3). All three only consider developing countries and assume that non-industrial use of wood is the same as woodfuel production. As they consider only stem volumes, the figures are probably conservative (FAO 2000). They do not take woodfuel derived from industrial plantations or agricultural tree crops like rubber or oil palm. Care is therefore needed in interpreting these results. It is also possible that some of these plantations might not be used for bioenergy, but go to other markets.

The key assumptions of the scenarios were:

Scenario 1: No expansion in planted area; replanting of harvested areas.
Scenario 2: New planting at a fixed annual rate of 1 percent of current forest area (plus replanting).
Scenario 3: New planting at current planting rates for the next 10 years, followed by a 20 percent decline each 10 year interval (plus replanting).

Asia and particularly India, dominate the scene (Tables 2, 3). The estimates suggest that India should account for about 45 percent of all the plantation woodfuel production in developing countries and it will have the greatest expansion in potentially available woodfuel from plantations. The situation is not so positive for Africa where, even under the optimistic scenario 3, the expansion in absolute terms is relatively small. Indeed for a few countries, e.g. Ethiopia, the prediction is that there will be a drop from current plantation woodfuel production over the next 10 to 20 years (Tables 2 and 3). A positive, modest expansion is predicted for Latin America.

On top of these potential production increases from non-industrial plantations, there will be increased possibilities to utilise wood wastes from factories based around industrial plantations; productivity of these plantations are predicted to expand rapidly (FAO 2000). The increase in woodfuel from this source between 1995 and 2020 for developing countries could be about half that predicted from non-industrial plantations (assuming medium scenario 2, with 20 to 25 percent of industrial roundwood volumes being used as fuel). The potential of the timber industry for energy production has been discussed in more detail by Gowen et al. (1994). They suggested that the biggest potential was in Asia and then Latin America, with more limited and concentrated options for Africa.

3.2 Planting systems

3.2.1 Forest plantations
3.2.2 Systems outside forests

3.2.1 Forest plantations

The woodfuel production trends from 'non-industrial plantations', that are discussed above, cover plantations which may range in size from woodlots, grown by individuals or communities, to larger forests usually under government or industry management. At the smaller scale they can be appropriate for supplying local needs of urban people. Larger scale plantations are more appropriate for supplying wood for charcoal or small-scale industries (e.g. bakeries, brick, potteries) or for use in woodfuel-based power stations or perhaps conversion to liquid fuels.

Industrial plantations offer considerable potential to supply wood wastes to the woodfuel markets or for use in co-generation activities (Gowen, et al. 1994; WEC 1999). Further, better management of these forests, with participation of local peoples, offers good near-term prospects of increasing the supply of woodfuel (WEC 1999). This could entail greater utilisation of thinning, pruning or clearfelling slash. Alternatively, as is being done in Scandinavia and Europe, this latter material might be mechanically collected and used in centralised energy plants.

Table 3: Projected production of plantation woodfuel between 2000 and 2020 under three scenarios* (from FAO 2000). Projections are given by region and for the largest producers in each region. The base year for projections was 1995.

Region and main countries		Woodfuel production m3 x 106
		2000	2010	2020
Scenario 1 - Total		130.5	155.6	163.8
Africa		12.4	12.1	12.7
	Ethiopia	1.4	1.2	1.2
	Madagascar	1.3	1.2	1.3
	Sudan	1.1	1.1	1.2
Asia + Oceania		94.4	119.7	118.3
	China	13.1	25.4	23.4
	India	62.4	73.7	72.6
	Indonesia	4.5	3.2	4.0
Latin America		23.7	23.8	32.8
	Brazil	15.0	13.2	21.0
	Peru	1.7	2.0	1.8
	Uruguay	1.8	2.0	2.7
Scenario 2 - Total		130.5	162.8	186.5
Africa		12.4	12.7	14.3
	Ethiopia	1.4	1.3	1.3
	Madagascar	1.3	1.2	1.5
	Sudan	1.1	1.2	1.3
Asia + Oceania		94.4	125.5	136.2
	China	13.1	26.6	27.2
	India	62.4	77.6	84.1
	Indonesia	4.5	3.3	4.5
Latin America		23.7	24.6	36.0
	Brazil	15.0	13.7	22.8
	Peru	1.7	2.0	2.1
	Uruguay	1.8	2.1	3.0
Scenario 3 - Total		130.5	202.6	302.4
Africa		12.4	14.8	20.6
	Ethiopia	1.4	1.4	1.6
	Madagascar	1.3	1.3	1.7
	Sudan	1.1	1.9	3.2
Asia + Oceania		94.4	160.2	234.8
	China	13.1	36.7	56.7
	India	62.4	97.0	137.7
	Indonesia	4.5	4.7	8.2
Latin America		23.7	27.6	47.0
	Brazil	15.0	14.4	25.1
	Peru	1.7	2.3	3.6
	Uruguay	1.8	2.7	5.9

Notes: see table 2.

