To resprout or not to resprout: factors driving intraspecific variability in resprouting

Resprouting is a mechanism that allows individual plants to persist in disturbance-prone ecosystems. It is often considered a binary trait, defining species as resprouters or non-resprouters. Although this dichotomous classification accounts for a high proportion of the interspecific variability in resprouting, it does not account for the intraspecific variability, as not all individuals of resprouting species successfully resprout, even if they are subject to a similar disturbance. To ascertain the causes of the intraspecific variability in resprouting we propose a conceptual model that disaggregates the process of resprouting into three sequential steps: initial ability to resprout, resprouting vigour and post-resprouting survival. To test this model, we clipped 151 plants of three resprouting species (Anthyllis cytisoides, Globularia alypum and Linum suffruticosum) and, for each individual, we analysed the carbohydrate (starch and soluble sugars) and nutrient (N and P) concentrations in the roots at the moment of the disturbance (clipping all aboveground biomass). We then monitored initial ability to resprout, resprouting vigour and post-resprouting survival in each individual during a one-year period. Anthyllis showed high initial ability to resprout and high post-resprouting survival. Globularia and Linum had low final resprouting success, mainly due to their low post-resprouting survival, but also to the low initial ability to resprout in Linum. All three species showed variable resprouting vigour. Our results suggest that resprouting success is limited by different phases of the process of resprouting, depending on the species. Intraspecific variability in resprouting supported the importance of: a) the pre-disturbance state of the plant (i.e. plant size and stored resources) on the initial ability to resprout and on the resprouting vigour, and b) the initial post-disturbance capacity to acquire resources (i.e. resprouting vigour) on the post-resprouting survival. The proposed three-step model of resprouting provides a mechanistic description of the factors driving intraspecific variability in resprouting.