28 http://www.earthislandjournal.org
tapped in the address of a park.
Behind those trees, in an open-air
cafeteria, ecologists Ratnam and Joshi
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co author, Mahesh Sankaran, on a late
July afternoon. Joshi and Sankaran
speak softly, and Ratnam often takes
long pauses before responding to a
question, silences that suggest she’s
wary of making the science seem
simple.
Grassland temperatures in the
Nilgiris often drop much lower than
in the region’s forests, according to
their Journal of Ecology study. Frigid
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and stop them from taking hold in
grasslands, sustaining the tropical
montane ecosystem of the Nilgiri
plateau. Acacia, they tell me, has upset
this balance because it doesn’t mind
the cold as much as native trees. Now,
it’s also poised to spread more quickly
in the warmer years to come. The
ecologists studied how invasive acacia
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land and saw its survival rate soar close
to 100 percent.
The jump in acacia survival rates
is an existential threat to a traditional
livelihood of the Toda, an Indigenous
community whose people have long
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lands. As open space shrinks, they’ve
abandoned the practice in favor of
growing vegetables such as carrots and
potatoes, and have found work in local
tea plantations.
Shriveling grassland is also
squeezing animals whose lives are
intimately tied to it, such as the Nilgiri
pipits — little golden-brown birds with
dark streaks at the crown, which eat
grass seeds and build cup-like nests
on open ground — and the endemic
Nilgiri tahr; only about 100 of these
endangered ungulates remain in the
region that gives them their name.
Though roughly 1,900 Nilgiri tahrs live
elsewhere in South India, the species
may go locally extinct as invasive trees
push into grassland on which they
graze. “It doesn’t have any place to go,”
Joshi says.
Non-native trees have also warped
the water table. Eucalyptus sucks huge
amounts of water from the ground,
and according to the initial results
of separate research conducted inpart by Jagdish Krishnaswamy, an
ecohydrologist studying the region,
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thirst, and Krishnaswamy says it lowers
the level of water in local streams and
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The combination of sun, heat,
eucalyptus, and acacia can also drain
reservoirs that sustain local and
downstream residents through the
dry months, leaving them worryingly
low. “We believe that exotics have
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of water that is discharged into our
streams,” Ravinder Singh Bhalla, an
ecologist with the Tamil Nadu-based
Foundation for Ecological Research,
Advocacy, and Learning who is also
studying the hydrology of the Nilgiris,wrote in an email. “This has obvious
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for human consumption, including
power generation.”
In wet months, too, acacia causes
problems that native trees don’t. Initial
results of research Bhalla and others
are working on shows that acacia soak
up less water than native shola trees
during brutal downpours like the one
the Nilgiris saw in August, which are
likely to become more frequent as
the area heats up. By retaining more
rainwater during a downpour and
releasing it slowly, shola forests keep
the surrounding soil moist and ensure
a more prolonged stream of supply to
local waterbodies. By absorbing less
water and releasing it faster, acacia
allows precious freshwater little
time to percolate into local
watersheds before making its
way down the mountains and
out to sea. Drier watersheds
mean smaller streams for rivers
such as the Kaveri, which
supplies water to farmers
across South India and drinking water
to millions of people in Bengaluru and
Chennai, cities that are increasingly
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during the dry season every year.R
AIN RATTLES OFF THE ROOF
of the Nilgiris South district
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trucks rumbling over a metal grate.
People darting from buildings to cars
are immediately soaked. Just outside
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an open layout, pale green walls, and
wooden desks weighed down by tall
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manila folders. The district forest
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Dabbala, mustachioed and soft-
spoken, has only been in charge hereGrasslands restoration is much more
complex than bringing back a crop of trees.