A review of dipterocarps - Center for International Forestry Research

Seed Handling 75
Table 1. Likely periods for flowering and seed production of important Dryobalanops, Dipterocarpus, Shorea, and Anisoptera
species (Krishnapillay, unpublished).
Species
Over the last 25 years various authors have reported
detailed phenological records. Studies include those of
Burgess (1972), Cockburn (1975) and Ng (1981, 1984)
for the Malaysian aseasonal forest, and Sukwong et al.
(1975) for the dry forest of Thailand. In Table 1, there is
a general summary for the important timber species of
Peninsular Malaysia.
The infrequency and irregularity of dipterocarp
flowering and fruiting in the aseasonal areas have already
been referred to above. A further feature is that flowering
tends to be gregarious and may be limited or may extend
throughout an entire region.
Flower and seed surveys indicate:
1. whether flowering is scattered and confined to
particular species or whether it is a mast flowering;
2. whether the amount of seeds available is sufficient to
meet seed collection requirements;
3. whether the crop is sound or has been attacked by
pests or insects; and
4. the time when the seeds will mature.
The natural trigger for mast flowering and fruiting
among dipterocarps has been sought by looking for
associations with several factors. Foxworthy (1932) and
Months
J F M A M J J A S O N D
many others suggested an association between flowering
and strong droughts but Wood (1956) disputed the
conclusion. Ng (1981) suggested that a dry spell
preceding leaf flush accompanied by a rising gradient of
daily sunshine induces flowering. Again, Ashton et al.
(1988) proposed that the environmental trigger is a
protracted low night temperature over a period of about
3-4 days. However, experimental evidence is required
to establish cause and effect. The matter is further
discussed in the Seed Physiology chapter.
Seed Procurement
Frequency
Dryobalanops aromatica x x x x x x x x x x x biennial
Dryobalanops oblongifolia x x x x x x x x x x biennial
Shorea leprosula x x x x x x x 3-4 years
Shorea parvifolia x x x x x x x 3-4 years
Dipterocarpus baudii x x x x x x x annual
Dipterocarpus costulatus x x x x x x x 4-5 years
Anisoptera scaphula x x x x 4-5 years
Anisoptera laevis x x x x 4-5 years
Dipterocarpus kerrii x x x x 4-5 years
Shorea macrophylla x x x x x x x x x x x x annual
Shorea macroptera x x x x x 3-4 years
Shorea ovalis x x x x x x x 3-4 years
Shorea platyclados x x x x x 3-4 years
Shorea acuminata x x x x x x x 2-3 years
Shorea bracteolata x x x x x x x 2-3 years
Shorea curtisii x x x x x 3-4 years
Current research on artificial regeneration has been
reviewed by Mok (1994), whilst Barnard (1950) and
Appanah and Weinland (1993) outline some procedures
that have been used to procure dipterocarp seeds for
planting programmes. A more detailed procurement
procedure is needed. At present, most methods involve
collection of seeds on an ad hoc basis or the collection
of wildings. Seed procurement should involve planning,
collection, transporting, processing, testing, temporary
storage and nursery facilities. A general description of