Vegetation of Southeast Asia Studies of Forest Types 1963-1965

forest; The Montane forest may be subdivided into: (a) Lower
Montane; and .(b) Upper Montane.
(a) Lover Montane; A typical example of this sub-type is found '
in the Khao Yai National Forest, central Thailand (Fig. 30), on fairly
steep, veil-drained slopes and plateaus, at elevations of 3,000 to
U,500 ft. (950-1,1*00 m.), and where the annual rainfall ranges up to
approximately 120 inches (3,000 mm.). The forest is moderately tall
ranging up to 60 or 75 ft. (20-25 ra.). Most of the trees have rather
small crowns with slender branches. Their trunks are likewise more
Slender than those in ths Rain or Moist forests, straight to fairly
so, closely spaced, and usually without buttresses, a life-form that
is characteristic of the Wet Evergreen forest. Woody vines are present,
but bamboos, rattans and palms are few or absent. Herbaceous
plants are also sparse.
Dominant trees in the Lower Montane of the Khao Yai Forest are
oak (Quercus) and chestnut (Castanopsis)(Fig. 30). Of the oaks, the
most common species is Quercus flourii and of the chestnut, Castanopsis
acumjnatissirsa. Associates of these trees are: Llthocarpus spicatus,
Schina tfallichii, Dacrydium elatum and •Podocarpus neriifolia. This
forest type also covers the plateaus along the summit of the range.
There, in addition to oak species, trees of the genera Schima and
Pacrydium appear to be dominants. Small patches of sphagnum bogs
are found on the plateau, surrounded by trees of small stature, such
as species of Plea, with their trunks and branches covered with mosses,
influenced by the humid atmosphere.
(b) Upper Montane: This forest subtype is found in northern
Thailand, on the slopes and summit of such mountain peaks as Doi
Sutep, Doi Inthanon and Doi Chiengdao, in the region of Chiengraai
(Figs. 55, 56).
The east slope of Doi Sutep, which has an altitude of 5,^50 ft.
(1,676 m.), is covered by Dry Dipterocarp forest up to about 2,300 ft.
(700 ra.). Between 2,300 and 3,200 ft. (700-1,000 m), the vegetation
is an intricate mosaic of Dry Dipterocarp and Mixed Deciduous forests,
mixed with species of temperate evergreen belt. The forest is composed
mostly of species of oak (Quercus)and chestnut (Castanopsis).
Oak trees attain a height of 50 to 65 ft. (16-20 m.), ana about 12
in. (30 cm.) in diameter. A thin layer of humus and thick litter
accumulate on the forest floor, but the undergrowth is poor, mostly
composed matter of the ubiquitous 'khno-lan^1 grass (Imperata cylindrica).
The southern and southwestern slopes of Doi Sutep, up to the summit,
are occupied by low evergreen trees, such as species of Quercus,
Helicia, Castanopsis, lAtho-arpus, Dalbergia, PhyLlanthus, Camellia
and Molanorrhoea. The ground cover is a dense fjrowt.h of roujh grass.
This is probably secondary growth, as a result of shifting agriculture.