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 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 mangium Willd

Uses

Regarded first as a rather productive timber tree, secondly for firewood (specific gravity = 0.65). The hard, light-brown wood is dense, with narrow sapwood and a straight, close grain. It makes excellent particle board and could possibly be useful for furniture, cabinetmaking, and perhaps even pulp and paper. Capable of being directly sown, the tree appears quite promising for erosion control where adapted (NAS, 1979). Some success is indicated in the use of the species to correct the problem of the Imperata grasslands (Tham, 1979). Sabah foresters have converted 1,200 ha of degraded Imperata grassland into productive forest lands.

Folk Medicine

No data available.

Chemistry

According to Anderson (1978) the gum contains 5.4% ash, 0.98% N, 1.49% methoxyl, and by calculation, 32.2% uronic acid. The sugar composition after hydrolysis: 9.0% 4-0-methylglucuronic acid, 23.2% glucuronic acid, 56% galactose, 10% arabinose, and 2% rhamnose.

Toxicity

Dust from pods pounded during seed extraction causes a respiratory reaction in some people. No hint of pollen allergies has been reported (NAS, 1983d).

Description

Tree to 30 m tall, bole often straight, to over half the total tree height. Branchlets, phyllodes and petioles glabrous or slightly scurfy. Phyllodes 5–10 cm broad, 2–4 times as long as broad, dark green, chartaceous when dry. The phyllodes have (3–)4 longitudinal main nerves which join on the dorsal margin at the base of the phyllode, secondary nerves fine and inconspicuous. Flowers in loose spikes to 10 cm long, solitary or paired in the upper axils. Flowers pentamerous, the calyx 0.6–0.8 mm long, with short obtuse lobes, the corolla twice as long as the calyx. Pods linear, glabrous, 3–5 mm broad, ca 7.5 cm long when green, woody, coiled and brackish-brown when mature, depressed between the seeds. Seeds lustrous, black, ellipsoid, ovate or oblong, 3.5 x 2.5 mm, the orangish funicle forming a fleshy aril beneath the seed.

Germplasm

Native to the Australian Center of Diversity, the mange tree has been reported to tolerate heavy soil, laterites, low pH, poor soil, slopes, and weeds (NAS, 1979, 1983d). Hybridizes naturally with Acacia auriculiformis, producing hybrids which grow faster than either parent, but tending to retain the poor form of A. auriculiformis.

Distribution

Largely Australian with disjunct distribution of small stands in New Guinea and the Moluccas, as well as in Cape York Peninsula. In Indonesia A. mangium occurs on Taliabu, the most western island, and Sanana, a southern island of the Sula Island Group and near Waesalan in the southwest of the main Ceran group. Introduced to Banglasesh, Cameroon, Costa Rica, Hawaii, Indonesia, Malaysia, Nepal, Papua, and the Philippines (NAS, 1983d).

Ecology

Often in grasslands and on margins of lowland primary forests at altitudes of 10–50 m. Probably capable of ranging from Tropical Very Dry to Moist through Subtropical Dry to Wet Forest Life Zones, this species has outperformed Albizia falcataria, Gmelina arborea (considered among the fastest-growing useful trees on earth, NAS, 1979), and Pinus caribaea on poor sites such as disturbed or burned sites, on degraded lateritic clay underlain with volcanic rock, on soils so worn out that even shifting cultivation had been abandoned, and on slopes infested with Eupatorium and/or Imperata species. Mangium apparently tolerates annual precipitation of 10 to 45 dm or more, mean maximum temperature of 31–34°C in summer, mean minimum temperature of 12–25°C in winter, and pH of 4.2–7.5 (NAS, 1983d). It is reported on entisols and ultisols.

Cultivation

Sometimes sown direstly. During the first two years growth in Sabah Imperata wastelands, trees required some weeding and occasionally insecticidal treatment. Beyond that, little tending is required. Trees coppice readily and flower and fruit profusely and "continuously" (NAS, 1979). Many more details are reported by NAS (1983d).

Harvesting

Large-diameter logs can be sawn or peeled. Viable seed can be harvested only 24 hours after planting (NAS, 1983d). Fourteen-year old trees yield a kilogram of seed.

Yields and Economics

Said to be a very fast growing species attaining 15 m height and 40 cm DBH in 3 years. They have attained 23 m tall in 9 years.

