Figure 1

Effects of different levels of nitrogen (N) supply on plant growth in Sophora japonica, Robinia pseudoacacia, and Senna surattensis. (A) Height (n = 5–7); (B) Relative growth rate in height (RGRH) (n = 5–7); (C) Crown area (n = 5–7); (D) Basal diameter (n = 5–7); (E) Total biomass (n = 5–7); (F) Number of compound leaves (n = 5–7). Different lower-case letters for each species denote significant differences at various levels of N supply, and different upper-case letters denote significant differences of species under average level of N supply (p ≤ 0.05).