 |
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||
In the highlands (those areas above 1,000 m elevation) the problem of deforestation has become critical in many tropical developing countries. In part, the forests have been cut to make way for cultivation, but much of the denuded land results from the local population cutting trees and shrubs for fuelwood. The forests are receding rapidly up the hillsides as villages are forced to go higher in their constant search for fuel.
Only 10 percent of the population of tropical countries lives in the highlands, but the 40 percent living in the adjacent lowlands is also affected by the deforestation of hillsides that can no longer retain rainwater. The result is flash flooding, siltation, and drying up of streams needed for livestock and irrigation, all of which cut farmland productivity.
Reforestation of the highlands is official policy in many developing countries where subsistence farming is traditional, and efforts are under way to identify tree species best suited for these areas.
The first volume of this report described a number of species worth testing for highland fuelwood crops:
|
Acacia mearnsii |
Eucalyptus globulus |
|
Ailanthus altissima |
Eucalyptus grandis |
|
Alnus acuminata |
Grevillea robusta |
|
Alnus nepalensis |
Inga vera |
A Inus rubra
This section describes further species of trees and shrubs that merit testing in tropical highland areas.
Another species described in section III of this book that should be tested in the tropical highlands is Dalbergia sissoo.
Botanic Name
Acacia decurrens (Wend!.) Willd.
Synonym
Acacia decurrens var normalis Benth. The species is
closely related to Acacia mearnsii (black wattle) and Acacia dealbata (see
Firewood Crops Vol. 1), and in the literature these species have often been
confused.
Common Names
Green wattle, Sydney black wattle, king or queen
wattle
Family
Leguminosae (Mimosoideae)
Main Attributes
Acacia decurrens yields excellent fuelwood
and charcoal and has proved suitable for growing in many countries. The wood is
little used for fuel except in Australia, but the bark is esteemed second only
to that of Acacia mearnsii for tanning purposes. Like other acacias, green
wattle fixes atmospheric nitrogen.
Description
This is a beautiful tree with strong, upright
growth, usually reaching 6-12 m in height. In the Nilgiris (India) it attains a
height of 30 m and a diameter of 37 cm. It has a fern- or feather-like green
foliage and in spring has a crowded head of fluffy, golden flowers. The slender
seedpods, to 10 cm long, snap open when mature and throw the seeds a good
distance.
Distribution
This species is native to the coastal strip
within 200 km of Sydney, Australia, and to adjacent lower montane valleys. It
has been planted fairly widely on moist sites in southeastern Australia. It has
also been introduced to Sri Lanka, Fiji, India, Kenya, South Africa, Hawaii, the
Philippines, and parts of Central and South America.
Use as Firewood
The wood is not suitable for sawtimber
because of its small dimensions. It does make a good firewood, with a specific
gravity of 0.50-0.70. According to one report, it has a caloric potential of
3,530-3,940 kcal per kg.
Yield
A yield of 6-16 m³ per ha per year has been
reported, and in Sri Lanka the yield of firewood on a 15-year rotation averaged
25 m³ per ha.
Other Uses
· Tanning. The bark of Acacia decurrens
yields 35-40 percent good-quality tannin. However, it contains undesirable
coloring matter, which reduces the value of the leather; planting was therefore
stopped in favor of other acacias. Recent research, however, has shown that this
problem can be eliminated by changing the tanning process or by adding other
suitable tanning materials.
· Wood. The wood is used for building poles, mine props, fence posts, and, in recent years, for hardboard.
· Shelterbelt. The tree is used for shade and windbreaks. It has also been used as hedges on tea estates in Sri Lanka.
Environmental Requirements
· Temperature. Acacia
decurrens thrives in a climate of 12°-25°C mean annual temperature. It
is frost resistant and shade tolerant.
· Altitude. In its Australian home the tree grows in low valleys and on hillslopes (25-1,000 m), but mainly below 700 m. Elsewhere the tree may range up to 2,500 m.
· Rainfall. The mean annual rainfall for this species is 900-2,600 mm.
· Soil. Acacia decurrens prefers deep soils that are light to medium and free draining. It occurs naturally on soils of only moderate fertility: acid and neutral yellow earths, acid-bleached red duplex soils, podsols, and some brown friable earths derived principally from shales. The species also occurs on basalt-derived soils.
Establishment
The species spreads rapidly by seed and root
suckers and regenerates by coppicing. Seeds can be germinated after many years
of storage in a cool, dry place. Seeds germinate in 7-14 days, and seedlings can
be transplanted in 5-7 months.
· Seed treatment. The seeds are soaked 2 hours in acid or dipped in boiling water and left to cool and soak.
· Ability to compete with weeds. The tree spreads rapidly, forming solid stands too dense to permit grass or other vegetation to intrude.
Pests and Diseases
Acacia decurrens is susceptible to the
defoliator Acanthopsyche junode, but less so than Acacia mearnsii. Severe
attacks by the rust fungus Uromycladium in the 1920s caused most plantations in
New Zealand to be felled.
Limitations
Acacia decurrens, introduced to Hawaii about
1890, has been declared noxious for state land leases because it spreads rapidly
by seed and root suckers, crowding out other Plants.
Related species
· Acacia dealbata and Acacia mearnsii occur much more widely than Acacia decurrens. There are several species of relatively restricted distribution - for example, Acacia parramattensis, Acacia sylvestris, and Acacia fulva - with similar site requirements, but these have not yet been tested in cultivation.
Botanic Name
Eucalyptus robusta Sm.
