The geography of human-mediated dispersal

Dispersal is a key process in determining the survival of plant species following habitat fragmentation and climate change, as well as driving the introduction and spread of invasive alien species in new regions. Due to its passive nature, seed dispersal is particularly complex, and the rare long-distance events relevant for plant species' responses to environmental change are a barrier to its understanding. Attempts to simplify the seed dispersal process often ignore dispersal by humans, despite the huge influence humans have over ecological systems throughout the world. In this Biodiversity Viewpoint, we describe how the movement patterns of humans and human-mediated dispersal vectors can be useful for understanding potential patterns of dispersal at multiple spatial scales. Humans and their associated dispersal vectors such as livestock and motor vehicles can disperse huge numbers of seeds of many plant species very long distances. Their relationships with the physical environment affect their movement, and therefore the movement of the seeds which they can potentially disperse. Therefore, we believe that a geographical approach can be useful at a time where understanding and managing pathways of dispersal are of direct relevance to the challenges faced by plant species and communities.