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Tanya Ha - pets, pests and problem plants. -

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Tanya Ha: Rabbits are cute. Lantana is a beautiful and fragrant flower. Yet these examples of flora
and fauna are devastating the Australian landscape. How could something so fluffy or pretty wreak
so much havoc? When it comes to biodiversity it's all about balance and belonging. Problems can
arise from flora and fauna in the wrong place at the wrong time. In fact invasive species cost the
Australian economy an estimated $4 billion per year. From marsupials and drought tolerant plants in
Australia to polar bears and mosses in Canada's tundra, our planet's different landscapes have
particular plants and animals that belong there. These local species suit the local conditions, the
soil and weather patterns.

An introduced species, on the other hand, is one brought by humans to a particular region. In their
natural habitats, individual species play small but important roles. But if you put them into an
environment where they don't belong, they can die or, worse still, completely upset the local
ecosystem and become invasive, particularly if they have few predators or other forces to keep
their numbers down in their new home.

An invasive species can eat too much prey or vegetation for the landscape to support it. Invasive
species can also compete with native species for space, water, food and sunlight. They can become a
great burden on both the natural environment and agriculture. They can even cause extinctions.

Australia is home to 10% of the world's biodiversity. Its isolation from other continents and its
unique conditions has produced weird and wonderful flora and fauna. However, the unique Australian
environment has not responded well to many exotic species from overseas.

Take lantana as an example. If plants were characters in Hollywood movies, then lantana would be
the femme fatale, the highly attractive but ultimately destructive lady. Lantana is a perfumed and
beautifully coloured flowering plant originally from Central America. In the 17th century when the
European empires were expanding and founding colonies around the world, items brought back from the
Americas were the hip and happening trend. Lantana was brought to Europe where it became a popular
ornamental plant. As the empire spread they took their favourite plants with them, and so lantana
was spread around the world's warm regions. It was introduced in Australia in the mid 19th century
but quickly got out of hand. You see, lantana is a biodiversity bully. Its spread threatened the
survival of other native species. Lantana forms dense thickets that smother other vegetation. It's
also poisonous, killing thousands of animals each year.

And there are more examples. Cats were brought into Australia to control mice and other pests and
are now household pets. But cats are also predators. They can't help it, it's their nature.
Domestic, stray and feral cats all kill small native birds, mammals, reptiles and insects. Feral
pigs are destructive animals, wild pigs are ravaging the flora of the Daintree forest. The North
Pacific sea star is a voracious predator that feeds on a wide range of native marine animals. It's
believed that the sea star is affecting oyster farm production in Tasmania. And the European
blackberry was once promoted as a good plant to control erosion, produce nice hedges and provide
food, but it's now a major weed of both pastures and natural ecosystems.

Many invasive species were intentionally introduced to Australia's environment before we understood
the consequences. Some species were introduced to provide familiar foods. Rabbits, for example,
were brought to Australia as a protein source that would grow and reproduce quickly. And they
weren't wrong about that aspect; a single pair of breeding rabbits can multiply to 184 rabbits in
just 18 months. There were also active acclimatisation societies in the colonial era. Homesick
westerners would raise familiar plants and animals hoping to make Australia look a little bit more
like home. Some species, such as foxes, rabbits, deer and pheasants, were introduced for sport to
provide game for recreational hunters, and other species were introduced to control other pests
before becoming pests themselves. Cane toads and Indian Myna birds are well known examples of this.

As well as deliberate introductions, pests can also be brought to Australia accidentally. Soil can
carry with it weed seeds, eggs, micro-organisms and small animals. Pets and domesticated animals
can escape and go feral. Similarly invasive garden plants planted by ignorant gardeners can escape
from backyards into nearby agricultural areas or natural vegetation. Of the 2,800 or so plants
classed as weeds in Australia, about 700 of these are ordinary garden plants that have escaped from
our backyards. Some invasive species are stowaways on board ships or in the ballast water, and
tourists can also bring hidden biodiversity problems in food, souvenirs and other items made from
living or once living materials.

Scientists, government authorities, local councils, conservation groups and farmers are working
together on many fronts to take care of problem plants and animals and protect Australia's
agriculture and biodiversity. You may have met some of the four-legged frontline workers from the
Australian Quarantine and Inspection Service at places like Hobart airport. Beagles were chosen to
be friendly detector dogs. With a sense of smell thought to be about 100 times more acute than that
of humans, they're experts at sniffing out fruit, meat, plants, eggs and even smuggled animals. You
can also do your bit by taking quarantine laws seriously when travelling, gardening with plants
that aren't considered weeds in your local area and by being a responsible pet owner. Keep your
pets contained and have them de-sexed. After all, given half a chance rabbits will, funnily enough,
breed like rabbits.

Robyn Williams: Tanya Ha, who lives and works in Melbourne and whose new book is called Green Stuff
for Kids. And that's another word to watch in 2010, it will be the Year of Biodiversity.

Guests

Tanya Ha

Author and campaigner

Publications

Title: Green Stuff for Kids

Author: Tanya Ha

Publisher: Melbourne University Press

URL: http://www.tanyaha.com/Pages/books.html

Presenter

Robyn Williams

Producer

David Fisher

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