Researchers explain nitrogen paradox in forests

Nitrogen is essential to all life on Earth, and the processes by which it cycles through the environment may determine how ecosystems respond to global warming. But certain aspects of the nitrogen cycle in temperate and tropical forests have puzzled scientists, defying, in a sense, the laws of supply and demand. Trees capable of extracting nitrogen directly from the atmosphere often thrive where it is readily available in the soil, but not where it is in short supply. Now scientists from the Carnegie Institution have explained the paradox by recognizing the role of two other factors: temperature and the abundance of another key element, phosphorous.