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. We built a spatial individual-based model and simulated its population dynamics for a 30 year period. We compared the predicted spatial pattern from these demographic models with that observed among plants in a plots with similar areas in different conditions.
Results/Conclusions
Recruitment, survival and growth varied in relation with distance to neighbors and with neighboring cover of conspecifics. These demography responses were dependent of environmental conditions. Our prospective approach allowed us to demonstrate that conspecific plant-plant interactions affect spatial distribution of Croton aff. wagneri. Observed and simulated patterns indicated differences among sites in maximum aggregation and location of the distances with higher aggregation. We discuss how better consideration of potentially critical seed and juvenile stages and interspecific interactions could improve our understanding of spatial pattern and recommend that these factors be considered in future models