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 171<br />
fungal problems, bacterial and viral infections (Smits et<br />
al. 1991). Heart-rot <strong>of</strong> <strong>dipterocarps</strong> has been<br />
investigated, and is more serious in slow-growing than<br />
in fast-growing species (Hodgson 1937b, Bakshi et al.<br />
1963). Stand management strategies to control heartrot<br />
have been developed <strong>for</strong> Shorea robusta (Bakshi<br />
1957).<br />
With establishment <strong>of</strong> large-scale plantations <strong>of</strong><br />
<strong>dipterocarps</strong>, susceptibility to diseases and pests is bound<br />
to increase. The control <strong>of</strong> pests and diseases in<br />
nurseries is well developed and advanced. Chemical<br />
control is the prevailing method to fight the attack <strong>of</strong><br />
biotic agents. Chemical control is, however, not<br />
practicable after field planting. Prevention has to be<br />
secured by silvicultural means, e.g., species mixtures,<br />
structural diversity, avoidance <strong>of</strong> damage to trees and soil,<br />
etc. At present, there is an urgent need to survey diseases,<br />
defects and damages in existing dipterocarp plantations,<br />
particularly the incidence and possible causes <strong>of</strong> heartrot.<br />
Gaps in natural <strong>for</strong>ests and plantations are created<br />
by natural mortality, biotic and abiotic agents. Lightning<br />
is a major cause <strong>for</strong> the occurrence <strong>of</strong> gaps not only in<br />
natural <strong>for</strong>ests (Brünig 1964, 1973) but also in<br />
plantations. While in natural <strong>for</strong>ests such gaps drive the<br />
regeneration dynamics, in plantations such gaps, first <strong>of</strong><br />
all, reduce the stocking. The effect <strong>of</strong> lightning can be<br />
seen clearly in the plantation area <strong>of</strong> the Forest <strong>Research</strong><br />
Institute Malaysia (personal observation).<br />
Management Aspects<br />
The available in<strong>for</strong>mation, here, can be combined under<br />
the following categories: silvicultural systems, biological<br />
production, (especially growth), thinning schedules,<br />
stocking aspects, silvicultural diagnostics, and<br />
economics.<br />
‘A silvicultural system is a process, following<br />
accepted silvicultural principles, whereby the crops<br />
constituting <strong>for</strong>ests are tended, harvested and replaced,<br />
resulting in the production <strong>of</strong> crops <strong>of</strong> distinctive <strong>for</strong>m.<br />
The systems are conveniently classified according to the<br />
method <strong>of</strong> carrying out the fellings that remove the<br />
mature crop with a view to regeneration and according<br />
to the crop produced hereby’ (Ford-Robertson 1983).<br />
Silvicultural systems are discussed in the context <strong>of</strong> stand<br />
regeneration <strong>of</strong> plantations after the first rotation.<br />
In India, various silvicultural systems have been<br />
applied to encompass the wide ecological variation in<br />
the occurrence <strong>of</strong> <strong>dipterocarps</strong>. A selection system has<br />
been applied in seasonal rain <strong>for</strong>ests and moist deciduous<br />
<strong>for</strong>ests. Clearfelling and artificial regeneration have been<br />
carried out in moist deciduous <strong>for</strong>ests where frost is<br />
absent. Various <strong>for</strong>ms <strong>of</strong> shelterwood systems were<br />
applied in regions where frost was experienced. Coppice<br />
with standards was applied to Shorea robusta in dry areas<br />
and simple coppice systems used in wood lots in<br />
Karnataka.<br />
While the silvicultural systems <strong>for</strong> Shorea robusta<br />
<strong>for</strong>ests in India are clearly <strong>for</strong>mulated and understood,<br />
there is little in<strong>for</strong>mation in other parts <strong>of</strong> the region on<br />
what the silvicultural system <strong>for</strong> dipterocarp plantations<br />
should be. Most silviculturists would like to re-establish<br />
an existing dipterocarp plantation at the end <strong>of</strong> the first<br />
rotation by natural regeneration. In Malaya, Walton<br />
(1933, 1936a), Watson (1935) and others have indicated<br />
the possible species among the fast-growing lighthardwoods<br />
which can regenerate naturally in the rotation<br />
envisaged <strong>for</strong> plantations. Little is known about the<br />
capacity <strong>of</strong> plantation-grown dipterocarp species to<br />
regenerate naturally at a rotation <strong>of</strong> about 50 years. There<br />
is already some in<strong>for</strong>mation derived from planted<br />
species, e.g., Shorea leprosula, Dryobalanops spp.,<br />
Shorea spp. <strong>of</strong> the pinanga group and S. robusta, which<br />
can be naturally regenerated during such a rotation time.<br />
All the existing, mature, experimental, dipterocarp<br />
plantations in the region should be assessed <strong>for</strong> natural<br />
regeneration.<br />
The growth <strong>of</strong> <strong>dipterocarps</strong> under natural <strong>for</strong>est<br />
conditions has been observed early this century (e.g.,<br />
Edwards and Mead 1930, Watson 1931/1932a, Rai 1996).<br />
The observation <strong>of</strong> the growth <strong>of</strong> <strong>dipterocarps</strong> in plantations<br />
commenced only later. Analysis <strong>of</strong> 29 dipterocarp species<br />
in trial plots at the Forest <strong>Research</strong> Institute Malaysia<br />
indicates rotation ages <strong>of</strong> 40 to 50 years <strong>for</strong> the best<br />
per<strong>for</strong>ming species (Ng and Tang 1974). Individual volume<br />
and growth plots have also been analysed (Vincent 1961 a, b,<br />
c, d, Zuhaidi et al. 1994). The growth curves show a very fast<br />
early height and diameter growth with distinct differences<br />
between species in growth rates. Relatively impressive<br />
growth rates <strong>of</strong> the light red meranti group (Shorea spp.)<br />
have also been recorded in the Haurbentes experimental<br />
plantation stands in Indonesia (Masano et al. 1987, see also<br />
Ardikoesoema and Noerkamal 1955): a stand <strong>of</strong> Shorea<br />
leprosula achieved an average height and diameter <strong>of</strong> 44.6<br />
m and 77 cm respectively in 35 years. Shorea stenoptera<br />
was similarly fast growing with an average height and