A review of dipterocarps - Center for International Forestry Research

Plantations 162
Qureshi et al. (1968) investigated the effect of soil
working and weeding on the growth and establishment
of Shorea robusta plantations.
A common practice is to establish dipterocarp
plantations by line planting into forest vegetation. Ådjers
et al. (1995) have investigated the effect of line width,
direction and maintenance on survival and performance
of Shorea johorensis, S. leprosula and S. parvifolia. Line
direction had little effect on survival or growth, although
SE-NW line direction was best for S. johorensis. Line
width did not affect survival, but effect on growth was
significant. Line widths used were 1, 2 and 3 m. In the
control, the seedlings were planted under the forest canopy
without opening it above the planting line. Horizontal
line maintenance was better than vertical line maintenance
and growth of S. johorensis and S. parvifolia benefitted
from it. Survival was not affected. Omon (1986) tested
the strip width to be cut into secondary forest for optimal
growth of planted Shorea ovalis seedlings. He found that
strips 1 m wide were the best for survival and
performance.
Planting patterns in the context of underplanting were
discussed by Tang and Chew (1980). Shorea parvifolia
was underplanted in two patterns: (i) line planting, and
(ii) group planting in groups of 4-6 trees at final spacing.
Six months later the tree crowns overshadowing the
planting lines or the planting patches were removed.
Differences in growth were not significant, however,
survival was higher for the group planting. The authors
recommend removal of overhead shade after 6 months
and underplanting as group planting. Abalus et al. (1991)
recommend groups planted at a spacing of 10 x 10 m.
In an underplanting trial at Agumbe in Karnataka,
India, Vateria indica seedlings were planted in 1962 and
observed until 1978. Those growing under lateral shade
with sufficient light had grown to an average height of
over 5 m in 16 years while those which had no light
reaching them had survived but had grown only about
5 cm (Rai, personal communication).
Planting Techniques
Outside India, Indonesia and Malaysia no large-scale
plantations of dipterocarp species exist. Although
experimental forests have been established in several
regions information on the establishment techniques is
scarce. The most complete account of artificial
regeneration in the Malaysian context is by Barnard
(1956). Agpaoa et al. (1976) give an overview of the
planting techniques in the Philippines context. Most of
the information on planting techniques is contained in
instructions of forest services or of companies, and thus
not always readily available. Planting techniques have
been worked out very well for tropical conditions and
the basics are generally valid irrespective of region,
species or site.
Planting methods can be classified into: (1) planting
of potted seedlings or transplants, (2) planting of bareroot
seedlings or transplants, and (3) planting of stumps.
Normally, dipterocarps are planted as potted seedlings,
when they are about 9 months old and about 25-30 cm
tall. Size or age of planting stock has been investigated
by various researchers. In general, potted seedlings had
better survival (e.g., Barnard 1954, Cerna and Abarquez
1959). The planting holes are usually prepared to a depth
of 25 cm. The seedling or transplant is removed from the
container (polythene bag) with the earthball undamaged.
If broken, the beneficial effect of planting seedlings or
transplants with undamaged roots is lost. Different pot
types were used in the past, e.g., bamboo pots, veneer
pots, tin cans. However, a plastic bag of 500 cc content
(e.g., 10 cm x 15 cm and 6.3 cm diameter) is the bag size
commonly used. Barnard (1954) tested different sizes of
bamboo pots and larger pots gave better survival. A trial
on varying pot sizes using Shorea polysperma was carried
out by Bruzon and Serna (1980) and height development
in 8 cm diameter pots was best. When planting, the upper
part of the earthball should be slightly below the soil
surface for successful establishment, and never above it.
Depth of planting was investigated, e.g., by Shrubshall
(1940), and Walton (1938) who for Dryobalanops
oblongifolia found deep planting (collar 5 cm below
surface) gave the best results and shallow planting caused
75% mortality. Shrubshall (1940) also reported deep
planting gave the best results. Earth is firmly placed
around the plant to close the air spaces and finally, the
young plants are mulched with organic material to
prevent desiccation and overheating of the soil. Bareroot
seedlings can be planted in two ways: hole-planted
as in potted plants; and notch-planted. In notch planting a
cone- or wedge-shape hole is made with a spade or a
hoe. The roots of the plant are placed into the hole to the
required depth and the soil firmed around the plant.
Barnard and Setten (1955) reported on the comparison
of planting trials of Dryobalanops oblongifolia in
prepared planting patches and in notches. The
performance of two types of seedlings were compared: