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Amazon Observatory

In Peru, a lowlands-to-peak study has revealed how climate change is affecting forests—and helped nurture young scientists

PILLCOPATA, PERU—Twenty years ago, a dozen Peruvian biology undergraduates armed with machetes and tape measures laboriously cleared a trail down the steep eastern flank of the Andes Mountains near this sleepy Amazonian town. They staked out eight study plots along a 15-kilometer-long transect that stretched from the grasslands found near the relatively cool, treeless top of a 4020-meter-high mountain known as Apu Kañajhuay down the fog-shrouded Kosñipata Valley to the warmer forests below, which are soaked by as much as 5 meters of rain a year. Along the transect lies some of the world’s richest biodiversity.

Now, those 1-hectare plots in and near Manu National Park and Biosphere Reserve are the centerpiece of one of the longest running field studies of how an Amazon forest is responding to climate change. The effort, known as the Andes Biodiversity and Ecosystem Research Group (ABERG), involves researchers from around the world. It has produced thousands of data points and scores of publications that have offered new insights into how warming and drying are reshuffling tropical ecosystems.

ABERG has also left an indelible imprint on Peru’s scientific community, among the weakest in South America. Scientists from Europe and North America launched the project. But many of the students who helped hack out the original study plots went on to earn doctorates and academic posts and are now helping train a new generation of Peruvian scientists. The initiative became a “cradle of biologists,” says William Farfán-Ríos, a Peruvian ecologist at Wake Forest University (WFU) who was one of those machete-wielding students.

Earlier this year, Farfán-Ríos was one of more than 30 scientists who gathered at the Manu Biological Station here to mark the 20th anniversary of ABERG. Over 3 days in June, participants celebrated the project’s success at revealing an astonishingly diverse ecosystem and establishing a baseline for future studies of climate effects. But they also pondered emerging threats. The trail connecting the field plots has become a transit route for drug couriers, for example, and illegal gold mining is altering nearby ecosystems. And climate change itself may wipe out some of the biodiversity, which is still poorly understood. ABERG’s “fundamental [research] questions remain the same,” says Patrick Meir of the University of Edinburgh, one of the effort’s original scientists. “But the context has become more urgent.”

Two monkeys crawling along a tree branch, silhouetted against the sky.
The Andes Biodiversity and Ecosystem Research Group study plots sit in a biodiversity hot spot known for its rich flora and fauna, including primates.ALEX HYDE/NPL/MINDEN PICTURES

ABERG’S ROOTS reach back to the 1990s, when a flurry of studies coming out of the Manu park revealed that the region, where the Amazon lowlands meet the Andean cloud forest, is a biodiversity hot spot. It held notably high numbers of plant species and was an ornithologist’s paradise, reported researchers at the National University of Saint Anthony the Abbot in Cusco (UNSAAC) and foreign universities.

In 2002, in a bid to organize efforts to document the region, Conservation International and the Missouri Botanical Garden invited researchers from more than half a dozen universities in the United States and Europe to meet at the National Center for Ecological Analysis and Synthesis at the University of California, Santa Barbara. The scientists soon forged a loose alliance: Each group would seek funding to conduct its own studies but would share its findings—and a common research site.

Some of the researchers already had a working relationship with Norma Salinas, a botanist then at UNSAAC who was familiar with the area targeted for study. Salinas soon became a key figure in ABERG’s development. She recruited rotating brigades of students to create the study plots and spent her weekends shuttling people and supplies between Cusco and the field site, along a steep unpaved road plagued with rock falls. “She was an engine,” recalls WFU tropical ecologist Miles Silman.

The project’s first decade focused largely on tallying the region’s enormous biodiversity. Researchers identified 1255 species of trees growing in the plots, discovered a tree genus (dubbed Incadendron esseri) previously unknown to science, and snapped camera-trap photos of bush dogs (Speothos venaticus), mountain coatis (Nasuella olivacea), and Andean bears (Tremarctos ornatus) ranging farther afield than expected.

1 A “grass ceiling”

Many tree species are shifting their distribution upslope at an average of 2.5 meters to 3.5 meters a year, but the tree line does not always expand into high-altitude grasslands. Grass fires, grazing livestock, frost, and difficulty in spreading seeds could be limiting upward migration.

2 Landslide response

Lidar surveys have revealed how forests recover after landslides, a major cause of tree mortality. Older landslides that keep some residual vegetation develop taller, more varied canopies.