Synonym
Eucalyptus multiflora Poir.
Common Names
Swamp mahogany, white mahogany, Australian brown
mahogany, swamp messmate (Australia); robusta, beakpod eucalyptus (USA); brown
gum, red gum (Sri Lanka and India)
Family
Myrtaceae
Main Attributes
Swamp mahogany is one of the most widely
planted eucalypts. It grows well in plantations on good sites, but because of
its ability to grow on both poorly drained and droughty locations, it is usually
planted on adverse sites.
Description
Swamp mahogany is a tree normally attaining
heights of 25-30 m and diameters of 1-1.2 m (however, in Hawaii some giant
specimens have reached 55 m with a 25-m trunk). The trunk is typically straight
and branch free for about half the height of the tree. In open-grown trees the
crown has long, spreading, irregular, and brittle branches, forming a dense
canopy. In closely spaced plantations the branches are almost erect, so that
little crown spread occurs. In plantations in humid climates a portion of the
trees form aerial roots on the main trunk as far as 6 m above ground.
Distribution
The species occurs naturally in a narrow coastal
belt from Queensland to south of Bega, New South Wales, Australia. It grows from
sea level to about 100 m. It has been planted in many other countries and adapts
to varied conditions from equatorial regions to about latitude 35°,
provided frosts are not severe. In Madagascar 150,000 ha have been planted.
Use as Firewood
Eucalyptus robusta has been used as firewood
in Madagascar, Uganda, Cameroon, Papua New Guinea, Sri Lanka, and Malaysia. It
is also used for charcoal. The wood has a specific gravity of 0.70-0.80. The
species coppices well up to age 25.
Yield
Good yields have been reported from Brazil, Chile,
Madagascar (10-35 m³ per ha per year), Mauritius (10 m³ per ha per
year), Malawi, India, Malaysia, Papua New Guinea (21 m³ per ha per year),
Zaire (20-30 m³ per ha per year), and Florida (16.8 m³ per ha per year
from 10 year-old trees). In Hawaii, 23- to 38-year-old plantations have a mean
annual increment of 26 m³per ha.
Other Uses
· Wood. The timber is used in the round and
sawn for lumber, but there are limited supplies. In Hawaii, three companies were
reported in 1961 to be making veneer and plywood of the timber. The wood can
also be used for poles, fencing, wharf and bridge work, and general
construction.
· Shelterbelt. This species is suitable for planting in coastal areas as shelterbelts, and it makes a good roadside shade tree. It is intolerant of salt spray but is quite wind firm and is used as a windbreak.
· Pulp. The timber is used for pulpwood, but the pulp is dark reddish brown and is not as good for this purpose as some other species of eucalypts. The bark must be removed from the stem before pulping.
· Tannin. The gum contains about 30 percent tannin.
Environmental Requirements
· Temperature. Mean minimum
temperature in the coldest winter month is 3°-5°C. Winter frosts are
rare, but 5 or 10 frosts may occur as long as they are not severe. Summer
temperatures are warm, with a mean maximum of 30°-32°C. Humidity is
high in all seasons of the year.
· Altitude. The tree grows on coastal sites from sea level to 1,600 m, depending on latitude.
· Rainfall. Eucalyptus robusta does best in areas with evenly distributed rainfall of more than 2,000 mm a year. It will grow reasonably well when there is rainfall of 1,000-1,500 mm with a 4-month dry season.
· Soil. In its natural habitat in Australia the tree occurs mainly on bottom slopes, in swamps, and on the edges of saltwater estuaries and lagoons. When artificially assisted, it grows much more vigorously in better soils if there is no competition from other eucalypts. It does relatively well in stiff clays and leached sandy loams, but has done poorly on droughty sands in northern Brazil.
Establishment
Eucalyptus robusta is most commonly grown from
seeds in containers in nurseries. Vegetative propagation by grafting and rooting
of stem cuttings has been done with young trees, but it is not a common method
of reproduction. Seedlings are best planted early in the rainy season. Natural
regeneration on bare ground adjacent to plantations is common in many countries
where the tree has been introduced.
· Seed treatment. None required.
· Ability to compete with weeds. Removal of vegetative cover before planting is essential. Planted seedlings are susceptible to competition and shading and generally require two weedings in the first 6 months.
Pests and Diseases
In Sao Paulo, Brazil, Eucalyptus robusta
has been attacked by the bacterium Phytomonas tumifaciens. This same organism
has been detected in plants originating in the United States and Chile. The most
common injuries in swamp plantations in Uganda are windthrow and root rot. The
tree is also susceptible to attack by the Gonipterus beetle and to termites when
it is young.
Limitations
Eucalyptus robusta hybridizes with many other
eucalypt species, which can make the collection of seed of true origin
difficult. In California, USA, this tree has been abandoned for street planting
because the tops break readily in strong
winds.
Botanic Name
Eucalyptus tereticornis Sm.
Synonym
Eucalyptus umbellata (Gaertn.) Domin.
Common Names
Forest red gum, blue gum, mountain gum, red iron
gum, Queensland blue gum, red gum (Australia); Mysore gum (India)
Family
Myrtaceae
Main Attributes
Eucalyptus tereticornis grows rapidly and
withstands periodic flooding for short periods. It coppices vigorously and is
one of the principal eucalypts grown as fuelwood.
Description
A moderately large tree, Eucalyptus tereticornis
attains a height of 30-45 m and a diameter of 1-2 m. The trunk is usually
straight and at least half the total height. The crown is large and somewhat
open. Small clusters of white flowers appear every year, but heavy blooming
occurs only every 3 or 4 years in spring and summer.
