Part I
REGIONAL SYNTHESIS (continued)

Chapter III
FOREST RESOURCES OF TROPICAL ASIA (continued)

1. PRESENT SITUATION (continued)

Tables 1a to 1f summarize the estimates by country and subregion of the different classes of natural woody vegetation. All estimates refer to the end of 1980.

- Table 1a: areas of closed broadleaved forests

Closed forests correspond to stands without continuous grass cover, with trees whose crowns cover a high proportion of the area, generally multistoreyed, and which have not been cleared for agriculture in the past 20 to 30 years. They are either managed or unmanaged forests and may have been logged-over once or more times.

The total area of closed broadleaved forests in the region is estimated at 292 million ha of which 49% is in insular southeast Asia, 21% in continental southeast Asia (including centrally planned countries) 18% in south Asia and the rest in Papua New Guinea. Out of 292 million ha only 192 million ha (66%) are considered productive (of wood for industry) and the rest unproductive, either because of inaccessibility or due to statutory reasons (e.g. national parks).

Indonesia, India, Burma, Malaysia, Papua New Guinea and the Philippines, among them account for some 90% of the productive closed broadleaved forest area (NHCf1) of the region. In Indonesia more than half of these forests are confined to Kalimantan and Sumatra, and Irian Jaya accounts for some 36%: the predominant broadleaved forest type is “tropical rain forest” where dipterocarps are the most important botanical family by number and commercial value. In India NHCf1 forests are essentially tropical deciduous forests; tropical evergreen and semi-evergreen forests constitute only some 7% of NHCf1. In Burma NHCf1 includes forests with mixed species with a predominance of teak. In Malaysia and the Philippines mixed dipterocarp forests account for over 90% of the area; peat swamp forests of the Malaysian state of Sarawak are included under NHCf1.

The status of productive closed broadleaved forests under intensive management (NHCf1m) is reviewed below under paragraph “Management” of this section.

About one half of the productive closed broadleaved forests of the region are considered still “virgin”. Out of a total area of 97 million ha where there has been no logging (at least in the 60 to 80 years), some 39 million ha are in Indonesia (of which 26 million ha in Irian Jaya), 14 million ha in Burma and also in Papua New Guinea, 7.5 million ha in Malaysia (of which 5.7 million ha in the states of Sabah and Sarawak) and 3 million ha in the Philippines. The extent of these undisturbed productive forests gives a rough indication of the future log production possibilities in theses countries. Productive broadleaved forests which have been logged over but have not been converted to non-forestry uses after the first “creaming” amount to 58 million ha (about one fifth of the total closed broadleaved forest area). Indonesia, Malaysia and Philippines account for 75% of this area. They are part of the areas under concession which supply the bulk of tropical logs to international markets and domestic processing.

TABLE 1a - Areas of natural woody vegetation estimated at end 1980
Closed broadleaved forests (NHC)
(in thousand ha)

Among the unproductive closed broadleaved forests (NHCf2) are those which are inacessible or have no utilizable trees for wood for industry (NHCf2i). In 1980, some 84 million ha have been classified as such in the region. These areas constitute 84 % of the total unproductive closed broadleaved forest area. In addition some 16 million ha are classified as unproductive for statutory reasons - NHCf2r (e.g. national parks, biosphere reserves, etc). The break-up of unproductive closed broadleaved forests in the region is: 40% in Indonesia, 20% in Papua New Guinea, 8% in India, 8% in Burma, etc.

Mangrove forests are of special interest for ecological reasons. The following table gives countrywise distribution of these forests in tropical Asia.

