New research supports the concept of the Anthropocene, a proposed geological era characterized by the significant impact humans have had on Earth. This study used fossil pollen data to analyze changes in North American vegetation since the end of the Pleistocene. Their findings show that recent changes in vegetation are comparable to those observed during the last epoch transition, suggesting significant changes in ecosystem function that justify the classification of a new epoch. There is.
The researchers determined that human activity shaped the environment as much as the retreat of glaciers at the end of the Ice Age.
Scientists have long debated the Anthropocene, a proposed unit of geological time that corresponds to the most recent epoch in history. It is characterized by the enormous impact humans have on the earth.
Are we living in the Anthropocene? If so, when did it start?
In a research paper published this month, Proceedings of the National Academy of Sciences, Dr. Trisha Spanbauer of the University of Toledo and Dr. M. Alison Stegner of Stanford University lend credence to the argument for its existence. The pair analyzed open-source data to track changes in vegetation across North America since the end of the Pleistocene and concluded that humans have impacted the landscape as much as the retreat of glaciers at the end of the Ice Age. Ta.
research method
“As a paleolimnologist, I’m very interested in what the past can tell us about the future,” said Spannbauer, an assistant professor in the Department of Environmental Sciences. “Biological changes have been used to delimit eras in the past, so this analysis suggests that what we see today is what we would have seen during the transition between the Pleistocene and the Holocene. It provides valuable context for understanding whether the scale is essentially the same over time.”
Spanbauer and Stegner used the Neotoma Paleoecology Database, a community-curated repository of multi-species paleoecological data. They specifically looked at fossil pollen data from 386 sediment core records taken from lakes across North America.
Sediment cores are samples taken from the bottom of a lake that preserve the sedimentary order. Spannbauer and Stegner looked at samples taken during the late Pleistocene, about 14,000 years ago.
Analysis of ecological change
They analyzed the data according to seven indicators: taxonomic richness, or pollen diversity; seed; first occurrence data, last occurrence data, and short-term gains and losses in taxa. It measures how often species appear and disappear in the fossil record. A sudden change in the community, referring to the species identified in the sample. They organized data points within a 250-year period at both continental and regional scales, incorporated age model uncertainties, and produced conservative estimates to account for differences in sample sizes.
Their results show that vegetation changes over the past several hundred years are comparable to those associated with the last epochal transition, including increases in first and last emergence and abrupt community shifts.
“The power of a database like this is that you can ask questions about macroscale ecological change,” says Spannbauer. “While scientists have documented the effects of human activities on single species and on biodiversity generally, our study places these observations in a broader context. “We show corroborating changes in ecosystem function.”
Reference: “North American pollen record provides evidence of large-scale ecological change in the Anthropocene,” by M. Alison Stegner and Trisha L. Spanbauer, October 16, 2023. Proceedings of the National Academy of Sciences.
DOI: 10.1073/pnas.2306815120
Source: scitechdaily.com
