From
The Malay Archipelago
by Alfred
R. Wallace
Contrasts of Vegetation.
-- Placed immediately upon the Equator and surrounded by extensive
oceans, it is not surprising that the various islands of the Archipelago
should be almost always clothed with a forest vegetation from
the level of the sea to the summits of the loftiest mountains.
This is the general rule. Sumatra, New Guinea, Borneo, the Philippines
and the Moluccas, and the uncultivated parts of Java and Celebes,
are all forest countries, except a few small and unimportant tracts,
due perhaps, in some cases, to ancient cultivation or accidental
fires. To this, however, there is one important exception in the
island of Timor and all the smaller islands around it, in which
there is absolutely no forest such as exists in the other islands,
and this character extends in a lesser degree to Flores, Sumbawa,
Lombock, and Bali.
In Timor the most common
trees are Eucalypti of several species, also characteristic of
Australia, with sandalwood, acacia, and other sorts in less abundance.
These are scattered over the country more or less thickly, but,
never so as to deserve the name of a forest. Coarse and scanty
grasses grow beneath them on the more barren hills, and a luxuriant
herbage in the moister localities. In the islands between Timor
and Java there is often a more thickly wooded country abounding
in thorny and prickly trees. These seldom reach any great height,
and during the force of the dry season they almost completely
lose their leaves, allowing the ground beneath them to be parched
up, and contrasting strongly with the damp, gloomy, ever-verdant
forests of the other islands. This peculiar character, which extends
in a less degree to the southern peninsula of Celebes and the
east end of Java, is most probably owing to the proximity of Australia.
The south-east monsoon, which lasts for about two-thirds of the
year (from March to November), blowing over the northern parts
of that country, produces a degree of heat and dryness which assimilates
the vegetation and physical aspect of the adjacent islands to
its own. A little further eastward in Timor and the Ke Islands,
a moister climate prevails; the southeast winds blowing from the
Pacific through Torres Straits and over the damp forests of New
Guinea, and as a consequence, every rocky islet is clothed with
verdure to its very summit. Further west again, as the same dry
winds blow over a wider and wider extent of ocean, they have time
to absorb fresh moisture, and we accordingly find the island of
Java possessing a less and less arid climate, until in the extreme
west near Batavia, rain occurs more or less all the year round,
and the mountains are everywhere clothed with forests of unexampled
luxuriance.
Contrasts in Depth
of Sea. -- It was first pointed out by Mr. George Windsor Earl,
in a paper read before the Royal Geographical Society in 1845,
and subsequently in a pamphlet "On the Physical Geography
of South-Eastern Asia and Australia", dated 1855, that a
shallow sea connected the great islands of Sumatra, Java, and
Borneo with the Asiatic continent, with which their natural productions
generally agreed; while a similar shallow sea connected New Guinea
and some of the adjacent islands to Australia, all being characterised
by the presence of marsupials.
We have here a clue
to the most radical contrast in the Archipelago, and by following
it out in detail I have arrived at the conclusion that we can
draw a line among the islands, which shall so divide them that
one-half shall truly belong to Asia, while the other shall no
less certainly be allied to Australia. I term these respectively
the Indo-Malayan and the Austro-Malayan divisions of the Archipelago.
On referring to pages
12, 13, and 36 of Mr. Earl's pamphlet, it will be seen that he
maintains the former connection of Asia and Australia as an important
part of his view; whereas, I dwell mainly on their long continued
separation. Notwithstanding this and other important differences
between us, to him undoubtedly belongs the merit of first indicating
the division of the Archipelago into an Australian and an Asiatic
region, which it has been my good fortune to establish by more
detailed observations.
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