As an ecologist, Dr. Julia Tavares often has to think about how to collect data from remote locations.
But nothing had fully prepared her for the challenges she faced when starting her PhD. at the University of Leeds.
As a doctoral researcher in the School of Geography, she had the task of organizing and eventually leading an expedition into the Amazon rainforest to record data from the dominant trees that were present in locations ranging from Brazil to Peru and Bolivia.
The study involved supervising the collection of hundreds of tissue samples, work that had to be done in the middle of the night, all in the pursuit of the latest science.
The research team worked in extreme humidity and temperatures that reached 30 degrees Celsius by 8 am and more than 35 degrees by midday. The hot and humid weather brought clouds of mosquitoes.
The study involved a collaboration of 80 scientists and support staff, and was looking at how different tree species adapt to drought, and how vulnerable different forest regions are to climate change.
It was the first investigation into the water stress faced by trees across the entire Amazon basin and how they might cope if, as some climate models predict, the Amazon gets warmer and precipitation patterns change.
The results of the research were published today, Wednesday, April 26 in the journal nature.
Take samples from the tree canopy
More than 540 trees were sampled. These were the predominant umbrella types, with some reaching over 30 meters in height. Tissue samples were used to measure the hydration of the strand, and this fluctuated over a 24-hour period.
The scientists needed to measure the percentage of water during periods of low and high water stress. To do this, samples were taken at 3 a.m. — when the rainforest was in complete darkness and plants were recharging water levels — and again at midday.
As part of the expedition, the science team brought a mobile laboratory, packed in 16 flight cases, into the forest with giant cylinders of nitrogen gas.
Dr Tavares said: “We had a team of expert tree climbers whose job it was to use ropes and climbing equipment to go up the trees and get the samples.
“We were surveying the site the day before because we intended to take the samples. Remember we were working in a dense rainforest and some of the sampling was happening at night, so we needed to identify the trees and branches we wanted for tissue samples.”
Tree climbers used telescopic shears, which could extend six meters or so, to reach through the vegetation and harvest the branch they were after.
The rainforest is a beautiful and wonderful place that takes on a different character at night, said Dr. Carol Signori Müller, an environmental physiologist formerly at the University of Campinas in Brazil and now at the University of Exeter.
She said, “At night it is very dark. The moonlight can be obscured by thick vegetation. And it is very silent.”
“There is hardly any sound from the birds. All you can hear is the croaking of frogs or the movement of branches. You become attuned to the sounds around you because you need to be aware that something can suddenly appear from behind the bush.”
During one of the daytime sampling sessions, a jaguar emerged from the bushes and began playing with ropes attached to its climbing equipment, the way a cat would play with a ball of wool.
Added Dr. Tavares, “The team had to stop what we were doing and walk away — just watch the jaguar, who ended up destroying some climbing equipment.”
Access to the various forest sites will involve driving in ATVs or by boat and scientists and support staff will involve camping or staying at a field station.
The team wore tall boots to protect themselves from the snakes that live in the rainforest.
The results of the study will help identify areas of the rainforest most at risk from climate change, which will enable conservationists to direct resources and policies to those areas.
Dr Halina Soares-Jankowski, who took part in the expedition while at Mato Grosso State University in Brazil and now works with the Secretariat of the Environment in the municipality of Nova Zavantina, in the west-central region of Brazil, said, “I consider this study very important because it helps us understand how we deal with Forests with the impact of climate change. Especially in the Amazon – Cerrado transition zones, which are more vulnerable to climate extremes than in the core regions.”
Dr Tavares added, “At the beginning of my PhD, if you told me I was going to take part in a major expedition to the Amazon and I was going to lead a scientific collaboration on one of the most important ecological questions facing this very important ecosystem, I would have thought you were joking.
“But, with an amazing team, that’s exactly what we did.”
Basin-level variation in tree hydraulic margins predicts carbon balance in Amazonian forests, nature (2023). DOI: 10.1038/s41586-023-05971-3. www.nature.com/articles/s41586-023-05971-3
the quote: Scientists Take Portable Laboratory to the Amazon to Study Trees’ Adaptation to Drought (2023, April 29), Retrieved April 29, 2023 from https://phys.org/news/2023-04-scientists-portable-laboratory-amazon-trees. programming language
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