Refer to the graph, which is from Tilman's study on species diversity and community function in grassland ecosystems.It shows the change in efficiency of nitrogen use correlated with number of species in a community. Based on the graph, one can conclude that as species richness increases,
A) nitrogen use decreases and nitrogen soil content increases.
B) nitrogen use increases and nitrogen soil content decreases.
C) both nitrogen use and nitrogen soil content increase.
D) both nitrogen use and nitrogen soil content decrease.
E) nitrogen use appears to decline but individual points show it is random.

Question

Refer to the graph, which is from Tilman's study on species diversity and community function in grassland ecosystems.It shows the change in efficiency of nitrogen use correlated with number of species in a community.  Based on the graph, one can conclude that as species richness increases,
A) nitrogen use decreases and nitrogen soil content increases. 
B) nitrogen use increases and nitrogen soil content decreases. 
C) both nitrogen use and nitrogen soil content increase. 
D) both nitrogen use and nitrogen soil content decrease. 
E) nitrogen use appears to decline but individual points show it is random.

Quizplus · Accepted Answer

The graph shows that as the number of species in the community increases, the efficiency of nitrogen use also increases, meaning that more nitrogen is being taken up by the plants. At the same time, the nitrogen content in the soil decreases, indicating that the plants are taking up more nitrogen from the soil. Therefore, option B is the best choice.

Refer to the Graph, Which Is from Tilman's Study on Species