Intraspecific interactions affect the spatial pattern of a dominant shrub in a semi-arid scrubland: a prospective approach

Dispersal, physical conditions and biotic interactions contribute to determine the spatial distribution of individuals in plant populations. Much of what we know has been learned from studies that retrospectively posit mechanisms presumed to have generated the observed spatial patterns. Here we present a prospective approach. We start by measuring spatial demographic effects and evaluate if they can generate observed spatial patterns. We evaluated the influence of interactions among conspecifics on vital rates, demography and spatial distribution of Croton aff. wagneri, a dominant shrub in dry Andean ecosystems. Recruitment, survival and growth varied in relation with distance to conspecifics neighbors and with their summed cover. We built a spatial individual-based model and simulated its population dynamics in 30 × 30 m plots for a 30 year periods. We compared the predicted spatial pattern from these demographic models with that observed among plants in sixteen independent plots with ...