Invasive plant species have long had a reputation as being bad for a new ecosystem when they are introduced.
Stan Harpole, assistant professor of ecology, evolution and organismal biology at Iowa State University, is founding organizer of a team of more than 70 researchers working at 65 sites worldwide that tested that assumption.
They wanted to know if it is true that problematic invasive species often spread widely in their new habitats because they don't encounter predators or diseases that help keep them in check in their home ranges.
"There is this assumption that when plants invade a new area that they become much more abundant in the new area than they were in the native areas," said Harpole. "It turns out that, on average, they aren't any more abundant away from home than they are at home."
Harpole says there is a "rule of 10s" that can apply to invasive species.
"Of, say, 100 plants that arrive in a new area, only about 10 percent of those will survive without being in a greenhouse or some other controlled area," said Harpole. "Of those 10 that can survive, only about 10 percent of those really cause problems.
"When you think about all the species we've brought over from other areas, relatively few have become serious pest species. The problem is we've brought over so many that quite a few have become major problems and they get a lot of attention."
Harpole points to the kudzu plant as an example.
Kudzu was introduced from Asia as a soil erosion plant more than a century ago. It now chokes out native species from Texas to Maine to Florida, according to the U.S. Department of Agriculture.
Problem plants like this are uncommon when compared to all the exotic species in a region, but they do get the most interest and may give the impression that species that escape their home range often spread and take over new habitats and become more abundant than before, says Harpole.
Invasion can also be thought of more generally as a process in which new species enter new habitats. Even plants now considered native were once invaders, says Harpole.
When glaciers receded from the Midwest 10,000 years ago, there were no native species in the area -- the retreating ice left bare ground open for invasion.
"All the plants that are now seen as native were invasive in the past in the sense that they had to spread across the landscape," he said.
"What's different today is that we move plants so much faster than they would move by themselves. Now a species can become global in a matter of years, where it may have taken tens of thousands of years in the past," said Harpole.
Harpole is coauthor of a research paper led by Jennifer Firn of Queensland University of Technology, Australia, and is published in the journal Ecology Letters. Coordination of the study was funded by the National Science Foundation.
Source:http://bit.ly/gbjOi7
Thursday, March 3, 2011
Poacher who killed 15 rhinos arrested
KATHMANDU, Feb 28: The Central Investigation Bureau (CIB) on Saturday arrested a notorious rhino poacher who killed more than 15 rhinos in Chitwan for the past few years.
The rhinos, all from the Chitwan National Park, were killed for their horns that fetch high prices in the black market.
The poacher is Kajiman Praja, 32, of Korak-9 in Chitwan and he has killed six rhinos in less than a year. Praja has been listed by the World Wildlife Fund for Nature as the deadliest rhino poacher of the time. He was arrested by the CIB´s virgin operation hunt.
Praja´s is a rags to riches story. He would employ his wives and two other female members of his family for rhino poaching and has so far earned at least Rs 15 million by selling rhino horns.
One-horned rhino is an endangered animal and its population in Nepal is around 435.
The arrest of Parja, who hails from the backward Chepang community that chiefly resides in the periphery of the park, which is home to most of the country´s one-horned rhinos, has raised hopes among conservationists and served a major blow to poachers.
"We are very happy that CIB has nabbed a kingpin who single-handedly rendered conservation efforts ineffective," said Diwakar Chapagain, the country director of WWF.
Need for sustainable approach
DIG Rajendra Singh Bhandari, the CIB chief, says operation hunt is the first high-profile venture undertaken to fight organized crimes in the wildlife sector.
"Now we will look into the arteries of wildlife crimes that portray Nepal as a major transit in the world," he said. "We see that our investigation into wildlife crimes could reveal their linkages to other organized criminal rings that thrive on smuggling."
Chapagain has similar impressions. "In place of Kajiman, they could pose a Ramman or somebody else if this problem is attacked at its roots," he said.
Bhandari also holds that an integrated program should be developed targeting the backward communities residing alongside major wildlife habitats.
Source:http://bit.ly/fs2irc
The rhinos, all from the Chitwan National Park, were killed for their horns that fetch high prices in the black market.
The poacher is Kajiman Praja, 32, of Korak-9 in Chitwan and he has killed six rhinos in less than a year. Praja has been listed by the World Wildlife Fund for Nature as the deadliest rhino poacher of the time. He was arrested by the CIB´s virgin operation hunt.
Praja´s is a rags to riches story. He would employ his wives and two other female members of his family for rhino poaching and has so far earned at least Rs 15 million by selling rhino horns.
