Fig. 1From: Effects of nitrogen addition and drought on the relationship between nitrogen- and water-use efficiency in a temperate grasslandResponses of averaged WUEINST (a), NUEINST (b), WUELT (c) and NUELT (d) to different treatments (C: control, N: N addition, D: drought, ND: combined drought and N addition). Data are shown as mean ± SE. Different lowercase letters above any two bars indicate significant differences among the treatments at p < 0.05Back to article page