A new look at Amazonian resilience
Small-scale land use by indigenous communities led to more resilient Amazon regions. For policymakers, this is an important insight. “The use of fire and low levels of deforestation back then created plant species more resistant to today’s wildfires and drought.”
UvA researchers William Gosling and Crystal McMichael of the Institute for Biodiversity and Ecosystem Dynamics (IBED) have a new take on the resilience of the world’s largest rainforest: the Amazon. Indeed, historical land use led to forest areas that are more resistant to wildfires and drought.
Hundreds of years ago, indigenous communities carried out small-scale agricultural practices in certain parts of the Amazon. Those forest areas were exposed to man-made fires, among other things, as well as wildfires. The strongest plant species survived the fires. This made some areas more resistant to forest fires and drought and thus important for the Amazon’s ability to recover. “Especially after the departure of Brazilian former president Jair Bolsonaro,” McMichael says. Under his leadership, large parts of the Amazon disappeared.
“An important aspect in Amazon conservation is to get a good understanding of that resilience,” Gosling said. To do that, satellites and drones are being used today to collect real-time data, a method that has only been around for 30 years. It includes the rate of change and “greenness” over time, following human disturbance. According to Gosling, this data is not sufficient to say anything about the degree of resilience of an area. “For that, we need an understanding of larger time spans appropriate to the life cycle of a tree that can be hundreds of years old.”
In the study, the scientists show that since the start of industrial deforestation (about a hundred years ago), the intensity, frequency, and severity of disturbances in the Amazon have greatly increased. “Those deforested areas are so large that the degree of resilience has been greatly reduced,” McMichael says. Forest use 500 years ago was much less intensive. “The use of fire and low levels of deforestation back then created plant species more resistant to today’s wildfires and drought.” That’s good news for policymakers.
Urbanization and deforestation are the biggest threats to the Amazon. That’s why resilient areas are of particular interest to policymakers. “These areas contain an essential seed bank for surrounding forest restoration,” McMichael says. “With climate change, it is certain that forest fires and droughts will become more frequent.” To which Gosling adds, “That’s why we want to protect the forest areas with the greatest chance of survival.”
Follow-up research is currently focusing on the intensity of wildfires to gain an even better understanding of historic land use and forest restoration. Gosling and McMichael are also busy working on a research proposal to use multiple data collection methods to further understand how the Amazon rainforest works. With a network of 1,500 research sites across the Amazon, supported by data from drones and satellite imagery, they hope to gain a comprehensive picture of this crucial ecosystem.
