2023-11-17 11:36:14
MADRID, 17 Nov. (EUROPA PRESS) –
Humans moved to the Andes about 15,000 years ago and their regular introduction of fire into the landscape created a new ecosystem, research in Nature Communications.
Florida Tech scientists studied hundreds of samples of fossil pollen and charcoal from a 100-meter-long sediment core lifted from Lake Junín, at an altitude of more than 4,500 meters in the grasslands of the Peruvian Andes. This sedimentary record spanned the past 670,000 years and represented the longest continuous, empirically dated record of changes in tropical vegetation to date.
The pollen showed that the area had gone through seven glaciations, each separated by a warmer period, known as an interglacial, like the one we live in now. “The fossil record revealed how the vegetation around the lake changed as these ice ages came and went.“said Jake Schiferl, a graduate student at the Institute for Global Ecology at Florida Tech, who co-authored the study.
The team found that the current high Andean grassland ecosystem, pictured above, was quite different from ecosystems found in other interglacials. In previous interglacials, the lake was surrounded by a mixture of grasslands and shrublands that developed without or with very little fire.
Co-author Mark Bush, professor of ecology, said: “As soon as people reached the plateau surrounding the lake, the occurrence of fossil charcoal increased dramatically, indicating that people were burning the landscape.”
Understanding how tropical systems have responded to large-scale climate change, such as glacial-interglacial fluctuations, and how human impacts have altered those responses, is key to current and future ecology.
The fires were probably started deliberately to drive out game as part of a hunting strategy and to promote the growth of new grasses that would increase the abundance of hunted animals. The net effect was to send the ecology of the Junín Plateau on a new path.
The study reveals that the vegetation of our modern interglacial, that is, of the last 12,000 years, began in a similar way to that of other interglacials, but about 4,000 years ago it diverged. and became completely different from any of the other warm periods of the last 670,000 years. Modern Andean grassland ecosystems were created by long-term human manipulation of the environment.
These data affirm that the period of profound human environmental alteration, often called the Anthropocene, began in the Andes about 4,000 years ago. This study adds weight to scholars who suggest there was an “early” onset of the Anthropocene, as opposed to those who see it as a product of the industrial revolution or oil-based economies.
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