Vegetation changes and sequential flowering after rain in the southern Atacama Desert

We describe the changes in plant cover, species richness, and flowering aft er rainfall over an entire growing season (September 1989-January 1990) in a southern Atacama Desert site in Chile. One month after the rain, vegetati on was dominated by annuals and geophytes which dried out after 19 weeks. A mong all species, including shrubs, we found differences of 4-10 weeks in t he length and peak of the flowering period. The flowering sequence of the s pecies belonging to the families Brassicaceae, Liliaceae, Onagraceae, and A steraceae matched closely the sequences described for temperate plant commu nities, suggesting that this phenological character is phylogenetically det ermined. (C) 1999 Academic Press.