Species colonising new environments (e.g. after clear-cutting, volcanic eruptions or fire) and starting a plant succession.
Usually referring to fast growing, soft-wooded trees that are very intolerant of shade, such as Cecropia, Ochroma, and Heliocarpus species. These are early colonizers of open areas such as landslides, forest gaps, or abandoned pastures. Also used for herbs “pioneering” on newly exposed soils.