Distribution
This species occurs naturally in the widest
latitudinal range of any eucalypt (6°-38°S) along the eastern
Australian coast from southern Victoria to Queensland. It grows also in the
savanna woodlands of Papua New Guinea's south coast. It is found in open forest
or as scattered trees on alluvial flats and along stream banks, including
brackish water. It has been introduced to many tropical and subtropical
countries in Africa, Asia, and South America. More than 400,000 ha have been
planted in India.
Use as Firewood
The wood is hard, heavy, and strong (specific
gravity 0.75 or higher). Density is lower in plantations in the tropics. The
tree produces first-class fuelwood, which also - makes good charcoal. Coppice
regeneration has been widely used and it can be done three to four times on a
10-year rotation.
Yield
The yield is very dependent on moisture. Higher yields
are reported along canal banks and under irrigated conditions. In unirrigated
plantations under good conditions in Africa the tree will yield 20-25 m³
per ha per year for the first 15 years; thereafter, the yield drops to 10-15
m³ per ha, unless the trees are coppiced.
Other Uses
· Wood. The wood is immune to termites and
dry rot and is therefore one of the most durable of timbers, valued for
construction, especially underground. It has a variety of other uses including
poles, posts, fiberboard, and particle board.
· Pulp. This is considered one of the best trees for fiber for paper pulp and rayon-grade pulp in India, Africa, the Pacific basin, and Latin America.
· Intercropping. Eucalyptus tereticornis has been used as an intercrop; for example, in Pakistan it is used with maize, especially during the first 6-12 months after planting, and in India with tapioca (cassava) during the first 2 years.
· Sand dune reclamation. In Uruguay and Costa Rica Eucalyptus tereticornis has been used for sand dune reclamation.
· Afforestation and reforestation. The species is extensively used in afforestation works in India, from the coastal plains to the mountains in the Himalayas, and in West Africa, notably Zaire.
· Oil. The leaves are among the commercial sources of eucalyptus oil.
· Honey and pollen. This species is an important provider of nectar and pollen for honeybee colonies.
Environmental Requirements
· Temperature. Eucalyptus
tereticornis occurs within a wide climatic range with mean annual temperatures
from 17°C to 38°C. This tree may withstand up to 15 frosts a year in
the southern end of its natural range. In South China and Pakistan it is
reported to survive temperatures down to - 7°C.
· Altitude. In its natural habitat this species ranges from 600 m in Papua New Guinea to 1,000 m in Australia. As an exotic, it is planted from sea level (Zaire) to more than 1,000 m.
· Rainfall. The tree is widely planted in areas of summer rainfall with moderate to severe dry seasons. The optimum precipitation appears to be between 800 mm and 1,500 mm, but trees have been planted in areas with lower rainfall (400 mm in India, 550 mm in Israel, and 580 mm in Zimbabwe) and with considerably higher rainfall (2,180 mm in Colombia and 3,500 mm in Papua New Guinea).
· Soil. This species does best on deep, welldrained, light-textured soils that are neutral or slightly acid. It will tolerate some flooding, but not seasonal inundation. Outside its range it has been planted on a wide variety of sites that include alluvial soils, silts, and sandy clays.
Establishment
For Eucalyptus tereticornis the site of the
seed collection is important, and advice should be sought in selecting the most
appropriate provenance in a new locality.
In most countries, seedlings 15-25 cm high are used as planting stock, and they can be produced in the nursery in 3-4 months.
·Seed treatment. None required; however, seeds from native stands in both Australia and Papua New Guinea may need cold, moist stratification.
· Ability to compete with weeds. Eucalypts are very sensitive to grass competition, and weeds should be removed until the canopy closes.
Periodic soil working between rows by tractors has given good yield.
Pests and Diseases
Most plantations have been free of pests
and diseases. Termites will attack the young plants unless they are protected,
and some countries have reported problems with varied fungi like
Cylindrocladium, the climber Merremia, the snout beetle Gonipterus, and the mole
cricket.
Limitations
Because it is closely related to river red gum
(Eucalyptus camaldulensis) and intermediate forms occur, care needs to be taken
in assessing reports of growth.
Related Species
· Eucalyptus rostricta Schlecht. has
similar wood that is used for the same purpose.
· Eucalyptus camaldulensis Dehnh. is closely related, and intermediate forms occur commonly in Queensland.
· Eucalyptus glaucina (Blakely) L. Johnson, now regarded as a species, was formerly Eucalyptus tereticornis Sm. var glaucina (Blakely) Cameron. It occurs in northern coastal New South Wales.
· Eucalyptus amplifolia Naudin is a some what smaller tree that grows on clay soils (sometimes waterlogged) often at slightly higher altitudes than Eucalyptus tereticornis in eastern New South Wales.
· A number of land races, some of which were thought to be hybrids, occur. Some of these are: -"Mysore hybrid," Mysore gum, India -Eucalyptus "C," Zanzibar -Eucalyptus "12ABL," Madagascar, Zaire.
Botanic Name
Gleditsia triacanthos L.
Synonym
The genus name has also been spelled Gleditschia
Common Names
Honeylocust, soetpeul, sweet locust, thorntree,
three-thorned acacia
Family
Leguminosae (Caesalpinioideae)
Main Attributes
Honeylocust is widely planted as an
ornamental and for windbreaks, fodder, and hedges. It is a moderately
fast-growing tree with hard, strong wood that is quite resistant to decay. It is
tolerant of low temperature, drought, and salt. The tree's pods are rich in
sugar and are enjoyed by people, livestock, and wildlife.
Description
A broad-crowned, flat-topped tree, the
honeylocust typically attains a height of 24 m, with trunk diameters of 60-90
cm. Although some bisexual types are known, most specimens are either male
(pollen producing) or female (fruit producing). Trunks and limbs of wild trees
usually bear branching thorns, but a thornless form (f. inermis Schneid.) has
been developed for cultivation; it has small, greenish, fragrant flowers in
spring and flat, crooked pods in fall.
Distribution
This valuable tree legume, well suited to cooler
zones, can be found in North America from Ontario to Texas. It has also been
naturalized in Europe and introduced into parts of Africa, Australia, New
Zealand, and South America.
Use as Firewood
Honeylocust has strong and durable wood of
specific gravity 0.70-0.80. The trees coppice freely.
Yield
Growth is fairly rapid on good sites under average
conditions. Trees 18-35 years old in plantations in the Central Plains of the
United States had an average increase in diameter of 4.6 cm each 10 years.
Height growth in shelterbelts throughout the Central States has averaged 0.5 m
per year for 7 years.
Other Uses
· Timber. The timber is hard, heavy, and
strong, and the heartwood is durable in contact with the ground. The wood is
used principally for posts, but on a smaller scale for furniture, structural
work, and general utility purposes.
· Pods. The long pods, borne in profusion, have sweet-tasting pulp that is relished by people and animals alike, and so the tree is often planted for pasture shade. The pods make high-quality livestock feed, especially when crushed to make the high-protein seeds more digestible.
· Erosion control. A strong taproot, many-branched lateral roots, tolerance of alkaline and saline sites, and ease of reproduction make honeylocust a valuable erosion control species for temperate and subtropical areas. It provides light shade that encourages a grass cover.
· Ornamental and shade tree. In temperate areas of many countries such as South Africa, the United States, and Australia, the species is often planted for shade and beautification along roads and in towns. It is also used for hedges (the thorny kind makes impenetrable hedges) and windbreaks.
Environmental Requirements
· Temperature. Honeylocust is
tolerant of low temperatures, and northern races are hardy to - 34°C.
Southern races are subject to frost damage when planted in cooler areas. The
tree needs light.
· Altitude. This species can be grown up to altitudes of 1,500 m or more. A plantation in Colorado had good survival at 2,100 m, although the trees averaged only 2.4 m tall. The tree seems particularly worth testing as a new crop for tropical highlands such as those found in Nepal, northern Thailand, Central Africa, and Latin America.
· Rainfall. Honeylocust has deep roots and can make use of the moisture reserves of the subsoil, even if the surface is dry. In this way it is able to survive on all but the driest sites. Normal annual precipitation for good growth varies from 500 mm to more than 1,500 mm.
· Soil. The tree grows in most soil types, but occurs most commonly on rich alluvial floodplains of major rivers and on soils of limestone origin. The species tolerates both alkaline and acid soils, but develops best on those with a pH between 6.0 and 8.0.
Establishment
Propagation by seedlings is easy and can be
achieved by grafting, budding, or cuttings taken from hardwood, softwood, or the
roots. Root cuttings and budding appear to be the best methods of reproducing
desirable strains as fruit trees. Large seed crops are produced every 1-2 years,
and the seeds will remain viable for up to 2 years when stored at room
temperature and for several years if stored in sealed containers at
0°-7°C.
· Seed treatment. Before germination can occur, the hard seedcoat must be made permeable, either by covering with hot water (88°C) until the seeds swell or by soaking in concentrated sulfuric acid for 1-2 hours and then washing in water. Treated seeds cannot be stored and must be sown promptly.
· Ability to compete with weeds. The tree needs weeding until it is well established.
Pests and Diseases
Honeylocust is relatively disease free,
but it is subject to a canker that can be fatal, and also to several wood rots.
The leaves are eaten by mimosa webworm in some areas of North America.
Limitations
Honeylocust may suffer some crown damage during
high winds and is easily damaged by fire. Its extensive root system can block
sewers and
drains.
Botanic Name
Melaleuca quinquenervia (Cav.) S. T. Blake
Synonyms
Melaleuca quinquenervia is one of a group of six
closely related species (notably Melaleuca leucadendron, Melaleuca cajuputi, and
Melaleuca viridiflora) that occur in Oceania and have been cultivated and
naturalized in other areas. Their identities have been confused, and many
references (both past and recent) must be treated with caution.
Common Names
Broad-leaved tea tree, tea tree, paperbark tea
tree, belbowrie (Australia); melaleuca, cajeput, paperbark, punktree (USA);
niaouli (New Caledonia)
Family
Myrtaceae
Main Attributes
Melaleuca quinquenervia is a moderately
fast-growing tree suitable for plantation cultivation on wet soils, including
those subject to high rainfall and even inundation. It will grow at high
planting densities, which quickly shade out competing vegetation. It survives
fires, but has only slight resistance to freezes (although rootstocks survive
and sprout). The species has shown promise in plantations in northern Nigeria.
Description
The tree is usually medium sized, growing in
Australia up to 25 m tall; the bole is short, 4-5 m high (and to IS m in rare
cases), and often crooked or twisted. However, if grown in dense stands it
develops relatively straight, clear stems. It is easily recognized by its odd,
whitish, thick, and spongy bark, which splits and peels in many cork-like layers
and becomes rough and shaggy. The tree has narrow, stiff, aromatic leaves, 5-9
cm long, and "bottlebrush-shaped" clusters of fuzzy, white, malodorous flowers.
Distribution
This species is native to Australia from Sydney
north along the coast to the Cape York Peninsula in Papua New Guinea and to New
Caledonia. It typically grows in almost pure stands or with only a few
associates such as Casuarina glauca, Eucalyptus robusta, or Eucalyptus
tereticornis. It has been planted and naturalized in many tropical regions. In
southern Florida it escaped cultivation on seasonally wet sites and is
constantly multiplying as a weed tree.
Use as Firewood
The wood is an excellent fuel, but the thick
bark of mature trees must be peeled off because only the outer layers will burn.
The tree could be used as a woody biomass fuel; the problems of dust from the
bark of mature trees and the low density of the bark can be overcome by properly
engineered systems. Bark of young seedlings has a greater heating value per unit
of oven-dry weight than the wood itself. The wood has a specific gravity of
0.60-0.74.
Yield
In the Florida Everglades, unmanaged melaleuca stands
that appear mature may have 7,000-20,000 stems per ha with an outside bark basal
area up to 133 m² her ha and an outside bark volume of 792 m³ per ha.
Forty-year-old trees on good sites in Hawaiian plantations average 50 cm in
diameter and 18 m in height at 6 m x 6 m spacing. The largest trees there reach
a diameter of 90 cm and grow 24 m tall. Stumps sprout readily.
Other Uses
· Wood. The wood of paperbark is valued for
wharf piling, boat knees, railway ties, mine braces, posts, fence rails,
flooring, and rafters, and, if carefully seasoned, for gunstocks, cabinetwork,
and carving. When the wood is well finished, some people consider it more
beautiful than mahogany.
· Bark. The bark of paperbark is an effective insulator and was first used for packing the walls of cold storage rooms in Australia in 1861. It is mildew resistant and is long lasting under water, so that sheets of bark have been used for caulking boats. When chopped, it makes an excellent filler in nursery potting mixes.
· Honey. The tree blooms much of the year, providing abundant pollen and nectar. The honey is strongly flavored and dark and is not used as table honey. Because of its low cost, there is a strong demand for it by the baking industry and by natural health food dealers in Florida.
· Ornamental. Seedlings are transplanted from the wild (especially mature trees) for landscaping new developments in Florida because of their availability and low cost.
· Oil. Leaves, twigs, and seed capsules are crushed and distilled to produce niaouli oil, which together with cajeput oil from Melaleuca cajeputi has pharmaceutical and other specialty uses.
Environmental Requirements
· Temperature. Paperbark
grows in areas with mean annual temperatures ranging from 18°C to
34°C.
· Altitude. In Australia the tree occurs in low altitudes up to 500 m in the coastal belt, most commonly in seasonal swamps and the edges of tidal waters. In Hawaii it grows well in wet conditions up to 1,400 m altitude.
· Rainfall. The trees grow well in rainfall of as little as 1,000 mm at lower elevations and as much as 5,000 mm at higher elevations.
· Soil. In Australia paperbark can grow down to the sea's edge and is also found 40 km inland. It occurs on old and new alluvial soils, on shallow soils, and on degraded soils left after shifting cultivation. Trees grow to great size in oolitic limestone in Florida.
Establishment
The seeds need wet soil for germination, and
once established, seedlings can survive complete immersion for several weeks.
· Seed treatment. No pretreatment is necessary. The seeds are small (30,000 seeds per g).
· Ability to compete with weeds. The tree successfully competes with and outgrows other vegetation. The deep shade beneath a dense melaleuca canopy, combined with intense root competition and possible allelopathic influences, restricts the need for weed control to about the first 6 months.
Pests and Diseases
None of importance has been reported.
Limitations
Because of its high incidence of seeding,
adaptability to a variety of growth conditions, rapid growth, and resistance to
damage by disease, insects, flooding, and fire, the paperbark tree has spread
rapidly throughout southern Florida. In wetlands it has crowded out native
vegetation and destroyed wildlife habitats. Control by conventional means is
difficult.
Volatile substances excreted by the flowers have been implicated as the cause of acute respiratory problems in Florida.
Related Species
In Thailand, Melaleuca cajuputi is the species cultivated; it occurs naturally from tropical Australia to Burma and Vietnam. Melaleuca leucadendon occurs in northern Australia, New Guinea, and northwestward to Amboina; Melaleuca viridiflora occurs in western and northern Australia and New Guinea.
Botanic Name
Melia azedarach L.
Synonym
Melia orientalis M. Roem.
Common Names
Chinaberry, Persian lilac, alelaila, paraiso,
pride of India, pride of China, bead tree, umbrella tree, bastard cedar, cape
lilac, white cedar, drek
Family
Meliaceae
Main Attributes
The chinaberry is well known and has already
been planted in many countries as an ornamental. Its quick growth and small
dimensions make it a good choice for fast fuelwood production for household
needs. In the Middle East the species has already been used for this purpose.
Description
Chinaberry is a medium-sized deciduous tree, 6-30
m tall and 50-80 cm in diameter. It is popular for its showy clusters of pale
purplish spreading flowers and for the shade of its dense, dark green foliage in
summer. Its clusters of small, fragant flowers are succeeded by glossy, golden,
berrylike fruits that remain long after the leaves fall. The tree is closely
related to the neem tree, Azadirachta indica (see Firewood Crops Vol. 1), which
differs in having longer leaflets, white flowers, and a more spreading and open
crown.
Distribution
This native of Asia is probably from Baluchistan
and Kashmir, but has long been cultivated throughout the Middle East and India
and is now cultivated and naturalized in most tropical and subtropical
countries. It is grown throughout the West Indies, southern United States and
Mexico, Argentina and Brazil, West and East Africa, Southeast Asia, and
Australia.
Use as Firewood
The species is often planted for fuel supply
in the Middle East as well as in Puerto Rico and Nigeria. It is planted in
reforestation projects in Thailand for veneer and fuel, and in Assam (India) it
is grown on tea estates for fuel. Its specific gravity is about 0.66 (calorific
value 5,043-5,176 kcal per kg).
Yield
Under good conditions the chinaberry grows fast. In
Uganda it may grow 1.70 m in height each year. But growth slows down before
large dimensions are attained, and trees of large girth are often hollow. Thus
the trees are grown on short rotations. They regenerate readily from stump
sprouts or root suckers.
Other Uses
· Wood. The wood is moderately soft and is
weak, brittle, and susceptible to attack by drywood termites. Uses of wood
include tool handles, cabinets, furniture, face veneer for plywood, cigar boxes,
and the manufacture of writing and printing paper.
· Insecticide. Chinaberry, like neem, has insecticidal properties and its leaves and fruits are used to protect stored clothing and other articles against insects. Leaves, seeds, and fresh fruit contain substances that inhibit the feeding of the desert locust.
· Fodder. The leaves may be used for goat fodder.
· Seeds. Chinaberry seeds are often used for beads and rosaries.
· Ornamental. The tree is widely grown in warmer parts of the world for its scent and for shade. It is also used to shade coffee trees and to shelter cattle.
Environmental Requirements
· Temperature. The species
grows in tropical, subtropical, and warm-temperature climates where mean annual
temperatures are at least 18°C. Young trees are frost tender, but older
trees resist frost (to a minimum of -15°C).
· Altitude. The tree grows up to 2,000 m in the Himalayas. In Africa the species has been recommended for lowlands and medium elevations.
· Rainfall. The species is drought hardy and can grow in areas with 600-1,000 mm annual precipitation. In drier climates it will perform well on wet soils along rivers or when irrigated, as is done in the Middle East for fuelwood production.
· Soil. The tree grows on a wide range of soils, but best growth is obtained on well-drained, deep, sandy loams.
Establishment
Chinaberry is easily propagated from seed or
cuttings. Fruits number 1,400-2,500 per kg and may be used directly or macerated
to remove the pulp. Each fruit contains 1-5 seeds, which if not extracted may
produce several seedlings. Seeds number 4,000-13,000 per kg. Average germination
is about 65 percent. As planting stock, I-year-old seedlings are preferred in
temperate climates, while 6-month-old seedlings are used in the tropics.
· Seed treatment. To hasten germination, seeds should be soaked in water for a few days.
Seeds retain viability for a year, or for several years if kept in sealed cold storage.
Pests and Diseases
The tree - especially if forced into fast
growth - is susceptible to wind damage. From Jamaica, attacks of shootborers are
reported. Several other pests and diseases have only been observed incidentally
and are not particularly significant.
Limitations
The tree is short-lived and its brittle limbs are
easily broken by the wind. The fruits are bitter and have poisonous or narcotic
properties.
Related species
· Melia azedarach L. var australasica
(A. Juss.) C.DC. (white cedar, tulip cedar) from Australia (synonym Melia
dubia). This species grows to a much larger size than Melia azedarach and is
widely planted in Australia as a shade tree.
· Melia a. forma umbraculiformis Berckm. (Texas umbrella, chinaberry).
Botanic Name
Robinia pseudoacacia L.
Common Names
Black locust, false acacia, yellow locust
Family
Leguminosae (Papilionaceae)
Main Attributes
Black locust is fast growing. It can be
planted and regenerated easily, has no serious diseases, is an important
nitrogen-fixing species, and tolerates a wide variety of soils. Because of this
adaptability, the species is often used for afforestation of gullies and
surface-mined areas in the United States. The wood is perhaps the best firewood
in North America.
Description
A medium-sized, deciduous tree reaching 18-25 m
tall, black locust has an open, irregular crown and a straight bole if forest
grown. It has short, upright, brittle branches and a wide-spreading, shallow
root system with no taproot. There are many verities of the tree, with variable
form and growth. Most are spiny, but spineless individuals are known.
Distribution
Native to the Appalachian and Ozark mountains of
the southeast and central parts of the United States, this species is now grown
in most temperate and Mediterranean zones of the world. Hungary, for example,
has almost 300,000 ha of black locust plantations. In central and eastern Europe
considerable work on selection and improvement of the species has been carried
out for more than a century, using a series of cultivars in pure and mixed-wood
plantations.
Use as Firewood
As firewood, black locust is popular for its
high caloric value and its good combustibility, even when wet. lt is slow to
ignite, but burns like coal, with a bright blue concentrated flame. The specific
gravity of the wood is 0.70-0.80, and it is well suited for charcoal production.
In India and South Korea the species has been used to establish fuelwood
plantations.
