Human activity promoted soil erosion 4,000 years ago

Mohammed Shaban

Soil is the foundation of all vital processes that occur on the surface of the earth. Over the course of thousands of years, changes in the composition of the earth's crust (tectonic changes) as well as climate have played a significant role in the erosion and erosion processes that have occurred in the soil.

But in the short term and small local levels, human activity has become the main driver of soil erosion. To study this change, an international team of European and Canadian researchers from the Max Planck Institute in Germany and the National Institute for Scientific Research in Canada recorded time changes in soil erosion.

Researchers have studied soil erosion that has occurred in past times by analyzing the deposits of 632 lakes around the world collected over the past decades.

Nature Archive for Soil Erosion Operations
"Lake sediments are natural archival records of erosion activities," said Dr. Jean-Philippe Jenny of the Max Planck Institute for Biochemistry and the Cartel Center for Lakes Science and lead author of the study. Chronologically in the form of sedimentary layers accumulated at the bottom of the lakes. "

Using radiocarbon measurements, scientists were able to determine the age of the sediments of the lake sediments, as well as the accumulation rates of these sediments.

"This is the first time we have seen a general form of sediment buildup at the bottom of a number of lakes that occurred during the modern geologic period," explains Professor Pierre Frankies, co-author and chair professor at the National Institute for Scientific Research in Canada. With the Holocene (10,000 years ago). "

To investigate the possible causes of these sediments, the researchers studied the pollen fossil records in the lakes themselves, to see what changes occurred in land cover and preserve them individually.

"I was really surprised to find that the increase in the accumulation of this sediment 4,000 years ago coincided with the decline of tree pollen. Of course, this decline reflects changes in land cover, particularly as a result of ground-clearing operations," Jenny said. And settle them into suitable for agriculture and settlement, which is likely to have led to the deterioration of the soil condition and erosion. "

This was supported by statistical analyzes indicating that the change of land cover was the main driver of the accelerated accumulation of these sediments in these lakes, and thus led to soil erosion.

Soil erosion and its association with civilizations and empires
By scrutinizing the data, the researchers also found a link - at the local level - between changes in the accumulation of these sediments, and associated social and economic developments that occurred during human settlement of these areas.

For example, the increase in soil erosion in North America was more recent than in Europe, reflecting the delay in the implementation of European agricultural activities following the settlement of Europeans in North America.

On the contrary, the decrease in the accumulation of these sediments in 23% of the sites was associated with increased dam construction and water use, especially in the Roman and Chinese empires 3,000 years ago.

Human activity accelerates soil erosion
Overall, this study suggests that the change in the abundance of trees was the main driver of soil erosion. In addition, deforestation - caused by humans - explains the acceleration of soil erosion over the last 4,000 years.

"These results will provide us with a better and more accurate forecast for the long-term carbon cycle," he said.

"The impact on the environment was not a recent result of the blatant changes caused by greenhouse gases," Dr. Jenny said.