3.1 Seed production under the N and P addition treatments
Across the three sampling years, seed production was consistently and significantly affected by N and P addition in the temperate steppe (bothP > 0.05; Figure 1, Table 1). The low N addition enhanced seed production by 814%, 1371%, and 1321% under ambient, low, and high P addition treatments, respectively (all P< 0.05; Figure 1 left insert). The high N addition increased seed production by 2136%, 3560%, and 3550% under ambient, low, and high P addition treatments, respectively (all P < 0.05; Figure 1 left insert). However, neither a low nor high P addition altered seed production under ambient N (both P > 0.05; Figure 1 right inert). The low and high P addition augmented seed production by 65% and 65% under low N addition, and by 68% and 74% under high N addition treatments, respectively (all P < 0.05; Figure 1 right insert).