A review of dipterocarps - Center for International Forestry Research

Plantations 164
Tomboc and Basada (1978) tested the performance of
Shorea contorta sown on open areas and under secondary
growth canopy. Survival was highest under the cover of
the forest, while growth was better in the open. Maun
(1981) suggests that it will be necessary to germinate
direct-sown seeds and grow the seedlings of S. contorta
initially in shaded conditions. Later, the vegetation should
be opened for better growth of the seedlings. Similarly,
Strong (1939) found in a trial of direct sowing into
cultivated areas (taungya) and into high forest that the
germination of Dryobalanops oblongifolia and Shorea
sumatrana failed in the cultivated areas largely as a
result of drought and heat. The seeds were also attacked
by insects and rodents. Sowing under the shelter of
Paraserianthes falcataria was successful with Shorea
stenoptera (Sudiono and Ardikusumah 1967).
Chakravarti (1948) found direct sowing is the only
method to artificially regenerate Shorea robusta forests
in India. The principal adverse factor to germination and
survival of seeds is drought and shade is essential for
successful regeneration. Suggestions on the best type
of nurse crop are given. Sown seeds may be attacked by
insects or rodents. Barnard and Wyatt-Smith (1949)
reported high mortality in their sowing trial of
Dryobalanops aromatica in secondary vegetation
mainly caused by rodent attacks on the germinating seeds.
In comparison to other methods of artificial
regeneration, the sowing method is less convincing.
Cerna and Abarquez (1959) compared growth and survival
of S. contorta plants that originated from transplants and
from direct-sown seeds 11 years after stand
establishment. Heavy mortality of seedlings resulted
from direct sowing. S. contorta is very sensitive to bareroot
planting and planting of balled plants was the most
successful method.
Stand establishment by sowing is a very wasteful
practice because of the large amount of seeds needed
for sowing operations,
Stand Tending
‘Tending, generally, is any operation carried out for the
benefit of a forest or an individual thereof, at any stage
of its life. It covers operations both on the crop itself,
e.g., thinnings and improvement cuttings, and on
competing vegetation, e.g., weeding, cleaning, climber
cutting, and girdling of unwanted growth, but not
regeneration cuttings or site preparation’ (Ford-
Robertson 1983). Stands develop and grow through
various developmental stages from seedling or coppice,
through thicket, sapling, and pole, to the tree stage, i.e.
to maturity, and finally to overmaturity, but sometimes
ending in residual standards. Residual standards are trees
that remain standing after the rest of the stand has been
removed or has died.
Weeding and Cleaning
The immediate post-planting care (mainly weeding),
which covers the time until the plantation can be
considered established, is crucial for planting success.
Weeding is an operation whereby mainly herbaceous
vegetation is eliminated or suppressed during the seedling
stage of the forest crop. It is, therefore, the first cleaning
and aims to reduce competition within the seedling stand.
Cleanings to eliminate or suppress undesirable vegetation
(mainly woody including climbers) are carried out when
the young plant is in the sapling stage (1.5 m height and
5 cm diameter). Cleanings are carried out during the
thicket stage of a forest crop and therefore before, or at
latest with, the first thinning, so that better trees are
favoured. Removal of overtopping vegetation must be
carried out during weeding and clearing operations in
dipterocarp plantations established either under a nurse
crop (natural or planted) or in existing, line-planted, taller
vegetation (e.g., secondary forest). Watson (1931/32e)
classified trees according to their silvicultural importance.
He, especially, distinguished between undesirable weeds
which needed to be eradicated under nearly all
circumstances and harmless tree species which are useful
for shade or cover. Barnard (1954) recommended the
removal of the overhead shade as soon as the young trees
have recovered from the transplanting shock. He also
found that the slightly increased light due to the cutting
of planting lines was beneficial. Tang and Wadley (1976)
discuss the technique of line opening and shade regulation.
Techniques of line opening in the context of enrichment
planting are described, e.g., by Chai (1975), Tang and
Wadley (1976) and Lai (1976).
A common practice is to mark planting places with
small poles with the empty plastic bag pulled over the tip
so that the location of the plant can be detected by the
weeding crews. The weeding can be done for example,
as strip or ring weeding. Normal practice is to blanket
weed the planting lines and remove the weeds by slashing.
However, woody vegetation grows more vigorously if
cut, requiring additional weeding operations. Since the