Yield
Young black locust trees grow fast on good sites, but
the species matures early and growth rate decreases rapidly after 30 years. In
Korea, on clay loam, the yield of fuel material per year per hectare from the
coppice of black locust fuelwood plantations ranges from 10 to 17 tons 3 years
after establishment. In Hungary, where the rotation age is 25-35 years, the
average standing volume at age 1-10 is 23 m³ per ha; at age 11-20, 100
m³ per ha; at age 21-30, 149 m³ per ha; and, finally, 184 m³ per
ha at age 31-40. Coppicing brings excellent results and may be done twice
without reduction of volume increment.
Other Uses
· Wood. Robinia pseudoacacia wood is heavy,
hard, and strong. It is highly resistant to shock and is extremely durable. It
is used extensively for round, hewn, or split mine timbers and for fence posts,
poles, railroad ties, stakes, and electric insulator pegs.
· Erosion control. Black locust is commonly planted for erosion control. Because of the nitrifying bacteria in nodules on its roots, it is especially effective in improving the fertility of eroded soils. It has also grown quite well when planted on spoil banks created by mining.
· Shelterbelts and sand dune stabilization. Because of its wide-spreading root system, which suckers vigorously, it is used all over the temperate regions of the world for fixing coastal and continental sand dunes. It has also often been planted in shelterbelts.
· Fodder and wildlife use. In Hungary the leaves are readily eaten by game and grazing animals, with no harmful effects observed. The seed is eaten by quail.
· Ornamental. The tree has attractive flowers and is widely planted as an ornamental on farmsteads and roadsides. The flowers are used intensively by bees for producing honey, which is regarded as one of the finest in the world.
Environmental Requirements
· Temperature. The tree grows
in areas with a mean annual temperature of 8°-18°C and a mean minimum
temperature in the coldest month of -8.1°C. It is tolerant of temperatures
as low as -18°C to - 20°C. It is a light-demanding species.
· Altitude. Black locust is found from sea level up to 2,500 m.
· Rainfall. Precipitation in its native habitat is more than 1,000 mm per year, mainly in the summer. The tree has been successfully planted where the rainfall is lower, down to 300-400 mm, and in areas with a winter maximum of rainfall. The species can withstand dry periods of 2-6 months.
· Soil. The species will grow on a variety of soils, including light sand and strongly acid soils and mine spoils, with limestone soils being most favorable. Compact, plastic soils are unfavorable, since black locust does not grow well in waterlogged areas. It is able to withstand air pollution and is sometimes planted in industrial areas for this reason.
Establishment
Good seed crops are produced nearly every year.
Seeds number 35,000-70,000 per kg and can be stored for several years under dry,
cold conditions. In the past, black locust was established mainly from planted
seedlings, but today direct seeding is a common practice, especially on steep
slopes on disturbed sites where seeding is easier, safer, and less costly than
hand planting.
· Seed treatment. Pretreatment is needed to break seed coat dormancy, either by mechanical scarification, by immersion in concentrated sulphuric acid for 20-60 minutes, or by pouring boiling water (five times as much water as seeds) over seeds. Germination of pretreated seed averages about 70 percent.
· Ability to compete with weeds. Black locust is intolerant of shade but is fairly tolerant of herbaceous competition in humid environments. In the Appalachian area of the United States the trees often coexist with a luxuriant understory of cool-season grasses and fortes.
Pests and Diseases
In the United States the saplings are
often heavily damaged by the locust borer Megacyllene robiniae. Trees in the
open and in pure plantations are especially subject to the attack of a
woodboring insect (Cyllene robiniae Forst.), which frequently renders them
unsightly for shade and unfit for timber, but not for fuelwood. However, few
pests of any importance have been reported.
Limitations
A vigorous growth of suckers with stout spines is
produced from the roots, and this can be particularly objectionable in the
garden, on the farm, or in public areas.
Although the foliage is used for livestock in some countries, it has been reported that humans, horses, cattle, sheep, and poultry may be poisoned by eating roots, bark, sprouts, seed pods, and trimmings.
Frost damage can decrease growth, and because black locust branches are fragile and the wood splits easily, the tree suffers from wind damage and ice and snow break.
Botanic Name
Sapium sebiferum (L.) Roxb.
Synonyms
Stillingia sebifera Mich., Croton sebiferums L.,
Excoecaria sebifera Muell. Arg., Stillingia sebifera Boj.
Common Names
Chinese tallow tree, Chinese vegetable tallow
tree, soap tree, popcorn tree, pau de sebo (Brazil), tarcharbi or pahari shishum
(India), arbor de la cera (Cuba)
Family
Euphorbiaceae
Main Attributes
The Chinese tallow tree holds promise as a
highly useful species for shortrotation, intensive silviculture. It is a
fastgrowing, insect- and disease-resistant tree, and tolerates a wide range of
soil conditions, including poorly drained and saline soils. Prolific sprouting
occurs from stumps and injured roots.
Description
A small, deciduous tree, it seldom grows taller
than 12 m. Superficially, it resembles an aspen with glossy, heart-shaped leaves
and a rough, grey bark. Form ranges from low, spreading, and multiforked strains
to slender and columnar strains with small pendant branches. Seeds are borne in
clusters of green capsules, which dry and split to expose white, pea-sized
seeds. Their color results from a covering of hard tallow. The trees are notable
because they turn brilliant autumn colors even in warm regions where other trees
remain green.
Distribution
The Chinese tallow tree is native to
semitropical areas of central South China. Usually occurring below about
32°N, it may be found at higher latitudes in coastal areas. It has been
widely introduced and has been reported in Japan, Taiwan, Vietnam, Burma,
northern India, Java, Pakistan, Hawaii, Brazil, Cuba, St. Vincent, Martinique,
southern Europe, and the Sudan. It is very likely present, but simply not
recognized, throughout the semitropical and milder temperate zones of the world.