Energy

Yields as high as 30 m³/ha/yr have been reported, but 20 m³ has been reported on poor sites. The timber, recommended for testing as firewood, has potential for firewood and charcoal (NAS, 1983d). The wood has 4,800–4,900 kcal/kg. Untended 9-year old stands have yielded 415 m³ timber per ha, representing annual productivity of 46 m³ (NAS, 1979). The MAI in Sabah varies from 13.8–44.5 m³/ha.

Biotic Factors

There are problems with leaf insects. Mangium has symbioses with the bacterium Rhizobium and the fungus Thelephora. Specimens (ca 12%) in Sabah suffer from a heart rot and a "pink disease" (Corticium salmonicolor). Seedlings in Hawaiian nurseries are attacked by a powdery mildew (Oidium sp.). Three pinhole borers attack the tree in Sabah, especially on poorer sites. Carpenter ants (Camponotus sp.) form galleries in the heartwood of young trees. Wood borers of the genus Xystrocera may be a problem. Seedlings may be defoliated by Hypomeces squamosus. Scale insects and mealy bugs may also be problematic with young plants (NAS, 1983d).

References

• Anderson, D.M.W. 1978. Chemotaxonomic aspects of the chemistry of acacia gum exudates. Kew Bull. 32(3):529–536.
  
• N.A.S. 1979. Tropical legumes: resources for the future. National Academy of Sciences, Washington, DC.
  
• N.A.S. 1983d. Mangium and other acacias of the humid tropics. National Academy Press, Washington, DC.
  
• Tham, C.K. 1979. Trials of Acacia mangium Willd. as a plantation species in Sabah. Forest Genetic Resources Information 9. FAO Forestry Occasional Paper 1979 (No. 1).

Acacia mangium Willd

Uses

Regarded first as a rather productive timber tree, secondly for firewood (specific gravity = 0.65). The hard, light-brown wood is dense, with narrow sapwood and a straight, close grain. It makes excellent particle board and could possibly be useful for furniture, cabinetmaking, and perhaps even pulp and paper. Capable of being directly sown, the tree appears quite promising for erosion control where adapted (NAS, 1979). Some success is indicated in the use of the species to correct the problem of the Imperata grasslands (Tham, 1979). Sabah foresters have converted 1,200 ha of degraded Imperata grassland into productive forest lands.

Folk Medicine

No data available.

Chemistry

According to Anderson (1978) the gum contains 5.4% ash, 0.98% N, 1.49% methoxyl, and by calculation, 32.2% uronic acid. The sugar composition after hydrolysis: 9.0% 4-0-methylglucuronic acid, 23.2% glucuronic acid, 56% galactose, 10% arabinose, and 2% rhamnose.

Toxicity

Dust from pods pounded during seed extraction causes a respiratory reaction in some people. No hint of pollen allergies has been reported (NAS, 1983d).

Description

Tree to 30 m tall, bole often straight, to over half the total tree height. Branchlets, phyllodes and petioles glabrous or slightly scurfy. Phyllodes 5–10 cm broad, 2–4 times as long as broad, dark green, chartaceous when dry. The phyllodes have (3–)4 longitudinal main nerves which join on the dorsal margin at the base of the phyllode, secondary nerves fine and inconspicuous. Flowers in loose spikes to 10 cm long, solitary or paired in the upper axils. Flowers pentamerous, the calyx 0.6–0.8 mm long, with short obtuse lobes, the corolla twice as long as the calyx. Pods linear, glabrous, 3–5 mm broad, ca 7.5 cm long when green, woody, coiled and brackish-brown when mature, depressed between the seeds. Seeds lustrous, black, ellipsoid, ovate or oblong, 3.5 x 2.5 mm, the orangish funicle forming a fleshy aril beneath the seed.

Germplasm

Native to the Australian Center of Diversity, the mange tree has been reported to tolerate heavy soil, laterites, low pH, poor soil, slopes, and weeds (NAS, 1979, 1983d). Hybridizes naturally with Acacia auriculiformis, producing hybrids which grow faster than either parent, but tending to retain the poor form of A. auriculiformis.

Distribution

Largely Australian with disjunct distribution of small stands in New Guinea and the Moluccas, as well as in Cape York Peninsula. In Indonesia A. mangium occurs on Taliabu, the most western island, and Sanana, a southern island of the Sula Island Group and near Waesalan in the southwest of the main Ceran group. Introduced to Banglasesh, Cameroon, Costa Rica, Hawaii, Indonesia, Malaysia, Nepal, Papua, and the Philippines (NAS, 1983d).

