Founder control and coexistence in a simple model of asymmetric competition for light

Size asymmetry in plant light acquisition complicates predictions of competitive outcomes in light-limited communities. We present a mathematically tractable model of asymmetric competition for light and discuss its implications for predicting outcomes of competition during establishment in two-, three-, and many-species communities. In contrast to the resource-reduction model of symmetric competition for a single resource, the model we present predicts that outcomes of asymmetric competition for light will sometimes depend on the timing of establishment and the consequent hierarchy among species in canopy position. Competitive outcomes in the model depend on the minimum light requirements (L_c) and self-shading of species lower in the canopy compared to the light available (L_out^*) beneath species higher in the canopy. Succession progresses towards species with decreasing values for L_c, but arrested successions occur when initial dominants have relatively high values for L_c but low values for L_out^*, leading to founder control. A theoretically limitless number of species may coexist in competition for light when dominance is founder controlled. These model predictions have implications for an array of applied ecological questions, including methods to control invasive species in light-limited restored ecosystems.