- Recently, Tropical montane grasslands (TMG) in the Shola Sky Islands of the Western Ghats have suffered big losses due to invasions by exotic trees.
Back to basics
About Sky Islands
- These are the tops of tall mountains that become environmentally isolated from each other even if they are close together, geographically speaking.
- The Western Ghats are a mountain chain in southwest India home to spectacular and unique sky islands.
- The peaks of the Western Ghats, ranging between 3,000 and 8,500 feet above sea level, host an almost unbelievable array of microclimates, looking like “patches of forests floating in a sea of grasslands.
- One of the specific habitats unique to the sky islands of this area is a type of low-temperature, high-humidity tropical cloud forest full of stunted trees mixed with grasslands called the Shola.
- The Shola forests of South derive their name from the Tamil word solai, which means a ‘tropical rain forest’.
- Classified as ‘Southern Montane Wet Temperate Forest’ the Sholas are found in the upper reaches of the Nilgiris, Anamalais, Palni hills, Kalakadu, Mundanthurai and Kanyakumari in the states of Tamil Nadu and Kerala.
- These forests are found sheltered in valleys with sufficient moisture and proper drainage, at an altitude of more than 1,500 metres.
About Tropical montane grasslands (TMGs)
- These are high elevation grasslands forming only 2% of all grasslands in the world.
- Among their functions is regulating the global carbon cycle and serving as a source of water to downstream communities.
- Researchers say grasslands do not benefit from conservation and restoration efforts afforded to tropical montane forests, possibly due to limited information.
Threats to due to invasive species
- Loss of grasslands due to invasive exotic trees is a “novel threat” through the establishment and expansion of exotic tree plantations.
- These exotic trees include acacias, pines and eucalyptus, shrinking the range sizes of endemic species, including plants, birds, amphibians and mammals.
- In the Western Ghats, 23% of montane grasslands were reportedly converted into invasive exotic tree cover over a period of 44 years.
- Attempts to manage invasive exotic trees in montane grasslands incorporated approaches that include prevention and mechanical, chemical and biological control.
- For invasive species such as Acacia mearnsii that grow rapidly and disperse seeds widely, removing mature trees is often ineffective.