Albizia adianthifolia, locally known as rough-bark albizia is from the kingdom: plantae, class equisetopsida, order: fabales, family: Mimosaceae (leguminosae–Minosoideae), genus: albizia
It is distributed across Senegal east to Kenya, south to Angola, and Swaziland and also in eastern Madagascar and also Ghana, Togo, Nigeria... It is locally valued as a shade tree for crops; examples of such crops are cocoa and coffee plantations; this can be seen in Sierra Leone. It is also retained or planted for soil improvement and conservation; this can be seen in Cameroon. In forest management there is generally no focus on Albizia adianthifolia because it is not a preferred timber tree, and sometimes even considered an aggressive colonizer. It is occasionally planted as an auxiliary tree in agroforestry systems. In planting experiments in Ghana Albizia adianthifolia showed a survival rate of 89% three years after planting Although this species is not threatened at the moment, over exploitation and ring barking of trees for the medicinal purposes is becoming more and more common.
Albizia adianthifolia is distributed as above in the map presentation.
THE AIM
The aim of this project is to modify the drying schedule, determine the degree of shrinkage and susceptibility such as splitting, cracks and end checks of Albizia adianthifolia spp.
OBJECTIVES
To determine a drying schedule for the wood species Albizia adianthifolia.
To modify the obtained drying schedule for Albizia adianthifolia
To determine the shrinkage character and susceptibility of the wood species during drying
Albizia adianthifolia timber has no importance on the international market however small volumes maybe mixed and sold with timber of other albizia spp in order to export the wood.
Production Uses:
The wood of Albizia adianthifolia is used for light construction (e.g. posts, rafters) and carving (e.g. images, spoons, masks, clubs). It is also suitable for light flooring, joinery, interior trim, furniture, cabinet work, boat building, vehicle bodies, toys and novelties, tool handles, baseball bats, boxes, crates, hardboard and particle board. The wood is used as firewood, although it burns quickly; it is also made into charcoal.
Albizia adianthifolia is locally valued as a shade tree for crops, e.g. in cocoa and coffee plantations in Sierra Leone, and is also planted or retained for soil improvement and conservation (e.g. in Cameroon). The gum from the bark is sometimes used in local cosmetics. The young leaves are eaten as a vegetable in DR Congo and Zimbabwe. A sauce is made from the seeds. The foliage of Albizia adianthifolia is browsed by cattle and wild ruminants, especially the coppice-growth.
Various plant parts are used in traditional medicine. Bark sap is applied to the eye to treat river blindness and conjunctivitis, and internally against respiratory complaints, as an anodyne and to treat allergic reactions; it is also applied to sores and to allay toothache. A bark infusion or decoction is administered to treat scabies and other skin complaints, and to treat fever. Pounded bark is applied externally to boils and itching skin, and internally as a vermifuge. A twig-bark decoction is administered as a purgative and anodyne. In traditional South African medicine the bark of Albizia adianthifolia is used to improve memory and to treat Alzheimer’s disease. A root infusion is applied to treat eye complaints, and powdered roots are administered to women in labor or with irregular menstruation. The leaves are used internally against diarrhoea and gonorrhea, and externally to treat wounds and sore feet. A fruit extract is drunk to relieve stomach-ache. In southern Cameroon the gum from the bark is used in hunting poison. In the Central African Republic bark and international trade
Albizia adianthifolia timber has no importance on the international market. However, small volumes may be mixed and sold with timber of other Albizia spp. Parts of the plant are exported from Madagascar as a medicine.
PROPERTIES The heartwood is pale brown or golden brown, sometimes with a greenish tinge, and distinctly demarcated from the c. 5 cm wide whitish or pale yellow sapwood. The grain is straight or interlocked, texture moderately coarse to coarse.
The wood is moderately light, with a density of 520–580 kg/m³ at 12% moisture content. It dries slowly, but generally with little degrade. The rates of shrinkage are moderate: from green to 12% moisture content 1.7% radial and 4.1% tangential and from green to oven dry 2.3–2.4% radial and 6.5–7.0% tangential. At 12% moisture content, the modulus of rupture is 99–136 N/mm², modulus of elasticity 9300 N/mm², compression parallel to grain 52.5–57.5 N/mm², cleavage 11.5–27.4 N/mm and Chalais-Meudon side hardness 1.9–2.8.
