A review of dipterocarps - Center for International Forestry Research

Introduction
As a consequence, much of the knowledge on
dipterocarps appears to be accessible only to specialists.
The potential benefits of this family have not been fully
recognised, and if the present situation is allowed to
proceed, mankind may lose important opportunities. The
following examples affirm this view. Few realise that the
only moist tropical forests in the world where sustainable
forest management has been demonstrably practiced are
the dipterocarp forests (FAO 1989). The best silvicultural
system that was ever formulated for a tropical forest is
perhaps the Malayan Uniform System which is based on
the exceptional regeneration properties of dipterocarps
(Wyatt-Smith 1963). In fact dipterocarp forests are the
envy of foresters and silviculturists toiling in the African
and neotropical areas. However, these facts are seldom
if ever highlighted.
The general lack of comprehension about the family
has led to a tide of opinion that it is not possible to
manage tropical forests, an opinion strongly contested
by those involved in dipterocarp forest management. Few
realise that the apparent failures in establishing
sustainable yields were more the result of changes in
landuse patterns and economic restructuring than from
an inherent inability of the forest to respond to
appropriate silvicultural interventions (Appanah and
Weinland 1990). To a degree, this lack of understanding
has led us to exploit the forests somewhat carelessly
without considering the wonderful opportunities they
offer for practicing sustainable forestry.
This ignorance of the qualities of dipterocarps has
also led us to search elsewhere for usable tree species
when interest in timber plantations for the moist tropics
developed (e.g. Spears 1983). The general impression
was that dipterocarps, as a group, are slow growing and
planting material difficult to procure. Such overgeneralisations
made us miss some important
opportunities with dipterocarps. There are dipterocarps
which make excellent plantation species (Appanah and
Weinland 1993), and several have growth rates that are
acceptable or superb for this purpose (Edwards and Mead
1930). Few recognise the potential of dipterocarps with
their mycorrhizal associations to grow under poorer soil
conditions. Nor has attention been focused on the variety
of dipterocarp species available that are adapted to a wide
range of habitats and edaphic conditions making it
possible to match species to specific conditions in
plantations.
Now that attempts to establish fast growing hardwood
plantations based on exotic timber species in moist
forests of Asia have met with many difficulties, there is
a resurgence of interest in indigenous species for this
purpose. Many of the species under consideration are
dipterocarps (Anon. 1991). Throughout Southeast Asia,
plans for planting dipterocarps are regularly announced
while major reforestation activities are often based on
the use of species from this family. Meanwhile, forest
scientists and managers from all over the world are
looking to dipterocarp forests to provide models for
sustainable forest management for the moist tropics and
ensure a steady supply of industrial wood in the future.
Currently, numerous initiatives, both national and
international, are underway to address the variety of
issues related to dipterocarps and dipterocarp forests.
These issues under investigation cover a very wide
spectrum, from basic management issues (e.g. National
Institutes, Food and Agriculture Organization (FAO),
International Tropical Timber Organisation (ITTO),
Department for International Development (DFID)), to
producing quick field identification guides (DFID), and
biodiversity (DFID), ecology and economics (National
Science Foundation, Center for Tropical Forest Science),
vegetative propagation (TROPENBOS, Japanese
International Cooperation Agency), mycorrhiza
(TROPENBOS, National Institute for Environmental
Studies, European Commission), non-timber forest
products, plantations (ITTO, TROPENBOS, Forestry
Research Support Programme for Asia and the Pacific),
and so on. In addition to the interest in planting
dipterocarps, there is also a general surge of excitement
over all other aspects of this family. Some major studies
currently underway include sustainable management of
dipterocarp forests (Sabah Forest Department/Deutsche
Gesellschaft Fuer Technische Zusammenarbeit MbH)
and carbon sequestration and reduced impact logging
(Forest Absorbing Carbon-dioxide Emissions
Foundation).
While the above endeavours are laudable, and bear
testimony to the value of dipterocarps, we view this
proliferation of apparently uncoordinated initiatives with
some concern. Undoubtedly, these undertakings are
going to vastly increase our knowledge of the trees and
the ecosystem, so that in the final analysis we get closer
to our ultimate goal – the ability to manage these forests
on a sustainable basis. But at what price in terms of
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