August 17, 2009

Islands Being Invaded By Non-Native Plant Species

Several of the world's oceanic islands are being invaded by nearly 400 outside plant species.

Almost half of the species already dominate their new homes, and hundreds more are expected to make progress across the islands in the near future, according to BBC Earth News.

These outside plants can wreak havoc in their new environments, where they are viewed as invasive weeds.

Botanist Dr Christoph Kueffer of the University of Hawaii in Honolulu and colleagues studied data from 30 island groups in the Atlantic, Caribbean, Pacific and Western Indian Ocean.

They told the BBC that they discovered 383 species of spermatophyte, or seed-bearing plant, had entered at least one of the 30 islands they were monitoring.

They noted that 181 of those species had become dominant on the islands they had invaded.

Kueffer and his team warns that if the invasion continues at the current rate, some 500 to 800 spermatophyte plants will find new homes on islands at latitudes between 35 degrees North and 35 degrees South.

They added that 250 to 350 of those would likely become the dominant species on at least one island.

"For Hawaii alone, it is said that 10,000 non-native plant taxa have been introduced to the islands," Kueffer told the BBC.

He said that 47 of those non-native plants have become significant weeds in Hawaii.

"A particular challenge is to predict which non-native plant species may become a problem, in order to prevent [their] introduction to a new place," said Kueffer.

His team also studied what made certain plants able to inhabit new islands with greater ease. These conditions included the plant's biology, the isolation, geography and ecology of the islands or the extent of human development.

"Human action is a predominant factor in driving invasive species patterns on islands," Kueffer told the BBC.

"A vast majority have been deliberately introduced and planted."


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