Rainforest canopy in the Peruvian Amazon. Photo by Rhett A. Butler
In the Western Amazon—arguably the world’s most biodiverse region—scientists have found that not only is the forest super-rich in species, but also in chemicals. Climbing into the canopy of thousands of trees across 19 different forests in the region—from the lowland Amazon to high Andean cloud forests—the researchers sampled chemical signatures from canopy leaves and were surprised by the levels of diversity uncovered.
“We discovered that this incredible region is a patchwork mosaic of trees with chemical signatures organized into communities to maximize their growth potential given their local soils and elevation—two geological factors they must negotiate as living organisms,” said lead author Greg Asner with the Carnegie Institution for Science. “Within these communities, the trees have evolved chemical portfolios that are different from one another, maybe to help each species take a place in its community—what we call a niche.”
Trees use a wide swathe of chemicals to capture light, synthesize and store carbon, develop foliage, and even defend themselves. The study, published today in the Proceedings of the National Academy of Sciences (PNAS), found that the suite of chemicals used by canopy trees often depended on elevation, climate, and soil.
Carnegie botanist Felipe Sinca is high in an Amazonian tree canopy. Photo by Greg Asner.
“Variation in this leaf chemical portfolio expresses multiple strategies evolved in plants to maximize fitness through growth and longevity in any given environment,” the scientists write.
Asner and his team took samples from an astounding 2,420 tree species, more than double the number of species found in the U.S. and Canada combined. In order to obtain these precious samples the team climbed into the canopy of 3,560 trees; the scientists than spent five years in lab work analyzing the chemicals found in the leaves. The massive study is the first foray of Carnegie’s Spectranomics project, which seeks to study the link between biological diversity and ecological function.
But the Amazon is currently facing a barrage of unprecedented threats, including clearing for agriculture, livestock, and logging; illegal mining and poaching; and worsening climate change. The scientists write that their finding may help uncover how tree species will fare in the future, especially in a warmer world.
“A clearer sense of the diversity and organization of canopy chemical traits may help us to forecast winners and losers
within specific communities in response to climate change. Predicted warmer temperatures may favor species that have evolved to invest more in light capture and growth chemicals.”
But the findings go beyond helping scientists to predict future survival, they also act as a warning of what’s at stake, according to Asner.
“I view the results as a wake-up call that we are shaking up a special tropical region full of chemically unique forest communities that have undergone millions of years of evolution and biogeographic construction.”
- Gregory P. Asner, Roberta E. Martin, Raul Tupayachi, Christopher B. Anderson, Felipe Sinca, Loreli Carranza-Jiménez, and Paola Martinez. (2014) Amazonian functional diversity from forest canopy chemical assembly. PNAS.
(01/14/2014) Often touted as low-impact, remote oil roads in the Amazon are, in fact, having a large impact on frogs living in flowers in the upper canopy, according to a new paper published in PLOS ONE. In Ecuador’s Yasuni National Park, massive bromeliads grow on tall tropical trees high in the canopy and may contain up to four liters of standing water. Lounging inside this micro-pools, researchers find a wide diversity of life, including various species of frogs. However, despite these frogs living as high as 50 meters above the forest floor, a new study finds that proximity to oil roads actually decreases the populations of high-living frogs.
(12/16/2013) In what will likely be considered one of the biggest (literally) zoological discoveries of the Twenty-First Century, scientists today announced they have discovered a new species of tapir in Brazil and Colombia. The new mammal, hidden from science but known to local indigenous tribes, is actually one of the biggest animals on the continent, although it’s still the smallest living tapir. Described in the Journal of Mammology, the scientists have named the new tapir Tapirus kabomani after the name for ‘tapir’ in the local Paumari language: Arabo kabomani.
(10/23/2013) It’s hard to mistake an arapaima for anything else: these massive, heavily-armored, air-breathing fish (they have to surface every few minutes) are the megafauna of the Amazon’s rivers. But despite their unmistakability, and the fact that they have been hunted by indigenous people for millennia, scientists still know relatively little about arapaima, including just how many species there are. Since the mid-Nineteenth Century, scientists have lumped all arapaima into one species: Arapaima gigas. However, two recent studies in Copeia split the arapaimas into at least five total species—and more may be coming.
(06/12/2013) From 2000-2009, scientists described on average seven new bird species worldwide every year. Discovering a new bird is one of the least common of any species group, given that birds are highly visible, mobile, and have been scrutinized for centuries by passionate ornithologists and birders. But descriptions this year already blows away the record year over the last decade (in 2001 when nine new birds were described): scientists working in the southern Amazon have recorded an incredible 15 new species of birds according to the Portuguese publication Capa Aves. In fact, this is the largest group of new birds uncovered in the Brazilian in the Amazon in 140 years.
(05/16/2013) Jaguars (Panthera onca) are the biggest cat in the Americas and the only member of the Panthera genus in the New World; an animal most people recognize, the jaguar is also the third largest cat in the world with an intoxicatingly dangerous beauty. The feline ranges from the harsh deserts of southern Arizona to the lush rainforests of Central America, and from the Pantanal wetlands all the way down to northern Argentina. These mega-predators stalk prey quietly through the grasses of Venezuelan savannas, prowl the Atlantic forests of eastern Brazil, hunt along the river of the Amazon, and even venture into lower parts of the Andes.