Acacia mearnsii de Wild

Uses

Tree of economic importance in South and East Africa, Rhodesia, India, and Rio Grande do Sul area of South America etc. for tanning of soft-leather. Ranging from 30–54 percent tannin in dried bark. Wood furnishes badly needed fuel and building material in some areas. Trees not only provide tannin and fuel, but also add nitrogen and organic material to improve the soil. Bark is used for wood adhesives and flotation agents (Duke, 1981a). The pulp is suitable for wrapping paper and hardboard. Some regard it as an attractive ornamental. Sometimes used for erosion control on poor sloping soils unsuitable for agriculture. Densely packed plantations are effective in preventing further erosion on 50° slopes. Some farmers claim that tobacco and vegetable yields are doubled in rotating with the black wattle. In places it is regarded as a "green cancer", spreading vigorously as a weed (NAS, 1980; Little, 1983).

Folk Medicine

Products are often used in folk medicine as styptics or astringents (Duke, 1981).

Chemistry

Black wattle bark contains (-)-robinetinidol and (+)-catechin; the biflavonoids (-)-fisetinidol-(+)-catechin (2 diastereoisomers), (-)-robinetinidol-(+)-catechin and (-)-robinetinidol-(+)-gallocatechin; triflavonoids and condensed tannins. The heartwood is rich in (+)-leucofisetinidin (mollisacacidin) together with (-)-fisetinidol, (+)-fustin, butin, fisetin, butein, and biflavonoid condensates (tannins) (Duke, 1981).

Description

Tree 6 to 20 m tall, 10 to 60 cm in diameter; crown conical or rounded; all parts except flowers usually pubescent or puberulous; stems without spines or prickles; leaves bipinnate, on petioles 1.5–2.5 cm long, with a gland above; rachis 4–12 cm long with numerous raised glands all along its upper side; pinnae in 8–30 pairs, pinnules in 16–70 pairs, linear-oblong, 1.5–4 mm long, 0.5–0.75 min wide; flowers in globose heads 5–8 mm in diameter, borne in panicles or racemes, on peduncles 2–6 mm long; pale yellow and fragrant; pods gray-puberulous, or sometimes glabrous, almost moniliform, dehiscing, usually 3–10 cm long, 0.5–0.8 cm wide, with 3–14 joints; seeds black, smooth, elliptic or compressed ovoid, 3–5 mm long, 2–3.5 mm wide; caruncle conspicuous; areole 3.5 mm long, 2 mm wide. Seeds 66,000 to 110,000/kg (Duke, 1981a).

Germplasm

Can be crossed with Acacia decurrens, hybrids show more sterility than parents. Meiosis is regular, with no gross cytological abnormalities, and sterility may be due to gene differentiation between species. There is little geographic overlap in the native Australian ranges of the species, and there are differences in phenology (flowering; seedset). Most of the characters that vary among the species are quantitative. The development of black wattle strains or of hybrids with enhanced vigor, better quality bark, outstanding stem form, or resistance to insect pests and disease would benefit the wattle industry. Assigned to the Australian Center of Diversity, black wattle or cvs thereof is reported to exhibit tolerance to drought, laterite, and poor soil (Duke, 1981). For an Acacia, it is relatively tolerant to frost, and its growth is slowed by high temperatures. (2n = 26.)

Distribution

Native to Southeast Australia (Victoria to New South Wales and southern Queensland) and Tasmania. Introduced and cultivated widely for afforestations. See Sherry (1971) for details.

Ecology

In Kenya grows on or near Equator at altitudes of 2,000–2,800 m, is well adjusted to the climate of East Africa. Grows well at 30°S Lat. in South America on rolling terrain at altitudes of 50–70 m. Thrives on poor, dry soils but favors deeper, moister, more fertile soils. In Australia, black wattle may occur on soils derived from shales, mudstones, sandstones, conglomerates, and alluvial deposits. In Kenya on podsols, krasnozems, sandy hills, lava flows or on mixtures of lava and contemporaneous volcanic tuffs and breccias. In South America, grown on red clay or sandy soils that have suffered from severe erosion and soil depletion (ferruginous clay loams with little or no free silica). In East Africa grows where annual rainfall is 1,041–1,321 mm, (about 75% between April and September). On the equator where black wattle is grown in South America, the rain pattern is nearly opposite, mean annual temperature range is 17–23°C; there is little seasonal variation, but considerable diurnal variation. At higher altitudes in South America, frost is a risk and heavy snows may break tree limbs. Tannin content varies inversely with precipitaton. Ranging from Warm Temperate Dry through Tropical Thorn to Tropical Moist Forest Life Zones, black wattle is reported to tolerate annual precipitation of 6.6–22.8 dm (mean of 6 cases=12.6), annual mean temperature of 14.7–27.8°C (mean of 6 cases=2.6°C), and pH of 5.0–7.2 (mean of 5 cases = 0.5).

Cultivation

Propagation by seed is easy. Seeds retain their viability for several years. For germination seed are covered with boiling water and allowed to stand until cool. This cracks the hard outer coat and facilitates germination. Seeds may be broadcast or sown in rows on any barren site. Usually they are sown about 5 cm apart in seedbeds, and are transplanted after 3–6 months. In South America, fields are usually plowed and harrowed in April or May. Seedlings are set out May–November, but usually in winter, June–August, after a rain. Plants are spaced 2 m each way, at rate of 2,500/ha. Propagation by cuttings is almost impossible without mist. Air layering is more promising. Two types of farmers grow acacia: the tanner or business man plants 200 ha or so entirely to black wattle, usually one section at a time so that he can plant and harvest within the same year and continue year after year; the farmer plants half or less of his land to black wattle and the rest to crops such as corn, beans, maniac, sugarcane, other vegetables, or pasture. He plants 2–6 hectares of acacian each year and thus evenly distributes work and production. Oxen may be useful for plowing, but most work is by hand. Usually only plows and hoes are used in Cultivation. Intercrops may be grown the first year during which trees grow about 4–5 m in height, and about 2.5 cm in diameter (Duke, 1981).

Harvesting

Trees provide bark 5–10 years after seeding (avg 7). Bark is stripped from lower part of tree, then tree is felled, the remaining bark removed, and tree and bark are cut into 1 m lengths. Thoroughly dried bark is arranged in bales of 75 to 80 kg when ready for transportation. Tanning power improves by 10–15% in bark carefully stored for a season. Percent tannin does not differ between barks harvested in dry and wet seasons. However, the amount of bark on trees may be less on poor than on rich soils. Tannin runs about 25–35% per kilo of dried bark, on either poor or rich soil. Acacia bark may be sold as baled bark, or bark powder. Dried bark may go first to commercial bark processors where it is ground or shredded in a hammermill, then sold in 40-kg sacks. Bark powder is sold in 60-kg sacks. Liquid extract is sold in 300-kg wooden barrels. In Rio Grande do Sul an estimated 5,000 MT of liquid extract is produced annually (Duke, 1981a).