3 Species riches

Researchers have described many new species previously unknown to science, including a tree genus, Incadendron esseri, that grows at 1800 meters to 2400 meters.

4 Unprecedented warming

Pollen grains and isotopes in lake sediment cores show precipitation and forest composition have fluctuated with warming and cooling cycles since the last glacial maximum 21,000 years ago. But the current rate of warming is much faster.

5 Some species can’t cope

To simulate rising temperatures, researchers moved tree seedlings, including of the abundant Weinmannia bangii, to lower elevations. Many failed to thrive, suggesting some species might not adapt to warming.

6 Clues to the future

Studies of the functional traits of plants, such as their biochemical and morphological characteristics, could provide clues to how warming could transform the region’s ecosystems.N. BURGESS/SCIENCE

They also traced the region’s ecological history, including how ecosystems responded to warming and cooling cycles since the last ice age some 21,000 years ago. Some researchers extracted cores of sediment from lakes in the region, analyzing oxygen isotopes and pollen grains that traced how temperatures and vegetation had changed over the past 46,000 years. Those studies made it clear that modern warming in the region was occurring more rapidly than it had in the past, raising the question that has moved to the center of ABERG’s work: How will climate change affect trees and other organisms along its sloping transect?

In general, climate scientists expect plant species that are adapted to warmer, lower elevations to shift upslope as higher elevations become warmer and more welcoming. But exactly how this process works—and which species will benefit or be harmed—remains murky, especially in tropical regions.

To help provide some clarity, ABERG researchers ultimately expanded their network of research plots from eight to 24. Temperatures drop by about 19°C from the lowest plot, which sits at about 200 meters, and the highest, at about 3650 meters. ABERG researchers “are really working in the most dramatic environmental gradient in the tropics,” says tropical ecologist Bill Laurance of James Cook University, who is not involved in the effort. “That’s the kind of place where we expect to see climate change and its broader effects manifesting, but there are tons of things about it that we don’t understand yet.”

A young brown-headed capuchin monkey plays in the treetops near Manu, Peru. DAVID TIPLING/UNIVERSAL IMAGES GROUP VIA GETTY IMAGES

AS EXPECTED, some kinds of trees are expanding their range upslope, as an ABERG team led by tropical ecologist Kenneth Feeley of the University of Miami showed in 2010. From 2003–04 to 2007–08, trees in 38 genera migrated upslope at a rate of 2.5 to 3.5 vertical meters a year, they reported in the Journal of Biogeography. That was a slower pace than the researchers had expected, and it raised concerns that some species would not be able to keep up with the region’s warming, which has advanced by 0.5°C to 1°C over the past 20 years.

But although trees are shifting upslope, studies show the tree line separating forest from high-altitude grassland is holding steady. A number of factors may be preventing the trees from colonizing the grasslands, researchers say, including limited frost tolerance, an inability to disperse seeds, and human activities such as grazing livestock and burning vegetation. But species unable to penetrate this “grass ceiling” may risk extinction.

A constant theme at the meeting was how much scientists still don’t know. More than half of the 1255 identified tree species found in the field plots, for example, are known from just one individual. And in many cases researchers have never seen those trees flower or fruit. As result, Feeley says, “We don’t know what their roles are” in the ecosystem, or how they might respond to climate change.

A close up hands holding leaves and seeds. The several leaves, held in one hand, range in color from tan to dark reddish brown and have a rounded shape. The two seeds, held in the other hand, are round and black, about an inch in diameter, with three lobes.
The seeds and leaves of Incadendron esseri, a tree genus found along the transect that is new to scienceMILES SILMAN

The researchers hope to eliminate some of those unknowns in coming years. One key question is how a warming climate could affect species’ biology, and therefore their role in ecosystems. To find answers, they hope to make greater use of research technologies—such as remote sensing and genetic analyses—that weren’t widely available 2 decades ago. They would also like to replicate experiments done elsewhere that have pumped carbon dioxide into enclosed forest areas to see how plants might respond to high carbon levels in the future. So far, however, the researchers don’t have the necessary funding.

ABERG researchers are also considering ways to conduct studies that could help local residents and Indigenous communities improve their lives and protect a world-renowned biodiversity hot spot. Ongoing habitat loss means “we’re throwing stuff away before we know what role it plays,” Feeley says, “and that’s a dangerous thing to do.”

