Abstract
Invasive species represent a threat to many ecosystems but are nearly absent from arctic and subarctic Canada. The subarctic town of Churchill, Manitoba, has an unusually high number of invasive species due to the presence of a grain port and railway, but few of these species have spread to the surrounding tundra. I am attempting to understand why one of these species, common dandelion (Taraxacum officinale), currently is restricted to town, focusing on the tendency of buildings to provide shelter and, thus, allowing it to persist. I surveyed the distribution of T. officinale and a native congener, T. lacerum, relative to existing structures. My results show that T. officinale's distribution is influenced by the availability of human-created microclimate more than that of T. lacerum. These results suggest T. officinale may spread beyond these refuges as the climate continues to warm.