For example, grasshoppers get quite anxious when they know there's a deadly spider about, and it puts them off their food. Since their food is grass, nervous grasshoppers leave more grass intact to perform photosynthesis, turning sunlight and carbon dioxide into plant food. More CO2 in these grasses and their roots means less CO2 in the air. That's according to a new paper published in Proceedings of the National Academy of Sciences.
Yale researchers tracked CO2 as it cycled through Plexiglass cages containing just grass, grass and grasshoppers, or grass, grasshoppers and spiders. Grasses stored 1.4 times as much carbon with spiders about than when grasshoppers were allowed to roam unmolested. That's even better than when there were no grasshoppers at all because nervous grasshopper grazing did little damage but spurred greener growth.
In other words, spiders protect the climate, just by being spiders and scaring grasshoppers.
Similar results may also prove true in ecosystems with larger predators, whether wolves and caribou or lions and zebras. Keeping predators around may be another way to combat climate change.
—David Biello
