The international journal Biological Conservation recently published a study, stating that the Western Ghats have lost nearly a quarter of high-altitude grasslands over the past four decades. The significant culprits behind this loss are exotic invasive trees which include species like pine, acacia, and eucalyptus.
Threat of Invasive Alien Species
Invasive alien plant species are non-native organisms that spread rapidly and create havoc in a new ecosystem. They pose a substantial threat to the native biodiversity, consequently leading to economic loss. These invasive species hinder the growth of local plants and disrupt the movement of wildlife due to their dominating spread.
Major Observations from Satellite Data
Satellite images reveal shocking statistics: 60% of the shola-grassland landscape has undergone a change, with almost 40% (516 km2) of native high-elevation grasslands now vanished. Although no plantations were established between 2003 and 2017, existing trees propagated invasion that increased areas under exotic plantations (such as acacia, pine, and eucalyptus) by 27% in the Palanis and 17% in the Nilgiris.
Changes across the Ghats
The satellite data also laid bare how shola-grasslands across the Ghats – from Karnataka’s Baba Budan Hills to the Ashambu Hills of Tamil Nadu – altered in size between 1972 and 2017. In general, the shola-grassland ecosystems located in Tamil Nadu experienced the highest invasion rates. This loss mostly occurred on the mountain tops of the Nilgiri, Palani, and Annamalai hill ranges, accounting for more than half of the Ghat’s shola-grassland ecosystems, primarily due to the expansion of exotic trees like pine, acacia, and eucalyptus. Interestingly, the shola forests remained “relatively unchanged” over these years, with Annamalai-Munnar areas also attaining stability.
The International Convention on Invasive Species
The Convention on Biological Diversity (CBD) was adopted in 1992 and came into effect in 1993. Its primary purpose is to prevent the introduction of, control or eradicate those alien species which threaten ecosystems, habitats, or species.
About Shola Forests
The Sholas are a unique blend of montane evergreen forests and grasslands. They are exclusive to high altitude (>1500 meters) regions within the tropics and are confined to the southern part of the western ghats. Characterized by rolling grassland patches interspersed with clusters of stunted evergreen tree species, they are home to a variety of endemic and endangered plants and animals. Besides, they play a pivotal role in sustaining water cycles.
| Detail | Statistic |
|---|---|
| Percentage of Grassland Lost | 25% |
| Range of High-Elevation Grassland Lost | 516 km2 |
Preserving the Remnants – The Way Forward
As per the scientists at IISER Tirupati, it is paramount to focus all possible efforts on conserving the remaining grassland patches. Shockingly less research is centered on grasslands, and restoration mechanisms for them are scarce when compared to forests. The immediate reaction would be to remove all exotics, including mature plantations from grasslands. However, such an abrupt move could potentially disrupt the ecosystem severely. A thoughtful and balanced approach is required to address this crisis effectively.
