Friday, May 25, 2007

The law of unintended consequences: Lantana camara

Blue Tiger butterfly
A superficial glance at this post might lead you to think it's about butterflies. It is in an oblique fashion, but it's mostly about the plant they are all feeding on, Lantana camara. Lantana off course is an exotic, among ecologists a much reviled one.

The native range of this plant is in Central and South America and the Carribean. Lantana was probably introduced into India as far back as the 19th century. It has probably been introduced on multiple occasions as a ornamental or hedge plant. Since then it has nearly taken over the landscape in India, and is now found just about everywhere. It has the dubious honour of being listed as one among the top hundred worst invasive species in the world.

Common Rose butterfly
But it is not the damage that this weed does to local ecology, displacing native species, outcompeting them for resources that makes Lantana the poster-child for the "Law of unintended consequences". No that would be too simple, and many other contenders vie for that title. Whether it is the ill-fated attempt to get Indians to eat snails which now overrun the countryside eating their way through everything green or the cane toads in Australia. The world is rife with examples of human hubris gone awry.

Striped Tiger butterfly

Lantana carves a niche all its own though. It take things one step further. It not only makes itself ubiquitous it has also made itself indispensable. Well, perhaps that's going a bit far out on the line, but certainly key to many ecosystem processes. The key to this plant's success in novel habitats has been two-fold, it's wide tolerance for habitats and it's fruiting and flowering phenology.
Lantana camara flowers and hence fruits through out the year. This plant is a readily available, ubiquitous and massive source of nectar and fruits. With native plants out-competed and locally extinct, Lantana becomes the key source of nectar for many species of butterflies. It is similarly extremely important to several birds as a source of fruit available throughout the year.

Common Nawab
This double whammy means once established Lantana cannot be easily removed without serious ecosystem disruption. Some unpublished work has apparently suggested that several populations of Western Ghat species now rely on Lantana and a crash will be imminent if there is uncontrolled removal of this weed. This off course makes removal of this weed and subsequent restoration of local ecology difficult. Many parameters will have to be considered when attempting such an exercise.

Twany Coaster

Not that dealing with this invasive has been easy. Large seed loads mean that even burning and massive chopping are simply a set-back, not an eradication. This has been a hard hard weed to deal with incredible rebound capabilities. ATREE in Bangalore has been leading one of the more interesting efforts to deal with this menace.

Hawk moth (shot of the week!)
Lantana furniture! Made by tribals in the Male Madeshwara Hills in Karnataka, the project is an interesting mix of community involvement into conservation practices with payoffs for both. So all of you homesteaders who might want to buy furniture might want to give ATREE a call and check out their Lantana catalogue at their offices. You'd be doing your bit.

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