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