An Uphill Battle for the Rainforest
Migration isn’t just for animals now.
Trees in the Andes rainforest in Peru are on the move as average global temperatures continue to rise, according to a study published in Nature.
This tree migration, or shift upward in the distribution of species living within the forest isn’t novel. As shown through pollen research, this movement upwards has been traced back thousands of years. What is new and of concern, however, is the inability for these species to migrate quickly enough to survive increasing temperatures caused by climate change.
The result? A decrease in biodiversity, or the variety of life on Earth, in rainforests brimming with unique plants and animals.
“If the climate keeps changing at the pace it is,” says Dr. Miles Silman, a biologist at Wake Forest University, “it looks like many of these plants won’t be able to keep up and they’ll be left behind.”
Silman, a biology professor and director of the Center for Energy, Environment, and Sustainability, has spent the past several years analyzing this reaction to increasing temperatures in the Andes Mountains in Peru with other leading experts, including Wake alumni Dr. Kenneth Feeley of Florida International University of Miami and Dr. William Farfan-Rios of Washington University at St. Louis.
Due to the limited range of temperatures suitable for trees in the rainforest, species are moving upward to seek cooler climates. On average, these tree species climb upward 2.5 meters a year.
However, this increase doesn’t mean an overall shift upward of the whole population. Rather, it is a product of the destruction of slower moving individuals.
“What we find is that there are very few trees that are actually increasing the range,” says Silman. “Most of the trees are actually dying on the lower end of the range.”
Unfortunately, a recent study analyzing a larger scope of South American rainforests shows that even species able to migrate quickly aren’t necessarily in the clear either. Due to drastic changes in environmental conditions, many species are unable to migrate as far upwards as once possible due to human disturbances.
“We’ve effectively made the mountains shorter than they should be,” says Feeley.
This shrinkage in land available is partially due to clearing space for agriculture and cattle, leaving species unable to climb past unsuitable grasslands. Because of this, there is little room for species to survive in increasing temperatures.
“[The mountain] is like a cone,” Feeley says. “You go higher up, and there’s less land available. As [tree species] have less, the population size is going to shrink. They’re going to be more at risk of extinction.”
With the threat of mass extinctions of plant species unable to migrate, biodiversity within the rainforest is at risk. The impact of decreased biodiversity stretches well beyond the Peruvian rainforest and its surrounding areas.
Ecoservices, or services provided to humans by the environment, are abundantly supplied by rainforests like those found in Peru. Functions such as storing carbon, releasing oxygen, and impacting global weather, may all be impacted by the decrease in biodiversity that will be seen if the current trajectory of climate change continues.
“We all depend on the ecoservices of those forests,” says Farfan. “Even if we are in the United States, we still depend on the Andes and Amazon [rainforests] for water circling or air circling because all of the components are tied together globally.”
As a result, experts like Silman, Farfan, and Feeley continue to research and analyze the rainforest, hoping to expand our understanding of the consequences of increasing temperatures.
“We’re trying to understand why some species move faster than others,” says Feeley, “and trying to expand the scope of our studies to gain a deeper knowledge.”
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https://onlinelibrary.wiley.com/doi/10.1111/j.1365-2699.2010.02444.x
https://science.sciencemag.org/content/303/5659/827.abstract
https://www.nature.com/articles/s41586-018-0715-9
https://www.nationalgeographic.com/news/2013/9/rain-forest-plants-race-to-outrun-global-warming/
Science Journalism- Abby Vogeley 