A rare leafy tree of the Cerrado savannah in the Brazilian state of Minas Gerais, notable for its clusters of yellow flowers and seed pods that exude a sweetish scent, has seen its prospects for conservation improve. Since barely a decade ago, when only about 20 specimens were counted, the faveiro-de-wilson (Dimorphandra wilsonii) has now become better known. In recent years, its genetic diversity has been mapped, its enemies identified, and more than 200 specimens found in nature. These findings increase the chances of preventing the disappearance of the species.
The work of understanding what was happening to this naturally rare tree relatively new to science—it was not described until 1969—began in 2003 through the efforts of researchers from the Belo Horizonte Zoo-Botanic Foundation (FZB-BH). The project attracted the interest of teams at other centers and made the plant a symbol of Minas Gerais endurance.
In April 2015, a research group led by Luiz Orlando de Oliveira of the Federal University of Viçosa (UFV) published the most recent genetic profile of the tree. When they began the research, only 21 adult specimens were known to exist in nature. The researchers’ concern focused on knowing whether the conservation of the faveiro had been compromised because of the species’ low levels of genetic diversity, detected years earlier by biologists Helena Souza and Maria Bernadete Lovato of the Federal University of Minas Gerais (UFMG).
“Endogamy—inbreeding among similar individuals—can lead to the emergence of detrimental characteristics,” Oliveira explains. “Several seedlings from seeds that we collected exhibited chlorosis (chlorophyll insufficiency), indicating that there may be some kind of problem. This may be the result of endogamy.”
While analyzing the genetic makeup of the seeds, however, Oliveira noted that these trees were not reproductively isolated. They were being fertilized by other specimens of the same species from unknown locations. He and biologist Christina Vinson concluded that it would be necessary to gather seeds from about 150 trees in order to ensure the genetic integrity of the species, even though no one knew whether that many existed in nature.
After submitting the paper to the journal Tree Genetics & Genomes in June 2014, the researchers got good news. In July, a team from FZB published the findings from a search for new specimens, which recorded 219 adult faveiros with reproductive capability in 16 municipalities in Minas Gerais (see map).
Those findings were the outcome of a decade-long project—the Faveiro-de-wilson Conservation Program—led by Fernando Moreira Fernandes, a forestry engineer with the Foundation. To find the trees, the researchers made up “wanted” posters, distributed them throughout the municipalities in that region and talked with about a thousand people.
The material showed how to identify a faveiro and gave the researchers’ contact information. Whenever there was a positive tip-off, they would go into the field to confirm the tree’s existence and map its location. With over a hundred specimens catalogued in 2010, the researchers developed a spatial distribution model for the species, using climate and environmental variables, in order to attempt to predict where the tree might occur and select targets for new expeditions.
“We have now probably identified most of the individuals that remain in nature, because we explored the entire area of occurrence,” says biologist Juliana Rego of FZB, who took part in the project with Fernandes. According to Rego, there is cause for concern, because 219 is not enough trees to remove the faveiro from “critically endangered” status.
The main difficulty encountered by the researchers was that seeds that germinate in pastures and are left unmonitored may not survive. A UFMG research study indicated that the principal enemy of the growth of this tree are the Brachiaria (signalgrasses).
These African grasses of the genus Urochloa, which were introduced into Brazil to provide pasture cover and feed cattle, grow quickly. “Competition from Brachiaria can limit root growth and prevent seedlings from developing,” says Marcel Giovanni Costa França, a professor at UFMG and a co-author of the study, published in the journal Journal of Plant Interactions in 2014.
To get around the problem of competition from African grass, the national action plan for conservation of the species, drawn up by the FZB, the National Center for Plant Conservation and 12 more entities, provides for measures including training for landowners and technicians to try to hold back the advance of the invasive grasses, protect the existing faveiros and plant new ones. Under ideal conditions, in 10 years a faveiro-de-wilson will reach a height of 15 meters and achieve reproductive maturity. By propagating seedlings, planting them in suitable places and attempting to monitor their growth, the plan is aimed at taking the species off the critically endangered list by the year 2025.
FERNANDES, F. M. e REGO, J. O. Dimorphandra wilsonii Rizzini (Fabaceae): distribution, habitat and conservation status. Acta Botanica Brasilica. V. 28, No. 3, p. 434-44. 2014.
VINSON, C. C. et al. Population genetics of the naturally rare tree Dimorphandra wilsonii (Caesalpinioideae) of the Brazilian Cerrado. Tree Genetics & Genomes. 2015.
FONSECA, M. B. et al. Early growth of Brazilian tree Dimorphandra wilsonii is also threatened by African grass Urochloa decumbens. Journal of Plant Interactions. V. 9, No. 1, p. 92-9, 2014.