Ecology

Often in grasslands and on margins of lowland primary forests at altitudes of 10–50 m. Probably capable of ranging from Tropical Very Dry to Moist through Subtropical Dry to Wet Forest Life Zones, this species has outperformed Albizia falcataria, Gmelina arborea (considered among the fastest-growing useful trees on earth, NAS, 1979), and Pinus caribaea on poor sites such as disturbed or burned sites, on degraded lateritic clay underlain with volcanic rock, on soils so worn out that even shifting cultivation had been abandoned, and on slopes infested with Eupatorium and/or Imperata species. Mangium apparently tolerates annual precipitation of 10 to 45 dm or more, mean maximum temperature of 31–34°C in summer, mean minimum temperature of 12–25°C in winter, and pH of 4.2–7.5 (NAS, 1983d). It is reported on entisols and ultisols.

Cultivation

Sometimes sown direstly. During the first two years growth in Sabah Imperata wastelands, trees required some weeding and occasionally insecticidal treatment. Beyond that, little tending is required. Trees coppice readily and flower and fruit profusely and "continuously" (NAS, 1979). Many more details are reported by NAS (1983d).

Harvesting

Large-diameter logs can be sawn or peeled. Viable seed can be harvested only 24 hours after planting (NAS, 1983d). Fourteen-year old trees yield a kilogram of seed.

Yields and Economics

Said to be a very fast growing species attaining 15 m height and 40 cm DBH in 3 years. They have attained 23 m tall in 9 years.

Energy

Yields as high as 30 m³/ha/yr have been reported, but 20 m³ has been reported on poor sites. The timber, recommended for testing as firewood, has potential for firewood and charcoal (NAS, 1983d). The wood has 4,800–4,900 kcal/kg. Untended 9-year old stands have yielded 415 m³ timber per ha, representing annual productivity of 46 m³ (NAS, 1979). The MAI in Sabah varies from 13.8–44.5 m³/ha.

Biotic Factors

There are problems with leaf insects. Mangium has symbioses with the bacterium Rhizobium and the fungus Thelephora. Specimens (ca 12%) in Sabah suffer from a heart rot and a "pink disease" (Corticium salmonicolor). Seedlings in Hawaiian nurseries are attacked by a powdery mildew (Oidium sp.). Three pinhole borers attack the tree in Sabah, especially on poorer sites. Carpenter ants (Camponotus sp.) form galleries in the heartwood of young trees. Wood borers of the genus Xystrocera may be a problem. Seedlings may be defoliated by Hypomeces squamosus. Scale insects and mealy bugs may also be problematic with young plants (NAS, 1983d).

References

• Anderson, D.M.W. 1978. Chemotaxonomic aspects of the chemistry of acacia gum exudates. Kew Bull. 32(3):529–536.
  
• N.A.S. 1979. Tropical legumes: resources for the future. National Academy of Sciences, Washington, DC.
  
• N.A.S. 1983d. Mangium and other acacias of the humid tropics. National Academy Press, Washington, DC.
  
• Tham, C.K. 1979. Trials of Acacia mangium Willd. as a plantation species in Sabah. Forest Genetic Resources Information 9. FAO Forestry Occasional Paper 1979 (No. 1).

Acacia tortilis (Forsk.) Hayne

Uses

Since this is one of the few timber species of the Arabian deserts, it is suspected as being the wood from which the Biblical Ark of the Tabernacle was made. Kaplan (1979) says rather emphatically it is the Shittim of the Bible, which provided the Israelites with the large-size timbers for the Ark. The timber is also used for fenceposts, firewood, furniture, and wagonwheels. The prolific pods made good fodder for desert grazers and the foliage is also palatable, being one of the major dry season fodder trees for the Sahara-Sahelian belt. Bark, used for string in Tanganyika. Gum used as a poor man's gum arabic, said to be edible. It is the tree most recommended for reclaiming dunes in India and Africa (Roy et al, 1973). The thorny branches are used to erect temporary cages and pens. Bark said to be a good source of tannin (Roy et al, 1973). Africans once strung the pods into necklaces. Senegalese use the roots for spear shafts, Lake Chad natives use the stems for fish spears. African nomads often use the flexible roots for frameworks of their temporary shelters.

Folk Medicine

While I find few data specific to this species, I suspect that the gum is used like that of gum arabics in folk remedies. In French Guinea, the bark is used as a vermifuge and dusted onto skin ailments (Dalziel, 1937).

