A review of dipterocarps - Center for International Forestry Research

Management of
Natural Forests
S. Appanah
The view that it is not possible to manage natural forests
in the tropics for their timber has its adherents.
Considering the widespread failures in many countries,
such a view is conceivable. A review by International
Tropical Timber Organization estimated that only an
insignificant amount of the world’s tropical moist forests
is sustainably managed (Poore 1989). Fortunately,
numerous reports suggest otherwise for some
dipterocarp forests of Asia. The state of tropical forest
management worldwide is in such a quandary that any
success, however meagre, requires close examination.
Such a success may provide the flicker of hope that is so
urgently needed in our efforts to save these tropical
forests.
The dipterocarp forests in the perhumid zone of Asia
form the cradle for a considerable proportion of life
forms found on Earth. It is arguable that the only effective
way to preserve a sizable portion of this biodiversity will
be through effective management, including production
of timber and other valuable products.
Fortunately, history is on the side of dipterocarp
forests. The origins of scientific tropical forest
management began in Asia, particularly in British India
around the mid-19th Century. Together with teak, the
dipterocarp forests were among the first tropical forests
to be managed. The Indian experience formed the basis
for management in the Malayan realm (Hill 1900). The
conditions for management have changed considerably
since then, but the experience and understanding gained
form an excellent basis for developing appropriate
management regimes for tropical forests.
Forest Composition, Distribution and
Structure
Although the family Dipterocarpaceae is presently
recognised pantropical, with three subfamilies
Chapter 8
Monotoideae (Africa, Colombia), Pakaraimoideae
(Guyana) and Dipterocarpoideae (Asia), it is the last
subfamily that is of significance as a timber group
(Ashton 1982). The present review will be confined to
the Asian subfamily. It comprises 13 genera and some
470 species, distributed from the Seychelles in the west
to Papua New Guinea to the east. In Chapter 1 more
details on the taxonomy, distribution and diversity of this
subfamily are given (see also Champion 1936, Symington
1943, Ashton 1980, 1988).
Dipterocarps are limited to tropical climates with a
mean annual rainfall exceeding 1000 mm, with only short
dry spells. The Asian dipterocarp forests can be divided
into two basic zones, viz. the Moist Tropical Forests and
the Dry Tropical Forests (Champion and Seth, 1968,
Collins et al. 1991). Within these two basic moist and
dry tropical forests, four forest types can be distinguished
(Table 1).
Our knowledge of these forests, especially the
distribution of dipterocarps within them is incomplete.
This is particularly the case with forests of Indochina
and southern China. Under these circumstances, and for
the sake of brevity, the presentation is simplified to three
groups of dipterocarp forests, viz. the Dry evergreen
dipterocarp forests (Dry tropical forests), Seasonal
evergreen dipterocarp forests (Tropical semi-evergreen
and Tropical moist deciduous forests), and the Aseasonal
evergreen dipterocarp forests (Tropical wet evergreen
forests). Some information on their distribution and
structure is given below.
Dry Evergreen Dipterocarp Forests
These forests are found in Central and East India, Burma,
Thailand and Indo-China. The forests are dry, with less
than 2000 mm of annual rainfall and a dry season of 3 to
5 months. The forests are medium in stature, with an even
canopy and no emergents. Shorea robusta (Indian sal)