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 />
1. Heavy pressure from politicians to practice<br />
accelerated felling cycles, clear felling, re-entry, and<br />
leniency with regard to logging damage and illegal<br />
cuttings;<br />
2. Uncertainty <strong>of</strong> <strong>for</strong>est tenure, due to rapid conversion<br />
<strong>of</strong> <strong>for</strong>est lands to agriculture, uneven distribution <strong>of</strong><br />
land, and short logging tenures which discourage<br />
private investment; and<br />
3. Grossly undervalued resources, with timber prices<br />
not including replacement or silvicultural costs and<br />
non-timber values. The stumpage and royalty fees are<br />
kept too low, and the governments do not receive the<br />
logging pr<strong>of</strong>its needed <strong>for</strong> silvicultural treatment.<br />
An Evaluation<br />
Silvicultural systems <strong>for</strong> natural <strong>for</strong>ests have to ensure<br />
natural regeneration succeeds, and the quality, quantity<br />
and size <strong>of</strong> the chosen tree species are enhanced, without<br />
destroying the <strong>for</strong>est structure and function. Enrichment<br />
planting is an expensive alternative that should be<br />
minimised. Both the Shelterwood (monocyclic) and<br />
Selection (polycyclic) Systems are being purportedly<br />
used <strong>for</strong> managing dipterocarp <strong>for</strong>ests in Asia. But how<br />
do the two systems stand up in real practice <strong>for</strong> managing<br />
dipterocarp <strong>for</strong>ests? Shelterwood Systems depend<br />
directly on treating the desired seedlings <strong>for</strong> the next<br />
crop. This is a conceptually simple system which requires<br />
less supervision, and if done carefully, there is little<br />
damage to the next stand (Putz and Ashton, unpublished).<br />
Several workable examples <strong>of</strong> Shelterwood Systems have<br />
existed, the Malayan Uni<strong>for</strong>m System being a well known<br />
one among them.<br />
The critical factor seems to be the ease with which<br />
regeneration can be secured. It is this particular feature<br />
<strong>of</strong> <strong>dipterocarps</strong> that makes it much easier to manage them<br />
compared to other <strong>for</strong>est types. In the case <strong>of</strong> sal <strong>for</strong>ests,<br />
natural <strong>for</strong>est management seems sustainable only where<br />
regeneration is easy to secure. This is the case with<br />
Coppice Systems, provided grazing and fire are<br />
controlled. The MUS has also capitalised on the pr<strong>of</strong>use<br />
seedling regeneration capacity <strong>of</strong> the family.<br />
Nevertheless there are elements within Shelterwood<br />
Systems that are discouraging:<br />
1. Logging has to be delayed until the regeneration is<br />
ensured;<br />
2. Rotations are long, by human terms;<br />
3. Heavy felling might induce weed growth, and expose<br />
fragile soils to erosion; and<br />
143<br />
4. Unwanted trees which were <strong>for</strong>merly girdled can now<br />
be exploited with improved technology and<br />
diversified markets. Although such canopy openings<br />
would have allowed the highly preferred target trees<br />
to maximise their growth.<br />
The Shelterwood Systems developed <strong>for</strong> all three<br />
dipterocarp <strong>for</strong>est types showed signs <strong>of</strong> success. But<br />
in many instances the Shelterwood Systems seem to have<br />
fallen victims <strong>of</strong> outside changes. Workable systems have<br />
thus been continuously incapacitated by the demands <strong>of</strong><br />
society, rapid and unplanned landuse changes, illegal<br />
felling, fire and grazing, and finally our complete<br />
bewilderment with tropical ecosystems. The four<br />
examples below highlight them:<br />
1. The Coppice Systems in India have been clearly<br />
worked out, and may be the only dipterocarp <strong>for</strong>ests<br />
sustainably managed <strong>for</strong> 3 rotations or more. But the<br />
demand <strong>for</strong> timber and fuelwood in India exceeds the<br />
production. The silvicultural response has been to<br />
shorten rotations. This has not been a realistic<br />
solution because increased frequency <strong>of</strong> removal<br />
results in degradation <strong>of</strong> stumps. Leaving behind<br />
standards to assist natural regeneration to<br />
compensate <strong>for</strong> the degradation was tried. This too<br />
proved unsuccessful because these <strong>for</strong>ests are close<br />
to villages and the demand <strong>for</strong> grazing lands is high.<br />
When the demand <strong>for</strong> firewood and small timber<br />
exceeded biological capacity, shorter rotations were<br />
resorted to to enhance supply. This has accelerated<br />
the decline, and the areas have to be planted up as a<br />
consequence.<br />
2. In the Malayan case, the MUS which took <strong>for</strong>m<br />
following the Japanese Occupation (1942-1945)<br />
could never really be put into practice. During the<br />
1950s Emergency in Peninsular Malaysia guerrillas<br />
took refuge in these very <strong>for</strong>ests. It was difficult to<br />
work long in a <strong>for</strong>est - it was <strong>of</strong>ten a case <strong>of</strong> log and<br />
leave. The 1970s saw peace and an acceleration <strong>of</strong><br />
economic growth. Large tracts <strong>of</strong> the lowland<br />
dipterocarp <strong>for</strong>ests, <strong>for</strong> which the MUS was<br />
<strong>for</strong>mulated, were converted to plantations <strong>of</strong> cash<br />
crops. Thereafter, logging was confined to the hillier<br />
terrain. Here the MUS was considered unsuitable and<br />
selective fellings have been applied.<br />
3. In some instances sheer confusion seems to have<br />
prevailed in our attempts to manage dipterocarp<br />
<strong>for</strong>ests. In Malaya, Departmental Improvement<br />
Fellings <strong>of</strong> the 1930s proved ineffective on the poles