A ruderal species is a plant species that is first to colonize disturbed lands. The disturbance may be natural (e.g., wildfires or avalanches), or due to human influence – constructional (e.g., road construction, building construction, or mining), or agricultural (e.g., abandoned farming fields or abandoned irrigation ditches).
Ruderal species typically dominate the disturbed area for a few years, gradually losing the competition to other native species. However, in extreme disturbance circumstances, such as when the natural topsoil is covered with a foreign substance, a single-species ruderal community may become permanently established, as depicted in the image on the right. In addition, some ruderal invasive species may have such a competitive advantage over the natural species that they, too, may permanently prevent a disturbed area from returning to its original state despite natural topsoil.
Features contributing to a species' success as ruderal are: