Not by carbon alone: Aridity and nitrogen limit CO2 effects on root biomass
![400 times magnification of an oak root](https://lternet.edu/wp-content/uploads/2018/01/quercus-root-cross-section-400x300.jpg)
A recent meta-analysis found that aridity and low soil nitrogen levels seem to limit — rather than stimulate — plants’ ability to increase production of fine roots under elevated carbon dioxide conditions.