Yields and Economics

Except for some mangrove species, black wattle in pure stand produces more tannin per hectare than most tanniniferous plants. In South Africa well-managed have produced the equivalent of 3 MT/ha tannin, about twice the average, when grown in rotations in excess of 12 years. One 7-yr-old tree produces 3–5 kg of dried bark. Twelve trees produce 1 cu m of firewood. The wood of debarked trees is dried and used for mine timbers, pulpwood, and fuel. Moisture loss is rapid in first 4 weeks after felling, then much slower. Wood weighs 708.7 kg/cu m. One tree can produce up to 10 cwt of bark or about 5 cwt stripped. One ton of black wattle bark is sufficient to tan 2,530 hides, best adapted for sole leather and other heavy goods; the leather is fully as durable as that tanned with oak bark. One ton of bark yields 4 cwt of extract tar. Destructive distillation of the wood yields 33.2% charcoal, 9.5% lime acetate, and 0.81 methyl alcohol. As a source of vegetable tannin, black wattle shares with quebracho and chestnut a large portion of the world market for vegetable tannins. According to Sherry (1971), plantation grown wattle in South Africa, Rhodesia, Tanzania, Kenya, and Brazil supplied about 38% of world demand for tannin. South Africa was the largest producer, with annual output of 72,000 MT of ca 120,000 MT on the world market. Eucalyptus grandis produces more wood than wattle, but it is inferior for fuel and charcoal. At one time in South Africa, 56% of the proceeds from wattle was from bark, the balance from timber (Duke, 1981a).

Energy

An efficient N-fixer, it is reported to annually yield 21–28 MT/ha wet leaves containing 245–285 kg N. If we put the information in our cultivation paragraph and our yields paragraph, we find the improbable 2,500 plants per hectare, with 12 producing 1 m³ firewood, suggesting a potential of more than 200 m³/ha for 7 year old trees, suggesting annual yields of ca 30 m³/ha. NAS (1980a) reports annual thickwood production of 10–25 m°3/ha and bark production of 0.8–4.0 MT. The dense wood (sp. grav. = 0.7–0.85) 3,500–4,000 kcal/kg (oven-dry Indonesian specimens 4,650 kcal/kg), its ash content ca 1.5%. The charcoal (sp. grav. = 0.3–0.5) has a calorific value of 6,600 kcal/kg, with an ash content of 0.4%.

Biotic Factors

The most serious disease is disback, caused by Phoma herbarum. Other fungi attacking black wattle include: Chaetomium cochliodes, Daldinia sp., and Trichoderma viride. In Rio Grande do Sul, disease and insects cause about 20% loss of trees. Principal insects attacking Brazilian wattle are Molippa sabina, Achryson surinamum, Placosternus cyclene, Eburodacrys dubitata, Neoclytus pusillus, Oncideres impluviata, Oncideres saga, and Trachyderes thoracica. Ants, termites, and borers are the most damaging. The sauva ant which attacks the leaves is fought constantly with arsenicals and carbon disulfide. Nematodes reported on this species include Meloidogyne arenaria, M. incognita acrita, and M. javanica (Golden, pers. commun. 1984).

References

• Duke, J.A. 1981a. Handbook of legumes of world economic importance. Plenum Press. NewYork.
  
• Little, E.L. Jr. 1983. Common fuelwood crops: a handbook for their identification. McClain Printing Co., Parsons, WV.
  
• NAS, 1980.
  
• N.A.S. 1980a. Firewood crops. Shrub and tree species for energy production. National Academy of Sciences, Washington, DC.
  
• Sherry, S.P. 1971. The black wattle (Acacia mearnsii de Wild.). University of Natal Press. Pietermatitzburg.

Acacia mearnsii de Wild

Uses

Tree of economic importance in South and East Africa, Rhodesia, India, and Rio Grande do Sul area of South America etc. for tanning of soft-leather. Ranging from 30–54 percent tannin in dried bark. Wood furnishes badly needed fuel and building material in some areas. Trees not only provide tannin and fuel, but also add nitrogen and organic material to improve the soil. Bark is used for wood adhesives and flotation agents (Duke, 1981a). The pulp is suitable for wrapping paper and hardboard. Some regard it as an attractive ornamental. Sometimes used for erosion control on poor sloping soils unsuitable for agriculture. Densely packed plantations are effective in preventing further erosion on 50° slopes. Some farmers claim that tobacco and vegetable yields are doubled in rotating with the black wattle. In places it is regarded as a "green cancer", spreading vigorously as a weed (NAS, 1980; Little, 1983).

Folk Medicine

Products are often used in folk medicine as styptics or astringents (Duke, 1981).

Chemistry

Black wattle bark contains (-)-robinetinidol and (+)-catechin; the biflavonoids (-)-fisetinidol-(+)-catechin (2 diastereoisomers), (-)-robinetinidol-(+)-catechin and (-)-robinetinidol-(+)-gallocatechin; triflavonoids and condensed tannins. The heartwood is rich in (+)-leucofisetinidin (mollisacacidin) together with (-)-fisetinidol, (+)-fustin, butin, fisetin, butein, and biflavonoid condensates (tannins) (Duke, 1981).

Description

Tree 6 to 20 m tall, 10 to 60 cm in diameter; crown conical or rounded; all parts except flowers usually pubescent or puberulous; stems without spines or prickles; leaves bipinnate, on petioles 1.5–2.5 cm long, with a gland above; rachis 4–12 cm long with numerous raised glands all along its upper side; pinnae in 8–30 pairs, pinnules in 16–70 pairs, linear-oblong, 1.5–4 mm long, 0.5–0.75 min wide; flowers in globose heads 5–8 mm in diameter, borne in panicles or racemes, on peduncles 2–6 mm long; pale yellow and fragrant; pods gray-puberulous, or sometimes glabrous, almost moniliform, dehiscing, usually 3–10 cm long, 0.5–0.8 cm wide, with 3–14 joints; seeds black, smooth, elliptic or compressed ovoid, 3–5 mm long, 2–3.5 mm wide; caruncle conspicuous; areole 3.5 mm long, 2 mm wide. Seeds 66,000 to 110,000/kg (Duke, 1981a).

