Pollinator visitation and floral resource production in Black Sand plots for 2019

Anthropogenic climate change is altering interactions among numerous
species, including plants and pollinators. Plant-pollinator
interactions, crucial for the persistence of most plant and many
insect species, are threatened by climate change-driven phenological
shifts. Phenological mismatches between plants and their pollinators
may affect pollination services, and simulations indicated that these
mismatches may reduce floral resources available to up to 50 percent
of insect pollinator species. Although alpine plants rely heavily on
vegetative reproduction, seedling recruitment and seed dispersal are
likely to be important drivers of alpine community structure.
Similarly, advanced flowering may expose plants to increased risk of
frost damage and shifted soil moisture regimes; phenologically
advanced plants will experience these environmental factors
differently, which may alter their floral resource production. Some
species of alpine plants on the Niwot Ridge have displayed advanced
phenology under treatments of advanced snowmelt (Forrester,
unpublished data). However, little is understood about how these
differences in distribution and phenology affect floral resources,
pollinator community composition, and plant fecundity. Here we strive
to examine how changes in the timing of flowering and number of
flowers produced by plants, driven by experimental changes to climatic
conditions at individual sites impact pollinator communities. In
summer 2019, we found that plots with advanced phenology experienced
peaks in pollinator visitation rates and pollinator diversity earlier
than plots with unmanipulated snowmelt. We expect this to be because
of the advanced floral phenology of certain key species in these
plots. We did not find evidence that plants with advanced phenology
produce fewer floral resources.