Focus: GS-I Geography, GS-III Environment and Ecology
Introduction
- Tropical montane grasslands (TMG) in the Shola Sky Islands of the Western Ghats have suffered big reductions due to invasions by exotic trees such as acacias, pines and eucalyptus, shrinking the range sizes of endemic species, including plants, birds, amphibians and mammals. Some populations are being driven to local extinction.
- But researchers have now identified areas suitable for grassland restoration and conservation to reverse the decline.
Details on reversal of Decline
- The researchers focus on identifying grassland restoration sites using satellite images with a high spatial resolution (RapidEye), and have recommended careful removal of young and isolated exotic trees at the invasion front and restoring grasslands, instead of removing dense stands of mature exotic trees.
- TMG 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.
- Loss of grasslands due to invasive exotic trees is a “novel threat” through the establishment and expansion of exotic tree plantations. 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.
Example
- The Palani Hills and Anamalai lost grasslands due to invasive species.
- Most of these species were planted, but that programme was stopped around the 1990s, and since then, they were purely invasive.
- The species have a very high seed bank, about which nothing can be done, but cutting them will require multiple cycles.
Way Forward
- For invasive species such as Acacia mearnsii that grow rapidly and disperse seeds widely, removing mature trees is often ineffective.
- An approach that targets the removal of young exotic trees would be more effective. Similarly, restoring grasslands where isolated but mature trees exist in grassland patches could be an easy way to restrict further dispersal.
-Source: The Hindu
