Vegetation of Southeast Asia Studies of Forest Types 1963-1965

The Rain forest is a community with a large series of co-dominants.,
or sometimes there may be only one or two dominants. While rich in
spocies, the trees are remarkably uniform in their general appearance
and physiognomy. Among dominant trees the boles are usually straight,
rather slender in relation to their height or compared with the girth
of some large trees in higher latitudes, and are generally clear of
branches for JO to 90 feet (22 to 28 m.). Their crowns are relatively
restricted, of variable form frcrn \vide-spreading, round or umbrellashaped
to narrow and irregular. Plunk buttresses, flange-like outgrowths
at the base, are characteristic of Rain forest trees, and
which are less developed, cometimes absent, in other Forest Types. The
bark may be thin to thick, smooth or rough, scaly with deep fissures,
plates or conspicuous lenticcls.
The type and density of foliage are variable in the Rain forest.
The majority of mature trees, as well as seedlings and shrubs have
large, leathery, dark green leaves, with entire or nearly entire margins.
The Rain forest nay contain some deciduous or partially deciduous
trees, but to all intents and purposes it is constantly evergreen.
So that the term 'Evergreen 1 applied to this forest type is
redundant, as there is no Deciduous or Semi-Evergreen Rain forest.
Compound leaves predominate in the upper stories, simple leaves are
frequent in the lover scory. Most of the trees and shrubs have inconspicuous
flowers, often whitish or greenish. Large and strikingly
colored floverv. are somewhat rare. The forest interior is usually'
gloomy, althou ;ri when the sur. is shining the floor may be dappled
with sun-fieeke. To some the Rain forest; gives the impression of the
vault or cathedral aisles. The uniform and generally somber hue of
tre leaves contribute in part to the monotonous character of this
forest.
Unlike forests in Temperate regions, in the Rain forest there
is r.o vell-de"i;:C!i periodicity of new leaf crop, flowering, fruiting,
or leaf sr.e 1/ !i.'i ~. It is a perpetual midsummer, although there are
•period.: cf r.oxlrvir. flower in ;, during which more species are in flower
than at; cl*:cr li.re:*, ay well Uo ueasoris of maximum production of
ycu;v; leaves. . rr the moat part, pltv.-t growth and reproduction arc
ccr.tir.uoJ3, ar.:t .iome flnw^rs nnu/or fruits can be found at any tir.e.
Thi:; is a direct Iriflucn^e of ':lin;ite, characterized by high temperature
and hu-.iuity, and ;-;li ,r:t seasonal variation.
Owing to t'^e treat ra:;gc i:; tlie height of trees, the Hair, rorest
is usually stratified or multi-layered in structure, itost often there
are three layers, in additicr. to a lower layer of shrubs ana a -round
cover of herbs. Ir: comparison with the number of woody species, life •
i'crno such a^ palms and paruiano (i'andanus) are less abundant, but
bar.ooos and rattans (Calanu:;) arc frequent. KtossetJ, liverworts,
lichenu and epiphytes, including a variety of orchids, arc also generally
abur.'lrnt, growing on trie trunks, .branches and in the crotches •
of trees arid J;irub3, in addition to ferns and flowering plants
ccvcrir.- the ground. The abundance of climbers, especially stout
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