Researchers reported that aside from the decreasing diversity, the loss of large animals that once roamed the Earth has another direct effect on the environment.
According to the researchers, these animals' waste, or generally speaking their poop, plays a major factor in fertilizing the planet, UPI reported.
The researchers explained that during the time of massive creatures such as dinosaurs and mammoths, the Earth was significantly more fertile than it is today. This is because these animals don't dump where they eat. Instead, they move around and conduct their business elsewhere.
Because of this behavior, they are able to spread their waste in different parts of the Earth, which greatly contributes to the distribution of phosphorous, a nutrient found in animal waste that promotes plant growth.
Other animals today, such as rhinos and whales, also spread phosphorous through their waste. However, due to their dwindling populations, the amount of this nutrient that fertilizes plants, trees and other vegetation has also dropped.
In fact, before the widespread hunting and habitat destruction that occurred during the last century, whale droppings accounted for a yearly average of 750 million pounds of phosphorous.
But now, as the number of whales around the globe continues to decrease, their annual phosphorous contribution has drastically dropped to only 165 million pounds.
Aside from the loss of animal populations, the process of domestication also affected the spread of phosphorous in the environment. According to researchers, caging animals and restricting their movements through fences such as in farms also limits the areas that can be naturally fertilized with phosphorous from their waste.
"Large free-ranging animals are much less abundant than they once were," lead author Chris Doughty of Oxford University told the Washington Post. "Today, if scientists were to study the role of animals they would find that it its important but small."
"However, in the past, we hypothesize that it would have been at least an order of magnitude larger than today," he added. "Essentially, we have replace wild free-roaming animals with fenced domestic cattle that cannot move nutrients in the same way."
The researchers warned that if these factors continue, the natural supply of phosphorous in the Earth could run out in as early as 50 years.
Fortunately, this can be prevented through major efforts such as stopping the commercial hunting of large animals such as whales. The researchers believe doing so will greatly help in restoring the natural supply of phosphorous.
The findings of the researchers were detailed in a report published on October 26 in the journal Proceedings of the National Academy of Sciences.