The fires spreading across the Pantanal could have major environmental consequences for the biome, which has not yet fully recovered from similar events in 2020. One year after the fires, the diversity of mammal species and abundance of animals in the worst-hit areas had fallen by half, on average. Endangered species such as the tapir (Tapirus terrestris) and the giant anteater (Myrmecophaga tridactyla) were even more severely affected: in some areas, the number of sightings decreased roughly tenfold, according to a study published in the journal Scientific Reports in June.
“The Pantanal fauna is still fragile and further fires could destroy habitats and even cause local extinctions,” says Marcelo Magioli, a biologist from the Ribeirão Preto School of Philosophy, Sciences, and Languages & Literature at the University of São Paulo (FFCLRP-USP), the Pro-Carnivores Institute, and the National Center for Research and Conservation of Carnivorous Mammals at the Chico Mendes Institute for Biodiversity Conservation (ICMBio/CENAP).
“As we have seen in other biomes, a second wave of fires can cause enormous destruction and lead the ecosystem to a permanent state of degradation,” adds Bernardo Flores, an ecologist from the Federal University of Santa Catarina (UFSC) who did not participate in the study. Flores observed the phenomenon in forests on the banks of the Rio Negro in the Amazon, which underwent major transformations after second fires. He is also studying the degradation caused by wildfires in riverside forests in the Cerrado (a wooded savanna biome).
Magioli’s study was carried out at the Taiamã Ecological Station (ESEC) in the municipality of Cáceres, Mato Grosso. The region is located in the north of the Pantanal and is home to the largest concentration of jaguars in Latin America, according to a study published in the journal Ecology in 2021. The protected area is an 11,555-hectare island in the Paraguay River — an area similar in size to the city of Manaus.
The team, comprising researchers from 13 institutions, conducted a survey of small to large mammals from August to November 2021, one year after fires hit the Taiamã ESEC. Medium and large animals weighing more than 1 kilogram (kg) were monitored by 50 cameras spread across the reserve. Using satellite imagery, the scientists measured how much of the area within a 1-kilometer (km) radius of each camera was damaged by fire.
The group also collected environmental DNA from water samples at 28 locations, including puddles, small lakes, streams, and rivers. This genetic material can help identify small animals in the area that weigh less than one kg.
With this set of data, they compared mammal diversity and abundance in two environments: the forests in the Abobral region, dominated by the purple coraltree (Erythrina fusca), a tree that grows to heights of up to 30 meters and has orange flowers and aquatic roots, making it well suited to flooded areas; and riverside forests, which are made up of several tree species and do not flood frequently.
Jaguars recolonized the region after wildfires in 2020Marcelo Magioli’s Team / USP
“The biggest impact was felt in flooded forests with just one species of tree, where mammal species richness fell by half on average, and some types of animals almost disappeared completely,” says Magioli. This vegetation grows in flat areas that are flooded most of the year. During more intense droughts, the organic matter in the soil becomes exposed and can easily ignite — fires can penetrate more than one meter into the soil.
Another study determined the impact of the 2020 wildfires on eight large mammal species. The research was carried out in the Amolar mountains of Mato Grosso do Sul, 130 km south of the Taiamã ESEC, by scientists from the University of Oxford, UK, the World Wildlife Fund (WWF), the US-based Panthera Cooperation, and the Homem Pantaneiro Institute. The abundance of six of the studied species has declined, including the collared peccary (Dicotyles tajacu), the ocelot (Leopardus pardalis), the tapir, and the giant armadillo (Priodontes maximus), according to the resulting article published in Global Change Biology in March. “The scale of megafires may inhibit successful recolonization,” warn the authors.
The giant armadillo suffered the most drastic population decline, with losses of around 80%. Jaguars were the only species whose numbers increased, almost doubling. The authors suggest that this is a result of immigration, since riparian forests, which recover quickly, are home to alligators and capybaras — common prey for the big cats.
Flores emphasizes that the impact of the current fires, if they continue to spread, depends on which areas are affected. In places that were previously damaged by fires in 2020, the effects could be devastating; in others, the impact may be less severe.
Signs of resilience
The Scientific Reports study indicates that the Pantanal was recovering after the great fires of 2020: all 18 species of medium and large mammals identified before the fires were found again a year later. According to Magioli, these animals likely found refuge in areas that were not damaged or they lived in the surrounding areas and then recolonized the region.
Interestingly, nine species were spotted in the Taiamã ESEC that were not there before the wildfires, including three species of deer and the tapir, observed in areas close to the ecological station. “After fires, some of the vegetation regrows, offering different types of shoots for animals that feed on plants,” says Magioli. The maned wolf (Chrysocyon brachyurus) and the hoary fox (Lycalopex vetulus), inhabitants of the Cerrado that do not normally enter the Pantanal, are attracted by the change in vegetation, which creates more open areas.
Carnivores such as jaguars and ocelots, which normally live in forests, were also seen in the fire-damaged areas, probably hunting for prey. The biologist emphasizes that this increase in diversity is not necessarily positive, but a sign of environmental degradation caused by fire.
Ten small mammals weighing less than 1 kg were also identified, including rodents and marsupials, that would have been unable to escape the fires. As such, there were no previous records to compare and determine the impact of the fires. “The mere fact that they are there is a sign that they resisted the fires or recolonized the area,” says Magioli.
The story above was published with the title “Mammals after fire” in issue 342 of august/2024.
Projects
1. The ecological and functional role of Xenarthra in food webs (nº 22/06791-9); Grant Mechanism Postdoctoral Fellowship; Supervisor Adriano Garcia Chiarello (FFCLRP-USP); Beneficiary Marcelo Magioli; Investment R$587.82.
2. Reassessment of mammal species believed to be locally extinct by the Pernambuco Center of Endemism (CEP), based on mixed DNA samples and metabarcoding (nº 22/01741-3); Grant Mechanism Postdoctoral Fellowship: Supervisor Pedro Manoel Galetti Junior (UFSCar); Beneficiary Bruno Henrique Saranholi; Investment R$221,371.26.
Scientific articles
BARDALES, R. et al. Neotropical mammal responses to megafires in the Brazilian Pantanal. Global Change Biology. vol. 30, no. 4. apr. 24, 2024.
CUNNINGHAM, C. X. et al. Increasing frequency and intensity of the most extreme wildfires on Earth. Nature Ecology and Evolution. Online. june 24, 2024.
MAGIOLI, M. et al. Forest type modulates mammalian responses to megafires. Scientific Reports. Online. june 12, 2024.
