Invasion of plants in towns and roadsides around the Iguaque massif (Boyacá, Colombia)

Cities and towns can be conceptualized as invasion hotspots. The connections created by roads or highways facilitate the mobility of these species, expanding their range of distribution and contributing to their expansion through the landscape to other urban areas or nearby natural and semi-natural ecosystems. Here we describe the actual distribution of invasive plants in a region of Colombia and determine the role that urban centers, road edges, and rivers have in shaping their distribution. We mapped—at high resolution—the distribution of exotic species in the Alto Ricaurte region (Boyacá, Colombia), specifically in the towns of Villa de Leyva, Sáchica, Sutamarchán, and Arcabuco and connecting roads. Initially, a list of 40 exotic plant species with invasive potential was assembled: 26 of which were mapped in the region. Then, we used Poisson models to test whether invasive species appear more frequently near cities, roads, and riverbanks. We found that roadside and riverbank areas host more exotic species than more distant zones. Our findings suggest that roads and rivers are efficient dispersal corridors connecting different invasive hotspots with other landscape elements. Urban centers act as islands of invasion and roads and rivers as corridors for species dispersal. This invasion scenario is already causing economic and ecological damage: roads are heavily deteriorated by R. communis, K. densiflora, and C. jubata, while P. aquilinum and M. minutiflora may increase the occurrence of fires in the region.