Elephant carcasses enrich soil and attract herbivores for years, study finds

Elephants continue to shape their environment for years after they die by releasing nutrients from their decomposing bodies, a new study has found. Researchers examined carcass sites in South Africa's Kruger National Park and discovered the process enriches the soil and stimulates plant growth. This effect attracts grazing animals like zebra, buffalo and rhinos to the location for more than seven years. The international team's findings were published Monday in a scientific journal.

Lead author Courtney Reed, an ecologist, said the research aimed to understand if an elephant's significant impact on the savannah persists after death. "What we didn't know was whether those impacts that are so significant when they're alive could actually continue after they die," Reed told CBC's As It Happens. She noted elephant bodies contain tons of nutrients like carbon, nitrogen and phosphorus. Reed conducted the work as a post-doctoral researcher at the University of California Santa Barbara and now works at Princeton University.

The study found the initial phase of decomposition creates a toxic environment for plants due to a massive pulse of nitrogen, often as ammonium. This kills off vegetation and leaves large bare patches, which researchers called 'cold spots' in biodiversity. "Too much of a good thing isn't always a good thing," Reed said. Over time, bacteria convert the ammonium into nitrate, a form plants can absorb, allowing the ecosystem to recover.

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The new vegetation that grows is rich in nitrogen, a key protein source for herbivores. "Then you have herbivores like zebra and buffalo and rhinos who are all coming in and they're selectively chewing on these nitrogen rich grasses," Reed said. This grazing activity continues for years after the elephant's death. The visiting animals further enrich the soil through their waste, creating a cycle of renewal.

Chase LaDue, an elephant ecologist at the Oklahoma City Zoo not involved in the study, said the findings show how delicate ecosystem balance can be. He said a carcass can sustain an ecosystem in a natural savannah shaped by disturbances. However, in landscapes shrunk by human encroachment, concentrated elephant deaths can disrupt that balance. "If enough elephants die in a very concentrated space, that has an impact on the biodiversity that sort of can't be spread out as it would in a more undisturbed larger landscape," LaDue said. LaDue pointed to southern Africa as an area with more elephants than the landscape can support. He suggested that even after death, elephants could negatively impact a landscape restricted by human activity. The research highlights the complex, long-term role elephants play as 'ecosystem engineers' both in life and death.

With files from CBC News