Timber plantations, expanding agriculture and the spread of invasive species have eaten into as much as two-thirds of natural grasslands in the Palani Hill range of Western Ghats, shows a recently published study.
Researchers from Ashoka Trust for Research in Ecology and the Environment (ATREE) in Bengaluru collaborated with a team from IISER in Tirupati, Botanical Survey of India, Vattakanal Conservation Trust and Gandhigram Rural Institute used satellite imagery to tabulate changes in the hilly landscape over nearly 530 sq.km. of the range which is popular for the hillstation, Kodaikanal.
Loss of grasslands
If in 1973, shola grasslands spread across 373.78 sq.km. of the landscape, four decades later in 2014, it had shrunk to just 124.4 sq.km., marking a 66.7% decline. The reduction is seen even in native shola forests, whose area has declined by a third to 66.4 sq.km.
“These declines caught us by surprise, particularly considering that these dramatic changes have been occurring only around two decades ago,” said Milind Bunyan, Coordinator at the ATREE Academy for Conservation Science and Sustainability Studies, and the lead author of the paper that was published in PLOS One.
These drastic declines are particularly stark in shola grasslands (which are stunted forest growths of diverse grass species), and seem to be accelerating through the decades.
For the shola forests, however, the decline seems to have been arrested since 2003. Does this imply better conservation strategy for the woody forests, accompanied by a neglect of the grassland?
“For the department, much of their training is in managing forests, either for conservation or a source of income. However, shola grasslands which are critical habitats for many species, continue to be viewed as lower priority or grassy blanks,” said Mr. Bunyan.
In the place of these grasslands and forests, timber plantations have thrived. From barely 18 sq.km. in 1973, plantations have grown by a staggering 1093% to 217 sq.km.
Similarly, agriculture and fallow land have increased three times to 100 sq.km. in the past four decades.
Invasive species
The use of satellite imagery also revealed the nature of the growth of plantations. If till the 90s, it was a policy push for plantations — particularly after the settlement of Sri Lankan refugees — after that, it seems to be a natural march of invasive species such as prolific-seed-producer, Acacia.
“The grasslands are in trouble, much more than the forests. It is important to preserve whatever patches are remaining and push back invasive species. Tackling this would require ecological understanding, rather than a knee-jerk reaction of harvesting invasive trees which (counter-intuitively) ends up actually accelerating the spread of Acacia,” said V.V. Robin, Assistant Professor at IISER Tirupati.
As grasslands vanish or become more fragmented, local flora and fauna, particularly endemic species such as Nilgiri Pipit, may be under threat.
“Grasslands are now fragmented which means specialists such as Nilgiri Pipit are immovably displaced. It does seem like there has been local extinction of the bird, particularly when compared to the sightings during the British Raj,” said Mr. Robin, whose team is now following the population and spread of the bird in the Palani Hill Range.
