Control measures for a recent invasion of Hieracium pilosella in Southern Patagonian rangelands

Abstract

Plant invasions have important ecological impacts on biodiversity, the functioning of ecosystems and economic sustainability. In this study, we evaluated the effects of four control measures (pasture sown + fertiliser, fertiliser and selective ⁄ non-selective herbicide applications) in two different grazing conditions (grazed and ungrazed) during a recent invasion of the exotic herb Hieracium pilosella in northern grasslands of Tierra del Fuego Island in Southern Patagonia, Argentina. As response variables, we measured the cover of the invasive species, the dominant growth forms of other plant species, litter and bare soil at patch scales (m 2 ) during two consecutive growing seasons. The effects of fertilisation depended on the grazing conditions; H. pilosella cover decreased by more than 92% and was replaced by dicotyledonous herbs in the ungrazed ⁄ fertilised subplots, while it exhibited no decrease in the grazed ⁄ fertilised subplots after the second growing season. Both herbicides (selective and non-selective) reduced H. pilosella cover by c. 63% compared with the untreated subplots independently of grazing. However, the non-selective herbicide application resulted in an increase in bare soil and litter cover in the treated grazed and ungrazed subplots respectively. In contrast, such effects were not observed with the selective broad-leaved herbicide application. A control strategy based on the local application of selective herbicides and ⁄ or NP fertilisers, in conjunction with a transient ban on sheep grazing, reduced the invaderÕs cover in the short term and at a local scale and also reduced the cover of bare soil through the restoration of native vegetation. An economic assessment of this strategy supported the profitability of these control measures.

Botanical composition of sheep diet in two contrasting environments at Tierra del Fuego steppe (Argentina)

“…In addition, these results contribute to the state of progress of the invasive species Hieracium pilosella in the Fueguian steppe and to the knowledge of the incorporation of this species in the diet of livestock, and possibly in that of native herbivores. [61][62][63]…”

Hieracium pilosella L. – a new adventive species for the flora of the Tian Shan (Kazakhstan)

“…Объясняется это быстрым разрастанием его из-за интенсивного вегетативного размножения с помощью надземных столонов. Именно по этой причине данный вид широко распространился по всему миру за пределами своего естественного ареала -в Северную и Южную Америку, Тасманию и Новую Зеландию, куда был интродуцирован как декоративное растение или занесен с семенами сельскохозяйственных культур (Webb et al, 1988;Rudman, Goninon, 2002;Gawrońska-Grzywacz et al, 2011;Cipriotti et al, 2012;USDA-NRCS, 2016). На этих континентах и островах H. pilosella рассматривается как агрессивный инвазивный вид, наносящий урон аборигенной флоре и сельскому хозяйству (Grundy, 1989;Wilson et al, 1997;Rudman, Goninon, 2002;USDA-NRCS, 2016).…”

Guanacos’ and domestic livestock’s summer diets comparison in ecotone of “Tierra del Fuego” (Argentina)

“…Intake was observed, with low frequency, in all diets the presence of an invasive species, Hieracium pistosella, which is being studied for its degree of progress in Tierra del Fuego. 23,39,40 When comparing the diet composition to the main components analysis, according to components 1 and 2 (97% of total variability), it was observed that cows and sheep group by the HD intake frequency (Figure 3), whereas guanacos differ according to the sampling area. The guanaco diet in the EaSJ was different from the others because of the intake frequency of Gr and SG; whereas in EaBa the diet was different due to the presence of bush species; and in EaU because of the intake of MLB (Figure 3).…”