Global climate change induced shifts in abiotic resources may affect plant-pollinator mutualisms

Background/Question/Methods

Rising temperatures and earlier snowpack melting due to climate change have been linked to alterations in the distribution, phenology, growth, and reproduction of many plants and animals. As individual species respond differently to climate change, ecological relationships, such as those between plants and pollinators, may be disrupted. Warmer springs and earlier snowpack melting are likely to alter the timing of plant reproduction (i.e. phenology) and also influence water availability in the soil during the growing season. I am investigating the potential effects of climate change on plant-pollinator mutualisms, as mediated by (I) plant responses to water availability and (II) phenological responses to temperature. My initial research focuses on the impacts of water availability on the pollination and subsequent reproductive success of the tall fringed bluebell, Mertensia ciliata (Boraginaceae). In 2012, I began a multi-year water manipulation experiment with a natural M. ciliata population (3000 m. a.s.l.) using a randomized block design with high, medium, and control/low water treatments. I measured plant and floral traits, pollinator visitation, and seed set.

Results/Conclusions

In 2012 flowering by M. ciliata was contingent on water availability, with flowering of plants in the water-added plots but not in the control plots (contingency analysis: water vs. no water). In addition, plants in the high water treatment began to flower 10 days earlier and produced more flowers than those in the medium water treatment. Plant growth (height and leaf count) did not vary significantly among water treatments. Flowering was extremely low in all treatments, which may be explained by the record early snowmelt in mid-April in 2012. Continuation of this experiment into multiple years is allowing assessment of how water-mediated changes in flowering influence the rate of pollinator visitation.