Narrow anthropogenic linear corridors increase the abundance, diversity, and movement of bees in boreal forests

Abstract

Understanding how invertebrates respond to disturbance is important to maintaining biodiversity. In western Canadian boreal forests, anthropogenic linear corridors associated with energy exploration are a pervasive disturbance that affect many species. Trees and large shrubs are removed in a grid of narrow corridors, but the understory vegetation is generally maintained, mimicking early seral conditions. Little is known about how bees, an important group of pollinators, respond to linear corridors, with their response having important implications for plant-pollinator communities. Here, we investigated how bee abundance, diversity, species composition, and movement respond to these anthropogenic linear corridors, locally known as seismic lines. We compared bee abundance and diversity from pan traps on seismic lines (6 – 12 m wide) to traps placed 50 m into the adjacent forest interior, across 12 replicated sites. Malaise traps were used to measure bee movements on seismic lines relative to paired interior forests, but also with respect to flight direction relative to the orientation of seismic lines. Abundance and richness of bees were 3-times and 1.5-times higher, respectively, on seismic lines compared to the forest interior, with significant differences in species composition. Bees were more than twice as abundant and diverse in malaise traps that caught bees flying along seismic lines than any other combination of trap orientation and location. These results demonstrate that narrow anthropogenic linear corridors are locally increasing bee abundance and diversity in boreal forests, as well as use of these lines for movement. These results have major implications for boreal forest plant-pollinator communities.