Germplasm

Can be crossed with Acacia decurrens, hybrids show more sterility than parents. Meiosis is regular, with no gross cytological abnormalities, and sterility may be due to gene differentiation between species. There is little geographic overlap in the native Australian ranges of the species, and there are differences in phenology (flowering; seedset). Most of the characters that vary among the species are quantitative. The development of black wattle strains or of hybrids with enhanced vigor, better quality bark, outstanding stem form, or resistance to insect pests and disease would benefit the wattle industry. Assigned to the Australian Center of Diversity, black wattle or cvs thereof is reported to exhibit tolerance to drought, laterite, and poor soil (Duke, 1981). For an Acacia, it is relatively tolerant to frost, and its growth is slowed by high temperatures. (2n = 26.)

Distribution

Native to Southeast Australia (Victoria to New South Wales and southern Queensland) and Tasmania. Introduced and cultivated widely for afforestations. See Sherry (1971) for details.

Ecology

In Kenya grows on or near Equator at altitudes of 2,000–2,800 m, is well adjusted to the climate of East Africa. Grows well at 30°S Lat. in South America on rolling terrain at altitudes of 50–70 m. Thrives on poor, dry soils but favors deeper, moister, more fertile soils. In Australia, black wattle may occur on soils derived from shales, mudstones, sandstones, conglomerates, and alluvial deposits. In Kenya on podsols, krasnozems, sandy hills, lava flows or on mixtures of lava and contemporaneous volcanic tuffs and breccias. In South America, grown on red clay or sandy soils that have suffered from severe erosion and soil depletion (ferruginous clay loams with little or no free silica). In East Africa grows where annual rainfall is 1,041–1,321 mm, (about 75% between April and September). On the equator where black wattle is grown in South America, the rain pattern is nearly opposite, mean annual temperature range is 17–23°C; there is little seasonal variation, but considerable diurnal variation. At higher altitudes in South America, frost is a risk and heavy snows may break tree limbs. Tannin content varies inversely with precipitaton. Ranging from Warm Temperate Dry through Tropical Thorn to Tropical Moist Forest Life Zones, black wattle is reported to tolerate annual precipitation of 6.6–22.8 dm (mean of 6 cases=12.6), annual mean temperature of 14.7–27.8°C (mean of 6 cases=2.6°C), and pH of 5.0–7.2 (mean of 5 cases = 0.5).

Cultivation

Propagation by seed is easy. Seeds retain their viability for several years. For germination seed are covered with boiling water and allowed to stand until cool. This cracks the hard outer coat and facilitates germination. Seeds may be broadcast or sown in rows on any barren site. Usually they are sown about 5 cm apart in seedbeds, and are transplanted after 3–6 months. In South America, fields are usually plowed and harrowed in April or May. Seedlings are set out May–November, but usually in winter, June–August, after a rain. Plants are spaced 2 m each way, at rate of 2,500/ha. Propagation by cuttings is almost impossible without mist. Air layering is more promising. Two types of farmers grow acacia: the tanner or business man plants 200 ha or so entirely to black wattle, usually one section at a time so that he can plant and harvest within the same year and continue year after year; the farmer plants half or less of his land to black wattle and the rest to crops such as corn, beans, maniac, sugarcane, other vegetables, or pasture. He plants 2–6 hectares of acacian each year and thus evenly distributes work and production. Oxen may be useful for plowing, but most work is by hand. Usually only plows and hoes are used in Cultivation. Intercrops may be grown the first year during which trees grow about 4–5 m in height, and about 2.5 cm in diameter (Duke, 1981).

Harvesting

Trees provide bark 5–10 years after seeding (avg 7). Bark is stripped from lower part of tree, then tree is felled, the remaining bark removed, and tree and bark are cut into 1 m lengths. Thoroughly dried bark is arranged in bales of 75 to 80 kg when ready for transportation. Tanning power improves by 10–15% in bark carefully stored for a season. Percent tannin does not differ between barks harvested in dry and wet seasons. However, the amount of bark on trees may be less on poor than on rich soils. Tannin runs about 25–35% per kilo of dried bark, on either poor or rich soil. Acacia bark may be sold as baled bark, or bark powder. Dried bark may go first to commercial bark processors where it is ground or shredded in a hammermill, then sold in 40-kg sacks. Bark powder is sold in 60-kg sacks. Liquid extract is sold in 300-kg wooden barrels. In Rio Grande do Sul an estimated 5,000 MT of liquid extract is produced annually (Duke, 1981a).

Yields and Economics

Except for some mangrove species, black wattle in pure stand produces more tannin per hectare than most tanniniferous plants. In South Africa well-managed have produced the equivalent of 3 MT/ha tannin, about twice the average, when grown in rotations in excess of 12 years. One 7-yr-old tree produces 3–5 kg of dried bark. Twelve trees produce 1 cu m of firewood. The wood of debarked trees is dried and used for mine timbers, pulpwood, and fuel. Moisture loss is rapid in first 4 weeks after felling, then much slower. Wood weighs 708.7 kg/cu m. One tree can produce up to 10 cwt of bark or about 5 cwt stripped. One ton of black wattle bark is sufficient to tan 2,530 hides, best adapted for sole leather and other heavy goods; the leather is fully as durable as that tanned with oak bark. One ton of bark yields 4 cwt of extract tar. Destructive distillation of the wood yields 33.2% charcoal, 9.5% lime acetate, and 0.81 methyl alcohol. As a source of vegetable tannin, black wattle shares with quebracho and chestnut a large portion of the world market for vegetable tannins. According to Sherry (1971), plantation grown wattle in South Africa, Rhodesia, Tanzania, Kenya, and Brazil supplied about 38% of world demand for tannin. South Africa was the largest producer, with annual output of 72,000 MT of ca 120,000 MT on the world market. Eucalyptus grandis produces more wood than wattle, but it is inferior for fuel and charcoal. At one time in South Africa, 56% of the proceeds from wattle was from bark, the balance from timber (Duke, 1981a).

Energy

An efficient N-fixer, it is reported to annually yield 21–28 MT/ha wet leaves containing 245–285 kg N. If we put the information in our cultivation paragraph and our yields paragraph, we find the improbable 2,500 plants per hectare, with 12 producing 1 m³ firewood, suggesting a potential of more than 200 m³/ha for 7 year old trees, suggesting annual yields of ca 30 m³/ha. NAS (1980a) reports annual thickwood production of 10–25 m°3/ha and bark production of 0.8–4.0 MT. The dense wood (sp. grav. = 0.7–0.85) 3,500–4,000 kcal/kg (oven-dry Indonesian specimens 4,650 kcal/kg), its ash content ca 1.5%. The charcoal (sp. grav. = 0.3–0.5) has a calorific value of 6,600 kcal/kg, with an ash content of 0.4%.

Biotic Factors

The most serious disease is disback, caused by Phoma herbarum. Other fungi attacking black wattle include: Chaetomium cochliodes, Daldinia sp., and Trichoderma viride. In Rio Grande do Sul, disease and insects cause about 20% loss of trees. Principal insects attacking Brazilian wattle are Molippa sabina, Achryson surinamum, Placosternus cyclene, Eburodacrys dubitata, Neoclytus pusillus, Oncideres impluviata, Oncideres saga, and Trachyderes thoracica. Ants, termites, and borers are the most damaging. The sauva ant which attacks the leaves is fought constantly with arsenicals and carbon disulfide. Nematodes reported on this species include Meloidogyne arenaria, M. incognita acrita, and M. javanica (Golden, pers. commun. 1984).

References

• Duke, J.A. 1981a. Handbook of legumes of world economic importance. Plenum Press. NewYork.
  
• Little, E.L. Jr. 1983. Common fuelwood crops: a handbook for their identification. McClain Printing Co., Parsons, WV.
  
• NAS, 1980.
  
• N.A.S. 1980a. Firewood crops. Shrub and tree species for energy production. National Academy of Sciences, Washington, DC.
  
• Sherry, S.P. 1971. The black wattle (Acacia mearnsii de Wild.). University of Natal Press. Pietermatitzburg.

Acacia cyclops A. Cunn. ex G. Don

Uses

Producing a dense high quality firewood, this species has been recommended for stabilization of coastal dunes. Goats and antelope browse the phyllodes. The seeds and their oily funicles are eaten by birds, primates, and rodents, and if crushed, might be suitable for cattle.

Folk Medicine

With its high tannin content, the species could serve as an astringent.

Chemistry

Bark has yielded 6.5% tannin, or in Natal, up to 12.1%. Seed contains 10% of fixed oil, the aril or funicle 40%.

Description

Dense, evergreen bushy shrub, often multistemmed, or small tree 3 to 8 m tall, with a rounded crown . In windy coastal sites it forms a hedge less than 0.5 m high. The foliage comprises light green phyllodes, varnished when young, and growing in a downward vertical position. Pods, maturing in summer, are not shed, but remain on the tree, exposing the seeds to predators and dispersers.

Germplasm

Reported from the Australian Center of Diversity, Acacia cyclops is reported to tolerate drought, salt, sand, weed, and wind.

Distribution

Native to southwestern Australia, where it grows mostly on coastal sand dunes. Used for stabilization in South Africa, it is spreading on sand and sandstone into coastal bush and heathland. This is an extremely weedy species spread by birds into indigenous vegetation. Once established, it is difficult to remove or replace. There is little vegetation cover beneath an Acacia cyclops thicket. The seeds remain viable in the soil for many years. It is relatively slow growing.

Ecology

Acacia cyclops can grow in dry areas with annual precipitation less than 300 mm. Tolerating salt spray, wind, sand-blast, or salinity, it is useful for dune stabilization. This species has a high light demand; it will not survive in deep shade. Monthly temperature means within the distribution range of this species vary from 5°C in winter to 31°C in summer. It is slightly resistant to frost. The species is generally found below 300 m altitude where annual rainfall is 200 to 800 mm. It grows on quartzitic or calcareous sand or limestone. It also is found in drier sites such as dune crests (NAS, 1980a).

Cultivation

Direct sowing of pretreated seed is recommended (NAS, 1980a). Seed are treated with abrasion, acid, and hot water treatment.

Harvesting

Trees may be harvested as needed. This species rarely coppices, and mature trees do not survive felling. The pods are nondeciduous and are therefore not easily gathered. Unlike many Acacia species, it is not considered a valuable tannin or gum producer (NAS, 1980a).

Yields and Economics

Standing biomass of Acacia cyclops in the southwestern cape of Africa, where it is replacing indigenous Fynbos vegetation and coastal shrub communities, was 131 MT/ha. Of this, the litterfall was said to represent 7.4% of the total biomass, 21.2% of the canopy mass.

Energy

Recommended by the NAS (1980a) as a firewood source. The wood is dense, the logs rarely exceeding 20 cm in diameter. It is a very popular firewood in South Africa, sold regularly in Cape Town. The annual litterfall of four Acacia species naturalized in the South African Cape, comprising 60% foliage and 30% reproductive structures, averages 7 MT/ha, double the value expected in evergreen scrub communities in winter rainfall regions. Standing biomass in the Acacia thickets is ca 10 times greater than that of mature Fynbos (11–26 MT/ha) and shrublands in other Mediterranean climates (15–30 MT/ha). Acacias lose ca 10% of their standing crop annually as litter, at a rate 3–4 times that of the Mediterranean heath and shrub communities. The litter accumulates on the ground. In a mature thicket, the dry mass of the ground litter per unit area exceeds that of the living canopy. The ground litter layer runs 14–28 MT/ha, which is fairly average by world standards. "The annual nitrogen and phosphorus input by Acacia litter should be about nine times as great per unit area as that of Fynbos." Assuming an N content of 1.5% and a P content of 1.13%, Acacia litter would contribute 105 kg N/ha and 92 kg P. In an area where the annual precipitation averages between 500 and 750 mm/yr and the annual temperature average ranges between 16 and 18°C, with radiation averaging 450–500 Langleys/day (Capetown has an average annual precipitation of ca 600 mm, average temperature approaching 18°C), the total annual litterfall is 9,680 kg/ha, with 1.4% as flowers, 35.5% as pods, 5.3% as seed, 11.3% as twigs, 39.0% as phyllodes, and 7.7% unidentified fragments. The total standing biomass was 131 MT/ha DM, ˜±4% (Milton, 1981).

Biotic Factors

Most African Acacias are thought to be cross pollinated. Pests and diseases are not an important factor in South Africa; in fact, the lack of seed destroyers is partly responsible for the weediness of the species. Grazers may damage seedlings.

References

• N.A.S. 1980a. Firewood crops. Shrub and tree species for energy production. National Academy of Sciences, Washington, DC.
  
• Milton, S.J. 1981. Litterfall. of the exotic acacias in the southeastern cape. J. S. Afr. Bot. 47(2):147-155.

Acacia cyclops A. Cunn. ex G. Don

Uses

Producing a dense high quality firewood, this species has been recommended for stabilization of coastal dunes. Goats and antelope browse the phyllodes. The seeds and their oily funicles are eaten by birds, primates, and rodents, and if crushed, might be suitable for cattle.

Folk Medicine

With its high tannin content, the species could serve as an astringent.

Chemistry

Bark has yielded 6.5% tannin, or in Natal, up to 12.1%. Seed contains 10% of fixed oil, the aril or funicle 40%.

