Competitive interactions shape plant responses to nitrogen fertilization and drought: evidence from a microcosm experiment with Lilium bulbiferum L. and Secale cereale L.

Abstract Many recent studies have analysed plant species responses to environmental change, but interactive effects of global change drivers and how they are modulated by biotic interactions still poorly understood. In a mesocosm experiment, we studied the nitrogen (N) fertilization drought events on growth these shaped competitive interactions, using segetal community typical lowlands central Europe (composed Lilium bulbiferum (segetal species) Secale cereale (crop species)). We expected that N increases sensitivity (negative interaction effect), interspecific competition with Secale. showed opposing (second year experiment): Whilst aboveground belowground biomass almost doubled fertilization, no response or decreased, respectively, providing advantage. tissue dieback (as proxy for vigour) was 22% in 35% treatments (control: 6%), reached 91% when combining treatments. Increasing strongly related decreasing (root) biomass, caused both negative direct combined (N + drought), indirect acting via treatment-induced increase biomass. Our results demonstrate can shape growth. This knowledge turn could be important conservation, particularly face ongoing shifts conditions.