* Scenario 1 - replant current areas; Scenario 2 - new annual planted area at 1 percent of current area; Scenario 3 - for 10 years new planted area at same as recent years, followed by a gradual decline

3.2.2 Systems outside forests

There are a wide variety of agroforestry, farm forestry or urban systems where trees are planted in non-forest conditions (Long and Nair 1999). With agroforestry and farm forestry, the general objective is to integrate tree growing with agricultural or fish production. As farmers and communities seldom plant for woodfuel as a primary goal, even where it is in short supply, agroforestry systems and the use of multipurpose trees (trees that provide a range of benefits) are often appropriate (Nair 1993, 1989). Rich farmers may use intensive silviculture which aim for maximum profit from their investment - it is unlikely that the highest value will be as woodfuel. Resource-poor farmers are more likely to want to use low-input approaches aiming for small, yet attractive, returns with minimum investment. It is often best to promote multiple-purpose tree species that have benefits other than fuel.

A wide variety of agroforestry systems are found in developing countries and their occurrence is often site specific (Long and Nair 1999; Nair 1993). Systems are characterised by environment, plant species and their arrangement, management and socio-economic functioning. Nair (1993) identified 18 different practices within the three main agroforestry systems:

• Agrisilvicultural systems - crops plus trees. These range from improved fallow to taungya, alley cropping, homegardens, shelterbelts etc.
• Silvopastoral systems - trees plus pastures and/or animals. They can include widely spaced trees over pastures and living fences to using trees as protein banks.
• Agrosilvopastoral systems - trees plus crops plus pastures and/or animals. This includes homegardens with animals, multipurpose woody hedgerows, woodlots and others.

As with agroforestry systems urban forests and tree planting have many forms and functions (Long and Nair 1999). Among these can be to provide significant quantities of woodfuel, either to individuals or to the wider community via municipal waste disposal facilities.

3.3 Species for energy

Useful criteria for selecting species for fuel-wood in developing countries are that they should be:

• Preferably coppicing hardwoods
• Adapt well to the site conditions
• Easy to establish and require minimum care, especially where the establishment is by farmers in agroforestry situations.
• Readily available as seed or plants
• Grow rapidly with early culmination of current annual increment
• Have nitrogen-fixing ability
• Produce high-calorific wood, which burns without sparks or toxic smoke, splits easily and dries quickly. Usually they are moderate to high-density species.
• Have resistance to goat and wildlife damage, unless grown also for fodder
• Multiple-use species.

Stem straightness is not a criterion per se for fuelwood especially for non-industrial users; nor is always desirable to grow large sized trees, as this can make manual handling difficult. There is a wide range of species that meet many of the above criteria (National Academy of Sciences 1980, 1983; Nair 1993). Some 1200 species have been identified of which 700 were highly ranked.

Good examples of tropical multiple-purpose species that make excellent woodfuel, for both plantations and outside forests, are given in table 4. Yields, given good sites without long dry seasons and careful management, can be high for some species such as some of the eucalypts and acacias. However, for arid regions without irrigation, productivity will be low. Many of the species suitable for these drier sites are either shrubs or small trees. Some potential species are aggressive pioneers and can become weeds (e.g. Prosopis juliflora and some acacias). Most of the species listed in table 4 are moderate to high density and have calorific values over 4000 Kcal/kg. Often species used are those that have proved themselves and are sold as woodfuel in the area, rather than being newly introduced ones. Indeed some woodfuel plantings by state agencies in India have found difficulty in marketing exotics such as Leucena, Casuarina and Eucalyptus species.

