Island Life; Or, The Phenomena and Causes of Insular Faunas and FlorasWallace, Alfred Russel
Science
Island Life; Or, The Phenomena and Causes of Insular Faunas and Floras
Wallace, Alfred Russel
Biogeography; Glacial epoch; Island ecology
_Fragmentary Character of the Mascarene Flora._--Although the peculiar
character and affinities of the vegetation of these islands is sufficiently
apparent, there can be little doubt that we only possess a fragment of the
rich flora which once adorned them. The cultivation of sugar, and other
tropical products, has led to the clearing away of the virgin forests from
all the lowlands, plateaus, and accessible slopes of the mountains, so that
remains of the aboriginal woodlands only linger in the recesses of the
hills, and numbers of forest-haunting plants must inevitably have been
exterminated. The result is, that nearly three hundred species of foreign
plants have run wild in Mauritius, and have in their turn helped to
extinguish the native {445} species. In the Seychelles, too, the indigenous
flora has been almost entirely destroyed in most of the islands, although
the peculiar palms, from their longevity and comparative hardiness, have
survived. Mr. Geoffrey Nevill tells us, that at Mahe, and most of the other
islands visited by him, it was only in a few spots near the summits of the
hills that he could perceive any remains of the ancient flora. Pine-apples,
cinnamon, bamboos, and other plants have obtained a firm footing, covering
large tracts of country and killing the more delicate native flowers and
ferns. The pine-apple, especially, grows almost to the tops of the
mountains. Where the timber and shrubs have been destroyed, the water
falling on the surface immediately cuts channels, runs off rapidly, and
causes the land to become dry and arid; and the same effect is largely seen
both in Mauritius and Bourbon, where, originally, dense forest covered the
entire surface, and perennial moisture, with its ever-accompanying
luxuriance of vegetation, prevailed.
_Flora of Madagascar Allied to that of South Africa._--In my _Geographical
Distribution of Animals_ I have remarked on the relation between the
insects of Madagascar and those of south temperate Africa, and have
speculated on a great _southern_ extension of the continent at the time
when Madagascar was united with it. As supporting this view I now quote Mr.
Bentham's remarks on the Compositae. He says: "The connections of the
Mascarene endemic Compositae, especially those of Madagascar itself, are
eminently with the southern and sub-tropical African races; the more
tropical races, Plucheineae, &c., may be rather more of an Asiatic type."
He further says that the Composite flora is almost as strictly endemic as
that of the Sandwich Islands, and that it is much diversified, with
evidences of great antiquity, while it shows insular characteristics in the
tendency to tall shrubby or arborescent forms in several of the endemic or
prevailing genera.
Public-domain text, read in full here on John Shaqi.
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