Explained: Why are fires frequent at the Bandipur reserve?

Mains Paper 3: Environment | Conservation, environmental pollution and degradation, environmental impact assessment

From UPSC perspective, the following things are important:

Prelims level: Bandipur Tiger Reserve

Mains level: Prevention of forest fires

A five-day fire that raged through the Bandipur Tiger Reserve has reportedly burnt more than 15,400 acres of forests.
Between February 21 and 25, the reserve saw 127 fire counts in various ranges of the 912 sq km forest.
While K’taka Forest Department scrambled to put out the blaze, an Indian Air Force helicopter sprayed over 19,000 litres of water in seven sorties.

Why it matters?

While fires are not uncommon at Bandipur, what has surprised officials is their intensity and frequency.
The worry now is the long-term damage to the ecosystem, which is a part of the Nilgiri Biosphere that hosts the world’s largest tiger population, at more than 575 (2014 census).
Over 400 fire watchers were placed, but questions have arisen whether the precautions were enough, especially since Bandipur has had frequent fires.

How susceptible is it to fires?

Bandipur is a dry deciduous forest in the rain shadow region of the Western Ghats, and is no stranger to fires. Periods of drought invariably lead to fires.
A study has shown that between 1974 and 2014, 67% of the Nilgiri Biosphere had seen some form of forest fire, with Bandipur having reported the most incidents.
The 2018 monsoon was particularly strong, but the year-end northeast monsoon has failed.
If the monsoon led to dense growth, the blistering heat since September has turned vegetation brittle and dry, with vast swathes becoming tinderboxes.
As with most forest fires, it is assumed that Bandipur’s ignition was man-made as miscreants set fire in multiple locations.
Compounding matters is the ubiquity of lantana camara, an invasive weed species native to South America, that has spread through nearly two-thirds of the forest area.

What is the impact?

India’s forest policy encourages a zero forest fire approach for its protected landscapes — whether it is Bandipur or the rainforests of the upper Western Ghats.
Scientific literature has shown this blanket approach may be doing harm to dry, deciduous forests where trees have evolved to co-exist with fire.
The trees in this landscape were closer to those in a savanna than in rainforests 100 km away. Trees have dramatically thicker barks, implying that they had evolved to be fire-resistant.
When fires are relatively frequent, adult tree mortality in these systems is very low.
Many saplings sprout shortly after the fire from underground reserves, and the system returns to its original state in a few years.
Conversely, when fires are suppressed — including by curbing the tribal practices of controlled fire burning — a greater biomass builds up that can lead to high intensity fires which affect the ecosystem negatively.