Vegetation of Southeast Asia Studies of Forest Types 1963-1965

HAZARDOUS VEGETATION
From the military standpoint, tre most critical forest types
in Thailand, and in the other Mekong basin countries, are thq taJ.l
Evergreen Rain and Moist forests on dry land, and the coastal Mangrove
swamp forest of smaller stature.
The continuous, dense canopy of the Evergreen Rain and Moist
forests, in which the trees are of large dimensions, often with
massive plank buttresses, many large woody vines and in particular
the generally dense undergrowth difficult to i^n^trate, provide
ideal sites for hiding. Mobility is a difficult problem in these
forests. Ground-to-ground visibility is low, usually limited to 15
or 20 feet. Ground-to-air visibility may be fair to good, depending
upon the depth and continuity of the canopy, but air-to-ground
visibility is fair to nil.
On the other hand, while the Rain or Moist Evergreen forest is
ideal for shelter and ambush, a guerrilla fighter, like the Viet
Cong, as a rule does not relish remaining for long periods in this
deep forest. The most/serious problem is survival, especially the
procurement of a steady supply of food. Second in importance is
the problem of health, especially when such pests as leeches, malariacarrying
mosquitoes and other insects are prevalent. Thirdly is the
depressing atmosphere of the dense forest, which may have a demoralizing
and psychological effect on some, when exposed to it for long
periods. People accustomed to working in open areas, such as rice
fields, do not care to work in the forests. Likewise, in Vietnam
as elsewhere, people who have lived in the plains do not want to move
to the highlands, and vice-versa. Even the Chinese, as I once found,
do not relish such experience.
Plants furnishing edible fruits, seeds, tubers, are somewhat
limited and uncertain. Many fruits are often high on trees, difficult
to gather, while others ripen only at irregular intervals. So that,
as a rule, a guerrilla fighter prefers to remain inside but near the
perimeter of the forest, within a distance of 1 or 2 niles from the
periphery, in open sites in the r orean or rubber plantations, in
open gras&covered areas, where v.-:re Is usually the 'kha-luan/f grass
(T'.npgrata oylindrica) tall .•.vu.-.i.-'n :"or hiding, or better still near
abcxfes, villages or towns, /r-.er^ food resources, especially rice
and fish, are more readily avaiiaole and easily transported to the
camp,
The Mangrove swamp forest is perhaps even more critical, from the
military standpoint as a staging area, than the tall Rain or Moist
forest, on account of its accessibility from the sea or by river, ease
of mobility by water in email craft within this type of forest, and
its low to fairly low stature. The network of uncharted channels in