Effects of Disturbance and Fertilisation on Plant Community Synchrony, Biodiversity and Stability Through Succession

Global change drivers alter multiple components of community composition, with cascading impacts on ecosystem stability. However, it remains largely unknown how interactions among global change drivers will alter community synchrony, especially across successional timescales. We analysed a 22-year time series of grassland community data from Cedar Creek, USA, to examine the joint effects of pulse soil disturbance and press nitrogen addition on community synchrony, richness, evenness and stability during transient and post-transient periods of succession. Using multiple regression and structural equation modelling, we found that nitrogen addition and soil disturbance decreased both synchrony and stability, thereby weakening the negative synchrony-stability relationship. We found evidence of the portfolio effect during transience, but once communities settled on a restructured state post-transience, diversity no longer influenced the synchrony-stability relationship. Differences between transient and post-transient drivers of synchrony and stability underscore the need for long-term data to inform ecosystem management under ongoing global change.