Fig. 2From: Nitrogen use efficiency of terrestrial plants in China: geographic patterns, evolution, and determinantsChanges in the NUE with ecosystems (a) and life forms (b). Different lowercase letters in the figure represent significant differences in the NUE between different ecosystems/life forms at the α = 0.05 level. Values in brackets are the numbers of observations in ecosystems/life forms. Life forms included, H herbaceous plants, T woody plants, S shrub plants, V vine plants, F fern plants, Subs subshrub plantsBack to article page