Abstract: Land use and nutrient enrichment can substantially affect biodiversity and ecosystem functioning. However, whether and how the responses of community temporal stability to land use and nutrient enrichment change with time remain poorly understood. As part of a 15-year (2005-2019) field experiment, this study was conducted to explore the effects of mowing, nitrogen (N) and phosphorus (P) additions on community temporal stability in a temperate steppe on the Mongolian Plateau. Over the 15 years, N and P additions decreased community temporal stability by reducing the population stability, especially the shrub and semi-shrub stability. However, mowing increased community temporal stability in the early stage (2005-2009) only. Nitrogen addition suppressed community temporal stability in the early and late (2015-2019) stages, whereas enhanced it in the intermediate stage (2010-2014). Phosphorus addition decreased community temporal stability marginally in the early stage and significantly in the late stage. The fluctuations of N-induced changes in community temporal stability are mainly explained by its diverse effects on species asynchrony and population stability over time. Our findings highlight the important role of plant functional groups and species asynchrony in regulating community temporal stability, suggesting that more long-term studies are needed to accurately forecast ecosystem response patterns in the context of global change.

Key words: diversity, land use, nutrient enrichment, plants, stability, temperate steppe