One-horned rhino is an endangered animal and its population in Nepal is around 435.
The arrest of Parja, who hails from the backward Chepang community that chiefly resides in the periphery of the park, which is home to most of the country´s one-horned rhinos, has raised hopes among conservationists and served a major blow to poachers.
"We are very happy that CIB has nabbed a kingpin who single-handedly rendered conservation efforts ineffective," said Diwakar Chapagain, the country director of WWF.
Need for sustainable approach
DIG Rajendra Singh Bhandari, the CIB chief, says operation hunt is the first high-profile venture undertaken to fight organized crimes in the wildlife sector.
"Now we will look into the arteries of wildlife crimes that portray Nepal as a major transit in the world," he said. "We see that our investigation into wildlife crimes could reveal their linkages to other organized criminal rings that thrive on smuggling."
Chapagain has similar impressions. "In place of Kajiman, they could pose a Ramman or somebody else if this problem is attacked at its roots," he said.
Bhandari also holds that an integrated program should be developed targeting the backward communities residing alongside major wildlife habitats.
Source:http://bit.ly/fs2irc
Tuesday, March 1, 2011
Sexy monkeys wash with own urine
Capuchin monkeys have what at first glance appears to be an odd habit: they urinate onto their hands then rub their urine over their bodies into their fur.
Now scientists think they know why the monkeys "urine wash" in this way. A new study shows that the brains of female tufted capuchins become more active when they smell the urine of sexually mature adult males.
That suggests males wash with their urine to signal their availability and attractiveness to females. Details of the finding are published in the American Journal of Primatology.
A number of New World monkey species, including mantled howler monkeys, squirrel monkeys and the few species of capuchins, regularly "urine wash", urinating into the palm of the hand, then vigorously rubbing the urine into the feet and hindquarters.
Several hypotheses have been put forward as to why they do it, including that it may somehow help maintain body temperature or allow other monkeys to better identify an individual by smell.
Most studies into the behaviour have been inconclusive. "But one study reported that when being solicited by a female, adult males increased their rate of urine-washing," said Dr Kimberley Phillips, a primatologist at Trinity University in San Antonio, Texas, US.
"Since female capuchins [when they are most fertile] actively solicit males, we reasoned that urine washing by males might provide chemical information to the females about their sexual or social status," she told BBC News.
To investigate, Dr Phillips and her colleagues scanned the female monkeys' brains while the animals sniffed adult male and juvenile male urine.
These magnetic resonance imaging (MRI) scans revealed that female tufted monkeys' brains became significantly more active when they sniffed the scent of urine produced by adult males compared to that from juveniles.
Since adult males are sexually mature, they excrete higher concentrations of the male sex hormone testosterone in their urine. The concentration of this testosterone is also linked to their social status; higher status males tend to produce more.
"Female capuchin monkey brains react differently to the urine of adult males than to urine of juvenile males," said Dr Phillips. "We suggest that this is used as a form of communication to convey social and or sexual status."
She added that it was surprising that capuchin monkeys appeared to respond to these cues, because the species is not known for using communication based on smell.
Source:http://news.bbc.co.uk
Now scientists think they know why the monkeys "urine wash" in this way. A new study shows that the brains of female tufted capuchins become more active when they smell the urine of sexually mature adult males.
That suggests males wash with their urine to signal their availability and attractiveness to females. Details of the finding are published in the American Journal of Primatology.
A number of New World monkey species, including mantled howler monkeys, squirrel monkeys and the few species of capuchins, regularly "urine wash", urinating into the palm of the hand, then vigorously rubbing the urine into the feet and hindquarters.
Several hypotheses have been put forward as to why they do it, including that it may somehow help maintain body temperature or allow other monkeys to better identify an individual by smell.
Most studies into the behaviour have been inconclusive. "But one study reported that when being solicited by a female, adult males increased their rate of urine-washing," said Dr Kimberley Phillips, a primatologist at Trinity University in San Antonio, Texas, US.
"Since female capuchins [when they are most fertile] actively solicit males, we reasoned that urine washing by males might provide chemical information to the females about their sexual or social status," she told BBC News.
To investigate, Dr Phillips and her colleagues scanned the female monkeys' brains while the animals sniffed adult male and juvenile male urine.
These magnetic resonance imaging (MRI) scans revealed that female tufted monkeys' brains became significantly more active when they sniffed the scent of urine produced by adult males compared to that from juveniles.
Since adult males are sexually mature, they excrete higher concentrations of the male sex hormone testosterone in their urine. The concentration of this testosterone is also linked to their social status; higher status males tend to produce more.
