Peril in the hills: Extreme weather a danger for Nilgiri ecosystem – Down To Earth Magazine

Despite consecutive years of extreme precipitation over short periods in the Nilgiri Biosphere, hardly any step has been taken to address ecological security

Thousands of trees lay dead and strewn around the western parts of the Nilgiri Plateau in southern India. Deep gashes scar ancient mountains, standing a stark contrast to the lush green vegetation that they otherwise support.

As conservationists and activists are fighting to protect forests and wilderness areas from being deforested, mined and diverted to developmental projects, there is another level of destruction happening to our last remaining wild spaces. Climate change is causing widespread collapse of ecosystems.

Carbon dioxide levels in the atmosphere hit a record-breaking 417 parts per million (ppm) in May 2020, highest inthreemillion years. Along with global warming caused sea level rise and the melting of polar ice caps and glaciers, the steep increase in greenhouse gas concentrations has led to a surge in the frequency of extreme climate events.

A region where climate change caused weather extremities are exceedingly apparent are the coastal plains and Western Ghats of southern India. In the last four years, this region has been affected by eight tropical cyclones and consecutive extreme rainfall events during the southwest monsoon periods of the last two years. These bouts of intense storms have been interspersed with periods of severe droughts, heatwaves, deficient and failed monsoons.

On August 8, 2019, the Avalanche and Emerald valley regions, which are part of the Kundha watershed, received an unprecedented 900 millimetre (mm) rainfall within 24 hours. It broke the record for the highest rainfall in Tamil Nadu, by nearly twice the amount. Over four days, the region experienced close to 2,500 mm rainfall.

To put this in perspective, Coimbatore, the nearest city in the plains of Tamil Nadu, receives 600 mm of rain annually. The Kundha watershed bore a deluge that was four times the annual rainfall amount, over just four days. The upper watershed of the Kundha river is a complex of several peaks above 2,400 m and broad deep valleys.

The river, which is a primary tributary to the Bhavani that feeds into the Cauvery, is fed by numerous streams and rivulets at the headwater sections. With the barraging downpour, nearly every stream and rivulet burst its course. Vast tracts of precious soil and shola ecology slipped away on either side of the watercourses.

Gone are the rich black soil layers topped with spongy humus that line the streams; washed away are the dark moss and wild balsam covered rocks that shaped the flow of every stream; lost are the thousands of shola trees, dwarf bamboo and forest kurinji (shrubs of blue flowers which covered the hills) that guarded the streams, saplings, ferns and orchids of the forest floor.

In place of these are deep cuts of gauged out Earth, revealing the underlying lateritic soil and rocks.

(Left) An Aerides ringens orchid growing on a shola tree; (Right)Neela-Kurinjior Strobilanthes kunthiana flowering in the grassland habitats of the Nilgiris. This spectacle takes place only once in 12 years.Photo: Godwin Vasanth Bosco

Shola-grassland mosaic in danger

The cloud forest ecology, known as sholas, grows along the folds and valleys of these mountains. They are old-growth vegetation and harbour several endemic and rare species of flora and fauna. These naturally confined forests are already some of the most endangered forest types because of habitat loss and destruction.

The recent episode of extreme precipitation caused landslides have dealt a telling blow on these last remaining forest tracts. What is even more shocking is that montane grassland stretches have also experienced large landslides.

The montane grasslands occur over larger portions of the mountains here, covering all the other areas that sholas do not grow in. Together, the shola-grassland mosaic is most adept at absorbing high rainfall amounts and releasing it slowly throughout the year, giving rise to perennial streams.

Over a year they can experience 2,500-5,500 mm of rainfall, which is intricately sequestered by complex hydrological anatomy that carefully lets down most of this water, using what is needed to support the ecology upstream.

The native tussock grasses are highly adapted to hold the soil strongly together on steep slopes. However, even this ecology is now giving way under pressure from extreme weather events.

The shola-grassland mosaic ecology cannot withstand the tremendously high amounts of rainfall (over 2,400 mm) that occur in significantly short periods (over four days). Worsening climate change is driving the intensity and frequency of extreme weather events, resulting in a level of ecosystem collapse, never witnessed before.

A massive landslide in one of the largest sholas in the Avalanche region, with hundreds of native trees and the stream ecology washed away. Photo: Godwin Vasanth Bosco

In the southwest monsoon season of 2018, unusually high rainfall over the highland districts of Idukki, Wayanad and Coorg caused hundreds of landslides. A predominant view was that this was primarily because of the indiscriminate construction of roads and proliferating concretisation of the hills.

However, even within the highly stable shola-grassland ecology, a large number of landslides occurred in spots with no apparent disturbance such as roads and pathways cut through them. This signifies that climate change has reached a level that is beyond the capacity of the ecosystem and land resilience.

What is causing the collapse of the last remaining wild spaces is the cumulation of every action that has contributed to the climate crisis. The actions invariably stem from places that have long lost their plant ecological cover the global urban-industrial-agricultural complex. There is no time to keep ignoring this primary cause.

If we overlook the main cause and only try to safeguard the last remaining wilderness areas from the more direct forms of destruction, they will be susceptible to climate change-related collapse. It is important that threats closer to the last remaining ecological spaces are also curtailed.

But despite the consecutive years of extreme precipitation over short periods in the Nilgiri Biosphere, hardly any step has been taken to address ecological security. Building regulations stand to get eased and road expansion works continue in full swing.

Till June-end, parts of Tamil Nadu experienced a 45 per cent deficiency in the monsoon. The trend is worryingly similar to what happened in the last two years when much of the annual rainfall was concentrated over a few days later in the monsoon period.

Destruction by dams and tunnels

The Kundha watershed region can be broadly divided into two the higher slopes and the descending valleys. Shola-grassland ecology dominates the higher slopes with various types of land uses such as tea cultivation, vegetable farming, villages and non-native tree plantations dominating the descending valleys.

An example of intact shola-grassland mosaic in the hills of the Nilgiri plateau, with the sholas growing in valleys and grasslands covering the slopes.Photo: Godwin Vasanth Bosco

The descending valleys are covered with several dams and hydroelectric structures. The Kundha Hydro-Electric Power Scheme is one of the largest hydropower generating installations in Tamil Nadu with 10 dams, several kilometres of underground tunnels and a capacity of 585 MW.This system is getting two more dams and a seriesof tunnels to set up a pumped storage hydropower facility, which is claimed to generate 1500 MW for peak hour demand but will expend 1800 MW in the process.

With the level of destruction that extreme precipitation events are bringing to the Kundha watershed, it is disastrous to add more large dams and tunnels. The intensity of floods has turned so strong that even the largest dam complexes in the world face threats of being breached.

Safeguarding the last remaining zones of ecology and biodiversity from threats of direct destruction is crucial. Concurrently, the larger worldwide urban-industrial-agricultural complex, from where the climate crisis stems from, needs drastic change. The constant incursions into more and more ecological spaces in the form of new dams, roads, and buildings are also connected to this complex.

Whether it is the landslides in the grasslands of the high elevation plateaus in southern India; the melting glaciers of the Himalayas in northern India; the dying coral and rising sea levels elsewhere in the planet; the COVID-19 pandemic that has brought about unimaginable changes we have to understand the interconnectedness of these dire effects and learn from nature.

Godwin Vasanth Bosco is an ecologist working to restore shola and grassland ecology in the Nilgiri Biosphere. He is the author of the book Voice of a Sentient Highland on the Nilgiri Biosphere

This was first published in Down To Earths print edition (dated 1-15 August, 2020)

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Peril in the hills: Extreme weather a danger for Nilgiri ecosystem - Down To Earth Magazine

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