Balance of nature: fragility of ecosystems (Introduction)

by David Turell , Monday, March 06, 2023, 17:44 (418 days ago) @ David Turell

A new worrisome study:

https://www.quantamagazine.org/simpler-math-predicts-how-close-ecosystems-are-to-collap...

"....the tipping of ecosystems like forests and meadows is arguably harder to forecast because of the extraordinary complexity that comes with so many distinct interactions, said Tim Lenton, who works on climate tipping points at the University of Exeter in England.

"...interactions between species, which field ecologists dutifully record in their observations, can seem inconsequential, taken individually. In aggregate, however, they describe the detailed dynamics of the species interactions that make up an ecosystem.

"Those dynamics are critical. Many natural environments are incredibly complex systems wavering near a “tipping point” of nearly irreversible transition from one distinct state to another. Each disruptive shock — caused by wildfires, storms, pollution and deforestation but also by species loss — perturbs an ecosystem’s stability. Past the tipping point, recovery is often impossible.

"Understanding what determines these environmental tipping points and their timing is increasingly urgent. A widely cited 2022 study found that the Amazon rainforest is teetering on the edge of a transition into dry grassland, as deforestation and climate change make drought more frequent and severe over larger areas. The effects of that transition could ripple out globally to other ecosystems. (my bold)

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"A recent breakthrough in the mathematical modeling of ecosystems could make it possible for the first time to estimate precisely how close ecosystems are to disastrous tipping points. The applicability of the discovery is still sharply limited, but Jianxi Gao, a network scientist at Rensselaer Polytechnic Institute who led the research, is hopeful that in time it will be possible for scientists and policymakers to identify the ecosystems most at risk and tailor interventions for them.

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"Thousands of calculations may be needed to capture the distinctive interactions of every species in a system, Barabas said. The calculations make the models immensely complex, especially as the size of the ecosystem increases.

"Last August in Nature Ecology & Evolution, Gao and an international team of colleagues showed how to squish thousands of calculations into just one by collapsing all the interactions into a single weighted average. That simplification reduces the formidable complexity to just a handful of key drivers.

“'With one equation, we know everything,” Gao said. “Before, you have a feeling. Now you have a number.”

"Previous models that could tell whether an ecosystem might be in trouble relied on early warning signals, such as a decreasing recovery rate after a shock. But early warning signals can give only a general sense that an ecosystem is approaching the edge of a cliff, said Egbert van Nes, an ecologist at Wageningen University in the Netherlands who specializes in mathematical models. The new equation from Gao and his colleagues uses early warning signals too, but it can tell exactly how close ecosystems are to tipping.

"Even two ecosystems showing the same warning signals, however, are not necessarily equally close to the brink of collapse. Gao’s team therefore also developed a scaling factor that allows better comparisons.

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"It took 10 years to develop this equation, Gao said, and it will take many more for the equations to accurately predict outcomes for real-world ecosystems — years that are precious because the need for interventions seems pressing. But he isn’t disheartened, perhaps because, as Barabas noted, even foundational models that provide a proof of concept or a simple illustration of an idea can be useful. “By making it easier to analyze certain types of models … they can help even if they are not used to make explicit predictions for real communities,” Barabas said."

Comment: the thrust of this article is an excited interest in protecting ecosystems. dhw refers to them as our food and constantly tries to diminish their importance. They were a major aspect of evolution, evolving as animals and plants evolved.