Pollinator visitation and floral resource production in Black Sand plots, 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(Forrester, unpublished data).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.