RESPROUTING AFTER DISTURBANCE: AN EXPERIMENTAL STUDY WITH SHORT-LIVED MONOCARPIC HERBS

Abstract: We experimentally demonstrated the ability of three short-lived monocarpic species to vegetatively regenerate (resprout) from roots after severe disturbance. We assessed the relationship between resprouting ability and (1) timing of injury with respect to life-cycle stage (reproductive vs. vegetative plant), life-history mode (annual vs. winter annual) and phenological stage (flowering vs. fruiting plant), (2) nutrient availability, and (3) disturbance severity (removal of all axillary buds Yes/No). In a chamber experiment with the annual or potentially winter annual Rorippa palustris, all injured plants resprouted in all nutrient levels and day-length regimes (day-length regimes simulated conditions of an annual and a winter annual cohort). The number of adventitious buds on roots was positively affected only by injury. The extent of regeneration and amount of regenerated biomass were higher at high nutrient level and long-day regime. In a field experiment with the biennials, Oenothera biennis and Oenothera issleri, both species responded to injuries by resprouting from axillary buds when at least only one axillary bud was still present. However, they were also able to resprout from adventitious buds on roots. Reproductive plants resprouted more frequently at the flowering stage than at the fruiting stage. Resprouting of vegetative plants (rosettes) was equal throughout the year and more frequent than in the reproductive plants