In Colombia, race is on to save 8 rare tree species found nowhere else

Researchers from Colombia’s Humboldt Institute are working with residents of the Claro River Basin in Antioquia department to conserve eight tree species in serious danger of going extinct.
The species are endemic to Colombia: five are found only in the middle section of the Claro River Basin, while the others have been recorded in the neighboring departments of Santander and Caldas.
Of the eight tree species being studied, Matisia serpicostata presents the most worrisome situation: only one specimen has been found in the area.
Researchers and residents have established three tree nurseries to grow these species from seeds and cuttings, and eventually plant the seedlings in the wild.

In January 2020, Luis Carlos Galeano was traveling with his family through the Claro River Basin in Colombia’s mountainous Antioquia department when his wife, Viviana Aguirre, pointed out a tree by the side of the road that seemed strange to her. They examined the shape of its leaves, its 15-meter (50-foot) brown trunk, and its small fruit. It was the exceedingly rare Rhodostemonodaphne antioquensis, a laurel species known locally as chupo colorado.

“We recognized the tree and looked at it to see if we could find any seeds to plant. It’s the only tree [of its kind] I’ve seen in that area, and in fact, it’s the only one I’ve seen in all my life,” said Galeano, a farmer from the municipality of San Luis in eastern Antioquia. The family’s discovery wasn’t exactly good news.

In early 2022, the chupo colorado they’d identified was included in a scientific monitoring project organized by residents of San Luis and scientists from the Alexander von Humboldt Biological Resources Research Institute interested in these trees. In a later expedition by the institute, only one additional adult tree of the species was located, yielding a grand total of just two specimens in the area. This worried the researchers. R. antioquensis is characterized as endangered on the IUCN Red List, meaning its population, endemic to Antioquia, is on the brink of extinction.

The leaves of Rhodostemonodaphne antioquensis. Image courtesy of David Sanin.

This tree species isn’t the only one in jeopardy in Colombia. The Humboldt Institute has identified seven other endemic tree species that are at risk of extinction in the country. The situation is critical: three of these species are in a state of high vulnerability due to their shrinking populations. In addition to the chupo colorado, the researchers located only one adult specimen of Matisia serpicostata (critically endangered) and 12 Melicoccus antioquensis trees (critically endangered), most of them young. All these specimens are endemic to the department of Antioquia and were located in the middle section of the Claro River Basin.

The main threat to the trees is deforestation; their forest habitats are being lost to timber logging and to destruction and degradation for agricultural expansion. However, the communities who live in these areas and who have historically worked as farmers and loggers are now focused on conservation. Together, they’ve developed propagation methods and created three tree nurseries. One of them is run by the Galeano family.

The ripe fruit of Rhodostemonodaphne antioquensis. Image courtesy of David Sanin.

“The nursery was born with the idea of giving back to nature what had been taken from it. We began to reproduce trees in danger of extinction. From there, we’ve been working and coming up with interesting things,” Galeano said of the tree cultivation methods they’ve learned and with which, through trial and error, they’ve achieved success.

The Humboldt Institute, with financing from the Franklinia Foundation, whose mission is to conserve threatened trees around the world, are promoting a new initiative in collaboration with the communities of the Claro River Basin to save the threatened species from extinction. As a team, they designed an action plan for the conservation of eight threatened tree species in the region.

Farmer Luis Carlos Galeano is one of the local researchers in San Luis working on the conservation of threatened trees. Image courtesy of Jorge Bedoya.

Claro River ecosystem

According to the Humboldt Institute, Colombia has the world’s second-largest number of plants, with 26,900 native species recorded. Of this total, more than 6,000, or 24%, are endemic, meaning they’re found only in this South American country. However, some of the endemic tree species aren’t well known and are highly vulnerable to human activity and climate change impacts, as most have restricted distributions and some are even found in a single locality, according to the institute. It notes that, of the 860 endemic trees and bushes recorded in Colombia, 45% are threatened to some degree.

Matisia serpicostata is the tree most at risk of disappearing; only one adult specimen was found. Image by Mónica Florez.

The Claro River Basin straddles the municipalities of Puerto Triunfo, San Luis, San Francisco and Sonsón. Jorge Bedoya, who coordinates the threatened tree conservation project at the Humboldt Institute, said the region’s geographic and geological characteristics favored the diverse evolution of plants, including several with restricted ranges and categorized as threatened.