Mangrove areas (1980)
(in thousand ha)

One important observation has to be made in relation with the above table. It is not clear indeed for all countries whether these areas include or not parts without forest cover (with only a bushy, or herbaceuous vegetation, or even entirely denuded in the saline coastal zones). Total “mangrove” area of India for instance was estimated by S.S. Sidhu in “Studies on the mangroves of India” (1963) at 682 000 ha but only 96 000 ha are estimated by the Indian Preinvestment Survey of Forest Resources to be covered with a dense tree or shrub formation. In this latter figure the 52 000 ha of mangrove areas of Kutch and Saurashtra are not included since they are physiognomically “open scrubby mangroves” while the figure given above for Pakistan includes mainly this type of areas. The woody cover of 2.5 million ha of mangrove area estimated for Indonesia, is not known exactly and the same observation applies also in particular to the figures given for Burma and Thailand.

- Table 1b: areas of coniferous forests

The area covered by coniferous forests is small (8.4 million ha) representing 2.5% of the forest area not affected by agriculture (N.f+NHc/NHO) in the region. About two thirds of these forests are considered productive and are essentially confined to the Himalayan belt in south Asia. India, Pakistan and Bhutan in that order have the largest area under productive coniferous forests. Burma, Thailand, Lao, Kampuchea and Viet Nam contain together about 500 000 ha of productive coniferous forests. In Indonesia (north Sumatra and Java) the extent of coniferous forest area is 320 000 ha, of which half is classified productive. The northern Luzon area of Philippines has some 190 000 ha under conifers. Although Papua New Guinea has over half a million ha under conifers, only one tenth of the area is considered productive.

TABLE 1b - Areas of natural woody vegetation estimated at end 1980
Coniferous forests (NS)
(in thousand ha)

- Table 1c: area of bamboo forests

The region has some 5 million ha under bamboo of which 3.5 million ha are considered productive. The major bamboo bearing areas are in India, (1.4 million ha), Viet Nam (1.2 million ha), Thailand (0.9 million ha), Burma (0.6 million ha) and in Lao and Kampuchea. In India bamboos (Dendocalamus strictus, Bambusa arundinaceae, Melocanna bambusoides, etc) are the major raw material supplying nearly two thirds of the fibre to pulp and paper industry.

- Table 1e: areas of open broadleaved forests (NHc/NHO)

These forests are mixed broadleaved and graminean formations with a continuous dense grass layer with 10% or more of the area covered by tree crowns.

Some 31 million ha of open broadleaved forests are present in the region, a predominance of them in Thailand, Lao, Kampuchea and Viet Nam. Together these four countries account for 58% of the region area under NHc/NHO; India has some 5 million ha, Indonesia 3 million ha and Papua New Guinea 4 million ha. Only a quarter of these forests are considered productive; nearly all the productive forests are in continental southeast Asian countries. In Thailand, the dry dipterocarp forests in the northeast are included in this class.

- Table 1f: areas of other woody formations

Fallows of closed forests

These consist of complexes of woody vegetation derived from clearing by shifting cultivation (traditional low intensity shifting cultivation with restricted burning) of closed forests (essentially broadleaved). They consist of a mosaic of “secondary bush”, “young secondary forests” or “secondary growth”. “Alang-alang” (Imperata cylindrica) fields which are the result of short rotation shifting cultivation with extensive burning are not included in the category of forest fallows since there is little or no chance for a rapid recolonization by a secondary forest growth. Ecologically, forest fallows have an impact on the maintenance of the environmental functions of the woody vegetation cover (soil conservation) and are therefore regarded as sufficiently important to attempt quantification. They are also important for wood production as forest fallows or as vegetated land where mature forests can be reconstituted if it is abandoned by agriculture. Their distribution, composition, structure and dynamics are important to understand the nature and quantity of deforestation that is taking place in tropical Asia.

TABLE 1c - Areas of natural woody vegetation estimated at end 1980
Bamboo forests (NHB)
(in thousand ha)

TABLE 1d - Areas of natural woody vegetation estimated at end 1980
Closed broadleaved, coniferous and bamboo forests (N.f)
(in thousand ha)

TABLE 1e - Areas of natural woody vegetation estimated at end 1980
Open broadleaved forests (NHc/NHO)
(in thousand ha)

¹ Intensively managed riverain forests