Competition exerted by native plant communities is an important component of biotic resistance against the spread and impact of non-indigenous plant species in novel habitats. However, how the role of biotic resistance varies along environmental gradients to delay invasions is less clear. We conducted two feld experiments to determine how competition from native communities afects colonization of a recognized invader of grasslands, Hieracium pilosella L., in the Fuegian steppe along diferent environmental gradients at regional and landscape scale. We assessed the role of competition on invader survival and growth along a climate gradient at regional scale (4.7–6.6 °C and 270–450 mm year−1), and across four major plant communities (i.e. meadows, grasslands, scrublands, and heathlands) along a topographic catena. At regional scale, the climate gradient showed a 33% reduction in H. pilosella survival at the coldest and wettest extreme, while reduced its biomass in 41% at the warmest and driest site, in the opposite extreme of the gradient. Competition caused a 34% decrease of the invader biomass, similarly along the climate gradient. At landscape scale, the topographic gradient had a stronger efect on invader survival reaching a 67% reduction in lowland meadows due to fooding events, while competition reduced in 29–39% the invader biomass only in grasslands or scrublands with negligible efects on low-resource heathlands. These results suggest that biotic resistance plays a signifcant and similar role along the climate gradient to delay invasion at regional scale, but at landscape scale is only determinant for rich-resource communities in absence of abiotic stresses.