Description

Dense, evergreen bushy shrub, often multistemmed, or small tree 3 to 8 m tall, with a rounded crown . In windy coastal sites it forms a hedge less than 0.5 m high. The foliage comprises light green phyllodes, varnished when young, and growing in a downward vertical position. Pods, maturing in summer, are not shed, but remain on the tree, exposing the seeds to predators and dispersers.

Germplasm

Reported from the Australian Center of Diversity, Acacia cyclops is reported to tolerate drought, salt, sand, weed, and wind.

Distribution

Native to southwestern Australia, where it grows mostly on coastal sand dunes. Used for stabilization in South Africa, it is spreading on sand and sandstone into coastal bush and heathland. This is an extremely weedy species spread by birds into indigenous vegetation. Once established, it is difficult to remove or replace. There is little vegetation cover beneath an Acacia cyclops thicket. The seeds remain viable in the soil for many years. It is relatively slow growing.

Ecology

Acacia cyclops can grow in dry areas with annual precipitation less than 300 mm. Tolerating salt spray, wind, sand-blast, or salinity, it is useful for dune stabilization. This species has a high light demand; it will not survive in deep shade. Monthly temperature means within the distribution range of this species vary from 5°C in winter to 31°C in summer. It is slightly resistant to frost. The species is generally found below 300 m altitude where annual rainfall is 200 to 800 mm. It grows on quartzitic or calcareous sand or limestone. It also is found in drier sites such as dune crests (NAS, 1980a).

Cultivation

Direct sowing of pretreated seed is recommended (NAS, 1980a). Seed are treated with abrasion, acid, and hot water treatment.

Harvesting

Trees may be harvested as needed. This species rarely coppices, and mature trees do not survive felling. The pods are nondeciduous and are therefore not easily gathered. Unlike many Acacia species, it is not considered a valuable tannin or gum producer (NAS, 1980a).

Yields and Economics

Standing biomass of Acacia cyclops in the southwestern cape of Africa, where it is replacing indigenous Fynbos vegetation and coastal shrub communities, was 131 MT/ha. Of this, the litterfall was said to represent 7.4% of the total biomass, 21.2% of the canopy mass.

Energy

Recommended by the NAS (1980a) as a firewood source. The wood is dense, the logs rarely exceeding 20 cm in diameter. It is a very popular firewood in South Africa, sold regularly in Cape Town. The annual litterfall of four Acacia species naturalized in the South African Cape, comprising 60% foliage and 30% reproductive structures, averages 7 MT/ha, double the value expected in evergreen scrub communities in winter rainfall regions. Standing biomass in the Acacia thickets is ca 10 times greater than that of mature Fynbos (11–26 MT/ha) and shrublands in other Mediterranean climates (15–30 MT/ha). Acacias lose ca 10% of their standing crop annually as litter, at a rate 3–4 times that of the Mediterranean heath and shrub communities. The litter accumulates on the ground. In a mature thicket, the dry mass of the ground litter per unit area exceeds that of the living canopy. The ground litter layer runs 14–28 MT/ha, which is fairly average by world standards. "The annual nitrogen and phosphorus input by Acacia litter should be about nine times as great per unit area as that of Fynbos." Assuming an N content of 1.5% and a P content of 1.13%, Acacia litter would contribute 105 kg N/ha and 92 kg P. In an area where the annual precipitation averages between 500 and 750 mm/yr and the annual temperature average ranges between 16 and 18°C, with radiation averaging 450–500 Langleys/day (Capetown has an average annual precipitation of ca 600 mm, average temperature approaching 18°C), the total annual litterfall is 9,680 kg/ha, with 1.4% as flowers, 35.5% as pods, 5.3% as seed, 11.3% as twigs, 39.0% as phyllodes, and 7.7% unidentified fragments. The total standing biomass was 131 MT/ha DM, ˜±4% (Milton, 1981).

Biotic Factors

Most African Acacias are thought to be cross pollinated. Pests and diseases are not an important factor in South Africa; in fact, the lack of seed destroyers is partly responsible for the weediness of the species. Grazers may damage seedlings.

References

• N.A.S. 1980a. Firewood crops. Shrub and tree species for energy production. National Academy of Sciences, Washington, DC.
  
• Milton, S.J. 1981. Litterfall. of the exotic acacias in the southeastern cape. J. S. Afr. Bot. 47(2):147-155.

Acacia auriculiformis A. Cunn.

Uses

Used for fuelwood plantations as an ornamental and shade tree, quite tolerant of heat, the Australian species is widely planted in Oceana and southeast Asia. The wood is also employed for making farm tools and furniture (NAS, 1983a). Recent Australian tests suggest that 10-year old trees can be pulped readily by the sulfate process, giving high pulp yields, with good strength properties. Also produces high quality pulp by the neutral sulfite semichemical process. The tannin produces a good quality leather, inclined to redden upon exposure to sunlight (NAS, 1980a). The plant is amazing in its ability to recolonize wastes, papermill sludge, pH ca 9.5; even uranium spoils, pH ca 3.0; the only tree found on 20-year old uranium spoil. Used for the cultivation of the lac insect in India.

Folk Medicine

No data available.

Chemistry

The gum contains 5.3% ash, 0.92% N, and 1.68% methoxyl, and ca 27.7% uronic acid. The sugar from the gum after hydrolysis, contained 10.1% 4-0-methylglucuronic acid, 17.6% glucuronic acid, 59% galactose, 8% arabinose, and 5% rhamnose (Anderson, 1978). Bark contains ca 13% water.

Description

Resilient, vigorously growing, crooked or gnarled deciduous or evergreen tree, possibly attaining 30 m height, 60 cm DBH. Leaves alternate, simple flattened phyllodes, lanceolate or oblong, arcuate, long-attenuate at both ends, 10–16 cm long, ca 1.5–2.5 cm broad, thick coriaceous, glabrous with several long parallel veins from the base. Spikes 5–8 cm long, paired at the leaf bases. Flowers sessile, ca 3 mm long, the calyx glabrous, 5-toothed, the 5 petals ca 2 mm long. Stamens numerous, filiform, ca 3 mm long. Ovary pubescent, the style filiform. Pods 6–8 cm long, 1–1.5 cm broad, flattened but coiled. Seeds several, flattened-ellipsoid, ca 5 mm long, with a reddish or orangish aril (Little, 1983). Seeds 53,000–62,000/kg.

