Fig. 4: Variations of soil N-source contributions to PUN with MAT.

ƒ_NO3- (a), ƒ_NH4+ (b), and ƒ_EON (c) are fractional contributions of soil NO₃^-, NH₄⁺, and EON to PUN, respectively. The 0.1° (latitude) × 0.1° (longitude) grid-based mean ± SD values are shown. The regression was analyzed by fitting effects with 95% confidence intervals.