"Female capuchin monkey brains react differently to the urine of adult males than to urine of juvenile males," said Dr Phillips. "We suggest that this is used as a form of communication to convey social and or sexual status."
She added that it was surprising that capuchin monkeys appeared to respond to these cues, because the species is not known for using communication based on smell.
Source:http://news.bbc.co.uk
Sunday, February 20, 2011
Tropical forests 're-shaped' by climate changes
Future climate change could change the profile of tropical forests, with possible consequences for carbon storage and biodiversity, a study says.
It suggests that if current trends continued, the drier conditions would favour deciduous, canopy species at the expense of other trees. US researchers based their findings on the changes they recorded in a Costa Rican forest over a 20-year period.
The team's paper has been published in the journal Global Change Biology.
"It is important because - depending on the rate of change, and the type of species that are found in the forests - it will influence a lot of ecosystem services and processes," explained co-author Brian Enquist from the University of Arizona.
"For example, we need to know how much carbon tropical forests are storing, and will store in the future. We also need to know how much CO2 they are taking out of the air."
Professor Enquist and his team examined how an area of forest had changed between 1976 and 1996. "We were fortunate that between the two dates, there was a series of quite impressive droughts - those droughts have been increasing in severity over the longer term," he told BBC News.
He said that there had been a "tremendous reduction" in the total number of trees in the forest. "Most of that reduction was in the smallest trees - such as the saplings and the smaller trees in the understorey," Professor Enquist observed.
"That was the first change that we immediately noticed, but then we began to look very closely and asked what was causing those trees to die.
"What we found was that there was a very distinctive signal in the types of trees that tended to survive and the types of trees that died - it came down to basic differences on how these trees functioned and worked.
"We found that those species that tended to require more moist conditions were the ones that dropped out very quickly, and those that were able to handle more drought-like conditions persisted."
Professor Enquist said the species that favoured such conditions were deciduous, canopy trees, and if the trend of drier conditions continued into the future then it would change the characteristics of tropical forests.
"The ecosystem implication is that those types of forests (dominated by deciduous, canopy species) tend to store less carbon and hold less biomass, which would then have a detrimental impact in terms of the entire biosphere's ability to help regulate or mitigate the effects of global climate change."
He said the study's findings, when combined with other results from other similar projects, created a picture of tropical forests that were changing "rather quickly".
Professor Enquist added that these forests appeared to be quite suseptible to changes in rainfall, and that future projections of changes in rainfall patterns were likely to have "immediate or very quick consequences".
More on This Story.
Sources:http://www.bbc.co.uk/news/science-environment-12496415
It suggests that if current trends continued, the drier conditions would favour deciduous, canopy species at the expense of other trees. US researchers based their findings on the changes they recorded in a Costa Rican forest over a 20-year period.
The team's paper has been published in the journal Global Change Biology.
"It is important because - depending on the rate of change, and the type of species that are found in the forests - it will influence a lot of ecosystem services and processes," explained co-author Brian Enquist from the University of Arizona.
"For example, we need to know how much carbon tropical forests are storing, and will store in the future. We also need to know how much CO2 they are taking out of the air."
Professor Enquist and his team examined how an area of forest had changed between 1976 and 1996. "We were fortunate that between the two dates, there was a series of quite impressive droughts - those droughts have been increasing in severity over the longer term," he told BBC News.
He said that there had been a "tremendous reduction" in the total number of trees in the forest. "Most of that reduction was in the smallest trees - such as the saplings and the smaller trees in the understorey," Professor Enquist observed.
"That was the first change that we immediately noticed, but then we began to look very closely and asked what was causing those trees to die.
"What we found was that there was a very distinctive signal in the types of trees that tended to survive and the types of trees that died - it came down to basic differences on how these trees functioned and worked.
"We found that those species that tended to require more moist conditions were the ones that dropped out very quickly, and those that were able to handle more drought-like conditions persisted."
Professor Enquist said the species that favoured such conditions were deciduous, canopy trees, and if the trend of drier conditions continued into the future then it would change the characteristics of tropical forests.
"The ecosystem implication is that those types of forests (dominated by deciduous, canopy species) tend to store less carbon and hold less biomass, which would then have a detrimental impact in terms of the entire biosphere's ability to help regulate or mitigate the effects of global climate change."
He said the study's findings, when combined with other results from other similar projects, created a picture of tropical forests that were changing "rather quickly".
Professor Enquist added that these forests appeared to be quite suseptible to changes in rainfall, and that future projections of changes in rainfall patterns were likely to have "immediate or very quick consequences".
Sources:http://www.bbc.co.uk/news/science-environment-12496415
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