This work focuses on clusters in Erica arborea L in western Algeria. To understand the floristic diversity of groups in Erica arborea. A floristic analysis was carried out based on floristic surveys on three regions in western Algeria according to an aridity gradient. This allowed us initially to count 100 species belonging to 75 genera and 40 families, which are predominated by asteraceae and lamiaceae with 08% of each family, Mediterranean elements dominate the biogeographical type with a percentage of 43% followed by the western Mediterranean elements. Therophytes predominate the biological spectrum of this flora with 39% followed by chamephytes with 28%. The abundance analysis shows the predominance of common elements with more than 83% of the flora, 12% of rare elements and 4% quite rare. Three morphological forms predominated by perennial woody. The Shannon (H) biodiversity index was between 2.99 and 3.37, while the Simpson index was between 0.91 and 0.95, and the Piélou equitability situated from 0.86 to 0.89. Whereas the disturbance index (DI) varied between 53 and 71% . These results show the anthropogenic pressure exerted on this ecosystem due to human activities and climate change, which requires the development of emergency restoration and conservation plans.
