The Question
Over the past 50,000 to 3,000 years, most of the world’s largest land animals disappeared — with 88% of megafaunal species lost in Australia, 84% in South America, 72% in North America, 36% in Eurasia and 18% in Africa — profoundly altering ecosystems. These mammoths, mastodons, giant ground sloths and huge marsupials, to name a few, were part of a global web of megafauna that coevolved with our current ecosystems.
Work in the Doughty lab has shown that large animals are disproportionately important for ecosystem processes, such as the movement of nutrients, seeds or pathogens, and are critical to modifying forest structure, which could affect the climate. Following the megafaunal extinction, for example, there was a more than 100-fold loss of horizontal biotic nutrient movement across the planet’s ecosystems.
Today, biodiversity loss and climate change are often viewed as separate issues facing humanity, but these critical environmental problems may be linked through the ecological roles of large animals in, for example, carbon cycling, vegetation structure and fire. Could the restoration of large animal populations significantly alter ecosystem processes in ways that help ecosystems adapt to climate change?
The Approach
The project Effects of Reintroduction of Large Animal Species on the Earth’s Adaptation to Climate Change is exploring this connection and aims to create a global tool for predicting how reintroducing large animals could modify ecosystem services or help ecosystems acclimate to climate change.
First, the research team will collect new empirical data on how large animals influence ecosystem structure, fire and nutrient flows, then integrate these relationships into global ecosystem models to better predict the effects of future losses or reintroductions.
The researchers have identified a series of field projects, examining:
- How large animals affect forest structure, temperature, carbon stocks and fire spread by looking at elephant presence or absence in Central Africa.
- Rhino relocations from South Africa to Uganda.
- Donkey and bison removal in the southwest US.
- A bushmeat hunting gradient to understand how all animals move nutrients away from the river floodplains of the Amazon River.
Using a consistent set of observational tools, including field measurements and NASA satellite data, the team will quantify how large animals modify key ecosystem functions. They will incorporate their findings into a global ecosystem model they helped develop, enabling them to predict how future animal reintroductions or removals could impact ecosystem structure, fire prevalence and nutrient movement.
The Effects of Reintroduction of Large Animal Species project is being led by Chris Doughty at Northern Arizona University in Flagstaff, US.
