Fig. 2.

The effect of nitrogen deposition, atmospheric temperature, and precipitation on the abundance of amoA gene type JR1 relative to the total AOB group. The mean relative abundance of JR1 is depicted for all samples, grouped by nitrogen, temperature, and precipitation treatments. For example, the first bar depicts the mean relative abundance of JR1 from all experimental plots under ambient nitrogen, ambient temperature, and ambient precipitation in the background of ambient and elevated CO₂ treatments (n =16). Error bars, 95% confidence limits.