Nitrogen addition stimulate random migration of plant community in a semiarid steppe

Abstract

Increasing atmospheric nitrogen (N) deposition causes profound changes in the plant community, significantly threatening the terrestrial ecosystem function and stability worldwide. Random migration is a primary determinant of plant community assembly in the neutral model. However, whether its role is affected by N deposition is obscure. Therefore, the effects of eight N application rates (0, 1, 2, 3, 5, 10, 15, and 20 g N m−2 yr−1) on the estimated migration rate of plant community were examined in a long-term field study in a semiarid steppe. Our results indicated that N addition significantly impacted the estimated migration rate (F = 4.89, P < 0.001) and positively correlated with the N application rate (r2 = 0.32, P < 0.001). By constructing a structural equation model, we observed that the effect of N addition was mainly mediated through soil pH, moisture, and fungi: bacteria ratio. Mantel test revealed that the estimated migration rate was correlated with the plant community composition in moderate-N (10, 15, and 20 g N m−2 yr−1) treatment, but not in control (0 g N m−2 yr−1) and low-N treatment (1, 2, 3 and 5 g N m−2 yr−1) groups. Overall, our findings highlight the key role of N addition on plant community migration.

Keywords

• N addition
• Semiarid steppe
• Migration
• Dispersal