Animal nitrogen swap for plant carbon

Predatory plants are typically found in discrete groups living under conditions of extreme nutrient stress. But we show here how a common species of boreal tree can act indirectly as a predator of arthropods living in the soil by virtue of a fungal symbiont that supplies it with animal nitrogen in exchange for the plant's carbon. If the way in which this partnership operates proves to be widespread, ideas about nutrient cycling1,2 and food-web dynamics3 in temperate forests may have to be modified.