Refer to the graph. In the key, "elevated" refers to the addition of CO₂ above ambient levels, and "fertilized" refers to the addition of nitrogen fertilizer to the soil.Based on these data, can one conclude that nitrogen fertilizer enhances the effect of increased CO₂ on NPP in the forest? A) Yes; NPP increases when both CO₂ and nitrogen are added but increases much less when only CO₂ is increased. B) Yes; NPP increases under both elevated conditions but not under either ambient condition. C) No; that information is not included in the data shown in the graph. D) No; NPP increases when nitrogen is added but not when CO₂ is added. E) No; NPP increases when CO₂ is added but not when nitrogen is added.

Question

Quizplus · Accepted Answer

The graph shows that NPP increases when both CO₂ and nitrogen are added but increases much less when only CO₂ is increased. Therefore, one can conclude that nitrogen fertilizer enhances the effect of increased CO₂ on NPP in the forest.

Refer to the Graph