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Termites and rising global temperatures

Study published in Science and which included the participation of researchers from Unicamp, relates the action of insects to climate change

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Reproduction of the cover of a magazine that features a photo of termite tunnels.

An international study that has just been published in magazine cover Science revealed that termites play an essential role in recycling wood in natural ecosystems. Without its existence, several biomes in the world would have accumulated a large pile of dead organic matter. These insects are responsible for the decomposition of wood, especially in hot places with little humidity, where microorganisms, the main decomposers, are not very abundant in times of drought.

The research, led by biologist Amy Zanne, from the University of Miami, is the result of a collaboration between one hundred researchers from different institutions around the world. During the investigation, participants applied the same experimental method in 130 locations distributed across six continents, seeking to study the behavior of termites in varying temperature and humidity conditions. At Unicamp, it included the participation of former student André Mouro D'Angioli, who contributed to the article as part of his doctorate in Ecology, defended at the Institute of Biology (IB) under the guidance of professor Rafael Oliveira.  

 

Photo of a woman appearing from the waist up. She is white, has short white hair and is wearing a red blouse. She is smiling.
Biologist Amy Zanne, researcher at the University of Miami and visiting professor at the Institute of Biology (Photo: Evan Garcia, University of Miami)

According to D'Angioli, the intention of this international partnership was to verify in which regions of the planet and under which climatic conditions there was a greater influence of termites – compared to bacteria and fungi – in the decomposition of dead wood, and how these animals are affected by changes in temperature and precipitation. “This is relevant data, because wood is an important carbon storage component. So, the faster it decomposes, the faster we lose the carbon that is stored in organic matter and the faster it is sent as carbon dioxide into the atmosphere”, he explains. 

The results indicate that, if predictions about climate change are confirmed, areas where the climate is hotter and drier – such as the grassland and savannah formations of the Cerrado – will expand. As a consequence, the environments in which termites are important decomposers will expand, generating a feedback scenario in which increased carbon dioxide emissions will cause global temperatures to rise. These, in turn, will expand the termites' operating space, which will release more carbon dioxide as they decompose the dead organic material. “In practical terms, we are understanding how the Earth system works and the interface between a biotic component, which is termites, vegetation, and an abiotic component, which is the climate”, explains Oliveira. “We need to understand how these elements cycle on Earth, especially carbon, because this way we can predict what will happen to different ecosystems if the climate becomes hotter and drier”, he adds. 

Composition with two photos. In the image on the left there is a man standing in an open field. He is white, wears a hat, plaid shirt, backpack and is smiling. In the image on the right there is a man crouched down in a forested area. He is white, has short hair, a thin beard, is wearing dark pants and a white t-shirt and is smiling.
André Mouro D'Angioli (right) who contributed to research on termites as part of his doctorate in Ecology, defended at IB under the guidance of professor Rafael Oliveira (left) (Photos: researchers' personal collection)   

Differential

The great difference of the research was the possibility of investigating the activity of termites in a wide variety of regions, with different levels of temperature and humidity, thus guaranteeing more robust results. As there is an extensive biogeographic distribution of termite species throughout the world, focusing the study on just one environment would yield much less efficient results on their role in the decomposition of organic materials such as wood. 

This large-scale cooperation, reveals biologist Amy Zanne, has allowed us to obtain more evidence about how carbon circulates across the planet. “Furthermore, as our protocol was simple and easy to apply, everyone from postgraduate students to senior professors could join the project. This allowed us to have a network of people and learn a lot from each other.”

The experimental model conducted by the one hundred collaborators consisted of inserting blocks of wood from a type of pine into their respective ecosystems. A portion of the blocks was wrapped with a protective net to prevent termites from eating them, while another part was left free for these insects to act (the meshes were perforated in the area that was in contact with the soil, allowing termites to enter through underground tunnels, but avoiding the entry of other insects). In this way, it was possible to compare the decomposition carried out by termites to that carried out by microorganisms such as bacteria and fungi, checking which had a more relevant role.

Composition with two photos. In the image on the left, rectangular-shaped networks appear distributed in an open field. In the image on the right there is a young woman crouching behind a termite mound.
A simple and cheap method for collecting data allowed experiments to be carried out in ecosystems in several countries (Photos: Jamie Cleverly and Rebecca Clemen)

“I consider this work a planning model, because it is very simple, it does not involve technology, just a good idea and a standardized and elaborate experimental design”, argues Oliveira. For him, this is an example of the plural character that science should have, especially in ecology. “Many of the so-called global studies have an overrepresentation of the northern hemisphere – the United States and Europe. With this article, we were able to sample different biomes around the world in a more equitable way,” he explains. 

In experiments conducted by D'Angioli, for example, wooden blocks were inserted in eight areas formed by field, savannah and forest, located in three specific regions of Brazil: Serra da Canastra, in Minas Gerais, an ecological station in Brasília and in the municipality of Itirapina, in the State of São Paulo. After the preparations and installation of the traps, in 2016, there were two years of fieldwork and another year to process the samples and obtain the data to write the thesis, which focused on the analysis of the biogeochemical cycles of elements in the cerrado. 

Currently, Zanne and Oliveira are continuing the study on termites with new investigations into their importance for Brazilian ecosystems. For this reason, the researcher came to Unicamp as a visiting professor to carry out research in Chapada dos Veadeiros. “The role of tropical regions and savannas in carbon storage and release is still very little studied. As Chapada has these ecosystems, in addition to a diversity of termites that determine the cycling of carbon from different materials, it made sense to me that this new stage of research would be carried out here”, concludes the researcher. 

JU-online cover image
Photo of a termite at the exit of a tunnel

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