EUROPA PRESS April 30, 2021, 07:55 A. M.
The rate of change of plant life in an ecosystem increases significantly during the years after human settlement, with the most drastic changes occurring in settled places in the last 1,500 years.
An international research team studied 5,000-year-old fossilized pollen, extracted from sediments from 27 islands. Analysis of the fossils allowed them to understand the composition of the vegetation on each island and how it changed from the oldest pollen samples to the most recent ones.
The study was led by Dr. Sandra Nogué, Professor of Paleoenvironmental Sciences at the University of Southampton (United Kingdom), and Professor Manuel Steinbauer, from the University of Bayreuth (Germany) and the University of Bergen (Norway). PhD student Álvaro Castilla-Beltrán was also part of the Southampton team.
Dr. Nogué explains that “islands are the ideal environment to measure human impact, since most of them were colonized in the last 3,000 years, when climates were similar to today. Knowing when the settlers arrived on an island means that scientists can study how the composition of their ecosystem changed in the years before and after, “he highlights.
The results, published in the journal Science, showed a consistent pattern on 24 of the islands where the arrival of humans accelerated the rotation of vegetation by, on average, a factor of eleven. The fastest changes occurred in the more recently colonized islands, such as the Galapagos, first inhabited in the 16th century. Islands that humans came to more than 1,500 years ago, such as Fiji and New Caledonia, experienced a slower rate of change.
“This difference in change could mean that previously populated islands were more resistant to human arrival, but it is more likely that land use practices, technology, and species introduced by later settlers were more transformative than those of the former “, explains Dr. Nogué.
The trends were observed across a range of geographic locations and climates, with islands such as Iceland achieving similar results to Tenerife and other tropical and temperate islands.
Changes in ecosystems can also be due to various natural factors, such as earthquakes, volcanic eruptions, extreme weather conditions, and changes in sea level. However, researchers have found that man-made disturbances outweigh all these phenomena and the change is often irreversible.
Therefore, they advise that conservation strategies take into account the long-term impact of humans and the degree to which current ecological changes differ from those of prehuman times.
“Although it is unrealistic to expect ecosystems to return to their pre-settlement conditions, our findings may help guide restoration efforts and provide a greater understanding of the islands’ responsiveness to change,” concludes Dr. Nogué.
Real the original coverage from Europa Press via El Tiempo at https://www.eltiempo.com/vida/medio-ambiente/estudio-revela-el-verdadero-impacto-humano-en-la-vida-vegetal-584964
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