Dynamics of plant communities in the Lomas of southern Peru

A study of the floristic composition of the plant communities of the Lomas was carried out in the Coastal Range of Arequipa, Peru. Data on the seasonal and elevational variation of those communities was obtained by monthly censusing a 20-meter circle sampling stations established at 100 m intervals from 300 to 1 000 m of elevation. The 80 recorded plants belong to 60 genera and to 20 families. Dominating life forms are Therophytes and Chamaephytes. Four vegetational zones (xeric, subxeric, mesic, and submesic), are separated by significant differences in the number of plants of each zone. Considering the entire Lomas transect, no significant statistical differences among the seasons were found. The floristic relationship among the altitudinal samples was found to be a reflection of a moisture pattern. The persistence in the Lomas of a mesophytic flora could be the result of a continuous adaptation to the fogginess and reduced solar radiation of this particular zone in a desert area.This study was supported by the Universidad Nacional de San Agustin, Arequipa, Perú, and by the Universidad de Los Andes through the Consejo de Desarrollo Cientifico y Humanistico (Proycet C-142-79). Amelia Díaz de Paseual, William E. Duellman, Evaristo López, Luis Malaret, Mario Ricardi and Antonio Vivas made helpful comments and criticisms. Field trips were shared with José Dávila, Evaristo López and Alberto Nuñez. The identification of plants was checked by Ramón Ferreyra and Oscar Tovar of the Museo Javier Prado, Lima, Perú, and Alwing Gentry of the Missouri Botanical Garden. I am grateful to all these institutions and people.