Regional Suitability Assessment for the Mouseear Hawkweed (Hieracium pilosella) Invasion in Patagonian Rangelands

Abstract

Several studies have been carried out to evaluate the main drivers behind biological invasions and their ecological consequences. Nevertheless, it is still extremely difficult to acquire a full understanding of the invasion process due to its high level of complexity. The problems that complicate invasion studies are low detection during the early stages of invasion, and the high survey cost of working over large, inaccessible, and rugged areas. The studies that develop efficient tools to reduce costs and time will help to control or mitigate the invaders' damaging effects. Hieracium pilosella is an aggressive invader of grasslands worldwide. The aim of this work was to conduct a regional assessment for the suitability of H. pilosella invasion in the Fuegian Steppe by combining field surveys, spatial modeling, and geographic information system tools. We recorded the invader cover in 167 sample sites and we determined the relationship between environmental variables and the probability of invasion. This was carried out by the selection of alternative generalized linear models. The best model indicates that disturbance and plant community were the main drivers to predict invasion suitability on a regional scale. Therefore, these two variables were used as main inputs to construct a regional invasion suitability map, which identifies the most critical areas for prevention, control, and further monitoring. This approach corresponds to a tool that permits us to evaluate the suitability of invasion even over large and inaccessible areas. The results especially warn about soil disturbance associated with usual management practices in Fuegian rangelands.