Assessment of the distribution and recent spread of the invasive grass Cortaderia selloana in Industrial Sites in Galicia, NW Spain

Abstract

In the autonomous community of Galicia (NW Spain) many Industrial Sites (ISs) were built mainly during the 1990s and 2000s to promote industrial activity in the region. ISs face different environmental issues, including a high frequency of opportunistic alien invasive species. In this research, we studied the patterns of occurrence and recent invasion in ISs of Cortaderia selloana, a perennial alien grass that has become one of the most aggressive invasive species in southern Europe. We used the online tool Google Street View (GSV), combined with field work, as a surveillance method for monitoring the recent spread of the invader. C. selloana occurs in over half of the ISs in Galicia. Closeness to the nearest invaded IS and low elevations were the two main explanatory factors of species occurrence and intensity of the invasion. Statistically significant differences of invaded ISs were also observed for closeness to the nearest highway, closeness to the coast, higher population density, higher area of occupancy of the IS and higher mean and minimum temperatures. Results from field surveys were consistent with those from GSV. Recorded temporal changes showed that new invasions are taking place at a regular rate of 1.86 new invaded IS each year during the period 2012-2018. We discuss the reliability of GSV as a tool for monitoring plant invasions in roadsides with low costs.