September 12, 2013
Peru’s Majestic Cloud Forests Under Threat
Brett Smith for redOrbit.com - Your Universe Online
According to a new study from Wake Forest University published by the journal PLOS ONE, a confluence of climate change and ecological factors could threaten Peru’s cloud forests, which are nestled along the eastern slopes of the Andes Mountains.
Home to one third of Peru's mammal, bird and frog species, the cloud forests are renowned for their biodiversity and high elevation. At altitudes between 6,500 and 11,000 feet, they are a remote, difficult-to-study ecosystem. Scientists estimate that they have discovered only a fraction of the species currently living in these perennially wet areas.
In a study based partially on predictions of 21st-century warming, Wake Forest researchers are warning that tree species in Peruvian cloud forests could decrease by 53 to 96 percent in the coming years. The loss would have significant knock-on effects for a variety of organisms dependent on the health of these forests.
The habitats found in these Andean forests are determined largely by temperature, which fluctuates rapidly on the sides of the Andes as a result of the region's terrain. This means most of the mountainside trees and plants can only thrive in a range that extends a few hundred yards.
"I could be standing among a group of one tree species and throw a rock completely across their ranges," said study author David Lutz, a former postdoctoral associate at Wake Forest University and current post-doctoral research associate at Dartmouth College in New Hampshire.
During previous periods of global warming, Andean cloud forest seedlings sprouted at a higher elevation, causing an uphill shift. However, if projections of a 41-degree F increase for the region come to pass, the trees will be moving up at an unprecedented speed, according to study author Miles Silman, professor of biology at Wake Forest. Silman said plants will have to migrate around 3,000 feet to keep pace with the warming climate by 2100.
Another major problem is that the trees can only move uphill as far as the high-elevation grasslands that bar their path. This transition between trees and grassland, referred to as an ecotone, is stationary in most areas – even at temperatures that should have pushed the border zone 660 feet higher, Silman said.
Taking only warming temperatures into consideration, the timberline would need to head almost 3,000 feet uphill to keep up with the cloud forest beneath it, Silman said. However, the results of the Wake Forest study indicate that this progression would take over 3,700 years in protected areas and 18,000 years in unprotected areas.
The researchers said frequent human-set fires and cattle grazing in the grasslands, combined with slow growth rates, could explain a large part the difference between the ecotone’s transition in protected and unprotected areas. The team also says that cloud forest trees can't go through or around the ecotone.
"Previous work we've done shows that the trees in the forest are migrating upwards, but this work shows the ecotone isn't," Silman said. "The ecotone presents a wall to species migration."
Lutz said conservation strategies should focus on reducing human impact and preventing human interference so that the cloud forest can evolve naturally. He added that a more proactive approach will be necessary in the immediate future to prevent massive population loss.