If success is measured in terms of how much land one acquires, eucalyptus is one of the most successful plants in the world.
Between its several hundred species, eucalyptus has covered over 6.5 million hectares of the earth’s surface, excluding its home turf in Australia.
India has had a two century old history with at least 12 species and numerous hybrids of eucalyptus, and as of 1996 eucalyptus plantations were spread over 1 million hectares of Indian soil.
Now, in a landmark decision, the Madurai bench of the Madras high court has decided that eucalyptus, along with another Australian plant called wattle (Acacia mearnsii), need to be removed from their colonised heartland in the Western Ghats, due to the ill-effects that these species have on tropical rainforests and water supply in the hills.
This ruling recognises that the long-term ecological impact of exotic species, like eucalyptus and wattle, far outweigh any economic gains to individuals or corporations in the short term.
The implications of this judgment are far-reaching, with the potential to precipitate similar public interest litigations in other states.
In the Nilgiris and the Palani Hills of Tamil Nadu, plantations of eucalyptus served the dual purpose of wood-pulp and drying out of swamps for human settlement.
These trees lose water to evaporation from their leaves in a process called transpiration, and their effect on water depletion is much more than local grasses, which have been residents of the Palani Hills for millenia.
As large swathes of grasslands on the tops of the Palani hills turned into eucalyptus forests, locals began to notice changes in their water supply.
In settlements close to Kodaikanal in the Palani Hills, water shortages became common soon after periods of good rainfall. While tourists in Kodaikanal often took the blame for water shortages in town, blame could not be assigned among the adivasis who were suffering the consequences of poor water supply, even though they lived far from the tourist-circuit.
Eucalyptus trees are known to cause a loss of between 20-40 litres of water/tree/day.
With about 11,000 hectares of eucalyptus in the Palani Hills, the daily water loss from eucalyptus alone could exceed Bangalore’s daily water supply.
Further, younger trees use more water than mature trees, consequently making new growth of eucalyptus more dangerous to an area’s hydrological cycle.
Studies by scientists with the Food and Agriculture Organisation of the United Nations have found that the thinning and selective cutting of mature eucalyptus plantations increased stream flow by an average of 400 mm/year.
In an area with average annual rainfall of 1600 mm/year, like the Palani Hills, such an increase in stream flow would make a huge difference to water supply.
Eucalyptus and wattle planting gained momentum after Indian Independence.
These species were the mainstay of several internationally backed social forestry programmes and centrally sponsored forest conversion schemes in the 1970s.
The aim for eucalyptus was to provide a source of pulpwood for the rapidly developing Indian paper-pulp industry by improving the productivity of forests.
The National Commission on Agriculture in 1976 recommended some eucalyptus species as some of the most suitable trees for this purpose.
At the same time, wattle was being promoted for fuel wood, local timber use and tanning bark as part of the social forestry programmes.
In Karnataka, for instance, 90 per cent of the seedlings planted as part of the Karnataka State Social Forestry Project of 1983, were eucalyptus species.
Most of the original plantations were raised between the 1960s and the 1980s, but the march of the exotic trees was not stemmed by a lack of extensive planting thereafter, because the trees had become so comfortable in the Indian environment that they could propagate on their own.
Karnataka, like Tamil Nadu, has been at the forefront of conflicts over eucalyptus plantations.
The state government promoted eucalyptus in a big way, clearing 100,000 acres of evergreen forest in the Western Ghats for plantations.
This loss of natural forest had terrible consequences for wildlife, water and soil erosion. Scientists have found that eucalyptus loses more water than the annual rainfall in the drier areas of Karnataka, such as Kolar.
While not drawing from the under-ground water table, eucalyptus certainly contributes to soil water loss.
At the same time, studies have documented the value of eucalyptus as an added source of income to farmers, and have suggested that it acts as an incentive to keep them farming.
This contribution of eucalyptus, however, is easily threatened.
For instance, the fungal infection called ‘pink disease’ wiped out the productivity of eucalyptus plantations in the Western Ghats.
Additionally, the market created for eucalyptus was riddled with scams.
For instance, the Karnataka state government was accused in the 1980s of signing agreements with paper mills for consignments of eucalyptus at throwaway prices.
It is not surprising then that the High Court found in favour of eucalyptus removal.
The Madurai bench of the Madras high court had directed the Tamil Nadu forest department to propose a removal plan by April 7.
Just as the judgment has set a benchmark, the removal process has the potential to be equally exemplary.
While felling the trees is clearly an important part of the removal process, what needs to be highlighted is that merely cutting these exotics do not kill them.
Regrowth from logged stumps is a common sight in the Palani Hills, which unfortunately accounts for greater water loss than the original trees that were felled.
The stumps that remain after a tree is cut need to be killed.
Additionally, young eucalyptus and wattle plants need to be uprooted and removed.
Such an operation would call for massive man-power and effort, given the scale of spread of these exotic species.
As a result, this logging would need to be phased and a study will need to be conducted to map the existing eucalyptus and plan how to phase its removal.
Environmentalists in the Palani Hills suggest that the eucalyptus and wattle around intact shola-grassland habitat should be targeted first, in order to secure the wild habitat before proceeding to remove these species from areas closer to human habitation.
Sholas are the stunted forests characteristic of high altitude and naturally occur in combinations with grasslands.
Many of these areas are relatively less accessible by road, and often this is the reason why these shola-grassland habitats have remained in existence.
Given the projected scale of the removal operation there is a fear that the process of removal might harm the wild landscape even more than the eucalyptus did.
Ecosystem dynamics also need to be considered when working in the shola-grassland ecosystem.
The shola forests are in a constant state of flux with respect to the grasslands, each trying to occupy the space of the other.
While the Court has decided to keep a close watch on proceedings with respect to this case, it is important to note that eucalyptus and wattle removal has to go beyond logging and must include the process of ecological restoration.
This case has the potential to be a benchmark for ways to deal with introduced species elsewhere in the country, particularly in the ecologically sensitive Western Ghats.
Measured and well planned action, based on scientific principles could go a long way in ensuring its long-term success.