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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Management <strong>of</strong> Natural Forests<br />
4. Clearfelling System<br />
This system is used when there is a need to change the<br />
composition <strong>of</strong> the crop to a more valuable species. The<br />
restocking is through natural or artificial regeneration,<br />
the latter used to introduce a new species or to change<br />
the <strong>for</strong>est composition. As a consequence, the more<br />
valuable teak is introduced into sal <strong>for</strong>ests. The trend is<br />
to convert most <strong>of</strong> these <strong>for</strong>ests into plantations, making<br />
the future <strong>of</strong> sal <strong>for</strong>ests uncertain.<br />
Peninsular Malaysia<br />
Forest Management Systems<br />
<strong>Forestry</strong> in the modern sense was started in 1883 with<br />
the establishment <strong>of</strong> the <strong>for</strong>estry service. Prior to<br />
introduction <strong>of</strong> <strong>for</strong>est management, logging was very<br />
selective, principally limited to the heavy hardwoods<br />
(mainly several dipterocarp secies), and only about 7m 3 /<br />
ha was taken out (Barnard 1954). Silvicultural operations<br />
were limited to enrichment plantings <strong>of</strong> the heavy<br />
hardwood, chengal (Neobalanocarpus heimii), which<br />
failed from lack <strong>of</strong> further tendings. But the demand <strong>for</strong><br />
timber increased, leading to over-exploitation <strong>of</strong> the<br />
select timbers. This prompted the authorities to develop<br />
a series <strong>of</strong> silvicultural systems.<br />
1. Regeneration Fellings<br />
In the beginning (1910-1922) Departmental<br />
Improvement Fellings were implemented. All species<br />
whose crowns interfered with the poles <strong>of</strong> any valuable<br />
timber species were removed. It was subsequently<br />
realised that such treatments had no impact on the<br />
immature trees. However, they resulted in pr<strong>of</strong>use young<br />
regeneration (Hodgson 1937). The improvement fellings<br />
had in fact been regeneration fellings. After 1932,<br />
Regeneration Improvement Fellings (RIF) came in to<br />
vogue. Inferior species were gradually removed over a<br />
series <strong>of</strong> fellings. If the regeneration was verified as<br />
successful, final felling <strong>of</strong> the valuable species was<br />
carried out. This in fact resembled the classical<br />
Shelterwood Systems.<br />
2. Malayan Uni<strong>for</strong>m System<br />
As a rule, no <strong>for</strong>ests were harvested without first carrying<br />
out RIF. During the Japanese Occupation (1942-1945)<br />
many <strong>for</strong>ests were clearfelled without the benefit <strong>of</strong> RIF.<br />
After the war, extensive surveys revealed that these areas<br />
contained adequate advanced regeneration without any<br />
137<br />
assistance. It was realised that if the <strong>for</strong>est had adequate<br />
regeneration <strong>of</strong> the fast growing dipterocarp species, a<br />
single clearfelling release could result in a greater<br />
stocking <strong>of</strong> a more uni<strong>for</strong>m crop <strong>of</strong> commercial species.<br />
This became the basis <strong>for</strong> the Malayan Uni<strong>for</strong>m System<br />
(MUS), which was introduced in 1948 <strong>for</strong> managing<br />
Lowland Dipterocarp Forests (Wyatt-Smith 1963).<br />
A detailed silvicultural system was developed (Wyatt-<br />
Smith 1963). It consists <strong>of</strong> felling the mature crop <strong>of</strong> all<br />
trees above 45 cm dbh, poison girdling all defective<br />
relics and non-commercial species down to 5 cm dbh,<br />
and releasing established seedlings. Seedling adequacy<br />
and suitable tendings underpinned the success <strong>of</strong> MUS.<br />
3. Modified Malayan Uni<strong>for</strong>m System<br />
In the mid-1970s, most <strong>of</strong> the lowland dipterocarp<br />
<strong>for</strong>ests were alienated <strong>for</strong> agricultural programmes, and<br />
<strong>for</strong>estry was confined to the hills and rough terrain<br />
unsuitable <strong>for</strong> agriculture. Under these new conditions<br />
it was considered difficult to apply the MUS. The<br />
principal problem was the lack <strong>of</strong> uni<strong>for</strong>m stocking <strong>of</strong><br />
natural regeneration. It was thought that enrichment<br />
planting could overcome this deficiency (Ismail 1966).<br />
This allowed all <strong>for</strong>ests to be opened up <strong>for</strong> logging,<br />
regardless <strong>of</strong> adequate seedling stocking, a prerequisite<br />
with MUS. Planting up understocked areas was carried<br />
out in the beginning, but their per<strong>for</strong>mance was very<br />
variable and unsatisfactory. Now, artificial regeneration<br />
is rarely carried out, or the practice is abandoned entirely.<br />
4. Selective Management System<br />
In the late 1970s, the Selective Management System<br />
(SMS) was introduced. This is a simplified version <strong>of</strong><br />
the Philippine Selective Logging System (see Appanah<br />
and Weinland 1990). The MUS was already discarded<br />
<strong>for</strong> working in the hillier terrain, and the modified-MUS<br />
proved unsatisfactory. The felling regime is <strong>for</strong>mulated<br />
on the basis <strong>of</strong> a pre-felling inventory. All commercial<br />
tree species above a certain size (ideally non<strong>dipterocarps</strong>,<br />
45 cm dbh; <strong>dipterocarps</strong>, 50 cm dbh) are<br />
felled, provided a sufficient number <strong>of</strong> residuals are left<br />
behind to <strong>for</strong>m the next cut in ca 30 years (Thang 1987).<br />
There<strong>for</strong>e the SMS relies on adequacy <strong>of</strong> healthy<br />
residuals which will respond to the cutting release <strong>for</strong><br />
the next cut some 25-30 years later. Seedling stocking<br />
is assumed to be present, or will be replenished by the<br />
maturing residuals. The SMS is regarded as more flexible<br />
<strong>for</strong> managing the highly variable <strong>for</strong>est in the hillier