In the United States it has become naturalized along the Gulf and southern
Atlantic Coasts from North Carolina to Texas, as well as in California.
Use as Firewood
Moisture content of tallow tree wood cut in
the Texas Gulf Coast ranged from 41 to 45 percent, wet basis. Specific gravity
ranged from 0.37-0.48. Energy values ranged from 4,134 to 4,277 kcal per kg. The
wood burns well in wood stoves or fireplaces if it has been allowed to dry
adequately. It produces a pleasant odor while burning and has been used for
Texas barbecues.
Yield
In Texas, Chinese tallow plantations with 0.6 m x 0.6 m
spacing produced 38.1 tons per ha of oven-dry wood at the end of four seasons of
growth (22 m³ per ha per year). Well-stocked 15year-old natural stands
placed under coppice management produced in excess of 45 tons per ha during 4
years of regrowth (26 m³ per ha per year). Roots and stumps cut at any time
of the year coppice prolifically.
Other Uses
· Wood. In China, the wood reportedly has
been used for making implement handles as well as carved-wood products. Its
durability and resistance to decay in exterior use are very low. The wood may be
suitable for pulp. Fiber lengths in trees from the vicinity of Houston, Texas,
averaged 0.8 mm, while similar measurements of trees from Taiwan averaged 1.3
mm.
· Seed. The white, aril-like outer covering of the seed contains a hard, edible tallow (commercially known as Chinese vegetable tallow), which has found use in soap and candle making and other traditional uses of tallow products. The kernel oil (stillingia oil) has been used as an illuminant and is a powerful drying oil that could substitute for similar oils such as tuna and linseed. The clusters of white seeds are attractive; in Texas they are used in decorative plant arrangements.
· Flowers. The showy yellow catkins of the male flower first appear during the third growth season and yield a major honey and pollen crop. The honey is moderately dark and exceptionally flavorful.
· Ornamental. The Chinese tallow has been used extensively as an ornamental tree. Because of its rapid growth, it produces quick shade, and some varieties are very colorful in the fall, even in warm climates.
Environmental Requirements
·Temperature. The tree will
tolerate frosts and, in the dormant state, will tolerate brief lows of
-10°C. There is considerable variability in cold tolerance among strains.
Some strains may be sensitive to high temperatures and some may require a period
of cool weather and dormancy for significant flowering to occur.
· Altitude. In the United States the tree is naturalized mostly in the coastal lowlands but has been observed as a planted ornamental at elevations of several hundred meters. In China it is reported at elevations of around 1,000 m and in India and Pakistan at about 2,000 m, which is probably its upper limit.
· Rainfall. Although the tree tolerates a wide variation in quantities of annual rain, it is generally considered to be a high-moisture plant; trees have survived for more than 2 years in areas flooded by dam construction. But in one instance, the trees grew well in a year when total annual rainfall was a mere 710 mm, and the species' lower limit is probably somewhat below 500 mm. There is no apparent reason why it cannot be grown in areas under irrigation. Preliminary observations suggest, however, that it is not an efficient user of water.
· Soil. The Chinese tallow tree possesses a remarkable capacity for thriving in widely varying soil types. In the United States it has been found growing on barrier islands, competing effectively in pure sand with oak, pine, and palm; in salt marshes and along salt creek borders; in rocky upland soils; and in dense clay soils subject to extended periods of flooding. Seeds have been observed germinating and the seedlings produced have become established in beds of oyster shell. The tree tolerates and competes well with other vegetation on poorly drained, nitrogen- and phosphorus-poor sites, but its response to phosphorus fertilization is dramatic.
Establishment
Plantations may be established from seed,
seedlings, or cuttings. The most convenient and economical method for
establishing stands is direct planting. Seedlings grown in a nursery are ready
for planting 6-8 weeks after germination. Special care in handling the seedling
is not necessary. Dense plantings are practical.
· Seed treatment. Storage of seeds in the cold in sealed glass or metal containers preserves viability for at least 2 years for most varieties. Pretreatment of the seed to remove the tallow coat is not necessary. Planting in autumn appears to promote more complete germination and allows the earliest possible start for growing seedlings. In some races, a significant percentage of seeds do not germinate until the second season after planting, and seeds planted in the late spring and summer often do not germinate until the following spring.
· Ability to compete with weeds. The large seedling is capable of growing ahead of most annual weeds, and in closely spaced plantings crown closure occurs early in the second season of growth, eliminating significant competition from grass and annual weeds. Grass is the major competitor.
Pests and Diseases
In the tree's native range, a number of
insect pests appear to have evolved with it. Chinese literature refers to the
ailanthus silkworm, poisonous moth, water green moth, and aphid. In India a
number of insects have been reported to defoliate the tree. It is not known how
serious these might be in firewood plantations. In the United States and
probably elsewhere outside the tallow tree's native range, there are no
significant diseases or insect pests.
Limitations
The Chinese tallow tree can be an aggressive
weed. The tallow-covered seeds are spread widely by birds, and once established
in agricultural lands, lawns, or gardens, seedlings and sprouts are difficult to
eliminate because of their capacity for sprouting from stumps and roots. In
general, there is a high resistance to herbicides. The reproductive strategy of
the Chinese tallow tree is such that breeding and production of seed of known
characteristics will be complex. The sap [latex) is a powerful irritant that
blisters the
skin.
 |
 |
