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While modern science has made significant progress in understanding how individual species respond to climate change, being able to apply that knowledge to an entire ecosystem has proven difficult.
Now, however, thanks to the work of scientists conducting field studies in Arctic climates on three continents, it may be possible to answer that question by shedding some light on the impact of climate on food webs.
Whereas previous studies have concentrated on the effect of climate changes at the species level, the new study, published in the journal Nature Climate Change, looked at the entire food-web structure and found that temperature played and unexpectedly important role.
Temperature, according to the biologists, affects which organisms interact with each other, and it is these interactions between predators and their potential prey that regulates energy flows in ecosystems.
“Predators,” said Niels Martin Schmidt, of Aarhus University and a co-author of the study, “are the most important pieces of the tundra food chains.”
He said the intensity of interactions between predators and prey varies with the body size of prey. A musk ox, for example, is far more likely to avoid being eaten by predatory animals than the lemming. However, should lemming populations decline, some predators would be required to find new sources of food, with some proving more successful than others.
Previous research has shown that lemmings, in particular, were crucial to food web dynamics, since they were accessible to the whole predator community.
Lemmings, which seek protection under snow cover during winter months, are highly vulnerable to predators when the snow melts.
A 2010 study concluded that shorter winters recorded in the early 2000s in Greenland had led to a collapse of that country’s lemming population. Animals such as the Arctic fox, that could switch their diet by eating the cadavers of musk ox, were able to survive more easily than predators such as the snowy oil that specialised in hunting lemmings.
Populations of these types of animals naturally rise and fall in concert with the lemming’s four-year reproductive cycle. A long-term decline in lemming population – caused by any reason – would translate into a similar decline in the populations of specialised predators, the report warned.
A similar study, published earlier this year, reported that since 1980 the instances of polar bears raiding the nesting colonies of common eider and thick-billed murre had increased seven-fold.
This occurred, according to the study, due the to the increased difficulty of hunting for seal as result of thinner ice, and was an example of how habitat changes have altered predator–prey dynamics, leading to knock-on impacts throughout the Arctic ecosystem.
By collecting data over a broad geographical area, it was possible for the team to producing the latest report come up with a picture of how food chains are influenced by different climate factors, according to Schmidt.
The findings are similar to the conclusions of studies looking into the food chains of African savannas. By combining the two results, the authors of the cold-climate study say, it may be possible to come up with a general description of how terrestrial ecosystems are structured.