Nutrients leach from elephant carcasses for at least eight years after their death, creating nutritious plant growth for herbivores
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A study found that elephant remains create nutrient hotspots that can persist on savanna landscapes for years, possibly even decades.
These nutrients help to fuel microbial activity and plant vigour, attracting herbivores to the site long after the visual signs of the elephant have disappeared, researchers found after analysing elephant carcasses in South Africa’s Kruger National Park.
The researchers compare elephant carcasses to whale falls, when giant whales sink to the seabed and trigger a plethora of activity and productivity. However, they acknowledge that decay happens much faster in sunny African savannahs than in icy ocean depths. Elephant carcasses disappear within several weeks as scavengers pick apart the meat and bones.
‘We know that these really charismatic megafauna have strong impacts on ecosystems while they’re alive, but until now we haven’t really understood how those impacts continue after they die,’ said lead author of the paper published in the Proceedings of the National Academy of Sciences Courtney Reed.
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Immediately after dying, an elephant carcass will flatten out any vegetation underneath, while activity from scavengers renders the surrounding ground bare.
‘It essentially resets the plant communities to zero,’ explained senior author Deron Burkepile, a professor of ecology, evolution and marine biology.
However, nutrients soon percolate into the ground from elephant remains. At fresh carcass sites, soil nitrogen concentrations can be up to 3,000 times higher.
This spike in nutrients doesn’t immediately promote regrowth; instead, it causes nutrient toxicity that initially prevents plants from growing back. After that, just a few fast-growing species become dominant in what is known as a biodiversity ‘coldspot’, a trend that persists for at least eight years after an elephant’s death.
The plants able to colonise the site are especially nutritious for herbivores, with grazers continuing to revisit carcass sites for years. Grazing animals’ manure further enriches these areas, boosting nutrient levels in the soil and keeping them consistently high.
Researchers say that in more dynamic ecosystems like forests or wetlands, the effect of elephant carcasses may be short-lived as nutrients leach out of the soil via rainfall. In deserts, water constraints may prevent microbes and plants from using moisture to take advantage of nutrients from the carcass.
‘When we got started, we didn’t know how the carcass of a four-tonne elephant would impact its environment,’ said senior author Dave Thompson. ‘Nothing of that magnitude had been studied in a terrestrial system.’