Germplasm

Reported from the Australian Center of Diversity, Acacia auriculiformis, or cvs thereof, is reported to tolerate alkalinity, desiccation, drought, fire, high pH, laterite, poor soil, sand dunes, and savanna. It is intolerant of hurricane, shade, and weeds, at least in early stages. Once established, the tree is quite competitive with weeds. Though somewhat tolerant of fire, it is not so resistant as Eucalyptus. (2n = 26)

Distribution

Native to the savannas of New Guinea, islands of the Torres Strait, and northern Australia, it has been widely introduced, e.g. in Fiji, India, Indonesia, Java, Malaysia, Niger, Nigeria, Philippines, Tanzania, Thailand, the Soloman Islands, Uganda, and Zanzibar.

Ecology

Estimated to range from Subtropical Moist to Wet through Tropical Dry to Wet Forest Life Zones, Acacia auriculiformis is reported to tolerate annual precipitation of 7.5 to 27 dm, annual temperature of 26 to 30°C, and pH of 3.0 to 9.5. With practically no maintenance it will grow on a wide range of deep and shallow soils, compacted clays, coral soils, laterites, limestone, mica schist, mine spoil, podzols, even sand dunes and unstable slopes.

Cultivation

It has been suggested as an interplant with long-term timber Dalbergias, itself serving as a short-term but renewable firewood source. Seeds, storable for 18 months in airtight containers, should be soaked in hot water for 24 hours. Sow in full light, allowing 6 days for germination (ca 80% germination after 2–4 weeks). To reforest grassland, burn and plant in holes ca 36 x 30 x 30 cm, spaced at 1–2.5 or 1–3 m if intercropped with Cassia siamea. Recent spacings have been 2.5 x 2.5 m.

Harvesting

In Indomalaysia, stands are operated on 10–12 year rotations. Trees coppice poorly. Indonesians have gotten some coppice when trees are cut at least 50 cm above the ground. When trees are felled, there is usually a swarm of seedlings, so cutover stands regenerate readily.

Yields and Economics

With rainfall at 2700 mm, at 3 years, average height of a stand with 1010 trees/ha was 12.4 m, average diameter 12.2 cm, standing wood volume 73.2 m³/ha; at age 4, 13.1 m, 13.6 cm, and 96.1 m³/ha. Stemwood volume is ca 60% of total above ground biomass. Leaf biomass is important, the LAI being 7–8, good for shading out weeds. Average amount of dead litter is 4800 kg/ha. In Java, there may be 3 MT/ha leaves and 2 MT/ha twigs and branches beneath the trees (NAS, 1982a). On infertile abandoned sites in Papua, trees grew 6 m in 2 years, 17 m in 8 years. On shallow arid soils in West Bengal, yields were only 5m³/ha/yr at the 15th year. Under moister conditions 10 m³ is reported, 17–20 in Indonesia and Malaysia.

Energy

Wiersum and Ramlan report that yields can run higher than 20 m³/ha/yr on a 10–20 year rotation. On poor soils yields drop to 8–12 m³. On the Island of Madura, with annual rainfall 1700–1900 mm, 7–12 year old rotations run 7.6–9 m³/ha/yr, but on West Bengalese laterites with annual precipitation 1,000–14,000 mm, yields are only 2–6 m³/ha/yr in 10–20 year rotations. With its capacity to produce good fuelwood on poor soils, even where there are extended dry seasons, the species "merits large scale testing as a fuelwood species" (NAS, 1980). Wood has specific gravity of 0.6–0.75 and calorific value of 4,800–4,900 kcal/kg. Wood yields excellent charcoal that glows well and burns without smoke or sparks. Litter beneath the trees, both branches and dried leaves, annually adds up to 4.5–6 MT/ha, all used for fuel in China. Hawaiian grown material possesses N-fixing nodules.

Biotic Factors

While no pest or disease problems are reported in Indonesia, insects and nematodes have been reported to attack seedlings in Zanzibar. The rust Uromyces digitatus has been a problem in Java, where it is also occasionally infested with a rather inocuous black mildew, Meliola adenanphererae. In India, the root rots are Ganoderma lucidum and Ganoderma applanatum. Hypothenemus dimorphus has caused shoot fatality in Malaysia. The weevil Hypomeces squamosus can be a pest in India and Malaysia. Used to cultivate Kerria lacca in India. On Java, the ant Iridomyrmex rufoniger may protect the plant from some phytophagous insects.

References

• Anderson, D.M.W. 1978. Chemotaxonomic aspects of the chemistry of acacia gum exudates. Kew Bull. 32(3):529–536.
• Little, E.L. Jr. 1983. Common fuelwood crops: a handbook for their identification. McClain Printing Co., Parsons, WV.
• N.A.S. 1980a. Firewood crops. Shrub and tree species for energy production. National Academy of Sciences, Washington, DC.
• N.A.S. 1982. Priorities in biotechnology research for international development. Proceedings of a Workshop. National Academy Press, Washington, DC.
• N.A.S. 1983a. Producer gas: another fuel for motor transport. National Academy Press, Washington, DC.

Acacia auriculiformis A. Cunn.

Uses

Used for fuelwood plantations as an ornamental and shade tree, quite tolerant of heat, the Australian species is widely planted in Oceana and southeast Asia. The wood is also employed for making farm tools and furniture (NAS, 1983a). Recent Australian tests suggest that 10-year old trees can be pulped readily by the sulfate process, giving high pulp yields, with good strength properties. Also produces high quality pulp by the neutral sulfite semichemical process. The tannin produces a good quality leather, inclined to redden upon exposure to sunlight (NAS, 1980a). The plant is amazing in its ability to recolonize wastes, papermill sludge, pH ca 9.5; even uranium spoils, pH ca 3.0; the only tree found on 20-year old uranium spoil. Used for the cultivation of the lac insect in India.

Folk Medicine

No data available.

Chemistry

The gum contains 5.3% ash, 0.92% N, and 1.68% methoxyl, and ca 27.7% uronic acid. The sugar from the gum after hydrolysis, contained 10.1% 4-0-methylglucuronic acid, 17.6% glucuronic acid, 59% galactose, 8% arabinose, and 5% rhamnose (Anderson, 1978). Bark contains ca 13% water.

Description

Resilient, vigorously growing, crooked or gnarled deciduous or evergreen tree, possibly attaining 30 m height, 60 cm DBH. Leaves alternate, simple flattened phyllodes, lanceolate or oblong, arcuate, long-attenuate at both ends, 10–16 cm long, ca 1.5–2.5 cm broad, thick coriaceous, glabrous with several long parallel veins from the base. Spikes 5–8 cm long, paired at the leaf bases. Flowers sessile, ca 3 mm long, the calyx glabrous, 5-toothed, the 5 petals ca 2 mm long. Stamens numerous, filiform, ca 3 mm long. Ovary pubescent, the style filiform. Pods 6–8 cm long, 1–1.5 cm broad, flattened but coiled. Seeds several, flattened-ellipsoid, ca 5 mm long, with a reddish or orangish aril (Little, 1983). Seeds 53,000–62,000/kg.

