Fig. 5

A conceptual model of the effects of N deposition on the terrestrial ecosystem processes. Blue oval frames represent greenhouse gas pools, yellow square frames represent material pools, green frames represent biological processes, pink rhomboid frames represent microbial functional genes, and pink rhombus frames represent microbial communities. Thick black arrows indicate material flows. Microbial mediation of soil biogeochemical process is marked by thin arrows in red and labeled with a “+” or “-” if increases or decreases in gene abundance are observed in this study. “?” represents uncertain microbial feedback. The pink upward arrow indicates the increase of soil pH, and the blue downward arrow indicates the decrease of soil temperature. The (i), (ii), and (iii) mechanisms are labeled near the pathway