| Dyera costulata
Apocynaceae
Hill
jelutong. Indonesia: jelutung bukit (general), melabuai (Sumatra),
pantung gunung (Kalimantan). Malaysia: jelutung bukit (general),
jelutong pipit, jelutung daun lebar (Peninsular). Thailand: teen-pet
daeng (Peninsular), ye-luu-tong, luu-tong (Malay, Peninsular) (Lemmens,
Soerianegara and Wong, 1995).
Distribution
Peninsular
Thailand, Peninsular Malaysia, Singapore, Sumatra, Borneo and intervening
islands (Lemmens, Soerianegara and Wong, 1995).
Habitat
The
species occurs in primary evergreen lowland or hill forest, in well-drained
locations up to 300 m (Lemmens, Soerianegara and Wong, 1995).
Population
status and trends
Jelutong
has a scattered natural distibution and has declined as a result
of tapping for latex and felling for timber. The risk of extinction
was recognised 60 years ago. In Peninsular Malaysia the species
has been reported to be threatened (Ng et al 1984). Jelutong does,
however, regenerate readily in logged-over forest. It is also planted
commercially for timber.
Role
of species in the ecosystem
Threats
Exploitation
for latex, felling for timber, conversion of lowland forests to
agriculture.
Utilisation
It
has a number of speciality uses such as pattern making in foundry
work, for drawing boards, pencils, picture frames, dowels, carving,
blackboards, wooden toys, clogs, brush handles and battery separators,
and it is also used for furniture parts, door knobs, ceilings, partitioning,
matchsticks, matchboxes and packing cases. The roots are used as
a substitute for cork and their wood for axe handles. The latex
is used in the manufacture of chewing gum, in paints, as priming
for concrete, or for sizing paper. Follicles are occasionally used
as torches by the local population or burnt to repel mosquitos (Lemmens,
Soerianegara and Wong, 1995).
Trade
In
the period from 1980-1990 the export of jelutong sawn timber from
Peninsular Malaysia was 32000-44000m3/year with a value
of US$ 5.1-10.8 million a year; in 1992 it was 19000 m3
with a value of US$ 8.3 million (US$440/m3) (Lemmens,
Soerianegara and Wong, 1995). In 1995, Malaysia (Peninsular) exported
5000 m3 of sawnwood at an average price of 710$/m3
(ITTO, 1996).
The
export from Sabah was 67000 m3 in 1987 with a value of
US$4.5 million and 23000 m3 (55% as sawn timber, 45%
as logs) in 1992 with a total value of US$ 3.5 million (US$ 215/m3
for sawn timber, US$ 82/m3 for logs). Japan imports comparatively
large amounts of jelutong, mainly from Sarawak and Sabah (Lemmens,
Soerianegara and Wong, 1995).
In
1987, Indonesia exported 2,183,462US$ worth of this species as jelutong
(WWF and IUCN, 1994-1995).
In
Malaysia, the trade in latex has declined since the peak production
period 1930-1940. The export of jelutong latex from Indonesia was
still around 3500 t in 1989 (Lemmens, Soerianegara and Wong, 1995).
Indonesia
is the main source of jelutong gum. Most is exported to Singapore,
mainly for re-export to the US. Some is exported directly to Japan
and Europe where Italy is the main importer (Coppen, 1995).
IUCN
Conservation category
LR-lc
(Asia Regional Workshop, 1997).
Conservation
measures
Jelutong
is subject to a log export ban in Peninsular Malaysia, and special
permission has been required to cut the tree in Thailand (Ministry
of Agriculture and Cooperatives Decree of 1988).
Regulations
on the methods of tapping the latex were introduced in the 1930s
(Coppen, 1995).
Forest
management and silviculture
In
Peninsular Malaysia D. costulata is chosen for enrichment
planting because it is easy to handle in the nursery, survives well
when planted out, has a good rate of growth and has good market
potential. Prolonged contact with acid water in peat forest harms
young plants. D. costulata is a very light-demanding species
and once a young tree is well established in full light, it tends
to spread its crown and develop into a pronounced 'wolf tree'. Sudden
opening of the canopy is favourable for its development (Lemmens,
Soerianegara and Wong, 1995).
D.
costulata coppices readily and is extremely resistant to girdling
(Lemmens, Soerianegara and Wong, 1995).
References
Asia
Regional Workshop, 1997. Conservation and sustainable management
of trees project workshop held in Hanoi, VietNam, August 1997
Coppen,
J.J.W. 1995
ITTO.
1996. Annual Review and Assessment of the World Tropical Timber
Situation.
Lemmens,
R.H.M.J., Soerianegara, I. & Wong, W.C. (Eds.) 1995. Plant
Resources of South-East Asia (PROSEA) 5(2) Timber Trees:
Minor commercial timbers. Backhuys Publishers, Leiden 655pp.
WWF
and IUCN. 1994-1995. Centres of plant diversity. A guide and
strategy for their conservation. Vol 2. IUCN publications Unit,
Cambridge, UK.
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