Biodiversity is critical for essential ecosystem functions and services to humans. If each species in a community is slightly better at obtaining a particular resource (e.g. acquiring nutrients vs. obtaining pollinator visits), then changes in the abiotic and biotic environment as a result of climate change could disturb the balance between interspecific and intraspecific competition. This may potentially cause some species to drive others extinct. For example, warming temperatures are causing some flowering species to emerge and reproduce earlier in the season, while others are flowering later. If species in a community respond unequally to the same environmental cues, populations might experience higher or lower levels of interspecific competition for shared resources than in the past, which could upset the balance of competition essential for coexistence. I am using experiments and observational data to examine the relationship between flowering phenology and plant-plant interactions for pollinators in a spring ephemeral system.
In the Duke Forest (Durham, NC), Claytonia virginica and Thalictrum thalictroides co-flower, although the degree of flowering overlap each year is variable. During a cooler year, flowering overlap between these two species was higher than in a warm year (2015: cool, 2016: warm). In 2016, I identified individual pollinators visiting C. virginica and T. thalictroides. Bombylius major visits both C. virginica and T. thalictroides, signifying potential for competition or facilitation between these two species for pollinator resources. Furthermore, when C. virginica is present locally, the average visitation rate to T. thalictroides is reduced, although not significantly. These preliminary results suggest that C. virginica and T. thalictroides may compete for shared pollinators. In the spring 2017, I will examine how the degree of flowering overlap correlates to competition for pollination with an experiment. These data are the first step towards a broader project aimed at understanding the ecological consequences of shifting phenologies.