A review of dipterocarps - Center for International Forestry Research

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damage to the next stand (Putz and Ashton, unpublished).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