“The Claro River is located in an ecosystem known as a karst zone,” Bedoya said. “Geologically speaking, its base, in the soil and subsoil, is a very particular rock because it’s like marble and creates very special conditions due to its pH, minerals and nutrients. There is a very strange microclimate there, with other conditions of humidity and temperature, which favors endemic flora.”

Jorge Bedoya, a researcher at the Humboldt Institute. Image courtesy of Jorge Bedoya.

The eight threatened tree species in southeastern Antioquia — an area of 85,106 hectares (210,302 acres) along Colombia’s central mountain range that rises to an elevation of nearly 2,300 meters (about 7,500 feet) — were initially identified between 1980 and 2003 by Colombian researcher Álvaro Cogollo. He’s worked in the region for more than 40 years and has made many significant contributions to scientific research focused on conservation.

“In Colombia, the research done by Professor Cogollo, who is a plant expert, is well known,” said Bedoya, who’s collaborated on research with Cogollo. “He said that he had found species new to science and about which there was no good information or record. When the species were evaluated, we realized that they are classified as [threatened under] IUCN [criteria].”

Unique trees facing common threats

The eight tree species now being studied by the Humboldt Institute are:

Matisia serpicostata, known locally as sapote de monte: Listed as critically endangered, with just one recorded specimen, standing about 12 m (40 ft) tall, with a brown stem and thick leaves.

Caryodaphnopsis cogolloi, known locally as yumbé: Listed as endangered due to deforestation and overexploitation for timber. The species is named after Álvaro Cogollo.

Cybianthus cogolloi, known locally as pipoly: The best-known of this group of threatened species, and listed as endangered. It grows to 12 m and is also named after Cogollo.

Duguetia colombiana, known locally as guanabanito: Listed as vulnerable. It’s threatened by the expansion of cattle pastures, hydroelectric projects, and oil and gas exploration and exploitation. It’s named after its fruit that resembles a small guanabana or soursop.

Melicoccus antioquensis, known locally as bush mamoncillo: Listed as critically endangered, with only 12 individuals found (two adults and 10 juveniles).

Pseudoxandra sclerocarpa, known locally as garrapato or frísolo: Listed as vulnerable. Researchers have collected its seeds and begun propagating the plant, but it has a very slow germination and maturation period.

Rhodostemonodaphne antioquensis, known locally as chupo colorado: Listed as endangered, and extremely scarce in the area, with only two adult individuals identified and no known seedlings. The main threats to the species are extraction of limestone rock and clay, as well as deforestation and cattle ranching.

Simira hirsuta: Listed as endangered. It has one of the best prospects for recovery as it has the largest number of individuals and seedlings. These trees can grow up to 25 m (82 ft).

Cybianthus cogolloi, or pipoly, is threatened by the expansion of farmland and pasture. Image courtesy of David Sanin.

The fruit of Duguetia colombiana or guanabanito, a species made vulnerable due to the effects of cattle ranching, hydroelectric projects, and oil and gas activity. Image courtesy of Mónica Florez.

The fruits of Simira hirsuta, a species whose habitat is affected by the exploitation of limestone rock and clay. Image courtesy of Carolina Castellanos.

“The idea is to collect seeds from all the specimens, germinate them, propagate them and thus distribute them in the region for conservation purposes,” Cogollo told the Humboldt Institute at the beginning of the project.

Five of the eight tree species are exclusive to the Claro River in Antioquia. However, three of them — C. cogolloi, D. colombiana and P. sclerocarpa — have also been recorded in the departments of Santander and Caldas.

Pseudoxandra sclerocarpa leaves. This tree has reportedly been used for medicinal purposes because it contains several types of alkaloids. Image courtesy of David Sanin.

Hope for the trees

The Humboldt Institute organized a series of workshops in late 2021 with the local community to develop an action plan for the conservation of the threatened trees. The institute worked with local researchers to study the eight species to learn more about their characteristics and georeference them.

“In the area, there was a great demand to cut down forests to obtain economically marketable timber that would be profitable for the community,” Bedoya said. “People didn’t know what species were there, but they identified some trees with common names. The second thing, which is the most critical in some ways, is the lack of knowledge about the local flora. For this reason, the Humboldt Institute wanted to work on participatory science and applied research with the communities to generate conservation strategies.”

The distribution of the eight tree species under conservation, based on records from biological collections and field observations. Image courtesy of the Humboldt Institute.

Of the three nurseries created, the community nursery of El Porvenir is the largest. It was established in 2022 as an initiative by the town of San Luis. The other two are veredas, or family propagation plots, created between 2020 and 2021, which also grow different species included in the project, although on a smaller scale.

“We have 12 people working on the project,” Bedoya said. “They help us identify [tree] species and locate them in their territories, as they’re the ones who’ve been in the area forever. They’re local researchers who support us in follow-up, monitoring and recording of the species so that we know, for example, when a tree flowers and when it bears fruit. That way, we can harvest those fruits at the right time and work on propagation.”

Based on the trees’ life cycles and climatic factors, the researchers have managed to propagate three species from seeds and to work with two others by vegetative propagation (from stems, roots and leaves). The process hasn’t been easy, Bedoya said, because these are “rare” or “unique” species, and hence it’s difficult to find seeds for their propagation. That’s why the team has had to resort to other methods.

One of the threats to Caryodaphnopsis cogolloi is the overexploitation of its wood, which is considered of high quality due to its natural hardness. Image courtesy of Carolina Castellanos/Humboldt Institute.

There are two ways to carry out vegetative propagation: the first is by finding a “mother” tree that has dropped seeds that have germinated in the surrounding soil. These seedlings are then taken to the nursery before being transplanted in other areas of the Claro River Basin, thus expanding the tree’s range. The second technique, according to Bedoya, uses cuttings from the tree and applying root hormone to stimulate growth. “Then we plant them in bags, run a nursery process, and take the seedlings out to the field,” Bedoya said.

They’re also testing a third strategy. In the case of the most threatened species, M. serpicostata, of which there’s only one specimen, the researchers intend to carry out vegetative propagation trials with air layering. This consists of scraping the bark off some branches and applying hormones and material such as soil and moss so that a new branch can emerge. This can later be cut and planted elsewhere.

So far, 345 seedlings have germinated in the project’s three nurseries from the seeds of S. hirsuta, P. sclerocarpa and R. antioquensis. A species that was successfully relocated is Cybianthus cogolloi, of which 50 specimens have been obtained. To date, 10 R. antioquensis and Cybianthus cogolloi specimens each have been planted in the field. Most of the saplings reproduced from seeds in the nurseries aren’t yet mature enough to be planted in their natural habitat.

Melicoccus antioquensis is a tree that can grow to a height of 26 m (85 ft). Image courtesy of Mónica Florez.

“We’re projecting we’ll be able to plant them within a month at maximum,” Bedoya said. “To achieve it, we have to wait for rain because it’s quite hot and the weather is still a bit dry, so we can’t risk the seedlings.”

The next step after planting is comprehensive monitoring for pests and diseases, maintaining constant hydration, and checking on “other plants that may compete with them and that can cause the seedling to grow poorly.”

This work has also led to conservation commitments. Several people working on the project have signed certificates formalizing the protection of almost 178 hectares (440 acres) of forest. Bedoya said these are places “where the community said: ‘I put my land, I put my forest at the service of conservation.’”

The community also provides continuous support. “We follow up with them, motivate them, provide them with information and training,” Bedoya said.

Leaves of Matisia serpicostata. Image courtesy of David Sanin.

Luis Carlos Galeano described the process he uses in his plot with his children. The first step is to observe and pay attention to a tree’s natural habitat. “We try to copy the material where it grows: we mix soil with a little sand to give it drainage. Germination is done in the soil and we keep an eye on its hydration under shade, to preserve humidity and prevent it from being damaged,” he said.

They’ve learned to make “little beds” for each species, sometimes using temporary containers for germination or sowing the seeds directly in the ground, carefully changing sites and always looking for new ways to obtain better results.

“It’s important to conserve these trees because there are very few individuals. Now that we have found species like chupo colorado and Matisia, we must reproduce them in order not to lose them and so that we can also tell our children about them; that way, they can become interested in learning about and caring for them,” Galeano said.