Highways to invasion: Powerline servitudes as corridors for alien plant invasions.

Abstract

Human use of powerline servitude corridors for the secure transmission and distribution of electricity disturbs natural landscapes and changes vegetation patterns. We examined vegetation communities under two powerlines in the Limpopo province, South Africa (Khakhu line 22KV and Fundudzi 132KV powerlines). Twelve invasive alien species were identified in Khakhu and Fundudzi, dominated by Khaki bush Tagetes minuta, common guava Psidium guajava, black-jack Bidens pilosa, fierce thorn apple Datura ferox and common lantana Lantana camara. Sites closest to human settlements showed high alien species richness, whilst sites located further away were dominated by alien L. camara, but had a low overall species richness. Conversely, areas away from human settlements showed lower levels of alien invasion. Weak overlaps in the principal coordinates analysis polygons for the two powerline servitudes suggest that alien plant compositions are dissimilar, with five identified species groups being identifiable among sites, and thus a high potential for invasion success from multiple taxa. The research findings showed that powerline corridors could potentially trigger invasion success via disturbance as they act as pathways for arrival and should be a focus for management efforts to prevent further spread.