Flower visitation and seed set in Melampyrum; Effects of elevation and Rubus idaeus

Abstract

Insect pollination is an important contribution to wild ecosystems in Norway and 80 % of plants seem to benefit from this important ecosystem service. During the last century, there has been an overall decline in pollinators, and climate change is one of the possible explanations to this trend. How will Norwegian plant-pollinator communities respond to climate change? By using a space for time substitute, I have observed pollinator visitation along an elevation gradient to see if the flower visitation rate to and pollinator community of the focal plants Melampyrum pratense and Melampyrum sylvaticum change under different climate conditions. I found no change in flower visitation rate or pollinator community, suggesting that climate change might not have that much impact on the future pollinator community around M. sylvaticum and M. pratense. One explanation could be the robustness of this plant-pollinator interaction, as both the pollinators and the plants are already adapted to unstable weather conditions and otherwise harsh enviroment. In addition I studied if elevation and flower visitation rate had an effect on seed set, and found a higher number of seeds per capsules at higher elevations and further that bumblebee visitation lead to higher seed set than fly visitation, suggesting that bumblebees are better pollinators then flies. I also looked at the magnet species effect of Rubus idaeus to see if the attractive flowers of R. idaeus might fascilitate or compete with M. sylvaticum and M. pratense when it comes to flower visitors and whether this could be reflected in seed set. The flower visitation rate did not change, but the seed set (and number of seeds per capsule) of M. sylvaticum and M. pratense increased when growing in proximity to R. idaeus.