paleoenvironmental

Global Nitrogen Availability Consistent for Past 500 Years

“People have been really interested in nitrogen in current times because it’s a major pollutant,” said Kendra McLauchlan, assistant professor of geography and director of the university’s Paleoenvironmental Laboratory. “Humans are producing a lot more nitrogen than in the past for use as crop fertilizer, and there is concern because excess levels can cause damage. The mystery, though, is whether the biosphere is able to soak up this extra nitrogen and what that means for the future.”

Nitrogen is a key component of the ecosystem and the largest regulator of plant growth. It determines how much food, fuel and fiber the land can produce. It also determines how much carbon dioxide plants remove from the atmosphere, and it interacts with several components of the climate system. Excessive amounts of nitrogen in ecosystems contribute to global warming and impairment of downstream ecosystems. […]

McLauchlan said the most surprising finding, however, was that although humans have nearly doubled the amount of nitrogen to the ecosystems, globally nitrogen levels have remained stable at most sites for the past 500 years.

One reason may be that plants are using more nitrogen than they previously have, keeping nitrogen levels consistent with those thousands of years ago even though humans continue to add carbon dioxide and nitrogen to the atmosphere. […]

“Based on what we learned from the past, if the response of plants to elevated carbon dioxide slows, nitrogen availability is likely to increase and ecosystems will begin to change profoundly,”



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Early modern humans hugged riverine woodland environments in Africa

Research in genetics and across a variety of archaeological sites in Africa and beyond has shown that anatomically modern humans (AMH) dispersed between regions within and also out of Africa from 70,000 to 35,000 years ago. Paleoanthropologists have long suggested that environmental changes have played a key role in this process. However, a clear understanding of the complexity and how this took place has been lacking due to the deficiency of archaeological evidence in association with paleoenvironmental data.

In a recent study conducted by Nicole Garrett of the University of Minnesota and colleagues, researchers have revealed additional information by applying stable isotope analysis of paleosols and fauna remains associated with Middle Stone Age (MSA) archaeological sites on Rusinga and Mfangano islands in Lake Victoria in East Africa. Read more.