ABERG’S CONTRIBUTION to strengthening Peru’s scientific community has been equally important. Several of the dozen undergraduates who helped establish the early study plots were the first in their families to attend college, for example. Eight of the 12 went on to earn doctorates and now oversee research of their own. Five have returned to work in Peru, and others pursue research in Peru from universities elsewhere.

Salinas recalls that one key to recruiting those students was the paid internships she could offer thanks to ABERG funds— “something that had never been done at the university.” Later, as foreign graduate students arrived, she matched them with Peruvian field assistants drawn from students she worked with. The Peruvian students soon found themselves immersed in an academic culture in which professors and graduate students welcomed their questions and ideas, unlike the formal, hierarchical style they usually encountered in their studies.

A researcher examines a tree trunk.
Ecologist William Farfán-Ríos measures a tree in the Peruvian Andes. Now at Wake Forest University, he helped establish the Andes Biodiversity and Ecosystem Research Group transect when he was an undergraduate student.JASON HOUSTON

Ecosystem ecologist Walter Huaraca Huasco was one of those field assistants. He grew up in a small Andean village and spoke only Quechua until he was 7 years old. When he saw that students who spoke English had more opportunities, he learned that language the same way he had learned Spanish—by watching TV shows. Working with ABERG gave him a chance to learn to use a compass, an altimeter, and a GPS mapping unit, he recalls. “It was technology we didn’t have here,” says Huaraca Huasco, who went on to earn a Ph.D. at the University of Oxford, where he continues to study carbon cycling.

Richard Tito, another assistant, was the son of rural Andean farmers and spoke only Quechua until he became the first person from his community to go to college. When he was a doctoral student in Brazil, he designed an experiment based on ABERG’s tree migration studies with farmers in his home community in the Apurímac region. the goal was to understand how climate change would likely affect crop plants, such as potatoes and corn. They found that a warming climate could reduce both the yield and the quality of their crops, says Tito, who is now on the faculty of the National University of San Marcos in Lima, Peru.

Tito’s research, Feeley says, underscores how Peruvian scientists, particularly those who speak Quechua, can relate to local people in a way that foreign scientists cannot. Peruvian researchers also have a distinct perspective on how science can influence public policy in their home nation.

PERUVIAN STUDENTS who earn advanced degrees abroad often face difficulty returning home because of a lack of research opportunities. After she completed her Ph.D. at Oxford, Salinas found there was no job for her at her previous employer, UNSAAC. (She ultimately found one at the Pontifical Catholic University of Peru.) Such obstacles are one reason why Peru’s scientific workforce has long lagged behind other South American nations. In 2020, it had just 0.44 researchers per 1000 workers, compared with the Latin American average of 2.23, notes Pedro Bernal, principal adviser to the president of CONCYTEC, Peru’s national science and technology council. Still, he notes that Peru has gained ground since 2011, when that figure was 0.07.

The country is aiming higher, hoping to match the roughly nine researchers per 1000 workers found in the 38 nations that are members of the Organisation for Economic Co-operation and Development. Over the past decade, for example, the government has helped fund new positions for 172 researchers, including 102 Peruvians. Among the beneficiaries was Salinas, who in 2019 received a $1 million grant that enabled her to add six postdoctoral researchers— including five Peruvians—to her team, which was studying secondary forests in Peru.

Tatiana Boza Espinoza, who was one of Salinas’s six postdocs, is now launching her own effort to strengthen Peruvian science. As a research adviser at Peru’s National Institute for Research on Glaciers and Mountain Ecosystems, she is collaborating with other institutions to design a new doctoral program at the National University of San Marcos. It aims to win funding from a World Bank program that will provide grants of more than $4 million each to 20 consortia to develop graduate programs in fields related to coping with climate adaptation and information technology.

One day, some of those students might end up working with ABERG—bringing a story that began 2 decades ago full circle. In the meantime, the project’s most recent class of undergraduates has just finished its work, which it presented at the June meeting. Many of the young scientists thanked the doctoral students, who often had once been field assistants themselves, for mentoring and advice. It was a reminder of how ABERG has helped bolster Peruvian science, Feeley says. “I love to see the students who are finishing their Ph.D.s—who started in the field, studying English with a headlamp—[who] are now professors and publishing,” he says. “The bar has been raised.”

Source : Science