COS 230-3 - Experimental advancement of snowmelt timing influences flowering phenology and insect visitation to mid-season flowering plants in an alpine ecosystem

Thursday, August 10, 2023

8:30 AM – 8:45 AM PDT

Location: B118

Presenting Author(s)

AR

Annika Rose-Person

PhD Candidate
University of California, Riverside
Riverside, California, United States

Coauthor(s)

MS

Marko J. Spasojevic

Assistant Professor
University of California, Riverside
Riverside, CA, United States
CF

Chiara Forrester, PhD

Department of Ecology and Evolutionary Biology, University of Colorado Boulder, United States
WB

William Bowman, PhD

Department of Ecology and Evolutionary Biology, University of Colorado Boulder, United States
KS

Katharine Suding

Professor
University of Colorado
MO

Meagan Oldfather, PhD

Department of Ecology and Evolutionary Biology, University of Colorado Boulder, United States
NR

Nicole E. Rafferty, PhD

Assistant Professor
University of California, Riverside, California, United States

Abstract: Anthropogenic climate change is altering interactions among species, including plants and pollinators. Plant-pollinator interactions, crucial for the persistence of most plant and many insect species, may be threatened by climate change-driven phenological shifts. In alpine ecosystems, phenological shifts in plants and insect pollinators may be driven by advanced snowmelt, which may in turn may be influenced by landscape topography. Although many alpine plants have reproductive assurance in the form of clonality, adaptation and long-term persistence likely rely on pollination services. Here we ask how experimentally induced changes in snowmelt timing interact with topography to impact the timing of flowering and plant-pollinator interactions at the Niwot Ridge Long Term Ecological Research site.

To determine if pollinator visitation rate and species richness differ between plants in early snowmelt and control plots, we performed pollinator observations on all flowering plants in plots where snowmelt timing was experimentally advanced using inert black sand and in paired plots with unmanipulated snowmelt timing. In total, we used pollinator observations from 32 plots with diverse topographies across three sites. We found that mid-season and late-season flowering species experienced an advancement in flowering phenology with advanced snowmelt timing (p< 0.01). Using piecewise structural equation models, we then assessed the interactive effect of topography and black sand treatment on snowmelt timing, floral phenology, floral abundance, and insect visitation to flowers. We found that in unmanipulated plots topography, the timing of snowmelt, flowering phenology, and floral abundance interact to predict the total abundance of insect visitors (p< 0.05). However, in plots with experimentally advanced snowmelt timing there were no significant predictors of total insect visitation to a plot. Further, the duration of flowering had a significant effect on the timing of insect visitation. This indicates that novel predictors are needed to understand the processes that shape insect visitation to flowers under novel climate conditions. Our findings elucidate the effects of early snowmelt on the plant and insect mutualists, as well as their interactions, of this alpine tundra ecosystem. Importantly, we demonstrate that advanced snowmelt alters which environmental drivers predict plant-pollinator interactions. Additionally, this study highlights the importance of landscape topography as a predictor of the impacts of climate change on plant-pollinator interactions.