Final answer:
Small and short-lived plants that colonize disturbed sites quickly are classified as R species. They exhibit rapid growth and reproduction, adapting to unpredictable environments and initiating ecological succession by improving soil conditions for other species to follow.
Step-by-step explanation:
The small and short-lived plants that rapidly colonize disturbed sites are classified by J. Phillip Grime as R species. These plants, sometimes known as pioneer species, are notable for their ability to quickly grow and reproduce in changing or unpredictable environments. The term R species comes from their reproductive strategy, which is characterized by producing a large number of small offspring, ensuring that some will survive in various conditions. Examples of R species include plants like dandelions, which produce wind-dispersed seeds. This category must not be confused with other strategies such as C, S or X species, which describe different survival and reproductive strategies in ecology.
Ferns are an example of a pioneer species that can colonize poor soils and grow rapidly, often replacing other plant forms in the landscape. The pioneer species play a crucial role in ecological succession, improving soil quality and paving the way for subsequent plant communities, including mosses, grasses, shrubs, and eventually forests.