Chemistry

Pods contain close to 19% protein (Palmer and Pitman, 1972). NAS (1979) reports unconfirmed allegations that the foliage can be toxic to livestock. Certainly HCN has been reported in several Acacias. The following tables are reproduced, with permission, from FAO's Tropical Feeds (1981):

Nutritive tables (Gohl, 1981)

		As % of dry matter
	DM	CP	CF	Ash	EE	NFE	Ca	P	Ref.
Fresh leaves, South Africa		19.2	11.6	8.7	6.1	54.4	2.27	0.17	213
Pods, South Africa		17.3	24.8	5.7	3.1	49.1	0.79	0.34	213
Seeds, South Africa		37.8	10.9	5.9	6.0	39.7	0.56	0.73	213
Pod husks, South Africa		8.7	34.3	6.2	1.6	49.2	1.10	0.14	213

Acacia tortilis (Forsk.) Hayne subsp. heteracantha (Burch.) Brenan

		As % of dry matter
	DM	CP	CF	Ash	EE	NFE	Ca	P	Ref.
Fresh leaves, Sudan	90.9	13.3	9.4	9.6	8.3	59.4	4.00	0.15	64
Pods, Tanzania		12.3	22.4	5.6	1.8	57.9	0.98	0.24	166
Pods, Kenya		17.8	17.5	8.4	1.7	54.6	1.34	0.36	129

		Digestibility (%)
	Animal	CP	CF	EE	NFE	ME	Ref
Pods	Cattle	46.2	42.0	74.0	76.6	2.30	166

Acacia tortilis (Forsk.) Hayne subsp. spirocarpa (Hochst. ex A. Rich) Brenan

Description

Medium umbrella-shaped tree 4–15 m tall, often with several trunks, reduced to a small wiry shrub less than 1 m tall under extremely arid conditions. Two types of thorns abound (1) long, straight, and white, and (2) small, hooked, and brownish. Leaves up to 2.5 cm long with 4–10 pairs of pinnae, each with ca 15 pairs of minute leaflets. Flowers white, aromatic, in small clusters. Pods flat, glabrose, coiled into a spring-like array.

Germplasm

Reported from North African and Middle Eastern Centers of Diversity, Umbrella Thorn, or cvs thereof, is reported to tolerate alkalinity, drought, heat, sand, slope, and stony soils. It seems to be more frost tolerant than Prosopis juliflora, still plants less than 2 years old are easily damaged by frost. Four subspecies are known in different ecological zones: subspecies tortilis—Sahel, Middle East; subspecies raddiana—Sudan, Middle East, Sahel(2n=104); subspecies spirocarpa—Eastern Africa, Sudan; and subspecies heteracantha—Southern Africa (2n= 52). The different subspecies seem to have different ecological tolerances, which is important to consider when choosing a subspecies for plantations. (2n= 52, 104)

Distribution

Native to much of Africa and the Middle East, this species has been introduced in many arid parts of the world. Ironically, it grows faster in the Rajastan Desert of India, where used for charcoal, firewood, and fodder, than in its native Israel (Kaplan, 1979). In Malawi, this species is already scorned by the rural public because it is thorny and difficult to work with. It is being tried for fencings (Nkaonja, 1980).

Ecology

Deemed the most promising of 56 Acacia species tried at Jodhpur, India. Probably ranging from Subtropical Desert to Dry through Tropical Desert Scrub to Very Dry Forest Life Zones, umbrella tree is reported to tolerate annual precipitation of 1 to 10 dm, estimated annual temperature of 18 to 28°C, and pH of 6.5 to 8.5. This species tolerates hot, arid climates with temperatures as high as 50°C subspecies raddiana grows where minimum temperatures are close to 0°C. It is best adapted to the lowlands. It thrives where rainfall is up to 1,000 mm. However, it is also extremely drought resistant and can survive in climates with less than 100 mm annual rainfall with long, erratic dry seasons. The tree favors alkaline soils. It grows fairly well in shallow soil, less than 0.25 m deep, though it develops long lateral roots that can become a nuisance in nearby fields, paths, and roadways. In shallow soil, the plants remain shrubby and must be widely spaced to allow for their lateral root growth.

Cultivation

For good seed germination, seeds should be treated with concentrated sulphuric acid for 30 minutes (Roy et al, 1973). Artificial regeneration aiming at large-scale nursery production requires full use of the germination capacity of the available seeds. This may be achieved by sulfuric acid pretreatment, which brings about the germination of all viable seeds. Treatment with boiling water is selective and mainly breaks the dormancy of bruchid-infested seeds, some of which are no longer able to germinate. Sowing of unripe seeds without pretreatment may be called for as an emergency measure in case of very severe infestation, to achieve at least partial success. Prior to storage, seeds should be fumigated to arrest progressing deterioration of seed viability by bruchids (Karschon, 1975). NAS (1980a) recommends dipping the seed in hot water to soak overnight. Seedlings require initial weeding to facilitate faster growth. Plantations can be spaced at 3 x 3 m.

Harvesting

Firewood harvested as needed, but 10-year rotations are suggested. In Jodhupr, flower initiation is ca May-June in 3-year old trees, fruits forming in July but ripening from November through February. Since the tree coppices well, there is no need to replant after every harvest.

Yields and Economics

Eleven-year old trees in deep sandy soils at Jodhpur averaged 6.4 m tall and 14 cm DBH. In shallow sandy loams over hardpan at Pali, India, 7-year old trees (98% survival) averaged 4.8 m tall, and 10 cm DBH. In sanddunes at Barmer, India, 5-year old trees averaged 3 m tall, 7 cm DBH. An average tree yields 6 kg pods of which 2.6 kg is clean seed. One tree is said to yield 14–18 kg pods and leaves per year in India (Muthana and Arora, 1980). Acacia tortilis has been reported to yield giraffe forage at 5 MT/ha/yr.

Energy

A 12-year-old plantation in India yielded 54 MT fuel , suggest, annual returns of 4.5 MT, not a bad return for the desert (NAS, 1980a). The heartwood has calorific value of 4,400 kcals/kg, making superior firewood and charcoal. It is one of the main firewood and charcoal sources in parts of Africa, e.g. around Khartoum. Nitrogen-fixing nodules are reported in South Africa and Zimbabwe.

Biotic Factors

Bruchids often damage or destroy the seeds, on the tree or after collecting. Herbivores, tame and wild alike, are liable to graze seedlings and innovations. Trees attacked by beetles, mimosoid blights, and caterpillars. The wood is susceptible to termites. In Tanzania, elephants which eat the bark are wiping out some park populations. In Israel, the native Acacias host several species (>40) of mostly monophagous insects, whereas on one exotic, Australian Acacia saligna, only a few polyphagous species occur (Halperin, 1980). Only Microcerotermes diversus and Kalotermes flavicollis, which feed on woody parts of both Acacias and Apate monachus (a beetle which tunnels the stems and branches, causing them to collapse in windblow), may seriously damage the tree. In nature, regeneration and spread of Acacias are probably limited by bruchids destroying much of the seed crop. Seedlings from natural regeneration may come from damaged seeds with a still intact embryo axis, since seedcoat dormancy is removed by the effect of exit holes permitting rapid water absorption and germination. Intact seeds with hard impermeable seedcoats may require a long time to germinate, and probably function as a reserve to ensure the survival of the species (Karschon, 1975).

References

• Dalziel, J.M. 1937. The useful plants of west tropical Africa. The Whitefriars Press, Ltd., London and Tonbridge.
  
• Gohl, B. 1981. Tropical feeds. Feed information summaries and nutritive values. FAO Animal Production and Health Series 12. FAO, Rome.
  
• Halperin, J. 1980. Forest insects and protection in the arid zones of Israel. J. Israel For. Assoc. 30(3/4):68–72.
  
• Kaplan, J. 1979. Some examples of successful use of Acacia for afforestation. J. Israel For. Assoc. 29(3/4):63–64.
  
• Karschon, R. 1975. Seed germination of Acacia raddiana Savi and A. tortilis Rayne as related to infestation by bruchids. Ag. Res. Org. Leaflet 52. Bet Dagan.
  
• Muthana, K.D. and Arora, G.D. 1980. Performance of Acacia tortilis (Forsk) under different habitats of the Indian arid zone. Ann. Arid Zone 19(1/2):110–118.
  
• N.A.S. 1979. Tropical legumes: resources for the future. National Academy of Sciences, Washington, DC.
  
• N.A.S. 1980a. Firewood crops. Shrub and tree species for energy production. National Academy of Sciences, Washington, DC.
  
• Nkaonja, R.S.W. 1980. Dryland afforestation problems in Malawi. J. Israel For. Assoc. 30(3/4):100–105.
  
• Palmer, E. and Pitman, N. 1972. Trees of Southern Africa. 3 vols. A.A. Balkemia, Cape Town.
  
• Roy, A.D., Kaul, R.N., and Gyanchand. 1973. Israeli babool a promising tree for arid and semiarid lands.