A study published recently showed that the extinction of iconic grazers recently triggered a drastic rise in fire activity in the world's grasslands.
As indicated in a Phys.org report, from 50,000 years to 6,000 years back, a lot of the largest animals of the world, which include these said ancient grassland grazers, including the giant bison, wooly mammoth, and ancient horses, had gone extinct.
Yale scientists, in cooperation with the Utah Natural History Museum, compiled a list of large extinct mammals, including their dates of extinction dates across four continents.
The data collected showed that most grazers, roughly 83 percent of all species in South Africa, went into extinction. It was then followed by 68 percent of all species in North America. Such losses were substantially higher than in Australia at 44 percent and in Africa at 22 percent.
Post 'Megagrazer Extinctions'
In their paper published in the Science journal, the researchers then compared their study findings with records of fire activity as shown in lake sediments.
With the use of charcoal decades for more than 400 global areas, which offered a historical record of regional fire activity through continents, the scientists discovered that fire activity amplified after the so-called "megagrazer extinctions."
Essentially, continents that lost more grazers, specifically South America and North America, saw more substantial increases in fire extent, while continents that saw lower extinction rates, specifically Africa and Australia, saw a slight change in grassland fire activity,
According to a postdoctoral associate and the paper's corresponding author, Allison Karp, from Yale's Department of Ecology and Evolutionary Biology, investigating such effects helps in the understanding of the manner herbivores are shaping global ecology today.
Widespread 'Megahbivore' Extinctions' Impact on Ecosystems
Essentially, widespread megaherbivore extinctions had a major effect on ecosystems, ranging from the collapse of predators to the loss of fruit-bearing trees that once relied for dispersal on herbivores.
Nevertheless, Karp and ecology and evolutionary biology Carla Staver, from Yale's Faculty of Arts and Science, wondered if there was a rise in fire activity as well, in the ecosystems of the world, particularly because of a buildup of dry grass, wood, and leaves as a result of loss of giant herbivores. The two discovered that, in grasslands, there was an increase in grass-fueled fires.
Nevertheless, Karp and Staver noted that a lot of browser species like mastodons, diprotodons, as well as giant sloths, which scavenged on shrubs and trees in wooden places, had also gone extinct during the same period, although their losses had less effect on fires in wooden sites.
The Function of Grazers in Fire and Climate Change
Furthermore, grassland ecosystems across the globe were transformed following the loss of the grazing-tolerant grasses because of the loss of herbivores and the rise in fires. New grazers, which included livestock, eventually adjusted to the new ecosystem.
This is the reason there is a need for researchers to consider the function of grazing livestock and wild grazers in mitigation of fire and climate change, explained the authors.
According to Steve, this work definitely underscores how essential grazers maybe for "sharping fire activity." She added, there is a need to pay close attention to such interactions if one wants to precisely forecast the future of fires.
Related information about extinct large mammals is shown on PBS EON's YouTube video below:
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