Forensic chemistry could stop African plant thieves

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Three of South Africa's 38 species of cycad are already extinct in the wild, and an illegal trade threatens to push more of these rare, slow-growing plants into oblivion.

Scarred earth meets visitors at the Kirstenbosch National Botanical Garden in Cape Town where some of South Africa's rarest plants once stood. In August, 24 of the park's cycads were stolen, probably to be sold on the black market as landscaping ornaments.

Now, in a last-ditch attempt to save several endangered species from extinction, scientists are turning to forensic methods to see if tracking the history of suspect plants can help to bring illegal traders to book. But time is running out for the plants, which are even more threatened than the countrys emblematic rhinos.

South Africas endemic cycads which look like a cross between a palm and a pineapple tree rank among the most endangered plants in the world. Of the countrys 38 cycad species, three are already extinct in the wild, and 12 others are critically endangered. Cycads grow slowly, and can live for hundreds of years.

Their striking looks and rarity make them prized collectors items, with individual plants able to fetch tens of thousands of US dollars. This profitability is fuelling illegal poaching, even though lawbreakers face up to ten years in prison if caught.

Attempts to prevent poaching by various methods have so far failed to stem the loss, especially in the wild. Microchip tags inserted in the plants have been spotted by thieves armed with X-ray machines, and gouged out. A more successful method sprays plants with microdot paint, which deposits tiny identification tags that cannot be seen with the naked eye. However, tagging every plant in a collection let alone in the wild is not always feasible.

The new method, developed by scientists at the University of Cape Town and at the South African National Biodiversity Institute in Pretoria, gets around this problem using the plants' own chemistry. It is based on stable-isotope analysis a common method in forensic science to track where a plant has lived over its lifetime.

In nature, the relative abundances of a chemical elements isotopes which differ in the number of neutrons they have in their nuclei vary from place to place. As organisms grow, they take building blocks from their environment, making these isotope signatures part of their bodies.

Stable-isotope analysis has helped to identify the origins of smuggled ivory, counterfeit money and drugs. But its suitability for tracking cycads was unknown, which is what UCT plant scientist Adam West and his colleagues wanted to change.

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Forensic chemistry could stop African plant thieves