Germplasm

Reported from the Australian Center of Diversity, Acacia auriculiformis, or cvs thereof, is reported to tolerate alkalinity, desiccation, drought, fire, high pH, laterite, poor soil, sand dunes, and savanna. It is intolerant of hurricane, shade, and weeds, at least in early stages. Once established, the tree is quite competitive with weeds. Though somewhat tolerant of fire, it is not so resistant as Eucalyptus. (2n = 26)

Distribution

Native to the savannas of New Guinea, islands of the Torres Strait, and northern Australia, it has been widely introduced, e.g. in Fiji, India, Indonesia, Java, Malaysia, Niger, Nigeria, Philippines, Tanzania, Thailand, the Soloman Islands, Uganda, and Zanzibar.

Ecology

Estimated to range from Subtropical Moist to Wet through Tropical Dry to Wet Forest Life Zones, Acacia auriculiformis is reported to tolerate annual precipitation of 7.5 to 27 dm, annual temperature of 26 to 30°C, and pH of 3.0 to 9.5. With practically no maintenance it will grow on a wide range of deep and shallow soils, compacted clays, coral soils, laterites, limestone, mica schist, mine spoil, podzols, even sand dunes and unstable slopes.

Cultivation

It has been suggested as an interplant with long-term timber Dalbergias, itself serving as a short-term but renewable firewood source. Seeds, storable for 18 months in airtight containers, should be soaked in hot water for 24 hours. Sow in full light, allowing 6 days for germination (ca 80% germination after 2–4 weeks). To reforest grassland, burn and plant in holes ca 36 x 30 x 30 cm, spaced at 1–2.5 or 1–3 m if intercropped with Cassia siamea. Recent spacings have been 2.5 x 2.5 m.

Harvesting

In Indomalaysia, stands are operated on 10–12 year rotations. Trees coppice poorly. Indonesians have gotten some coppice when trees are cut at least 50 cm above the ground. When trees are felled, there is usually a swarm of seedlings, so cutover stands regenerate readily.

Yields and Economics

With rainfall at 2700 mm, at 3 years, average height of a stand with 1010 trees/ha was 12.4 m, average diameter 12.2 cm, standing wood volume 73.2 m³/ha; at age 4, 13.1 m, 13.6 cm, and 96.1 m³/ha. Stemwood volume is ca 60% of total above ground biomass. Leaf biomass is important, the LAI being 7–8, good for shading out weeds. Average amount of dead litter is 4800 kg/ha. In Java, there may be 3 MT/ha leaves and 2 MT/ha twigs and branches beneath the trees (NAS, 1982a). On infertile abandoned sites in Papua, trees grew 6 m in 2 years, 17 m in 8 years. On shallow arid soils in West Bengal, yields were only 5m³/ha/yr at the 15th year. Under moister conditions 10 m³ is reported, 17–20 in Indonesia and Malaysia.

Energy

Wiersum and Ramlan report that yields can run higher than 20 m³/ha/yr on a 10–20 year rotation. On poor soils yields drop to 8–12 m³. On the Island of Madura, with annual rainfall 1700–1900 mm, 7–12 year old rotations run 7.6–9 m³/ha/yr, but on West Bengalese laterites with annual precipitation 1,000–14,000 mm, yields are only 2–6 m³/ha/yr in 10–20 year rotations. With its capacity to produce good fuelwood on poor soils, even where there are extended dry seasons, the species "merits large scale testing as a fuelwood species" (NAS, 1980). Wood has specific gravity of 0.6–0.75 and calorific value of 4,800–4,900 kcal/kg. Wood yields excellent charcoal that glows well and burns without smoke or sparks. Litter beneath the trees, both branches and dried leaves, annually adds up to 4.5–6 MT/ha, all used for fuel in China. Hawaiian grown material possesses N-fixing nodules.

Biotic Factors

While no pest or disease problems are reported in Indonesia, insects and nematodes have been reported to attack seedlings in Zanzibar. The rust Uromyces digitatus has been a problem in Java, where it is also occasionally infested with a rather inocuous black mildew, Meliola adenanphererae. In India, the root rots are Ganoderma lucidum and Ganoderma applanatum. Hypothenemus dimorphus has caused shoot fatality in Malaysia. The weevil Hypomeces squamosus can be a pest in India and Malaysia. Used to cultivate Kerria lacca in India. On Java, the ant Iridomyrmex rufoniger may protect the plant from some phytophagous insects.

References

• Anderson, D.M.W. 1978. Chemotaxonomic aspects of the chemistry of acacia gum exudates. Kew Bull. 32(3):529–536.
• Little, E.L. Jr. 1983. Common fuelwood crops: a handbook for their identification. McClain Printing Co., Parsons, WV.
• N.A.S. 1980a. Firewood crops. Shrub and tree species for energy production. National Academy of Sciences, Washington, DC.
• N.A.S. 1982. Priorities in biotechnology research for international development. Proceedings of a Workshop. National Academy Press, Washington, DC.
• N.A.S. 1983a. Producer gas: another fuel for motor transport. National Academy Press, Washington, DC.

Acacia albida Del.

Uses

Acacia albida is a widely used tree well documented for increasing the yields of crops grown under it. According to VITA (1977) "A. albida is highly valued in conservation efforts. It is the only species which loses its leaves during the rainy season; therefore, farming under these trees is not only possible but profitable." It is held sacred by the Africans of the Transvaal. In Nigeria, the pod is used as camel food. The gum that exudes spontaneously from the trunk is sometimes collected like gum arabic. The timber, though straight grained, close, and weighty, is soft, fibrous, and unsuitable for agricultural implements (Watt & Breyer-Brandwijk, 1962). One writer even questions its value for fuel wood. Masai use it as the soft flat wood upon which the firestick is twirled to make fire. Wood is used for canoes, mortars, and pestles. The bark is pounded in Nigeria and used as a packing material on pack animals. Ashes of the wood are used in making soap and as a depilatory and tanning agent for hides. VITA (1977) says the wood is used for carving; the thorny branches useful for a natural barbed fence. Pods and foliage are highly regarded as livestock fodder. Some 90% of Senegalese farmers interviewed by Felker (1981) collected, stored, and rationed Acacia alba pods to livestock. Rhodesians use the pods to stupefy fish. Humans eat the boiled seeds in times of scarcity in Rhodesia. Apparently it is erroneously taken as an indicator of a shallow well site.

Folk Medicine

Reported to serve as an emetic in fevers (Masai), taken for diarrhea in Tanganyika. Also used for colds, diarrhea, hemorrhage, and ophthalmia in West Africa. The bark of the Ana tree is a folk remedy for diarrhea among several tribes. On the Ivory Coast it is used for leprosy. The bark decoction curtails nausea. A liniment, made by steeping the bark, is used for bathing and massage in pneumonia. The bark infusion is used for difficult delivery, and is used as a febrifuge for cough (Irvine, 1961). Pods worn as charm by African women and children to avert smallpox.

Chemistry

The following table is reproduced, with permission from FAO's Tropical Feeds (1981):

Nutritive Table (Gohl, 1981)

		As % of dry matter
	DM	CP	CF	Ash	EE	NFE	Ca	P
Fresh flowers, Sudan	17.8	19.0	12.5	9.7	1.6	57.2
Fresh whole leaves, Niger		19.7	19.6	7.2	1.6	51.9	1.00	0.23
Fresh leaflets, Sudan	36.3	17.1	12.4	8.4	2.3	59.8
Pods, Tanzania		8.8	24.4	3.7	1.4	61.7	0.65	0.23
Pods, Niger		14.3	24.7	6.3	1.5	53.2	1.11	0.14

		Digestibility
	Animal	CP	CF	EE	NFE	ME
Pods	Cattle	51.0	16.5	71.4	74.8	2.09

Bark contains 2–28% tannin, the fruit 5–13%.

Description

A large thorny tree up to 20 m high and >2 m in diameter; bole forming up to 1/3 of height of tree; bark dull grey, fissured when old, crown dense; tree puts out leaves during dry season and sheds them during rains; branchlets light grey, spiny only at nodes, spines straight, up to 1 in. long; leaves pale and glaucous, bluish grey, glabrous or pubescent, 2-pinnate, 9 to numerous pairs of pinnae, cup-like glands on rachis, each pinna with 12 or more pairs of leaflets, leaflets oblong, up to 1 cm long, hairy, unequal at base; flowers (Jan., Apr., Nov.) in yellow spikes 10–12.5 cm long; fruits (Jan., May, Nov.) bright yellowish green when dry, up to 12–15 x 4 cm, slightly curved, ends rounded (Irvine, 1961).

Germplasm

Reported from the African Center of Diversity, the Ana Tree, or cvs thereof, is reported to tolerate poor soil, drought, savanna, and some waterlogging (VITA, 1977). Back in 1978, when Senegalese farmers wanted seedlings, none were available. There is great variability in the morphology and pod yields. Selection of wild plants for pod yield and/or fast growth would be a worthwhile contribution to arid developing countries. (2n = 26)

Distribution

Native to the Transvaal and Southwest Africa, through West and North Africa to Egypt, East Africa.

Ecology

Probably ranging from Tropical Thorn to Subtropical Moist Forest Life Zones, the Ana Tree is reported to tolerate annual precipitation of 3 to 6dm. Irvine (1961) describes it as the largest thorn tree in Savanna Forest, especially in inhabited areas; often left untouched, sometimes gregarious. In more mesic Sahelian regions (400–600 mm/yr), yields of millet, peanuts, and sorghum are increased from ca 500 to ca 900 kg/ha/yr by growing under the canopy of Acacia albida (Felker, 1978). Does best in sandy soils, growing well where millet grows. Though faring best on sandy soils, it will tolerate heavier soils with some waterlogging.

Cultivation

As late as 1978, techniques for establishing new seedlings had not been worked out, according to Felker (1978). Seeds devoid of bruchid holes should be scarified and started in deep containers to accomodate development of the tap root. Good-sized plants develop in 10–14 weeks, but frequent root pruning is advised. Transplants from the wild are usually unsuccessful because of the long tap root. VITA (1977) has a novel approach, feeding the seed to livestock, which then graze the desired areas, eliminating seeds with their manure. Nursery plantings, spaced at 10 x 10 m may require watering at first, and protection from grazing animals for 5–8 years.

Harvesting

Peasants gather pods to feed to their cattle, or lop the foliage in the dry season, when most other trees are leafless.

Yields and Economics

According to FAO (1980) a full grown tree can produce more than 100 kg pod/yr. Felker (1978) notes that pod yields range from 6–135 kg/tree. Some scientists believe that yields could be managed to a much higher level than those of the grasses and annual crops grown under the tree. Trees have reached 2 to 4 m after only 3 or 4 years growth.

Energy

Related species such as Acacia tortilis have been reported to yield giraffe forage to the tune of 5 MT/ha/yr. Yield increases under Acacia albida correlate with a several fold increase in soil N and organic matter, coupled with improved soil water-holding capacity. Acacia albida has been shown to nodulate and reduce acetylene. While Acacias cannot be recommended for cold and/or humid or everwet climates, they are suggested by the NAS (1980a) as firewood sources in developing countries. Among the species they consider are Acacia arabica, auriculiformis, brachystachya, cambagei, cyanophylla, cyclops, dealbata, decurrens, ehrenbergiana, fistula, heteracantha, holosericea, lysiophloia, mangium, mearnsii, mollissima, nilotica, nubica, raddiana, saligna, senegal, seyal, spirocarpa, tortilis, and verek. The Ana Tree was not recommended for firewood.

Biotic Factors

Caterpillars, locusts, and grazing animals may destroy the seedlings.

References

FAO Handbooks in Press (FAO, 1982)
1. Taxonomy of Acacia spp.
2.Seed Collection, Handling, Storage and Treatment of Acacia spp.
3. Seed Insects in Acacia spp.

• FAO. 1980a. 1979. Production yearbook. vol. 33. FAO, Rome.
• Felker, P. 1981. Uses of tree legumes in semiarid regions. Econ. Bot. 35(2):174–186.
• Felker, P. 1978. State of the art: Acacia albida as a complementary intercrop with annual crops. USAID Information Services. Washington.
• Gohl, B. 1981. Tropical feeds. Feed information summaries and nutritive values. FAO Animal Production and Health Series 12. FAO, Rome.
• Irvine, F.R. 1961. Woody plants of Ghana. Oxford University Press. London.
• N.A.S. 1980a. Firewood crops. Shrub and tree species for energy production. National Academy of Sciences, Washington, DC.
• VITA. 1977. Reforestation in arid lands. VITA Publications. Manual Series 37E.
• Watt, J.M. and Breyer-Brandwijk, M.G. 1962. The medicinal and poisonous plants of southern and eastern Africa. 2nd ed. E.&S. Livingstone, Ltd., Edinburgh and London.