Effect of Elevation Differences in Alpine Insect Activity on Silene Acaulis at Finse, Norway

Abstract

Global annual average temperature has increased since the industrial revolution and is predicted to continue to increase in the future resulting in altered species distributions. Alpine ecosystems are particularly vulnerable to long-term changes in climate because warmer temperatures may facilitate species migration from lower elevations that may outcompete the current species distribution. I used time-lapse cameras to investigate how flower visiting insects at Finse, Norway, respond to changes in temperature using an elevation gradient. I recorded number, duration, and taxa of insects visiting Silene acaulis. I measured floral traits to see if these changed with elevation, and if they could explain patterns in insect visits. I also collected capsules and looked for evidence of seed predation. I found that flower visiting insects were more abundant and had longer visits at higher elevations, while there was a more diverse flower visiting insect community at lower elevations. Flies represented the greatest proportion of insect visits at both elevations, with the flowers at high elevation being almost exclusively visited by flies. Butterflies were more common at lower elevations. There were no significant differences in plant traits of S. acaulis between the two elevations, and plant traits were unable to explain the pattern of insect visits. No predation of capsules or seeds was observed. There was, however, a large difference in production of capsules, with the low elevation site producing more capsules despite receiving fewer insect visits. Taken together, this suggests S. acaulis may act as an important refuge for insects in the extreme environment of high elevation alpine ecosystems.