Research published today suggests that large ecosystems such as the Amazon rainforest will collapse and disappear far quicker than previously thought once a global tipping point is reached. Writing in Nature Communications, the team used calculations based on real-world data to assess the speed at which ecosystems could likely collapse based on their size.
In the last year the world has seen two crippling wildfire events, as fires in the Amazon disintegrated 906,000 hectares (over 2.2 million acres) of forest while the devastating Australian bushfires destroyed one-fifth of the nation's forests and killed over a billion animals. After suffering such a loss to both carbon sinking forest habitats and wildlife diversity, researchers fear that many ecosystems are currently teetering on the edge of collapse.
"Unfortunately, what our paper reveals is that humanity needs to prepare for changes far sooner than expected," said joint lead author Dr Simon Willcock of Bangor University's School of Natural Sciences in a statement. "These rapid changes to the world's largest and most iconic ecosystems would impact the benefits which they provide us with, including everything from food and materials, to the oxygen and water we need for life."
When an ecosystem collapses it’s replaced with another, but what comes after may fail to provide the same balancing effects on our environment as those of the previous landscape. For example, once the 'point of no return' is reached, the Amazon rainforest could be transformed into a savannah-type ecosystem with a mix of trees and grass within 50 years, providing a less effective carbon-sink than the previous environment.
So, what can be done to slow these collapses? The researchers found that ecosystems made up of a diverse range of interacting species were more stable and would take longer to be transformed into an alternative state. This is compared to ecosystems that are dominated by a single species, whereby the extinction of what the authors term “keystone” species would have a dramatic and swift impact on the environment.
One such example the authors give is elephants, who have a disproportionately large impact on their environment as a keystone species. They push over trees and play a role in dispersing seeds over vast distances, shaping the landscape as it develops. If elephants were removed from the ecosystem, this vital role would go unfulfilled, transforming the landscape in a short space of time.
In ecosystems with a rich variety of interacting species, when one key player is lost there are others available to fulfill their ecological niche and role within the environment. This buffeting system allows for peaks and troughs in population numbers without reaching a tipping point in the functionality of the overall ecosystem.
The research provides further support to initiatives trying to protect our ecosystems and avoid further degradation of these vital habitats and their biodiversity. "We intuitively knew that big systems would collapse more slowly than small ones – due to the time it takes for impacts to diffuse across large distances," Prof John Dearing, from Southampton University, said. "But what was unexpected was the finding that big systems collapse much faster than you might expect – even the largest on Earth only taking possibly a few decades."