Trop picks: Lantana
The first time the lantana flower came on my radar was when the Australian film by the same name made the rounds at the film festivals, some fifteen years ago.
The movie was a much lauded exploration of how smooth social interactions gloss over the most dysfunctional of relationships. Recall the chilling opening sequence, where the camera pans in on a body of a dead woman hidden in a tangled understory of lantana. One critic speculated that the director had chosen to name the movie after the flower because it was a plant "whose delicate exterior leaves and flowers conceal dense thickets of sharp branches."
They were onto something.
This most benign-seeming of flowers is now threatening to bring down an entire ecosystem in the Indian sub-continent while the rest of us weren't paying attention.
The lantana was first brought over to the sub-continent from the New World Tropics (like so many other plants, although time has yet to tell what damage the others shall wreak) as an ornamental addition to colonial gardens. And it's still considered a harmless garden flower in other parts of the world. Still, whatever keeps it in check in those other environments is absent in the dry forests of the Western Ghats, where it is particularly abundant.
The plant thrives in the well-drained soils of the Ghats, more so in the disturbed spaces within the forests: edges, logging paths, small roads and other clearings (being a light-dependent species, its seeds are otherwise unable to penetrate closed-canopy forest). It is a very efficient competitor against native species, and in some places, it now comprises three-fourths of the understory biomass.
It's so crafty, it actually increases the frequency and intensity of forest fires in rainforests (where, um, because of all that rain, there never used to be any fires). Being quick-growing, dense and woody, it provides a large biomass of flammable material. The more fires in the forest, the more disturbances, and eventually, the more clearings in which the weed can flourish.
If you aren't already creeped out by this machiavellian cunning, consider how this flower has adversely affected the tiger, leopard and elephant populations in the Ghats.
By crowding out biodiversity in the forest, the shrub has made it difficult for the smaller herbivorous population of the Ghats to find food. As a result, these animals--traditionally prey for tigers and leopards--have had to move elsewhere, leaving their predators without a source of food in turn. It's no surprise that there have been increasing incidences of maneating in recent years.
As for the elephants, the increase in lantana growth means a reduction in grass cover, and grass forms the dietary mainstay of local elephant populations. Elephants, like people, are homey creatures--once they've made themselves comfortable in a habitat, they don't like to move on. Thus far, the elephants in the Ghats seem to be resigned to their reduced food supply, but as the situation becomes more dire, we could see changes in migratory behaviour, setting off another chain reaction in turn, or a drop in numbers.
