A review of dipterocarps - Center for International Forestry Research

Biogeography and Evolutionary
Systematics of Dipterocarpaceae
G. Maury-Lechon and L. Curtet
The history of Dipterocarpaceae botany, as understood
in modern terms, started more than two centuries ago
when Rumphius first mentioned the family in 1750. At
that time dipterocarp forests were considered to be
inexhaustible sources of wild products. The dipterocarps
were thought to dominate extensively throughout
southeast Asia. As soon as the high value of their products
(camphor, resins, timber) was perceived funds were made
available for botanists to conduct expeditions and
laboratory research. A considerable amount of
information has thereby been collected, and we now can
recognise the valuable timber species in the forests and
their natural distribution. The quality of market products
thereby has become more uniform and predictable, thus
favouring trade. At present, underestimated and
unrestricted exploitation has encouraged excessive
harvesting of dipterocarps and together with modern
technologies and economics, has finally endangered the
future of dipterocarp forests.
As early as 1824 and 1868 de Candolle emphasised
the importance of the number of stamens and their
position in relation to petals to separate dipterocarp
genera (Pentacme from Vateria, Petalandra from
Hopea). These characters may affect the quantity of
pollen produced and its availability for eventual
pollinators. Similarly fruit and seed structures and shapes
used in systematics also affect fruit-seed dispersal,
germination and plant establishment.
Present geographical distribution and the structures
and functions of tropical plants are the results of past
adaptations to environmental constraints. These features
were produced in geological time under the influence
of ancient climatic variation (Muller 1972, 1980).
During the last decades, the intensification of human
pressure on valuable trees has become the predominant
factor of transformation for tropical forests (Maury-
Lechon 1991). Excessive canopy openings provoke the
Chapter 1
rise of ambient temperature and desiccation. Faced with
these new drastic conditions, past adaptations may no
longer be suitable. If so, the definition of biological
plasticity of well defined taxa according to their
phylogenetic and ecological relations with the
congeners will provide useful tools for forest managers
(Maury-Lechon 1993).
Such knowledge in systematics may have value in
rehabilitation and sustainable management of forests.
Understanding events such as pollination, fruit dispersal,
seedling mycorrhization and survival, coupled with
biogeographic distribution and evolutionary systematics
may help to define lines of lesser phylogenetic resistance
(Stebbins 1960, Maury-Lechon 1993). Such an approach
provides the boundaries and physical limitations in which
a species is able to survive and can be used to identify
species most suitable for rehabilitation in the changing
conditions that man has introduced into the environment.
In this chapter, the present understanding of
biogeography and evolutionary systematics of the family
Dipterocarpaceae is reviewed and whenever possible
there are attempts to link this knowledge to its use in the
development sector. Finally, there are some notes on
further research needs and expertise in the field.
Presentation of the Family
Dipterocarpaceae
Taxonomy
All Dipterocarpaceae species are arborescent and
tropical (Fig. 1). The family type genus is the Asian
Dipterocarpus Gaertn.f. Dipterocarps are trees with
alternate entire leaves and pentamerous flowers. The
family Dipterocarpaceae sensu stricto is homogeneous
for only Asian plants while the Dipterocarpaceae sensu
lato include three subfamilies: Dipterocarpoideae in
Asia; Pakaraimoideae in South America; and