Pollinator-Mediated Interactions of Foundation Plants in the Mojave Desert

Pollination facilitation is an indirect interaction whereby one plant species positively influences the reproductive success of another plant species through pollinators. First, we conducted a systematic review of the experimental pollination facilitation literature. We found that the field of pollination facilitation advanced seven mechanistic hypotheses which we synthesized into a conceptual framework to summarize the extent of mechanisms tested to date. We then tested the capacity for the dominant, foundation shrub Larrea tridentata to facilitate its annual understory. We separated blooming and non-floral interactions while incorporating the temporal dimension by tracking pollinator visitation to the understory as L. tridentata went through spring flowering phenology. L. tridentata interfered with the pollination of Malacothrix glabrata before it bloomed, and visitation was significantly reduced with blooming. L. tridentata supported plant and arthropod communities while creating locally stable microclimates demonstrating that positive and negative effects by foundation plants occur simultaneously. This project contributes to a better understanding of the underlying mechanisms driving interactions in a critically understudied arid environment.