Tropical species face high extinction risk
mongabay.com
December 10, 2008
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Tropical plant species face an inherently high extinction risk due to small populations and restricted ranges relative to temperate species, reports research published in PLoS ONE. These traits leave them vulnerable to habitat disturbance and climate change.
Analyzing databases for the number of plant species at risk in each country of the world as well as human factors including GDP, population density and deforestation, Jana Vamosi and Steven Vamosi found that human activity was not the primary cause of the increasing risk of extinction in the tropics.
 Senecio keniodendron, endemic to Mount Kenya |
“Our findings differ from previous ones in that factors tightly linked to human activity were not particularly important in determining how many plant species were threatened with extinction. Instead, the most important factor seemed to be simply latitude. So, extinction dynamics may be very different between plant and animal species.” said Steven Vamosi, a biologist at the University of Calgary. “Plant species near the equator may persist at naturally low population sizes or have small ranges, making them intrinsically more susceptible to a given amount of disturbance.”
“This is not to say that human activities are not underlying contemporary risk of extinction; instead, it implies that plant species in a tropical country will, on average, be more sensitive to a given amount of human disturbance than those in a temperate country,” he added.
Vamosi says that 20 to 45 per cent of species in the tropics are at risk. The tropics hold 60 percent of Earth’s plant species despite making up only 12 percent of its land mass.
Jana Vamosi and Steven Vamosi (2008). Extinction Risk Escalates in the Tropics. PLoS ONE.
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