The wood generally saws and works easily with ordinary hand and machine tools. The use of a filler is necessary to obtain a good finish. The wood nails satisfactorily, and gluing and staining properties are good. The wood dust may cause irritation to nose and throat. The heartwood is only moderately durable, being susceptible to wood borer, marine borer and termite attacks. The heartwood is resistant to impregnation by preservatives, the sapwood moderately resistant to permeable.
A crude protein content of the foliage of 29 g per 100 g dry matter has been recorded. The leaves of trees growing on acid soils in south-eastern Nigeria contained per 100 g dry matter: N 3.72 g, P 0.13 g, K 0.88 g, Ca 0.48 g and Mg 0.38 g. Oleanane-type triterpene saponins were isolated from ethanolic extracts of Albizia adianthifolia roots. Some of these compounds showed immunomodulatory and haemolytic activities, particularly adianthifoliosides A and B. They also demonstrated a cytotoxic effect on human leukaemia T-cells. The bark contains large amounts (2 mg/g dry matter) of histamine and related imidazole compounds.
Description
Small to medium-sized deciduous tree up to 30(–35) m tall; bole straight and cylindrical in closed forest but often crooked and/or twisted in more open localities, up to 95 cm in diameter, without buttresses or with small, thick buttresses; bark yellowish brown to grey, smooth or rough, inner bark granular, creamy to yellowish, with clear gum; crown flattened, with large, spreading branches; young branches densely yellowish or reddish pubescent. Leaves alternate, bipinnately compound with (3–)5–10 pairs of pinnae; stipules ovate to lanceolate, up to 12 mm long, caducous; petiole 1.5–7.5 cm long, near the base at upper side with a sessile gland, rachis 3–12 cm long, yellowish or reddish pubescent; leaflets in 5–17 pairs per pinna, sessile, obliquely rhombic to elliptical-obovate, up to 1.5(–2) cm × 1 cm, cuneate to rounded at base, obtuse to acute at apex, pubescent below. Inflorescence, an axillary head on a 2–6 cm long peduncle. Flowers bisexual, regular, 5-merous, reddish or greenish white, almost sessile, subtended by up to 8 mm long, caducous or persistent bracteoles; calyx narrowly obconical, 2.5–5 mm long, pubescent outside; corolla 6–12.5 mm long, with 5–9 mm long tube, pubescent outside; stamens numerous, 3–3.5 cm long, united into a tube for most of their length, red to pink or greenish; ovary superior, narrowly ellipsoid, 2–3 mm long, gradually tapering into a 3–3.5 cm long style. Fruit an oblong, flat pod 9–19 cm × 2–3.5 cm, with stipe c. 0.5 cm long, densely but finely pubescent, transversely veined, pale brown when ripe, opening with 2 papery valves, 7–10-seeded. Seeds flattened globose, 6.5–9.5 mm × 6.5–8.5 mm. Seedling with epigeal germination; hypocotyl 2–6 cm long, epicotyl c. 1 cm long; cotyledons oblong, c. 1 cm long, thick and fleshy, rounded, early caducous; first 2 leaves opposite, bipinnately compound with 1 pair of pinnae.
Other botanical information
Albizia comprises about 120 species and occurs throughout the tropics. Approximately 35 species are found in continental Africa and about 30 in Madagascar. It is characterized by the head-like inflorescence, with 1–2 central flowers modified, functionally male and having a larger, nectar-producing staminal tube. Molecular analyses showed that Albizia is heterogeneous, and a revision of the genus is needed. Albizia adianthifolia is frequently confused with Albizia gummifera, which differs in its almost glabrous leaflets usually auricled at base, and glabrous pods. However, almost glabrous types of Albizia adianthifolia have also been recorded, and more research is needed to confirm the separation of the two species, the more so since hybrids have been recorded from Malawi and Mozambique.
Anatomy
Wood-anatomical description (IAWA hardwood codes):
Growth rings: (1: growth ring boundaries distinct); (2: growth ring boundaries indistinct or absent). Vessels: 5: wood diffuse-porous; 13: simple perforation plates; 22: intervessel pits alternate; 23: shape of alternate pits polygonal; 26: intervessel pits medium (7–10 μm); 29: vestured pits; 30: vessel-ray pits with distinct borders; similar to intervessel pits in size and shape throughout the ray cell; 42: mean tangential diameter of vessel lumina 100–200 μm; 43: mean tangential diameter of vessel lumina ≥ 200 μm; (46: ≤ 5 vessels per square millimetre); 47: 5–20 vessels per square millimetre; 58: gums and other deposits in heartwood vessels. Tracheids and fibres: 61: fibres with simple to minutely bordered pits; 65: septate fibres present; 66: non-septate fibres present; 69: fibres thin- to thick-walled. Axial parenchyma: 79: axial parenchyma vasicentric; 80: axial parenchyma aliform; 81: axial parenchyma lozenge-aliform; 83: axial parenchyma confluent; 91: two cells per parenchyma strand; 92: four (3–4) cells per parenchyma strand. Rays: (97: ray width 1–3 cells); (98: larger rays commonly 4- to 10-seriate); 104: all ray cells procumbent; 115: 4–12 rays per mm. Mineral inclusions: 136: prismatic crystals present; 142: prismatic crystals in chambered axial parenchyma cells; (143: prismatic crystals in fibres).
(P. Ng’andwe, H. Beeckman & P.E. Gasson)
Growth and development
Trees can grow rapidly, with a recorded maximum early height growth of 2 m per year. However, growth of planted trees is often much less and even slow during the first years. In planting experiments in Ghana 3-years-old trees reached a height of on average 1.5 m with a stem diameter of 1.5 cm. The roots develop nitrogen-fixing nodules containing Bradyrhizobium bacteria. Albizia adianthifolia trees live in association with arbuscular mycorrhizae. They usually flower at the end of the dry season, just after or with the emergence of new leaves. Insects such as bees are the main pollinators. The fruits dehisce on the tree and the papery valves with seeds still attached are spread by wind.
Ecology
Albizia adianthifolia has a remarkably wide ecological adaptation, occurring in high-rainfall forests as well as seasonally dry forests and even in wooded savanna. It occurs most frequently in moister types of semideciduous forest, where it is characteristic for secondary forest, forest edges, roadsides and abandoned farmland. It is common in many regions. In East and southern Africa and in Madagascar, it is found in lowland rainforest, deciduous woodland and wooded grassland, up to 2000 m altitude. It behaves mostly as a pioneer species. Albizia adianthifolia occurs on a wide range of soil types, often on deep and sandy soils.
Propagation and planting
Seedlings are classified as strong light demanders. The germination rate of seeds in the light and dark may be equal, but seedlings soon die in the shade. Regeneration is most abundant in forest disturbed by logging. In burnt forest, seedlings are less abundant. There are about 25,000 seeds per kg. Seeds should be collected from pods still attached to the tree to reduce damage by insects, and they should be dried immediately after collection. They can be stored for up to 3 months if ash is added to reduce insect damage. In cultivation seed may be used for propagation, but wildlings are sometimes also used for planting. Experiments in Ghana showed that Albizia adianthifolia can be successfully propagated vegetatively by root cuttings.
Management
In forest management there is generally no focus on Albizia adianthifolia because it is not a preferred timber tree, and sometimes even considered an aggressive colonizer. It is occasionally planted as an auxiliary tree in agroforestry systems. In planting experiments in Ghana Albizia adianthifolia showed a survival rate of 89% three years after planting.
Diseases and pests
Seeds suffer a high incidence of insect attack, probably often by bruchid beetles as in other Albizia spp.
Yield
The yield of timber per tree is often low for Albizia adianthifolia because the bole is often low branching and crooked.
Handling after harvest
Freshly harvested logs float in water and can be transported by river. Treatment of the logs with preservatives is necessary when they are left in the forest for some time. Logs are sometimes hollow.
Genetic resources
Albizia adianthifolia is widespread and locally common in secondary forest. It is therefore not easily liable to genetic erosion and protection measures are not needed.
Prospects
Albizia adianthifolia is a multipurpose tree. In general it is not a preferred timber tree because of its often short and crooked bole, but where it occurs in closed forest its bole may be longer and more straight, and may be harvested indiscriminately from other Albizia spp. which are more common in closed forest (e.g. Albizia ferruginea (Guill. & Perr.) Benth.). Albizia adianthifolia is often recommended as an auxiliary tree in agroforestry systems, improving the soil with its nitrogen-fixing root nodules, providing mulch with its leaf litter, reducing erosion with its large rooting system, and protecting crops from too much sun. However, the results of screening trials were quite variable, from disappointing due to slow initial growth in Tanzania and Zambia, to very good locally in Ghana. The existence of different ecotypes has been suggested, and this deserves more research attention because it may offer possibilities for optimizing the use of Albizia adianthifolia in agroforestry systems and afforestation programmes under different ecological conditions. With its flat, wide-spreading crown, it has value as an ornamental shade tree. Albizia adianthifolia is an important and widely used medicinal plant, and more research is desirable on its active compounds, some of which have already shown interesting pharmacological activities.