Research reveals changes in precipitation and vegetation through fossil rodent burrows in the Atacama Desert

Scientists analyze the correlation between leaf waxing and environmental changes.

By Jean Pierre Molina M., Journalist.- An investigation evaluated the content of leaf waxes from 24 fossil burrows from the pre-Puna del Atacama, which are up to 17 thousand years old. It was a study directed by Dr. Matías Frugone, associate researcher at the Catholic University of the Holy Conception (UCSC).

The research, “Hydroclimatic variation in the last 17 thousand years estimated from leaf waxes contained in fossilized rodent burrows in the Atacama desert”, in which Dr. Sergio Contreras, a UCSC academic, participates, uses a methodology to evaluate the presence of leaf waxes at the bottom of aquatic systems such as seabeds and lakes. On this occasion, it is applied to the study of leaves collected by rodents to build their burrows.

“We proposed using a methodology previously implemented and validated by Dr. Sergio Contreras at UCSC to investigate the evolution of vegetation changes in the desert. To do this, we carried out measurements in the central-southern Andes of the Atacama Desert, evaluating the presence of different types of waxes found inside these fossilized burrows”, explained Dr. Frugone.

Regarding the relationship between burrows, leaf waxes and climate changes, the researcher says that several studies in the United States, Australia and Africa have shown that fossil rodent burrows provide a good approximation of past climate changes. “We want to confirm this using fossil burrows collected in a study carried out by Dr. Claudio Latorre, from the Pontificia Universidad Católica de Chile, who analyzed the plant remains found in them. This idea led us to apply this molecular approach to the study of vegetation in the desert, an extremely dry environment, but highly sensitive to changes in humidity,” he added.

This study seeks to confirm the use of rodent burrows as climate indicators, and in turn to identify sources of moisture in the Atacama Desert. These sources may include moisture carried from the Amazon via the South American monsoon, as well as from the Gran Chaco in Argentina or from the coast in the form of mist known as camanchaca. Furthermore, all these sources of precipitation are influenced by El Niño and La Niña events, which could have impacted these desert ecosystems.

“In addition to extracting the lipids, we recovered the plant remains present in the burrows. This gives us the opportunity to compare the past climate and the vegetation communities that existed at the time. We establish a relationship between the current vegetation, the plant remains found in the burrows, and the waxes of the leaves,” the UCSC researchers noted.

The results of the study and its importance
Regarding the results of the investigation, both researchers pointed out that “Along the environmental gradient from the coast to the ridge, the presence of leafwax closely correlates with environmental changes. As humidity and vegetation diversity increase, there is an increase in both the quantity and variety of wax present,” they commented. The trend is also seen in burrows, giving a general idea of ​​past environmental conditions.

Regarding the importance of this study, Dr. Matías Frugone explained: “The study of the climate in the past or paleoclimate is of vital importance, since it allows us to understand the functioning of the climate system as a whole. We cannot limit ourselves to studying the current conditions of an ecosystem in a period of 20-30 years. It is essential to understand what it was like in the past to be able to predict and model the future more accurately.”

In closing, Dr. Contreras noted, “This allows us to take appropriate action in response to such changes. Paleoclimate studies are important to assess the ability of current instrumental models to accurately predict future conditions. Climate change on our planet is undeniable, and it is crucial to take action to mitigate it. Starting by addressing this challenge at the local level is a critical step in that direction.”