Transgenerational effect alters the interspecific competition between two dominant species in a temperate steppe

One of the key aims of global change studies is to predict more accurately how plant community composition responds to future environmental changes. Although interspecific relationship is one of the most important forces structuring plant communities, it remains a challenge to integrate long-term consequences at the plant community level. As an increasing number of studies have shown that maternal environment affects offspring phenotypic plasticity as a response to global environment change through transgenerational effects, we speculated that the transgenerational effect would influence offspring competitive relationships. We conducted a 10-year field experiment and a greenhouse experiment in a temperate grassland in an Inner Mongolian grassland to examine the effects of maternal and immediate nitrogen addition (N) and increased precipitation (Pr) on offspring growth and the interspecific relationship between the two dominant species, Stipa krylovii and Artemisia frigida. According to our results, Stipa kryloii suppressed A. frigida growth and population development when they grew in mixture, although immediate N and Pr stimulated S. kryloii and A. frigida growth simultaneously. Maternal N and Pr declined S. krylovii dominance and decreased A. frigida competitive suppression to some extent. The transgenerational effect should further facilitate the coexistence of the two species under scenarios of increased nitrogen input and precipitation. If we predicted these species' interspecific relationships based only on immediate environmental effects, we would overestimate S. krylovii's competitive advantage and population development, and underestimate competitive outcome and population development of A. frigida. In conclusion, our results demonstrated that the transgenerational effect of maternal environment on offspring interspecific competition must be considered when evaluating population dynamics and community composition under the global change scenario.