ment. Introduced food crops fall prey to
myriad pests, thanks to the rainforest’s
diversity of insects. Most of the paddy fields
made by the settlers are today either cov-
ered with weeds or waterlogged and saline.Mainland India is spending (by conserva-
tive estimate) tens of millions of rupees
annually to control the spread of invasive
species, whereas the island ecosystems
that are most vulnerable to such disasters
have been largely taken for granted. Ships
arrive in Great Nicobar from mainland
India without any quarantine, bringing
alien species along with grains, vegeta-
bles, poultry, livestock and other imports.
Even twenty-five years ago scientists had
noted the impact of invasives on Great
Nicobar. Recent surveys undertaken by our
team at the University of Delhi have iden-
tified forty-six exotic plant species on the
island, of which twelve are well knowninvasive species (see Table 2).^14 Clearings
made in the forest in recent decades
offered multiple niche opportunities to
invasive species; the invasives have spread
extensively and made the soil unsuitable
for agriculture. Though the nutrients in
the soil do not support agriculture after a
few cycles of cropping, they are enough to
sustain enormous weed populations.
Globally known terrestrial invasives such
as Chromolaena, Mikaniaand Ageratina
have covered clear felled areas on the
island (See Figure 4).Because they outnumber the tribal people
of Great Nicobar by a factor of at least
seven, and because tribals have been
granted distinct rights and immunities
(e.g., from provisions of wildlife protection
acts), the settlers represent a separate
political interest and they are able to make
their needs known to government. The
government undoubtedly spends much
more money in supporting these settlers
than the settlers—and the tribal popula-
tion—contribute to the national econo-
my.^15 Commercial fishing has not been
very profitable for localresidents, although
processing and storage facilities exist on a
number of islands. (The waters surround-
ing Car Nicobar have been over fished.
Some environmentalists have pointed to
unsustainable hunting of seas turtles by
Nicobarese and have suggested that, inHistory, cculture aand cconservation
Species Spread and kind of impact
Chromolaena
odorata
Has spread along open areas in the
forest close to human habitation.
Lantana camara Few clumps have been noted at
28-km point on East-West road.
Ageratina spp. Weed with a creeping habit, cover-
ing most open fields.
Merremia peltata Covers large patches close to
streams.
Ischimum rugosum Spreads over fallow land.
Cyperus rotundus Occupies marshy land cleared and
abandoned.
Mikania micrantha Found around abandoned
encroachments and forest edges.
Dogs Numbering approximately 2100: a
menace to sea turtles, Megapodes
and wild pigs, as they have taken
to pack hunting.
Cats Threat to Megapodes and other
ground birds, they are present in
numbers matching those of dogs.
Cattle Large number of cattle feed in the
forest, destroying ground flora.
Table 2.Table of major invasive species in Great
Nicobar Island.
Figure 4.Agricultural area covered by weeds.
(Courtesy Suresh Babu)