A review of dipterocarps - Center for International Forestry Research

Plantations 170
mono-layered. The regeneration period will be rather
short and the resulting stand after final felling will be
fairly regular. Species which fruit more irregularly might
require more irregular canopy openings following the
recruitment patches and a group shelterwood system
applied. The regeneration period will be protracted and
the resulting stand more irregular.
Reforestation and Afforestation of
Degraded Land
Reforestation is the re-establishment of a forest crop
on forest land. Afforestation is the establishment of a
crop on an area from which it has always or very long
been absent. Degradation in the pedological sense is ‘any
significant reduction in the fertility of the soil, whether
in the course of its natural development or by direct or
indirect human action’ (Ford-Robertson 1983).
There is a growing need for rehabilitation of
degraded forest sites following destructive logging, land
clearing or mining. Dipterocarp species are by nature
not very well suited for rehabilitation of severely
degraded forest land. However, in some instances,
dipterocarp species have been used with success (Ang
and Muda 1989, Ang et al. 1992, Nussbaum et al. 1993,
Nussbaum et al. 1995, Nussbaum and Ang 1996). Lately,
Nussbaum and Ang (1996) have carried out a review on
the rehabilitation of degraded land. Bieberstein et al.
(1985) and Thai (1991) recommended Dipterocarpus
spp. for the reforestation of devastated and shrub areas
in Vietnam. Mitra (1967) describes the management
measures carried out over large areas in West Bengal
since the acquisition of all private forest lands (which
were mainly Shorea robusta coppice forests) by the
State in 1953. Shorea robusta was planted in eroded
areas (Goswami 1957) and former bauxite mining land
in India (Prasad 1988), Hopea parviflora on bare lateritic
soil (Dhareshwar 1946) and Dryobalanops
oblongifolia on waste land (Landon 1941). An initial
burn and cultivation of planting patches were found to
be beneficial. Shineng (1994) reports using dipterocarps,
Dipterocarpus turbinatus and Parashorea chinensis,
for establishing plantations on degraded forest land in
tropical China but the growth rates of both dipterocarps
were almost the lowest among 26 tree species tested.
Mitchell (1963) explored the possibilities of afforesting
raised sea beaches along the east coast of Peninsular
Malaysia. Among the species tested was Hopea nutans
which failed (Ang and Muda 1989). Rai (1990) describes
a successful trial to restore degraded tropical rain forests
of the Western Ghats (India) in which Vateria indica,
Dipterocarpus indicus, Hopea parviflora and H.
wightiana were used.
Agroforestry
Not many dipterocarp species have as yet been included
in agroforestry systems. Shorea robusta is the only
species which has been researched intensively in the
context of the taungya system. Taungya is an ‘agrisilviculture
system for the raising of a forest crop (a
taungya plantation) in conjunction with a temporary
agricultural crop’ (Ford-Robertson 1983).
Nevertheless, agroforestry systems involving
dipterocarps have been practised throughout the Indian-
Southeast Asian region. Vateria indica and Shorea
robusta have been used in agroforestry systems in India.
Sal (Shorea robusta) taungya is a relatively well
developed system in India (Huq 1945, Osmaston 1945,
Kanjilai 1945, and others). Prominent in agroforestry
systems in Borneo are the dipterorcarp species that
produce edible nuts (Shorea spp. of the pinanga group)
(Seibert 1989). An agroforestry system in East
Kalimantan which often involves Shorea macrophylla
is called the ‘lembo’ system (Sardjono 1990). Resin
tapping of Shorea javanica is well developed in Sumatra
(Torquebiau 1984). Integration of farming into the
tending and conservation of logged forests was discussed
(Serrano 1987, Mauricio 1987b), as well as the propects
for agroforestry to be used for the rehabilitation of
degraded forest land in Indonesia (Kartiwinata and
Satjapradja 1983). Watanabe et al. (1988) investigated a
taungya reforestation method in the context of the
Government Forest Village Programme in Thailand,
where Dipterocarpus alatus is involved. An agroforestry
system using dipterocarps was also tried in West
Malaysia (Cheah 1971, Ramli and Ong 1972) but it has
not been adopted. These are but a few examples of
dipterocarp species used in agroforestry systems.
Forest Protection Aspects
The knowledge on pests and diseases of dipterocarps is
scanty, but a more systematic account is given in
Chapter 7. Insects attack dipterocarp fruit crops heavily
(Daljeet-Singh 1974). By comparison, their seedlings
are well protected (Daljeet-Singh 1975). Becker (1981)
investigated potential physical and chemical defences of
Shorea seedling leaves against insects. Diseases include