A Survey of Pollinators and Pollinator Behavior on Alpine Endemic Flowers Astragalus australis var. olympicus and Campanula piperi, Olympic National Park, WA

Eyer, Kevin

Plant-pollinator mutualisms are a critical part of alpine ecosystems. Climate change may have significant effects on the dynamics of these mutualisms, particularly for flowering plants and pollinators with restricted or sensitive distributions. The intent of this study was to identify the primary pollinators of two flowering plant species endemic to the Olympic Mountains in Washington State, Astragalus australis var. olympicus and Campanula piperi, in areas where their range overlapped, and to investigate the response of these pollinators to variations in daily temperature and weather patterns. Collections and observations took place over 120 hours between 7-25-11 and 9-2-11, observations lasting from 9AM to 6PM, at two high elevation sites of similar elevation, geography and bioltic distribution. Observed pollinators were identified to genus and the number of visits recorded compared to average temperature and weather modes from on site measurements. Bee bowls were also used to collect baseline data on bee diversity but could not be used for data analysis due to apparent bias in collections. From observations, solitary bees were the predominant pollinators for both flowering plants. Mason bees (Osmia sp.) were the most typcal pollinators visiting both flowering species. Duforea sp. preferentially visited flowers from the genus Campanula. Bumblebees (Bombus sp.) were also observed visiting both flowering plants but at extremely low numbers. Quantitative results suggest that temperature and weather have significant effects on pollinator behavior. Pollinator visits were positively correlated to temperature increases with >90% of recorded pollinator visits occurring above 11 degrees C. With the exception of one outlier, pollinators did not visit endemics under adverse conditions of fog, rain, or complete cloud cover, suggesting that significant numbers of poor weather days during peak flowering may be detrimental for small, isolated populations. While current regional climate models predict drier, hotter summers, conditions more favorable for increased pollinator visits to endemics, more research into the distribution and feeding behavior of solitary bees, and continued monitoring of biodiveristy at high elevation endemic hotspots, will be crucial to the continued conservation of these endemic flowers and their mutualist partners.