3.4 Silvicultural aspects

Silviculture needs to be adapted to the situation, taking into account the species, biophysical aspects (climate, site, weeds) and social setting. For agroforestry-based plantings and small farmer woodlots, the actual silviculture should be simple and readily adopted by local people. The most important factors that need to be considered are species choice, seed or plant availability, perhaps local nursery production, spacing and layout, planting, initial weed control and animal control, if palatable. Big productivity gains can often be made if quality planting-stock are handled and planted carefully and subsequently kept weed-free in the early years. Subsequent management and biomass harvesting depends on the agroforestry system (Nair 1987, 1993).

Plantations or woodlots designed for energy usually use the coppice system, providing that the species sprout reliably. The coppice with standards is useful where there is a desire to provide some larger logs for construction or other purposes, as well as woodfuel.

With wood-fuel woodlots on farms, spacing often range from 1 to 3 m, planted on a square pattern. Closer spacing generally will produce the largest biomass of small piece size in the shortest possible time; wider spacings have the ability to produce larger piece size and will give more flexibility with rotation length without risking suppression of some stools. Wider spacings also allow for some crops or animal grazing beneath and may be more suited to arid regions. Occasionally irrigation is a possibility in some drier areas and if used along with weed control, will increase productivity substantially. Rotation length will vary with site and species and with coppicing species is related to ensuring stools are not suppressed. Typically rotation lengths range from 3 to 15 years.

For larger scale industrial plantings more intensive silviculture may be possible, provided it is economic. For example, for eucalypts it could follow those used in pulpwood plantations and aim to produce uniform high-producing crops (Turnbull 1999).

Practices could include:

• Active seed selection and breeding programmes.
• The use of advanced nursery techniques, including clonal systems.
• Intensive establishment with practices such as soil cultivation, good chemical weed control and fertilisers at planting.
• Control of pests and diseases.
• Rotation lengths of 5-10 years.
• Mechanised harvesting which, where sustainability is a priority, will leave behind nutrient-rich parts of the biomass and concentrate removal of woody biomass.

Such advanced practices offer the possibility of increasing productivity substantially. There has been considerable research in northern temperate countries that have illustrated this possibility with closely planted willows, poplars and alders grown on very short rotations (Christensson et al. 1993; Makeschin 1999). In a few situations irrigation may be a possibility, such as where waste water from sewage treatment plants is available.

Table 4: Useful woodfuel species for tropical developing countries (based on National Academy of Sciences 1980, 1983, Nair 1993, FAO 2000, FFRD, 1994).

Species	Zone	Use*	Yield m3/ha/yr	Energy kcal/kg	Other major Uses**
Acacia auriculiformis	Humid	Pl, AF	6.5-10-20	4600-4800	Pw, C, Sc, Ta, Or, Nf
Acacia decurrens	Highland/subtrop	Pl, AF	6-20	3500-3900	T, C, Ta
Acacia mangium	Humid	Pl, AF	8-19-40+	4800-4900	Pw, T, C, Nf, Sb
Acacia mearnsii	Highland/subtrop	Pl, AF	10-25	4700-7800	Ta, C, Gm, Pw, Nf
Acacia nilotica	Arid/semi-arid	AF	5	4800-4950	T, G, B, Fo, Ta
Acacia saligna	Arid/semi-arid	AF	1-10		Sc, G, Fo
Acacia senegal	Arid/semi-arid	AF	4-7	3200	T, C, G, F, Nf, B, Sc
Acacia tortilis	Arid/semi-arid	AF		4400	T, C, Sc, Fo, B
Albizia lebbek	Arid/semi-arid	Af	5	5200	T, Or, Fo, Sc, B
Alnus nepalensis	Highland	AF		4600	T, C, Fo, Sc, Nf
Calliandra calothyrsus	Humid	Pl, AF	5-20	4500-4750	Pw, C, Fo, B, Sc, Nf
Casuarina equisetifolia	Humid	Pl, Af	6-18	4800-4950	T, C, Pw, Sc, Ta, Nf
Dalbergia sissoo	Humid	Pl, Af	3-5-8	4900-5200	T, C, Sc, Or, Nf
Derris indica	Arid/semiarid	Af		4600	T, O, Fo, P, Sc, Fi
Eucalyptus camaldulensis	Arid/semiarid	Pl, Af	15-25	4800	T, C, B, Pw
Eucalyptus grandis	Humid	Pl	24-55	4700-4800	T, Pw, C, B
Eucalyptus globulus	Sub-tropics	Pl	10-30	4800	T, C, Pw, B, O
Gliricidia sepium	Humid	Pl, Af	10-15	4700-4900	T, C, Fo, Gm B, Or, Nf
Gmelina arborea	Humid	Pl	12-19-30+	4800	T, Pw, C, B
Grevillia robusta	Highland/subtrop.	Pl, Af	10-15		T, C, Or, B
Leucaena leucocephala	Humid	Pl, Af	20-40	4200-4600	T, Fo, Gm, Sc, F, Nf
Mangroves	Humid	Pl, Af		4000-4300	T, C, Sc, Pw, Ta
Melia azedarach	Highland	Af	5-10	4600-5200	T, Sc, P, Fo, Or
Mimosa scabrella	Humid	Pl, Af			Pw, Gm, Nf
Paraserianthes falcataria	Humid	Pl, Af	20-40	2900-3400	Pw, C, T
Pinus caribaea	Humid	Pl	10-40	4200	Pw, T
Prosopis sp.	Arid/semi-arid	Af	2-9	~5000	T, C, B, Fo, Sc, Nf
Terminalia catappa	Humid	Af			Pw, T, Ta, Sc, F
Ziziphus mauritiana	Arid/semi-arid	Af		4900	T, C, Fo, Ta
Ziziphus spina-christi	Arid/semi-arid	Af			T, Fo, Sc

* Pl - plantation and woodlots; Af - agroforestry

** B - bees; C - good charcoal; G - gum; Gm - green manure; F - food; Fo - fodder; Nf - nitrogen fixing; O-oil; Or - ornamental; P - pest control; Pw - pulpwood; Sc - soil conservation; T - timber; Ta - tannin

3.5 Social and environmental aspects

The problems that have arisen with woodfuel planting in the past, as discussed in section 2.4, suggest that to be successful greater attention needs to be given to social aspects. This is needed at all levels from policy development down to actual implementation of a programme (WEC 1999). In particular, biomass based rural energy development needs:

• Strong political commitment by government with clear energy policies
• People at the heart of planning and implementation
• Programmes that have a bottom-up approach and take account of social structures.
• Clearly defined responsibilities
• Integration with other needs and activities (e.g. agriculture, education, infrastructure) and methods of improving energy-use efficiency.

The economics of growing trees for woodfuel production are often clouded because it must compete with the high proportion of woodfuel collected and marketed from public lands without payment. In India woodfuel prices have been artificially low because prices of woodfuel from government land have often been fixed or subsidised (Ahmed 1997; Saxena 1997; Long and Nair 1999). The use of multi-purpose trees in agroforestry systems acknowledges that planting solely for woodfuel is uneconomic. Many countries have used subsidies to encourage new tree planting, both in plantations and on farms.

Tree planting for woodfuel may have positive environmental outcomes. Ahmed (1997), for example, stated that 35 percent of the natural forests of India have been badly degraded by woodfuel collection and that the country's forests are being exploited in excess of their regenerative capacity; there is often a lack of regeneration. Nutrient cycling may also be interfered with, if the pressure of collection is too great, and in extreme cases the forest is destroyed. The increased production coming from tree planting (Table 3) can therefore be seen in a positive light, particularly if the planting programme continues, even if at the present time these new plantations have not stemmed forest degradation. In Brazil legislation requires that charcoal be produced from plantations rather than taken from natural forests (Turnbull 1999). Increased tree planting may thus act as a conservation tool.

Another benefit of using sustainable woodfuel plantations is that they do not add to the increasing atmospheric carbon dioxide level. Hence their use are preferable to fossil fuels. Other possible added environmental benefits include land rehabilitation, erosion control and watershed maintenance.

On the negative side there been criticism around the choice of species (e.g. eucalypts) and the impacts of forest monocultures. Some of this criticism was really about social, rather than environmental factors (Turnbull 1999). Cannell (1999) in his review of the effects of monocultural plantations on water use, acidification, wildlife conservation, and carbon storage, suggested that these are usually relatively minor, or of concern in specific situations. The continual collection of leaves and twigs, both of which tend to be high in nutrients, and the long-term use of short-rotation coppice poses a real risk of nutrient depletion. This will be particularly acute on low fertility sites. Currently, for example, very many eucalypt plantations have sub-optimal nutrition and there are particular concerns with the removal of P, K, Ca, and Mg, even with normal harvesting (Turnbull 1999). Returning the ash to the forest would assist. The use of N-fixing species, while important for the N status of the site, does not help the availability of other nutrients.