Brazilian Cassiana National Forest – Shortly after walking under the dense Amazon canopy, the forest suddenly opened. The fallen logs rot, the trees grow sparsely, and the temperature rises in the sun. This is what the severe drought in the world’s largest rainforest looks like.
But, about the size of the football field, this degraded forest is a scientific experiment. Launched in 2000 by Brazilian and British scientists (“Forest Drought Research Project” in Portuguese”, Esecaflor set out to simulate the future of the future where climate change could deplete rainfall Amazon. It is the longest project of its kind in the world and has become a source of dozens of academic articles in fields ranging from meteorology to ecology and physiology.
Understand how drought affects Amazon, which is twice as much as India’s region that spans South American countries, and has a far greater impact than that region. Rainforests store large amounts of carbon dioxide, a greenhouse gas that is the main driver of climate change. According to a study, Amazon stores global carbon emissions equivalent to two years, mainly from coal, oil and gasoline. When trees are cut down or withered and die from drought, they are released into the atmosphere of carbon they are storing, which accelerates global warming.
To mimic the stress of drought, the project is located in Cassiana National Forest, which assembles about 6,000 transparent plastic rectangular panels (2.5 acres) on one hectare (2.5 acres), transferring about 50% of the rainfall from the forest floor. Their sides are located 1 meter above the ground (3.3 feet) and 4 meters above the ground in the middle (13.1 feet). The water was leaked into the drainage ditch and the ditch was made by digging out the ditch around the plot.
Next to it is, an identical plot is not touched for control. In both areas, instruments are attached to trees, placed on the ground and buried to measure soil moisture, air temperature, tree growth, SAP flow and root development, etc. There are two metal towers above each plot.
In each tower, NASA radar measures how much water is in the plant, which helps researchers understand overall forest pressure. The data was sent to the Jet Propulsion Laboratory of the Space Agency in California, California.
“Forests initially seemed resistant to drought,” said Lucy Rowland, a professor of ecology at the University of Exeter.
However, this situation began to change for about 8 years. “We’re seeing a drop in biomass, huge losses and mortality rates for the largest trees,” Roland said.
This results in about 40% of the total weight of the vegetation and loss of carbon stored from the figure. The main findings were detailed in a study published in May in the journal Nature Ecology and evolution. It shows that during the years of vegetation loss, the rainforest was transferred from the carbohydrate tank (i.e., the carbon dioxide explorer) to the carbon emitter and then eventually stabilized.
There is good news: decades-long drought has not turned rainforests into savannas or savannas, as early model-based research predicted.
In November, most of the 6,000 transparent plastic covers were cleared, and scientists are now observing changes in the forest. There is currently no end date for the project.
“The forest has adapted. Now we want to understand what will happen next,” said meteorologist João De Athaydes, associate co-coordinator for Esecaflor, professor at the Federal University of Para, and co-author of Nature Studies. “The idea is to see if the forest can be regenerated from the beginning of the project and return to the baseline.”
During an April visit, Athaydes directed the Associated Press reporter through the website, which included many researchers. The area is so far away that most researchers have experienced a full-day boat trip in the city of Bellem, which will hold its next UN climate talks later this year. During the days in the field, scientists lived at the Ferreira Penna science base in the Emilio Goeldi Museum, a few hundred yards (meters) from the plot.
Four teams are working. A collected soil sample was used to measure root growth at the top layer. Another collects weather data and tracks soil temperature and moisture. One third of the measured vegetation moisture and juice flow. The fourth focuses on plant physiology.
“How our impact on drought affects soil processes,” said ecologist Rachel Selman, a researcher at the University of Edinburgh and one of the co-authors of Nature Studies, during the break.
Esecaflor’s drought simulation is similar to the last two years, when most of the Amazon rainforests experienced its worst drying spell under the influence of El Nino and under the influence of climate change. The devastating consequences range from the deaths of dozens of river dolphins, due to warmth and the cooling of huge wildfires to the old growing areas.
Rowland explained that the recent El Nino not only has a short-term, huge impact on Amazon by reducing rainfall, but also measures the degree of air drying through peaks of insufficient temperature and vapor pressure. Instead, the Esecaflor experiment focused only on manipulating soil moisture to study the effects of long-term changes in rainfall.
“But in both cases, we see a loss of forest ability to absorb carbon,” she said. “Instead, carbon is released back into the atmosphere, causing losses in forest cover.”
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